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Medical Geology Studies in South America

  • Bernardino R. FigueiredoEmail author
  • Marta I. Litter
  • Cássio R. Silva
  • Nelly Mañay
  • Sandra C. Londono
  • Ana Maria Rojas
  • Cristina Garzón
  • Tommaso Tosiani
  • Gabriela M. Di Giulio
  • Eduardo M. De Capitani
  • José Ângelo S. A. Dos Anjos
  • Rômulo S. Angélica
  • Maria Celeste Morita
  • Mônica M.B. Paoliello
  • Fernanda G. Cunha
  • Alice M. Sakuma
  • Otávio A. Licht
Chapter
Part of the International Year of Planet Earth book series (IYPE)

Abstract

“Earth and Health” or medical geology has been promoted worldwide as one of the fundamental themes of the International Year of Planet Earth (2007–2009). This was in response to relevant achievements noted in this new field of applied science from the time of the IGCP 454 project which led to foundation of the International Medical Geology Association (IMGA) in 2004. In association with international movements, several academic, professional, and student groups in South America began to study medical geology which started with scientific meetings held in Chile, Brazil, and Uruguay in 2002 and 2003. In this chapter, an attempt is made to describe South American scientists’ relevant contributions to various subjects such as arsenic, lead, mercury, and selenium as well as fluorine and environmental problems affecting different parts of the continent. Some societal issues arising from medical geology studies are also highlighted from the point of view of the international risk communication and risk governance debate and the pioneering ethnographic descriptions of geophagy in the Andean and Amazonian countries. Finally, some ongoing medical geology projects in South America are identified as inspiring initiatives that may encourage future educational and research activities in this science field.

Keywords

South America Brazil Colombia Uruguay Argentina Metals Arsenic Lead Selenium Mercury Risk communication Geophagy 

Historical Background and Scope of Medical Geology Studies

Medical geology has been recognized worldwide as a promising scientific field in which geosciences, environmental medicine, and other disciplines contribute together in attempting to test relationships between natural geological factors and the health of humans and of other living beings. Not coincidently, medical geology was included as one of the ten main themes of the International Year of Planet Earth under the title “Earth and Health – for a safer environment.” Under the coordination of IUGS and UNESCO, the International Year was conceived to show the general public how earth sciences are contributing to society’s well-being by making the world safer and healthier. Many initiatives and an extraordinary number of scientific activities were undertaken in the current decade to disseminate concepts and methods adapted to this new area of applied science. In South America the first short course on medical geology was held in Santiago in 2002 followed by the first workshops dedicated to the subject in Brazil, Uruguay, and Argentina from 2003 to 2007. Since then, South American professionals have made a modest but significant scientific contribution to this field. As an example, the first book on medical geology (in Portuguese) was published in 2006, only a year after “Essentials of Medical Geology” (Selinus et al., 2005) appeared. It is well known that other textbooks and an impressive number of papers were published in all continents during this period, showing that medical geology is already a consolidated international science.

Taking this historical background into account, it is easy to see that everything has happened very quickly for medical geology all around the world. South America is not an exception in this regard and, as in other parts of world, compiling medical geology accomplishments in the continent is not an easy task.

This chapter presents the first attempt to report recent and ongoing medical geology studies in South America and is far from being complete and should therefore be regarded as a partial inventory. Its aim is to motivate reflection among academics, professionals, and students on what is going on in some countries. The present monograph may stimulate updating efforts in the near future and hopefully it will inspire other researchers to further pursue the scientific lines described here. In South America there are around 400 million people interested in how medical geology can contribute to improve their standard of living without compromising the environment and save resources by pointing out the beneficial properties of rocks and minerals; by preventing adverse health effects for humans, animals, and plants; and by protecting those in need of more protection.

The presence of metals and other substances in South America is addressed and available information on human exposure and health effects is provided in this chapter. Additionally, some societal issues arising from medical geology studies are also highlighted from the point of view of the international debate on risk governance as well as from the pioneering ethnographic descriptions of geophagy in the Andean and Amazonian countries. Finally, some ongoing medical geology projects in South America are identified as inspiring initiatives that may encourage future educational and research activities in this science field.

In the following sections, the distribution of arsenic, lead, and mercury in South America is identified according to recently published reports. For a long time these substances have been considered the most dangerous toxic substances for humans (ATSDR – CERCLA, 2003). They are widely dispersed in the environment and may be as much a threat to human health as some agrochemicals and radioactive substances. These reported case studies were carried out in Argentina, Chile, Brazil, and Uruguay.

Arsenic in South America

Water contamination from arsenic is a worldwide problem when considering the number of regions where arsenic-contaminated surface water and groundwater are being consumed by the people. This problem is estimated to affect more than 100 million people worldwide.

Long-term ingestion of water with high concentrations of arsenic can lead to a disease known as chronic endemic regional hydro-arsenicism, highly prevalent in Asia and Latin America. Keratosis, hyperkeratosis, damage to the central nervous system and lever, loss of hair, incidence of different types of cancer such as skin cancer and cancer of internal organs (lung, kidney, and bladder) are epidemiological evidence of exposure to inorganic arsenic. There is not yet a medical treatment for hydro-arsenicism; hence, prevention and attenuation of human exposure to arsenic is the only way to solve the problem.

The presence of arsenic in water and soil comes from anthropogenic causes (mining, metal smelting and refining, use of pesticides, etc.) as well as natural processes. Arsenic can be mobilized from rocks and soils toward water bodies through biogeochemical processes, changes in pH, volcanism, and microbiological action (Mansilla and Cornejo, 2002).

The World Health Organization recommends the limit of 10 μg/L As for drinking water (WHO, 2004). Considering this limit, around 14 million people in Latin America are exposed to prolonged consumption of arsenic-contaminated water and threatened by serious health problems. Potentially dangerous situations in South America have been known for decades, especially in Argentina, Chile, and Peru. However, governmental intervention intended to solve this problem has not been effective and does not exist in many isolated regions where communities do not have access to pre-treated potable water.

The most critical areas of Latin America concerning arsenic contamination of surface water and groundwater are depicted in Fig. 1. Estimated population exposure for different countries in relation to the former limit of 50 μg/L As in drinking water is quoted, according to Bundschuh et al. (2008a) and Bundschuh et al. (2008b). In these countries arsenic is found mainly in groundwater as geogenic arsenic associated with Andean volcanism.
Fig. 1

Areas with high arsenic contents in surface water and groundwater in Latin America. 1 South Baja California, 2–9 Mexico, 10 Guerrero, 11–19 Central America, Mexico, 20–24 Bolivia, 25 Peru, 26 Atacama, Chile, 27–31 Argentina (Modified from Bundschuh et al., 2008a, b)

Considering a maximum limit of 50 μg/L As in drinking water, the exposed population in Mexico, Argentina, and Chile in relation to the total population is estimated to be 0.4, 3.0–5.1, and 3.1%, respectively. Only recently in Argentina a new regulation was introduced lowering the maximum arsenic content in drinking water to 10 μg/L (Argentina, 2007) in accordance to WHO regulations.

Argentina

In Argentina, the highest arsenic contents in groundwater are found in the Chacopampean plain, Puna, and Cuyo. However, the Patagonia region still needs to be studied in more detail. Updated information about these regions is presented below.

Chacopampean Plain

This is the largest and most populated geographic region in Argentina, covering more than 1 million square kilometers. Comprehensive information about arsenic sources, mobility, and concentration factors in shallow aquifers is not available due to the vast size of the area. However, a number of local studies point to several risk zones located in the north of La Pampa province, south and southeast of Cordoba province, Buenos Aires province, Santa Fe province, Santiago del Estero, Chaco and Salta provinces, and in the eastern portion of Tucumán province. A total population of 2 million people is estimated to be at risk of hydro-arsenicism. Besuschio et al. (1980) and Hopenhayn-Rich et al. (1996) have described several arsenic-related health problems affecting people in some parts of this region and drawn attention to an increasing prevalence of certain types of skin, bladder, digestive tract, and lung neoplasm.

Groundwater composition in the central north and southeast of La Pampa province varies. Arsenic contents range from less than 4 to 5,300 μg/L, and 99% of water samples exceed the reference value of 10 μg/L (Nicolli et al., 1997; Smedley et al., 1998, 2002, 2006).

For most sites located in southern Cordoba province, arsenic contents in groundwater fall in the narrow interval of 0–100 μg/L mainly consisting of As (V); however, at Alejo Ledesma groundwater was found to contain up to 300 μg/L As. In the province’s southeast plain, arsenic contents in groundwater vary from less than 10 to 3,810 μg/L with 46% of samples in the interval 100–316 μg/L (Nicolli et al., 1989). The highest anomalies were found in the San Justo, Marcos Juárez, Unión, Río Cuarto, Río Primero, and General San Martín departments where arsenic contents in groundwater range from 10 to 4,550 μg/L (Nicolli et al., 1985, 1989; Pinedo and Zigarán, 1998; Pérez Carrera et al., 2005).

