Persistent Organic Pollutants (POPs) in Eastern and Western South American Countries

Summary

Persistent organic pollutants (POPs) are a global issue. The recently signed Stockholm POP convention requires information from signatory countries regarding sources and environmental levels. In eastern and western South American countries, this information is not always easily accessible, and therefore an effort toward collection of updated information is required. This review attempts to fulfill these requirements by analyzing the existing information regarding environmental levels of POPs in eight countries of South America.

A regional trend for environmental POP information is the uneven contribution among countries, which reflects the different patterns of economic, technical, and scientific development. In general terms, the available information is strongly biased toward those countries with scientists, and technical facilities for performing research in POP-related issues. Data related to environmental levels and spatial patterns principally come from the densely populated areas along major rivers such as the Amazon, Paraná, and Río de la Plata. The database is thus strongly biased toward freshwater environments to the detriment of coastal marine areas, which have received proportionally less attention.

POP monitoring in air is infrequent in the Region. Data represent a few geographical areas within the Region. PCB levels in air from some urban areas in Argentina, Brazil, and Chile are low to moderate (0.7–6.5 ng/m³) but considerably higher than those reported for the remote Falkland Islands (Islas Malvinas) (5 pg/m³). POP monitoring in soils is also limited within the Region. There are no regional monitoring programs, and most data refer to agricultural areas in Chile and urban hot spots in Brazil. Chilean soil data from agricultural areas indicate generally low levels of chlorinated pesticides in spite of a relatively high detection frequency.

Overall, several high pesticide levels for freshwater in the Region suggest a complex situation, but the narrow coverage of the data requires a cautious interpretation. Usually, only suspected contaminated ecosystems are monitored, and large-scale regional water monitoring programs have never been undertaken. The few PCB reports indicate generally low to moderate levels (7–22 ng/L), higher than recommended guidelines in urbanized estuaries and rivers such as the Río de la Plata (Argentina) and Biobio (Chile). Pesticide levels show high variability (0.6–14, 160 ng/L), reflecting distinct ecosystem conditions from less-impacted environments to severely polluted streams located in densely populated areas near Buenos Aires and Sao Paulo. Heptachlor, HCHs, aldrin, and DDTs are the most frequently reported pesticides in water, accounting for more than 60% of the total database.

Regional POP information for sediments is also dominated by chlorinated pesticides, but presents a more balanced contribution of PCBs with a few reports for PCDD/F. Overall, as observed for waters, sediment data indicate a complex situation in densely populated areas affected by urban-industrial inputs that have high POP levels. The most frequently reported POPs are DDTs, HCHs, PCBs, and heptachlors. The concentrations show a large variability, principally introduced by some highly contaminated sites in Argentina and Brazil with levels 4–5 orders of magnitude higher.

Aquatic organisms are by far the most studied organisms in the region, among them principally bivalves and fish. As observed for other environmental receptors, the regional distribution of data is uneven, heavily centered in coastal environments and in some countries (Argentina, Brazil, Chile, and Peru). The most comprehensive POP monitoring program in the South American coastal environment is the Mussel Watch. Among the POPs studied, PCBs predominate, followed by DDTs and chlordanes. Baseline PCB concentrations range from 200 to 700 μg/kg lipids in unpolluted sites, from 1,000 to 3,000 μg/kg in moderately contaminated sites, and from 4,000 to 13,000 μg/kg lipids in most affected bivalves from the Río de la Plata (Argentine side), Recife (Brazil), and Punta Arenas (Chile). DDT averages in bivalves are an order of magnitude lower than those of PCBs, below the 5 ppm guideline, and follow a similar spatial pattern.

Other organisms that have been analyzed for POPs in the Region are crabs (Cyrtograpsus angulatus), dolphins (Pontoporia blainvillei), and porpoises (Phocoena spinipinnis) from the Atlantic Argentine coast and continental shelf. PCBs show the highest levels (averages, 296, 1980 and 3300 μg/kg lipid in crabs, dolphins, and porpoises, respectively) closely followed by DDTs (170, 1670, and 4320 μg/kg lipid). PCDD/Fs analyzed in the omnivorous blue crab (Callinectes sapidus) collected in the Santos Bay area (Brazil) showed total TEQ values of 1.5 pg/g wet weight with the predominance of octachlor dioxins, followed by heptachlor congeners. POP data in crustaceans and gastropods from the Valdivia area (southern Chile) show generally low levels, basically of DDTs and DRINs (0.8–5 ng/g ww), whereas very few data from organisms collected in the Peruvian coast show low DDT (1–10 ng/g), and PCB levels (0.12–17.8 ng/g).