Arsenic in water in Buenos Aires province is particularly but not exclusively related to the Pampean aquifer beneath a large area of the Pampean Plain. This aquifer is the major groundwater source for the whole region (south of the Santa Fe province: 0.13 mg/L As; Atlantic coast: 0.1–0.3 mg/L As; La Pampa province: 0.04–0.5 mg/L As). Fortunately, the northern part of Buenos Aires province is served by the Puelche aquifer with better water quality (As < 0.01 mg/L; F < 1.5 mg/L), although excess of nitrate may occasionally be caused by domestic sewers, waste disposal, or agrochemicals.

This Puelche aquifer in the western region of Santa Fe Province contains high-saline water, inappropriate for consumption. In the shallows, which contain bicarbonate-sodic water, arsenic is present at high concentrations, up to 0.78 mg/L As, along with some fluorine content (Nicolli et al., 2007a).

In Santiago del Estero province, Bhattacharya et al. (2006) determined that groundwater originated from a shallow aquifer, 12 m deep, had a mean arsenic content of 53 μg/L, and a maximum value of 14,969 μg/L As. The authors found that As (III) content in the water was 1.9–45% of total arsenic with an average of 125 μg/L As. Some phenomena such as mobilization of organic matter by excessive irrigation may alter the local physical–chemical conditions, facilitating arsenic mobility in the area.

In the Chaco province, people are affected by endemic hydro-arsenicism caused by ingestion of drinking water with high As content, with cases described as depending on genetic factors and exposure length. Specific damage was identified in patients from Resistencia, Roque Sáenz Peña, Santa Sylvina, Santa Iglesia, Charata, and other places (Web Odontológica, 2007). Water with high arsenic content (0.01–0.8 μg/L), mainly As (V), and high fluorine content led to a risk of hydro-arsenicism along with dental and skeletal fluorosis among rural and urban populations from Comandante Fernández, Independencia, Quitilipi, Maipú, Almirante Brown, General Belgrano, 9 de Julio, 25 de Mayo, 12 de Octubre, Mayor J. Fontana, and San Lorenzo (Osicka et al., 2007). According to Concha et al. (1998), in Taco Pozo, some individuals with 9.1 and 11 μg/L As detected in blood presented hydro-arsenicism from consumption of water with 200 μg/L As.

Groundwater from the Salí River basin is the most important arsenic reservoir in the eastern part of the Tucumán province, as identified by Nicolli et al. (1989), Smedley et al. (2002), and Tineo et al. (1998). Positive correlations between arsenic, fluorine, and vanadium contents in water were identified by Nicolli et al. (2001a). Arsenic and related elements (F, B, and other elements) are present in rather high amounts in quaternary loess deposit volcanic materials. High pH values (up to 9.24) in groundwater favor dissolution of volcanic glass and leaching of pyroclastic rocks, as stated by Nicolli et al. (1989). As (V) was shown to be the dominant species by Nicolli et al. (2007b), who noted as well an increase of the arsenic content predominantly in shallow waters caused by desorption phenomena. Similar arsenic concentrations were also found in this part of Tucumán province in the small basin of Burruyacú as identified by Nicolli et al. (2001, 2006).

Puna Province

The geological province of Puna, at the southern part of the Bolivian and Peruvian Altiplano, enters Argentinean territory from the Bolivia border (21°45′) down to San Buenaventura Cordillera (26°15′). Puna Alto has median altitudes exceeding 3,500 m above sea level. Prevalence of arid climate, oxidizing conditions, and high water salinity yield anomalous concentrations of certain anions such as arsenic complexes and fluoride in water. In the Pompeya and Antuco spring fields, elevated As contents were found in thermal water. Elevated arsenic concentrations in water from La Puna region were found by Farías et al. (2006). The highest As content in drinking water (up to 2,030 μg/L) was found in the locality called San Antonio de los Cobres.

Cuyo Region

Studies carried out in the southeastern part of the San Juan Province by Gómez et al. (2004) showed As concentrations greater than 150 μg/L in groundwater consumed by the 1000 rural and urban inhabitants of El Encón. In the study, arsenic contents in biological samples (hair, nail, and urine) and food samples were analyzed.

In the Mendoza province, elevated arsenic levels in water were found in the northern district of Lavalle. In the province of San Luis, arsenic contents in water exceeding 50 μg/L were recorded in the districts of Coronel Pringles, General Pedernera, and Gobernador Dupuy. In the Buena Esperanza district, arsenic contents ranging from 43 to 170 μg/L were found in water from 13 wells and from 90 to 97 μg/L As in treated water (González et al., 2003, 2004).

In the Patagonia region, data are scarce up to the present. Sandali and Diez (2004) monitored arsenic in drinking water from 27 localities in the Chubut province. In 25 of them, arsenic concentrations were below 20 μg/L, whereas contents of 30 and 50 μg/L were found at Garayalde and Camarones, respectively. Additional studies are needed in the region because the geological context suggests that higher As concentrations in water are to be expected.

Chile

In Chile, arsenic-related problems have been solved for most parts of the country but the arsenic levels found in drinking water in the north are still of great concern. This region is located between parallels 17°30' and 28°30'S (Fig. 2), 250,000 km2 in the middle of the Atacama Desert and extending from Arica to Antofagasta cities. In this region where 420 volcanoes can be seen, some still active, 35,000 km2 is made up of quaternary rocks (Cabello et al., 2007).
Fig. 2

Geographic map of northern Chile (Modified from Bundschuh et al., 2008b)

Total arsenic contents are very high in Chilean water sources such as rivers, springs, and brines, exceeding national and international standards by as much as 6–300 times. In some places, communities are at this very moment consuming water with As contents above the limit of 10 μg/L established by Chilean Regulation 409/1 in 2005 (Chile, 2005). These communities live in the middle of the largest desert in the world, where precipitation is zero and water is scarce. Surface water in this zone may contain 1,000–5,100 μg/L As and arsenic can also be found in bedrock, soil, and plants on riverbanks.

Arica and Parinacota Region

People from the rural zone of Arica have been affected by hydro-arsenicism for more than 4,500 years (Mansilla et al., 2003; Cornejo et al., 2006). Arsenic is derived from natural processes related to volcanic activity in Andean Cordillera. In Arica Province, arsenic is very common in water, soil and plants originating from minerals, and rocks transported from Cordilleran peaks by drainage.

Lluta and Azapa are two alluvium valleys that are very important for agriculture in the Arica and Parinacota region. The Lluta Valley is located only 10 km from the Peruvian border. This valley is formed by the 150 km long Lluta River that extends from the Tacora volcano to the sea, carrying water with around 200 μg/L As. In the Azapa Valley, only low arsenic concentrations in water have been observed (Cabello et al., 2007).

The 4,500-ha Camarones Valley is located 100 km south of Arica city and is crossed by the Camarones River, historically the most important water source in the region (Cornejo et al., 2006). Small local communities such as Esquiña, Illapata, Camarones, Taltape, and Huancarane with around 60 inhabitants each (Mansilla and Cornejo, 2002) were shown to be exposed to arsenic through water consumption in several different ways. People at Esquiña consume low-arsenic water from springs (Yañez et al., 2005) while people from the other communities are consuming surface water with high arsenic contents, in some cases greater than 1 mg/L As (Lara et al., 2006).

Antofagasta Region

Antofagasta is known as the mining capital of Chile and is one of the most important copper producers in the world. The region is extremely arid and Andean volcanism has been particularly intense considering the frequent volcanic eruptions and the number of geysers and thermal springs. The waters in the region altered by these phenomena have variable chemical compositions. Surface water originating in the Andean Precordillera is the main water source for human consumption and irrigation for around 3,000 people.

The Antofagasta Rivers are different in size and present variable arsenic concentrations in water ranging from 10 to 3,000 μg/L (Queirolo et al., 2000). In the Loa province (22°12' to 23°45'S; 68°20'W), however, high arsenic concentrations (100–1,900 μg/L) were found in water used in the area for human consumption and irrigation. In some rivers very high arsenic concentrations in excess of 3,000 μg/L were found by Oyarzun et al. (2004).

The Elqui Valley in the Coquimbo Region

This 9,800 km2 valley is also located in northern Chile. The river originates in the Andean peaks and in its course drains important hydrothermal alteration zones and epithermal ore deposits that contain copper, gold, and arsenic in the context of the famous El Indio mineral district. According to several recent studies (Oyarzun et al., 2004), river sediments and ancient lake sediments in the area are highly enriched with arsenic that comes not only from modern mining activity but mainly from long-term erosion processes that affected natural deposits of arsenic-bearing minerals and ores.

Brazil

Integrated studies on environmental and anthropogenic arsenic contamination have been carried out in only three areas of Brazil as seen in Fig. 3. They are (1) the Iron Quadrangle in the state of Minas Gerais, where large amounts of As have been released into drainage, soil, and the atmosphere as a result of gold mining over the last 300 years; (2) the Ribeira Valley, where As was dispersed as a byproduct of Pb–Zn mining over the last century and also as a result of weathering of natural Au-sulfide deposits located downstream from the mining area; (3) the Santana district in the Amazon region where As occurs in association with manganese ore processed locally in the last 50 years. To date, Brazil has had no reports of diffuse pollution sources (geological formations, rivers, and aquifers which extend across the region) such as those described in Argentina and Chile.
Fig. 3

Contaminated areas of arsenic in Brazil with geologic-tectonic units indicated (After Figueiredo et al., 2007)

The Iron Quadrangle

The Iron Quadrangle (in the state of Minas Gerais) has been the most famous gold-producing area in Brazil since colonial times. Arsenopyrite is commonly associated with gold ores hosted in metamorphosed banded iron formations, schist, meta-basalts, and sedimentary rocks. These terrains of the Archean and Paleoproterozoic ages are an important geochemical As anomaly in the southern portion of the San Francisco craton. During the last 300 years, most of the As-rich waste has been discarded into drainage or stored in tailing piles along river banks and until the seventies was also used for arsenic oxide production. Oliveira et al. (1979), Deschamps et al. (2002), and Deschamps and Mello (2007) have shown that soils around Iron Quadrangle gold deposits are enriched with As. The release of natural As originating from the oxidation of arsenopyrite into water was examined in situ by Borba and Figueiredo (2004) in several underground mines.

As previously mentioned, there is significant anthropogenic contribution to As pollution in the Iron Quadrangle. Arsenic contents in stream sediments (<63 μm) are at very high levels throughout the entire region and concentrations up to 4,000 mg/kg are common. On the other hand, high arsenic contents of up to 350 μg/L in surface water were only found near mines and tailing piles whereas exceptionally high As contents of up to 2,980 μg/L were observed for runoff water from some old gold mines in the region (Borba et al., 2003). In general, arsenic contents in surface water rarely exceeded the threshold of 50 μg/L established by former Brazilian regulations for non-treated water. Low As values, rarely exceeding the limit of 10 μg/L, were also found in spring water and tap water.

In 1998, human screening was carried out among school children (7–12 years) in two municipalities in the Iron Quadrangle which used arsenic content in urine as a bioindicator (Matschullat et al., 2000). The mean value of inorganic As content in urine for a population sample of 126 children was 25.7 μg/L with 20% of samples above 40 μg/L As, for which adverse health effects cannot be excluded on a long-term basis. The probable route of exposure was contact with contaminated soil and dust since As content in the domestic water supply did not exceed 10 μg/L. During the following monitoring campaigns the percentage of individuals in this class (>40 μg/L As) decreased consistently down to 3% in 2003 (Couto et al., 2007).

The Ribeira Valley

The Ribeira Valley is located in the southeastern region of Brazil (Fig. 3) extending for about 500 km in territories of the states of Parana and São Paulo.

Lead and arsenic contamination in the Ribeira River as a result of Pb–Zn ore production and smelting operations in the Upper Valley during the last century has long been demonstrated. In addition, in the Middle Valley, a number of noneconomic gold-sulfide deposits occur, forming a northeasterly geochemical anomaly, locally known as the Piririca belt (CPRM, 1982; Perrota, 1996). Most of Pb–Zn ore in the Upper Valley originated from lode ore deposits found in metamorphosed carbonate rocks and schist whereas the Piririca gold deposits are associated with metapelites and basic intrusions.

In the period 1999–2003, human exposure to arsenic was evaluated for the populations of all municipalities affected by mining and metal refining activities in the Upper Ribeira Valley and also for several resident communities in the Middle Valley (De Capitani et al., 2006). The population of Cerro Azul village, which is located far from the mining district, was chosen as a reference group. Different communities’ arsenic contents in urine as a bioindicator of recent human exposure are shown in Table 1.
Table 1

Arsenic contents in urine from various communities (children and adults) of Ribeira Valley, Brazil

Locality

No. of samples

Mean (μg/L)

Range

Cerro Azul

156

3.86

1–34.12

Serra district

175

8.90

1–62.54

Iporanga town

112

8.14

1–33.49

Pilões

49

4.63

1–68.92

Castelhanos

54

9.48

1–60.32

São Pedro

51

11.35

1–76.19

Ivaporunduva

30

10.02

1–34.57

Maria Rosa

26

2.24

1–24.34

Nhungara

22

6.98

1–36.55

Source: Sakuma (2004) and De Capitani et al. (2006)

As expected, the lowest values were obtained in control area Cerro Azul (3.60 μg/L for children, n = 73; 3.87 μg/L for adults, n = 83). The highest As contents in urine for the Upper Valley were found in Serra district, municipality of Iporanga (8.94 μg/L for children, n = 89; 8.54 μg/L for adults, n = 86). The difference in As levels between these groups was proven to be statistically significant, a finding that may be explained by the fact that the population of the Serra district is exposed to an environment that has been affected by Pb–Zn–Ag mines located in the vicinity.

In the Middle Valley, weathering of mineralized rocks gave rise to soils with high arsenic contents of up to 764 mg/kg As (Abreu and Figueiredo, 2004). In this area, stream sediments with as much as 355 mg/kg As (Toujague, 1999) can be found in contrast with low arsenic concentrations in surface water that do not exceed 10 μg/L according to Takamori and Figueiredo (2002).

Arsenic contents in urine were also low for this area (Table 1). However, the communities with highest As levels in urine are those living near Piririca belt. The difference between As levels in urine obtained at the Castelhanos, Ivaporunduva, and São Pedro localities and that from the control area in Cerro Azul is statistically significant and indicates that the quality of the environment is an important determining factor for human As exposure level. For Castelhanos and São Pedro only 3.4 and 11.8% of urine samples yielded arsenic concentrations greater than 40 μg/L, respectively (De Capitani et al., 2006).

The Santana District

The Santana district is located on the margin of Amazon River, in the state of Amapa. Arsenic dispersion originated from beneficiation of arsenopyrite-bearing manganese ore of the Precambrian Serra do Navio deposit that has been mined for more than 50 years. At Santana wastes contain up to 1,700 mg/kg As and some wells close to the facility were shown to contain extremely high As contents, as much as 2,000 μg/L.

Several studies were carried out in the area when arsenic hazards were revealed and these included surface and groundwater, stream sediment, soil, ore, and waste (Lima, 2003; Santos et al., 2003). Arsenic concentration in surface water was found to range from 5 to 231 μg/L, but most of the As values fell below 50 or even below 10 μg/L and they did not exceed 0.5 μg/L in residential tap water. Stream sediments and suspended particulate were particularly rich for arsenic, yielding maximum values of 1,600 and 696 mg/kg As, respectively.

Arsenic content in hair was determined in a sampling population of 512 people of a total population of around 2,000 residents at Santana. According to Santos et al. (2003), As mean value in hair was 0.2 μg/g with maximum concentrations lower than 2 μg/g As. According to Choucair and Ajax (1988) and Franzblau and Lilis (1989), As concentrations in hair and nails of 1 μg/g or less should be considered to be normal, which was also defined by ATSDR (2000).

These results suggest low human exposure to arsenic at Santana, which is rather consistent with ingestion of low-arsenic drinking water and with restricted contact of humans with poisoned soil and sediments.

These recurrent observations of low exposure levels for arsenic and low arsenic contents in natural water in different places in Brazil were interpreted by Figueiredo et al. (2007) in terms of relative immobility of arsenic in soil and derived sediments under the influence of strong, chemical weathering processes of tropical and sub-tropical regions. In addition, they observed that the communities investigated were less dependent on groundwater consumption and mostly made domestic use of treated surface water. Nevertheless, periodic health monitoring of these communities and periodic assessment of the environment were recommended to assure that the risk remains under control.

Additional Arsenic Cases in Brazil

Other point-source contaminated areas for arsenic are known in Brazil. Also related to gold mining, arsenic occurs in several places such as northern Bahia, Goiás, and northern Minas Gerais states, but no human monitoring has been reported for these places. Coal formations in southern Brazil are known to contain significant concentrations of sulfur and arsenic. A very preliminary hydrogeochemical study carried out in 21 wells yielded very low arsenic contents in groundwater from the Rio Bonito aquifer in the state of Paraná. This aquifer is located in coal-bearing formations that extend southward to the states of Santa Catarina and Rio Grande do Sul.

In Brazil 50% of municipalities are known to have some degree of dependence on groundwater usage for agriculture, industry, and domestic use. However, analytical data for arsenic are still very scarce for groundwater in Brazil. To date the arsenic content of major Brazilian aquifers remains unknown and any probable non-point-source contaminated areas for arsenic such as those previously identified in Argentina and Chile have never been revealed in Brazil.

Lead in South America

Lead has long been listed among the three most hazardous metals worldwide. Beyond recycled lead, which accounts for 50% of consumption, a significant amount of lead, around 3.4 million tons (estimation for 2006 from the Mineral Commodity Summaries, US Geological Survey), is still being mined and released into the environment as metallic lead and chemical compounds. Lead is used in the manufacture of automobile and industrial batteries (70%), paint pigment (12%), alloys, welding, gasoline additives, and pesticides as well as being part of domestic and industrial waste.

Chronic or acute exposure to lead can affect the human central nervous system and may cause several adverse effects on human health, e.g., anemia, gastric irritation, kidney, liver, and heart dysfunctions, and brain damage and mental retardation, especially among children. Since the main human intoxication route is through contact with polluted soil and dust, small children are the most exposed population group. Nevertheless, exposure of workers in mines, smelting plants, and other workplaces and contamination by inhalation of gases or aerosols or ingestion of lead enriched food should also be considered.

Average concentrations of lead in the Earth’s crust and soils are in the range of 5–20 ppm according to data compiled by Smith and Huyck (1999). According to Brazilian regulations, lead concentrations may not exceed 10 μg/L in surface water (CONAMA, 2005). Intervention values of 350 μg/g Pb and 200 μg/g Pb for soil in residential and agriculture areas, respectively, are defended by CETESB (2005). In relation to air quality, the upper limit of 1.5 μg/m3 Pb has been established by USEPA.

Lead-contaminated sites and regions are known in a number of South American countries. In 2007 the Blacksmith Institute (Green Cross of Switzerland) included the La Oroya Pb-mine in Peru in the list of the ten most contaminated areas in the world. However, integrated environmental–human exposure studies have so far been carried out in few areas.

Uruguay

Major sources of lead contamination in Uruguay are similar to those in other developing countries: metallurgical industries, lead-acid battery processing, lead wire and pipe factories, metal foundries, metal recyclers, leaded gasoline (phased out in December 2003 in Uruguay), lead water pipes in old houses, scrap and smelter solid wastes, and others. Non-occupational lead exposure usually results from living in or near current or former manufacturing areas or improper handling of lead-containing materials or solid wastes (a particularly important health risk for children).

Lead Contamination in Montevideo (La Teja)

The case of the neighborhood of La Teja, in Montevideo, Uruguay, arose in 2001 (Fig. 4). There, several families were exposed to lead from foundries of metallurgical companies that had shuttered in the last decades for economic reasons. The worst situation was identified in the slum settlements of La Teja and other areas where more than 3,000 μg/g Pb in soil was found (Mañay et al., 2003, 2008). In response to the strong mobilization of La Teja community demanding solutions, the Health Ministry established an interinstitutional and multidisciplinary committee to handle the situation. This committee included delegates from health, environmental, labor, education, and social security institutions as well as community organizations. The University of the Republic was partially responsible for technical support and for carrying out an ambitious human monitoring program for lead that has made more than 14,000 blood tests for lead available to date.
Fig. 4

Lead-contaminated site at La Teja in Montevideo, Uruguay

According to Alvarez et al. (2003a), the Toxicology Department of the Faculty of Chemistry performed 10,131 lead analyses on blood samples as a community and advisory service during the years 2001 and 2002. These samples were collected from 5,848 children and 1,268 adults; for 3,015 samples age was not specified. The analytical results are presented in Table 2. The average BLL found for children was 12.3 μg/dL and 60% of the values exceeded the 10 μg/dL limit (CDC, 1991). Since 2001, children with BLL higher than 20 μg/dL have received public health and/or medical assistance at the Chemical Pollutant Medical Care Center of the Pereira Rossell Hospital consisting of supplementing iron intake and improved nutrition. Mothers were oriented toward hygiene and diet practices and how to reduce lead absorption. Alvarez et al. (2003b) reported follow-up testing on 387 of these children. The results of these tests statistically demonstrated that BLLs have significantly decreased with the medical interventions that have been adopted.
Table 2

Average blood lead levels (BLL) from three population groups in Uruguay

 

Children

Adults

Known exposed adults

BLL (μg/dL)

12.3

14.6

37.1

Reference value (μg/dL)

10

25

30

Percentage above reference value

>60

13

9

Source: Mañay et al. (2006) adapted from Alvarez et al. (2003a)

Also since 2001, soil samples from several slum settlements undergoing environmental intervention have been analyzed for lead by the city of Montevideo in coordination with the Ministerial Division of Environment. The authors (IMM, 2003) attempted to assess possible sources of lead pollution and identified the primary pollution sources as local smelters and metallurgical factories, disposal of industrial wastes in landfills, battery recycling, burning wire for copper recovery, and vehicular traffic emissions. They concluded that soil is the secondary major source of human lead exposure but lead-based paint and lead residues in water from lead pipelines were also recognized as potential sources of lead exposure.

The high-quality data assembled on lead pollution in Uruguay between 2001 and 2004 enabled effective identification of lead pollution and facilitated official intervention to prevent new pollution events. Nevertheless, full research studies must still be done, including both environmental monitoring of soil, air, and water as well as extensive screening of BLL directed to some population groups. Future health and environmental actions are needed, not only to implement remediation strategies in some regions, but also to assess other sources of lead hazards.

Lead from Gasoline in Uruguay

In 2004, after lead in gasoline had been finally phased out, three population groups were sampled for the purpose of evaluating probable changes in blood lead levels of Uruguayan populations in a 10-year period (1994–2004) considering the current actions to prevent lead exposure risks. Those groups were children (n = 180), non-occupationally exposed adults (n = 708), and workers (n = 81). Besides blood lead level (BLL) correlation, variables such as age, sex, area of residence, environmental lead data, and others were considered. Mañay et al. (2006) compared the results with those from a similar screening study done 10 years before to assess the current risk factors with a statistical approach.

In 2004 the BLL for children (5.7 μg/dL) and adults (5.5 μg/dL) were significantly lower than those obtained in 1994 (9.9 μg/dL and 9.1 μg/dL, respectively) with p < 0.001.

Spot samples of gasoline were also analyzed after leaded gasoline was officially phased out in December 2003 and during the following months. Lead concentrations varied widely during 2004. Exposed gas station workers showed no significant BLL differences between 1994 and 2004 (49 and 42 μg/dL), although they exceeded reference values.

These results indicate the necessity for Uruguay to implement a more complete official surveillance screening program.

Brazil

Many areas in Brazil have been identified as being contaminated by lead in previous studies in both urban and rural areas. But integrated geochemical and human exposure studies have only been reported for three areas in Brazil: (i) Santo Amaro da Purificação in the state of Bahia, which lies in the northeastern region; (ii) Adrianópolis in the state of Paraná, in the southern region; and (iii) Bauru in the state of São Paulo, in the southeastern region.

Lead Contamination in Santo Amaro da Purificação

In the suburbs of this city (50,000 inhabitants), the ruins of the Plumbum smelter that operated from 1960 to 1993 can still be seen, surrounded by an extensive lead-contaminated area that was left behind (Fig. 5). The processed lead ore and concentrate were partially extracted from the Boquira mine, 700 km far from Santo Amaro, as well as imported from other countries. Dos Anjos (2003) reported contaminated soil in the vicinity of the facility with high metal contents of up to 8,200 μg/g Pb and 117 μg/g Cd.
Fig. 5

Ruins of the Plumbum smelter plant in Santo Amaro da Purificação, state of Bahia, Brazil (location map of Todos os Santos Bay and Salvador city)

An unfortunate situation well known in the city was that a large volume of slag and other harmful materials was donated by the company to pave the streets as well as to be used as landfill in the backyards of some houses in past decades.

Several studies carried out since 1980 have shown elevated lead contents in surface water, edible mollusks, cattle, and greens. Because of the size of population, the extension of lead and cadmium dispersion in the city, and the very high levels of human exposure at the time the facility was active, Santo Amaro is considered the most serious case of lead contamination ever described in Brazil.

Three human monitoring campaigns carried out among children in the period 1980–1998 yielded the mean BLL shown in Table 3. Regardless of sample population size, the decreasing lead exposure levels may reflect the shutdown of the facility and the effects of several environmental and sanitary actions implemented in the area since the results of initial studies in Santo Amaro were disclosed.
Table 3

Blood lead concentrations in children from Santo Amaro da Purificação, state of Bahia, Brazil

 

1980

1985

1998

Age

1–9

1–4

1–4

N

555

53

47

Mean BLL (μg/dL)

59.1 ± 25.0

36.9 ± 22.9

17.1 ± 7.3

BLL > 20 μg/dL

32%

  

Source: Carvalho et al. (2003)

Lead Contamination in Adrianópolis

Adrianópolis is located in the state of Paraná and until recently was the most important site of lead–zinc mining in the Ribeira Valley, southeastern Brazil. During much of the last century, several mines were in production in the region leading to widespread metal contamination in the Ribeira River basin, as identified in previous studies. More recently, additional geochemical and toxicological studies were carried out in the Upper Ribeira Valley and reported by Paoliello et al. (2002, 2003), Paoliello and De Capitani (2005), and Cunha et al. (2005). They clearly showed that sites with the most impact were the villages Vila Mota and Capelinha, in the vicinity of the Plumbum smelter and the Panelas mine both located not far from Adrianópolis center (Fig. 6). The Plumbum industry was in production from 1945 to 1995 when it was shut down probably for financial and technological reasons.
Fig. 6

Ruins of the Plumbum smelter in Adrianópolis and location map of the Ribeira Valley

Among all screened groups, the highest mean blood lead levels among children were found in these two villages and the results are shown in Table 4. Human monitoring among adults yielded quite similar results with a mean BLL of 8.80 μg/dL (n = 101).
Table 4

Blood lead levels of children from Adrianópolis and from Bauru city, Brazil

 

Adrianópolis (2001)

Bauru (2002)

Age

7–14

0–12

n

94

850

Mean BLL (μg/dL)

11.89

7.3

BLL > 10 μg/dL

59.6%

36.6%

BLL > 20 μg/dL

12.8%

8.05%

Source: Paoliello et al. (2002, 2003), Cunha et al. (2005), Freitas et al. (2007)

High lead concentrations in soil were found in the surrounding industrial areas by Cunha et al. (2005) with a maximum of 916 μg/g Pb in surface and vegetable garden soils from Vila Mota. Subsequently, Lamoglia et al. (2006) found lead contents in the interval from 100 to 1,500 μg/g in soil samples collected in residential areas. Lead concentrations in edibles from Vila Mota far exceeded the regulated limits in Brazil. These results led to the conclusion that the main routes for human contamination were thus exposure to soil and dust as well as consumption of contaminated food.

Lead Contamination in Bauru City

Environmental and human contamination for lead was brought to light in the city of Bauru (around 360,000 inhabitants) in 2002 when the State Agency for Environmental Control (CETESB) suspended the activities of Ajax company, a battery recycling plant that had been in production since 1974. Studies carried out by the agency and universities were then oriented to assess the quality of the environment and human contamination in the surrounding areas. The results of a very comprehensive study among children are shown in Table 4. The highest mean BLL was found in the 3- to 6-year-old age group. Blood lead values decreased with the distance of the residential area to the industry.

Soil sampling carried out 5 months after the facility was shut down yielded a maximum lead content of 1,071 μg/g inside the industrial facility. However, only low Pb concentrations were found in the surrounding area with maximum at 92 μg/g Pb. Soil samples were collected from 0 to 20 cm depth and slightly higher lead contents on the surface (0 to 2 cm depth) were noted.

Groundwater from one well close to the facility had 60 μg/L Pb, far exceeding the regulated limit of 10 μg/L Pb for drinking water. Several samples of edibles were analyzed in the period from September 2002 to August 2003 but excessive lead concentrations were found only for those collected inside the industrial area.

Following these studies some environmental intervention actions were implemented such as removal of topsoil from the area surrounding the facility, cleaning of houses, and restoration of water reservoirs.

The results summarized above for Brazil deserve some comments. In Adrianópolis as well as in Santo Amaro, poisoned soils function as secondary diffuse sources of lead in residential areas within distances of 500–1,500 m from the industrial plants. In both localities, elevated BLL levels reveal that people are coexisting with lead pollution for several years after the plant shut down. In the case of the Ajax battery facility, despite being located in an urban area (Bauru city), both environmental impact and human exposure were found to be less severe than in Santo Amaro and Adrianópolis. Additionally, environmental and societal actions were less difficult to implement in cosmopolitan Bauru than in other areas.

Few decades ago the area dominated by the Cubatão petrochemical industrial complex near the coast of the state of São Paulo was known as the most polluted site in South America. After a period when several environmental campaigns were undertaken, some data on human exposure for lead have been reported by Santos Filho et al. (1993). Mean BLL of 17.8 ± 5.8 μg/dL was found for a group of 250 children 1–10 years old from Cubatão. This case has not received much comment in recent times.

Also in the Ribeira Valley, human monitoring for lead was carried out among a group of 43 children from the Serra district located not far from some Pb–Zn mines. Cunha et al. (2005) reported a mean blood lead value of 5.36 μg/dL Pb with only 9.3% of samples exceeding the normal limit 10 μg/dL for children. These figures lie well below the exposure levels found in Adrianópolis where the Panelas mine and the Plumbum refinery were simultaneously in operation for decades. Although both sites could be considered industrial point sources, the dispersion of lead into the environment was more widespread in Adrianópolis than in the Serra district.

Additional point-source lead pollution associated with mining may be found at the Morro Agudo zinc mine (in the state of Minas Gerais) and around past lead-ore producers such as the Boquira mine (in the state of Bahia) and several middle-sized mines in the Ribeira Valley (in the states of Paraná and São Paulo).

Mercury in the Amazon

Human exposure to mercury is mainly by ingestion of contaminated food and can lead to adverse health effects such as fever, lung edema, pneumonitis, anorexia, irritability, emotional disturbances, photophobia, disorders of memory and cognitive functions.

Since the Minamata tragedy in the 1950s, mercury dispersion into the environment has become a subject of concern worldwide. Mercury is being investigated in a number of countries especially in places where it is frequently used for gold recovery in low-technology based mines. Hence, several studies have been carried out for mercury in South America in the past decades.

In Brazil most studies concentrated in the Amazon where rudimentary gold mining, locally called “garimpo,” made use of mercury for gold amalgam for decades at an annual rate of 80–100 tons according to reliable estimations (Veiga et al., 1999). The Brazilian Amazon covers 58% of the country and has a population of 20 million inhabitants (12% of Brazilian population).

It is well known that water and river sediments in “garimpo” areas often have higher Hg contents than those from remote areas. A compilation of mercury data for Amazon fishes from three major rivers (Madeira, Tapajós, and Negro) and from two water reservoirs (Tucuruí and Balbina) from various authors made by Malm (1998) indicate an average value less than 0.2 μg/g Hg (wet wt) for virgin areas and mercury contents of 2–6 μg/g Hg or even higher for contaminated areas, far exceeding the maximum tolerable limit of 0.5 μg/g established by Brazilian regulation in 1975.

Several determinations of mercury content in human hair from residents in the Tapajós River basin were compiled from various authors by Lima de Sá et al. (2006). Mercury contents from five exposed groups (n = 1,287) fell in the interval 11.8–25.3 μg/g whereas Hg contents from seven less exposed communities (n = 1,644) ranged from 4.0 to 10.8 μg/g. The latter were very consistent with the maximum tolerable level of 10 μg/g Hg established by WHO (1990).

Malm (1998) reported an even more comprehensive data set on mercury content in human hair from different areas and human groups in the Amazon as shown in Table 5. These data revealed that communities exposed to mercury in Amazon are not restricted to “garimpo” areas but may be found around water reservoirs, newly deforested regions, and even in protected indigenous peoples’ areas. This find was subsequently confirmed by Jardim and Fadini (2001) who reported elevated mercury contents in soil, water, and air in the Rio Negro River basin where no “garimpo” or any kind of factory has ever existed. The authors argued that the mercury levels in the environment were nevertheless comparable to other known industrial centers in developed countries.
Table 5

Total mercury contents in human hair from various Amazonian areas

Locality

No. of samples

Average (μg/g)

Madeira River

169

8.98

Madeira River

242

17.20

Tapajós River

432

16.76

Tapajós River

96

13.20

Negro River

154

75.50

Tucuruí Reservoir

125

35.00

Balbina Reservoir

58

5.78

Source: Malm (1998) compilation from various authors

After decades of research work on mercury in the Amazon, scientists are coming to the conclusion that mercury distribution in the region is much more widespread than was thought before. According to Malm (1998), concentration of methyl-mercury in sediment, water, and fish is a function of total mercury concentration, microbiological activity, concentration of organic matter, presence of methyl-group donors, pH, Eh, oxygen activity, and other factors. High mercury methylation rates were found in tropical aqueous systems such as seasonal inundated forest and at root zones of floating meadows formed by aquatic vegetation (Guimarães et al., 1997).

The physical, chemical, and biological functions of the Amazon rainforest to retain and recycle mercury of natural origin probably related to Andean volcanism still require future studies to be understood.

An interesting matter concerning mercury studies in the Brazilian Amazon is the lack of information on human health effects caused by mercury exposure. It is widely thought that the Amazonian population is protected against mercury intoxication by a selenium-rich diet that is widespread in the region.

Selenium in Venezuela

Since the 1970s some pioneering works on human and animal exposure to selenium have been carried out in Venezuela. Jaffé et al. (1972) described some symptoms such as hair loss and anomalies in the skin and nails among children from Villa Bruzual (in the state of Portuguesa, Fig. 7) and pointed out that those children presented a mean blood selenium concentration (813 mg/L) much higher than children from the capital, Caracas (0.355 mg/L). Mondragón and Jaffé (1976) found selenium concentrations in milk, egg, cheese, pork, and chicken produced in Venezuela exceeding selenium contents in similar products imported from eastern USA by 5 to 10 times. The authors believed that the probable cause of contamination is the Se-rich sesame cultivated in the Turén district, produced for animal feed.
Fig. 7

Map of the Amazon region with indication of locations cited in the text

Furthermore, it was noted that nursing children in the region ingest 10 times more selenium than children from Finland (Jaffé, 1992). This fact was anticipated by Otaiza et al. (1977) who investigated the blood Se levels in cows from three regions in Venezuela. They found an average Se level of 0.21 mg/L in the central region whereas in Portuguesa this average was 0.67 mg/L, reaching 1.02–3.24 mg/L for cows in the farms located in Turén.

More recently, studies on selenium were extended to the state of Merida, where an attempt was made by Burguera et al. (1990) to correlate blood Se levels with cancer prevalence in humans. Selenium contents fell in the interval 58–115 mg/L, well correlated with soil selenium. Cancer was less common in population groups with higher average Se blood levels. The hypothesis that ingestion of selenium prevents incidence of cancer had already been demonstrated in the 1970s in many countries (Shamberger and Frost (1969); Schrauzer (1977); Passwater, 1996). These results point to a favorable situation for Venezuela concerning consumption of food cultivated in selenium-rich soil. In addition, selenium deposits in Venezuela and human and animal exposure to selenium pose a very promising research topic for medical geology in Venezuela.

Fluorine and Fluorosis in Brazil

Fluorine has been investigated in many regions of South America, e.g., in the Andean countries, Argentina, Brazil, and other places. In Brazil, fluorine studies have been carried out in several states such as Santa Catarina, Paraná, São Paulo, Minas Gerais, Goiás, and Bahia. However, only a few integrated studies carried out in Brazil will be referred here.

In the state of Parana, south Brazil, following publication of the multi-elementary geochemical maps (MINEROPAR, 2001), two important fluorine anomalies were revealed for surface water, the largest one located in the northern part of the state and the other in the vicinity of fluorite mining areas in the Ribeira Valley (Fig. 8).
Fig. 8

Fluorine distribution in surface water, Geochemical Atlas of Paraná (MINEROPAR, 2001)

In northern Parana the fluorine anomaly was interpreted as geogenic and as derived from water–rock interaction. This motivated a research group to assess the probable fluorosis prevalence in the region. A group of 1,129 children from the São Joaquim do Pontal and Itambaracá municipalities was then screened for dental fluorosis. The results were reported by Cardoso et al. (2001) who pointed out incidences of light and very light fluorosis in 57% of children and incidences of moderate and severe fluorosis in 4% of sampled population.

In the Ribeira Valley, an environmental assay of water and stream sediments yielded the results reported by Andreazzini et al. (2006). In this region two fluorite mines are found but only one has been active in recent years. Fluorine contents in surface water exceeding regulated values for Brazil (1.4 mg/L F) were determined only in water samples collected from drainage close to the mines. Tap water analyses revealed fluorine contents in line with Ministry of Health recommendations. Elevated fluorine contents in stream sediments greater than 800 μg/g were restricted to areas surrounding the mines. Due to these positive results, implementation of an epidemiologic campaign for dental fluorosis was not considered necessary in the area.

Another comprehensive investigation of fluorine and human exposure was carried out in the state of Minas Gerais. Disseminated and vein-like fluorite occurs widely in limestone and other rocks of the Bambui Group in the northern portion of the state. Velásquez et al. (2008) identified fluorine in groundwater in northern Minas Gerais extending across 25 cities and towns. The main groundwater sources include karstic aquifers as well as Cretaceous sandstone and Cenozoic sediments. The authors reported fluorine contents from 155 wells out of 342 wells recorded. Average F content in the karstic aquifer is 0.72 mg/L and in the other aquifers 0.34 mg/L. Approximately 19% of wells show fluorine contents greater than 0.8 mg/L (Brazilian regulation) with maximum value of 11 mg/L F found in the town of Verdelandia. In two towns, Verdelandia and São Francisco, residents coexist with endemic fluorosis and people from other areas where water fluorine exceeds 1.5 mg/L are under risk of dental fluorosis.

In previous studies carried out in the region by a multidisciplinary team from the Federal University of Minas Gerais made up of geologists, dentists, epidemiologists, and other professionals, fluorine in groundwater and prevalence of fluorosis had been identified in the town of São Francisco. Since 2004 this project developed toward implementation of many activities oriented to disseminating information on the environment, fluorine hazards, and oral health in the region. In addition, they gave dentistry assistance to people affected by dental fluorosis. In this work, students and professionals of different specialties interact with social and health assistants and with the public in general (Castilho et al., 2004).

Societal Issues in the Scope of Medical Geology

As explained above, in connection with fluorine investigations in Brazil, very often geoscientists and other professionals working in medical geology must deal with societal issues. In many projects, collaboration of the public is essential not only because residents are a privileged information source but also because they are the leading actors to solve environmental and health problems of their concern.

To better understand the social scenery in which scientific work takes place, basic concepts of anthropology, environmental sociology, and risk governance are required, among others. Currently, two fields of interdisciplinary work that require methodological approaches from social science are being explored in the scope of medical geology in South America. A research group from the National University of Colombia is collecting data on geophagy practices in the continent and another team from the University of Campinas, Brazil, is investigating some communities that were exposed to lead contamination from the point of view of risk communication and risk governance.

There must certainly be other similar projects going on in South America, but in the scope of this chapter, only these two works are reported in the following sections.

Geophagy in South America

In South America, geophagy has been observed both in animals and in humans. Evidences found in archeological contexts have demonstrated the antiquity of this practice in the continent. It was reported in chronics written by the Spanish, Portuguese, and other researchers; explorers; and missionaries of the “New World.” Numerous elements, minerals, clays, loams, and soils were used in preparations or ingested in traditional therapeutics. Today this practice survives as part of the folklore and cultural heritage, although much of this knowledge has been lost to destruction of ancient cultures, evangelization, and ethnocide perpetrated by conquerors in the 16th century.

Animals may obtain benefits from this behavior in which they have persisted. In the Amazon rainforest, some nurturing places called salt licks could be damaged by deforestation, intensive eco-tourism, and changes in land use. These keystone resources can be lost, negatively affecting biodiversity (Montenegro, 2004). In this sense, understanding geophagy is a very important tool for conservation and for resource management at least for countries like the Amazonian countries (Brazil, Colombia, Ecuador, Peru, and Venezuela).

Geophagy in Animals

Geophagy has been reported in the Andes (Lizcano and Cavelier, 2004; Acosta et al., 1996; Downer, 1996) and in the Amazon rainforest for a wide range of wildlife species (Montenegro, 2004; Gilardi et al., 1999; Lips and Duivenvoorden, 1991; Emmons and Stark, 1979). Natural licks are particular sites and habitats often visited by wild animals with the purpose of licking or consuming soil. Among the users, there are medium to large species of birds such as rails, curassows, guans, pigeons, macaws, and parakeets; mammals such as large primates, ungulates, medium to large rodents, felines (jaguar and ocelot); and members of the bat families (Montenegro, 2004).

Species from the Camelidae family living in the Central Andes (lamas, vicugnas, guanacos, and alpacas) used to lick minerals enriched in clay phyllosilicates: smectites, kaolinites, chlorites, and illites (Browman, 2004). These same clays are those found to be ingested by humans. The composition of the deposits and the mineralogy of the salt licks show variations when compared with non-licking sites. But in some salt licks, the animals do not only consume soil but also drink the water at these sites. The composition of the water differs from adjacent waters. In the Andes, Lizcano and Cavelier (2004) report a higher content of sulfate, nitrogen, and zinc in water from licks when compared to an adjacent gully.

In the understanding of the indigenous society of the Uitotos from northwest Amazonia, Mother Earth nurtures the animals from the forest in these sites as if it were mother’s milk. They also believe that ingesting soil and water from natural licks is constrained to animals, but that they can benefit from these sites by hunting. Natural licks are important sites for the survival of these societies. That is why they can be listed as keystone resources (Montenegro, 2004; Primack, 1993), resources critical or limiting in particular habitats but crucial for many species of a community (Primack, 1993).

Natural licks are a result of particular hydrologic, ecologic, sedimentary, and mineralogical conditions. In some areas they may be controlled by the tectonic setting (Montenegro, 1998). Thus they are related to the environmental and geological evolution of a region. They also seem to be dynamic: they can dry out and another lick may appear somewhere else. Geologists can contribute to the study of these key resources. This knowledge is important for conservation plans, for natural resource management, and to understand the natural history and the world that has created us.

Geophagy in Humans: Positive Feedbacks

The Otomac tribe from South America was well known for their custom of eating large amounts of clay. The Otomacs used to live in the Neotropics, in the lower llanos of Apure, and on the banks of the Orinoco River (Venezuela, Fig. 7). Today they have disappeared. Among their representatives were the Guamos, Taparitos, Otomacos, and Yaruros. They all shared the taste for soil consumption.

The Otomacs caught the attention of naturalists such as Humboldt (1985) and different missionaries such as Father Gumilla (published in 1944) and Father Bueno (published in 1933). They recorded the Otomacs’ habit of eating clay in copious quantities. Clay was extracted from the alluvial beds from the Orinoco River, during high water levels, a period where the food seemed to be scarce, although geophagy was practiced all year long. Otomacs enjoyed eating clay, they cooked it and made small balls to be carried and consumed as a snack or as a small meal, and they also had recipes such as “clay bread”: They mixed clay with corn and turtle or caiman fat, left the mix for fermentation, and then ate it (Gumilla cited in Rosenblat, 1964).

In the Northern Andes, on the coast of Ecuador, certain “clay” artifacts were recovered from the Japotó and Acatames archeological sites by Guinea (2006). The objects were described as being composed of calcite-rich soils with a significant content of iron and other minerals such as feldspars, quartz, and sometimes very small amounts of smectite clay. They had prints of leaves and had elongated or spherical shapes (Fig. 9).
Fig. 9

Geological materials found in the Atacames and Japoto archeological sites. Note the leaf printing and the shape. (Reproduced with permission of M. Guinea, 2006)

They are reminiscent of tamales, bollos, and other traditional foods in which dough, paste, or batter is wrapped in leaves which add a natural flavor. They were found to have been cooked, and because of heating they could be preserved. Guinea (2006) assigns the earth to the taku, or pasa, or even poya type.

The pre-conquest cultures had vast knowledge about their environment. Their medical system was completely fused with their culture and religious views, as an emanation from the cultural frame (Gutierrez, 1985), making efforts to explain geophagy considering the ecological and cultural framework. Although traditional explanations of diseases could include supernatural forces or curses, some therapies have proven to be efficient, and some of them have been observed in very different cultures such as the ingestion of clays to treat digestive upset.

The use of clays as detoxifying agents is well known in traditional cultures. Johns (1986) reports the handling of clay material composed of kaolinite, interstratified illite-smectite, and chlorite by indigenous groups from Peru, Bolivia, and Arizona. Poisonous species of wild potato were covered with clay and then consumed without harm. Clays eliminate the bitter taste and absorbed the glycoalkaloid tomatine, preventing stomach aches and vomiting. A study conducted in the Central Andes (Bolivia and Argentina) by Browman (2004), reports 24 types of earths used by the inhabitants either as a food supplement or as drugs; the samples are composed of phyllosilicates, sodic and calcium earths, sulfur minerals, and another group made up of iron and copper salts. The inhabitants of the Central Andes may have learned the geophageal behavior from the Camelids.

This knowledge is part of their cultural heritage, as there were some samples recovered in archeological contexts and these raw materials can currently be found in local markets. The handling of these earthy materials dates back at least five millennia. Browman (2004) reports the traditional names as P´asa and C´hago for raw materials composed of mixed clays (smectites, kaolinite, chlorite, illite) being highly appreciated earths for their properties to alleviate gastrointestinal upsets related to phytotoxins present in domesticated plants (such as solanine in potatoes or saponine in quinoa).

Another case comes from the Aymaras that used to live in the high planes of Lake Titicaca. Women ate a plastic soil called Chaco as candy (Patiño, 1984). Half a century ago, Rowe (1946) stated that in the Inca Empire “a quantity of edible clay was collected and exchanged with some frequency in the southern mountains.”

During the evangelization period in South America, some Franciscan friars were prominent and well versed in medicine. A complete vademecum found in the provincial files was published in 2002 by the Colombian Academy of Exact, Physical and Natural Sciences. It was written by an anonymous Franciscan friar in the 18th century (Díaz and Mantilla, 2002). It is a result of mixing the legacy of occidental medicine and the traditional indigenous medicine.

Numerous reports accounted for geophagy as a form of pica since the period of the conquest. In the Franciscan vademecum mentioned in previous section, children with the habit of eating earth were treated with cow milk mixed with a little lead carbonate in the mornings, until they detoxify by vomiting (Díaz and Mantilla, 2002). In Colombia, reported remnants of that habit are found in Magdalena and in Naré; the disease caused by eating dirt was called “jipatera.” Colombian writer Gabriel García Márquez captured geophagy in his novel “One hundred years of solitude”: Rebecca was an orphan girl, with the custom of eating dirt and lime from the walls when she faced emotional crisis.

In the northwest Amazon basin, in Colombia, Londoño (2007) reports the ingestion of clay minerals in solution by the Uitotos indigenous society as a therapy for alleviating digestive upsets, detoxification of the liver, and counteracting poisonous compounds. The raw materials were dominated by clay and the composition was the same as that reported by Johns and Browman. In the Uitoto classification they belong to the Nógoras group (Fig. 10).
Fig. 10

Medicine man and woman from the Uitoto indigenous society collecting clay for medicine purposes in the Amazon rainforest. (After Londoño, 2007)

These examples reflect gaps that exist in our knowledge; the intricate relation between culture, ecology, and geological elements; and the interesting challenge that geophagy represents.

Soil Living Helminthes (Geo-Helminthes)

Soils and minerals may contain toxic compounds and pathogenic organisms. In fact, the excessive consumption of an essential mineral may lead to health problems. Geo-helminthiasis (caused by parasites that live in soil) is one of the most widespread parasites in the world, affecting almost 2,000 million people all over the world (WHO, 2002). The pathogenic agents (Ascaris lumbricoides, Trichuris trichiura, Uncinaria sp.) depend on many environmental variables during their early stages of life to become infectious for humans. Some of these variables include soil temperature, weather, air humidity, and soil properties. A first approach to assess this issue was attempted in 2005 with the study “Influence of geological factors on the prevalence of soil transmitted helminthes in Colombia” (Valencia et al., 2008). The main objective was to identify the most relevant environmental variables in an epidemiological sense.

The study was performed with epidemiological data in the form of prevalence of helminthiasis statistically correlated with environmental and geological data. A positive relationship was found between temperature, annual precipitation, and index of basic unsatisfied needs.

This compiled information leads to a conclusion that geophagia is a part of natural history. It is a behavior now restricted to certain cultural patterns and wild animals, its causes and consequences cannot be generalized. Medical geology can be an important contributor to the study of geophagia in trying to explain this behavior by integrating a variety of perspectives and disciplines.

Risk Communication and Risk Governance

In recent years, societies have had to face complex environmental and health risks, which are characterized by controversial values, high stakes, and urgent decisions. These problems, associated with chemical substances, unknown effects of hazards, and uncertainty within the scientific community demand a new approach to deal with these risks, called risk governance.

This approach considers that risk is more than a situation or an event during which something of human value, including humans themselves, is at stake and where the outcome is uncertain. Since risks can only be seen and measured within a social context, it must be understood as a social construction. This means that hazards interact with psychological, social, institutional, and cultural processes in ways that greatly affects public reaction to risk (Hannigan, 1995; Slovic, 1987).

This approach also takes into account that risks are part of our routine. This means that all actors involved in a risk situation have the right to participate in the definition of and solution to the problems that they face. This participation is facilitated when dialogue is encouraged. This dialogue is known as risk communication.

Conceptual Framework of Risk Communication and Risk Governance

Risk communication practices should not be limited to a knowledge deficit model, which considers that experts have to communicate their scientific knowledge to the lay public in order to stop them from continuing to live in a state of ignorance. The idea that lay knowledge is not irrational characterizes the dialogue among social actors involved within the risk management arena. It includes considering that value judgments and subjective influences are present in every phase of risk management, also dividing the experts opinions (Guivant, 2004). In this approach, risk communication must be a process that provides guidelines and strategic tools for scientists and authorities to create a confident atmosphere with all social actors.

The risk communication concept includes strategies that ensure information is supplied in a clear and explanatory manner, so that local populations are informed about and aided to understand pertinent information and its subsequent implications as well as being encouraged to actively participate in mitigation of risk (Horlick-Jones, Sime, and Pidgeon, 2003; Renn, 2003; Lundgren and McMakin, 2004; Wynne, 1989).

The concept of risk communication has undergone significant advancements and an increase in popularity since the Chernobyl nuclear accident that occurred in the Ukraine in 1986. The accident illustrated the difficulties that researchers were faced with in trying to adequately disseminate information to the public regarding risk assessments and their uncertainties (Wynne, 1989). Since then, scientists, communicators, and public administrators have highlighted the need to put an interactive communication process into practice, which can accommodate the necessary exchange of opinions between the various social actors involved during a risk management process. Today, more than 20 years after the Chernobyl incident, risk communication has gained ground on the public agenda. This change could be seen as better addressing the wide range of situation of risks that we live with, such as natural disasters, environmental changes, outbreaks of infectious or chronic diseases, as well as terrorism.

These events also help to promote a discussion about risk governance. The concept of governance is related to a new institutional arrangement where the decision-making process is collective and involves governmental and non-governmental actors. In this practice, the power of society is recognized and respected. Experts and authorities recognize that complex problems, such as those that are faced in situation of risks, demand more than a technical solution. The choice of these solutions is not a technical decision, but also has political, social, cultural, and economic aspects.

According to Jasanoff and Martello (2004), the concept of governance means rules, processes, and behaviors that affect how power is practiced, particularly regarding participation, accountability, efficiency, and responsibility in the decision-making process. These authors agree that in environmental situations, when the limits of science are so evident, the social dimensions of knowledge production must be recognized and more attention must be given to local perspectives and traditional knowledge.

The great interest in this new approach to dealing with risks (involving risk communication and governance) is a result of the debate about justice, trust, public participation, and democracy that has been happening in societies in recent years. These subjects have had a central role in the development of research and political agendas.

Interest is also related to the idea that it is possible to deal more efficiently with public answers to risk if people that really live these hazard situations are involved in the decision-making process. This means that the risk management must be an analytical and deliberative process in which the effects of social amplification of risk are included as an important element in the decision.

Social amplification of risk denotes the phenomenon by which information processes, institutional structures, social group behavior, and individual responses shape the social experience of risk, thereby contributing to consequences of risk (Kasperson et al., 2005). Therefore acceptance or non-acceptance of existence of a risk is determined by a number of elements such as an individual’s familiarity with the problem, ability to solve the problem, exposure to the media coverage, beliefs, and personal feelings (Duncam, 2004; Smith, 1992; Weyman and Kelly, 1999; Sturloni, 2006). The legitimacy of the institutions involved in risk management as well as the lack of direct participation during the decision-making processes of local people involved in a situation of risk influences the level of concern felt by a given population.

Many different experiences with environmental and health risks have shown that when people are involved in the decision-making process, they know and preserve better the place where they live and act individually and collectively to reduce risks. Besides, the chances to avoid a community or place being stigmatized by the risks that they are facing decrease when people are integrated in the solution of their problems.

Public participation in assessment and management of risks also has direct implications in the development of democratic principles. Even if not all desires and aspirations of the communities are satisfied, the simple fact that people are involved in associative models because they have a political project in common that could improve their life quality is a significant advance. It is the chance to develop those communities’ personal capacities of analyses and argument, tolerance, and solidarity which is so important in democratic societies.

Environmental Contamination and Health Risks

The debate and practices about risk communication and governance is more advanced in the United States and Europe. In the United States risk communication is often conducted as a result of a law, regulation, or other government inducement (Lundgren and McMakin, 2004), but it is a regular procedure during risk management. One example of this is the act known as CERCLA or Superfund (Comprehensive Environmental Response Compensation, and Liability Act). It requires that specific procedures be implemented to assess the release of hazardous substances at inactive waste sites. Those procedures involve the inclusion of “community relations” in the evaluation process. According to Lundgren and McMakin (2004) “community relations” refers to developing a working relationship with the public to determine acceptable ways to clean up the site so that the community is included in the decision-making process and participates effectively in risk management.

In Europe, although each country has a unique way to deal with risks related to contamination, there is a common idea about promoting an open debate with the public and giving more attention to local and traditional knowledge to face problems. The United Kingdom and France, for instance, have legislation about getting input from the public before some actions are taken by authorities in uncertain areas.

Unfortunately, the debate about risk communication and governance is still reduced in developing countries. The paradigm of assessment and management of risks includes numerical data about the intensity of pollution and measures to reduce threats, but it does not take into account – or perhaps barely takes into account – how people perceive and live with these risks.

Nonetheless, environmental and health researchers (and in some circumstances government) are convinced about the necessity to promote a dialogue between experts that assess and manage risks and the people that really live these risks. The latter’s experiences, especially those that involve environmental contamination and human exposure to dangerous substances, show the necessity to include social dimensions and all kinds of knowledge (technical, lay, traditional, and local) to deal with hazard situations (Di Giulio et al., 2008a, 2008b, 2008c).

This necessity is evident in a study focusing on three cases in Brazil (Adrianopolis, Santo Amaro, and Bauru) and one in Uruguay (La Teja) in which resident communities had to deal with environmental contamination and human exposure to lead.

Based on bibliographic research, analysis of journalistic articles, and interviews conducted with people who played different roles in the events, a lack of adequate planning for information release to local people was identified in Adrianópolis. This circumstance seriously undermined the relationships between researchers and community and contributed to a misperception of risk among people. There, the absence of a community involvement plan produced a feeling of exclusion from the decision-making process. In Santo Amaro a concern about risk communication was noted among researchers, although local people had always demanded more information about the problem. There is a local association of contamination victims that presses the government for solutions but the level of public involvement is probably not as extensive as it could be. In Bauru, the relatively good relationship between researchers, authorities, and local people was facilitated by the existence of a risk communication plan. The strategies of risk communication aimed at encouraging public participation in the solution of the problem, although this participation was limited to only public pressure. Local people insisted on actions directed to pollutant control, searched for clarification regarding the health effects of these pollutants and for assistance from the public health service. Finally, in La Teja (Montevideo) local people were from the beginning very engaged in handling the risks, although the risk communication strategies were not enough to open dialogue and to empower community representatives to actively participate in risk management. People’s engagement in La Teja resulted from the potential existence of social mobilization represented by a neighborhood association that played an important role in guaranteeing information to local people and to press governmental institutions to action.

These experiences show that even when there is a risk communication plan, the strategies formulated are still limited to a knowledge deficit model and not to contributing to create a trustful and confident relationship between all social actors involved in the risk arena. Without trust it becomes difficult to promote social interaction to handle the risks. This difficulty is more evident when experts and authorities adopt a risk management approach that underestimates potential input from the public. However, these experiences also highlighted that being aware of public values and character as well as taking into account social organizations’ input might be the easiest way to mobilize people and promote risk governance.

Other Medical Geology Studies in South America

As mentioned earlier in this chapter the list of environmental problems discussed above is far from exhaustive. Other hazardous substances such as chromium, cadmium, siliceous particulate, metallic or asbestos-bearing dust, agrochemicals, radioactive elements, and many other substances may cause harmful effects to exposed populations. These themes are focused in a number of ongoing projects and publications in South America. Additional information on Se, As, and Cu in Uruguay; on chemical composition of drinking water in several metropolitan areas in Brazil; on human exposure to atmospheric particulates in urban and rural areas; on natural gamma radiation in the environment as well as at U–Th mine sites; and on the presence of agro toxins in edibles are available in a number of papers, technical reports, dissertations, doctoral theses, and presentations in diverse congresses.

These environmental and human health studies cover a wide spectrum of scientific themes in response to real problems identified in South American countries. They benefit from a laboratory infrastructure that could be considered good especially in the more developed regions. In the past decades getting high-quality analytical data, for example, for lead in blood, arsenic speciation, or any trace-element concentration at ppb or ppt levels was an obstacle to scientific research in South America. However, substantial advances in laboratory facilities have occurred in recent years in many places that can largely benefit scientists, professionals, and students from less developed regions. Participation in various web lists and research networks that are active in the continent may be the best way to improve scientific research on medical geology in this part of world.

Future of Medical Geology in South America

In Brazil, the most promising medical geological initiative undertaken so far is the Geomedicine Project of the State of Paraná. Since 2006 a comprehensive study on surface geochemistry and public health has been conducted by the Pele Pequeno Principe Research Institute in cooperation with the local geological company Mineropar. Interest in this study has arisen from the fact that in the state there is an elevated incidence of TP33 genetic alteration generally associated with adrenal cortex cancer among children and mammal cancer. The project was designed to verify its existence and indentify probable relationships between health problems and environmental parameters. The research team takes advantage of the excellent geochemical database generated by Mineropar since the 1990s. A substantial amount of public health, demographic, social-economic, and surface geochemical data are being stored in a web mapping system from which different user friendly maps are produced for system users, according to Pedrini et al. (2010).

Current and future achievements of the Parana Geomedicine Project illustrate very well the thesis that significant advances in future medical geology will occur in those regions where geological and geochemical mapping efforts succeed. That brings attention to the strategic plans of geological surveys and other geological institutions in the continent. Incidentally, the Geological Survey of Brazil (CPRM) recently announced additional investments in low-density geochemical mapping of the country (Silva, 2008). These geochemical studies include the chemical compositions of surface water, stream sediments, and soil as well as trace-element analyses of treated water for domestic use in some metropolitan areas.

In connection with regional, geological, and geochemical mapping, a great number of new research initiatives may be undertaken by South American universities and research centers. They will also to a great extent be based on the results from current research work, which covers a wide thematic spectrum from investigations of air quality in urban and rural areas and probable correlations with lung and heart diseases and mortality rates; remediation experiments at laboratory and pilot scales on arsenic removal from acid mine drainage and chromium removal from contaminated water; use of phosphate or bio-accumulators for rehabilitation of contaminated soil for lead and other metals, etc.

Despite the difficulty of being able to create multidisciplinary research teams and interinstitutional collaboration between Earth, life and social scientific institutions, this seems to be the best model to follow and the most effective way for future medical geology studies in the continent to succeed in response to societal needs and scientific challenges.

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Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  • Bernardino R. Figueiredo
    • 1
    Email author
  • Marta I. Litter
    • 2
  • Cássio R. Silva
    • 3
  • Nelly Mañay
    • 4
  • Sandra C. Londono
    • 5
  • Ana Maria Rojas
    • 6
  • Cristina Garzón
    • 6
  • Tommaso Tosiani
    • 7
  • Gabriela M. Di Giulio
    • 8
  • Eduardo M. De Capitani
    • 9
  • José Ângelo S. A. Dos Anjos
    • 10
  • Rômulo S. Angélica
    • 11
  • Maria Celeste Morita
    • 12
  • Mônica M.B. Paoliello
    • 12
  • Fernanda G. Cunha
    • 3
  • Alice M. Sakuma
    • 13
  • Otávio A. Licht
    • 14
  1. 1.Institute of GeosciencesUniversity of CampinasCampinasBrazil
  2. 2.Atomic Energy National Commission, Consejo Nacional de Investigaciones Científicas y Técnicas and University of San MartínSan MartínArgentina
  3. 3.Geological Survey of Brazil – CPRMRio de JaneiroBrazil
  4. 4.University of the Republic of UruguayMontevideoUruguay
  5. 5.National University of ColombiaBogotáColombia
  6. 6.INGEOMINASBogotáColombia
  7. 7.Central University of VenezuelaCaracasVenezuela
  8. 8.Environmental Studies CenterUniversity of CampinasCampinasBrazil
  9. 9.University of CampinasCampinasBrazil
  10. 10.University of SalvadorSalvadorBrazil
  11. 11.Federal University of ParaBelemBrazil
  12. 12.University of LondrinaLondrinaBrazil
  13. 13.Adolfo Lutz InstituteSao PauloBrazil
  14. 14.MINEROPARCuritibaBrazil

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