Human Exposure to Lead in Chile

Summary

Lead is a very toxic environmental pollutant that affects people living or working in contaminated areas or ingesting this element. Since the beginning of lead use, it has left evidence of lead poisoning with dramatic effects on the destiny of ancient civilizations. It was recently proposed that this toxicity can also contribute to the decline of current societies through lead-induced impairment of intelligence, increased tendency to abuse of drugs, psychological and behavioral changes, and increase in delinquent behavior.

The effects of chronic exposure to lead in adolescents or adults may be reversed, at least in part, after a decrease in the blood lead levels. In contrast, in children, especially at earlier ages, the effects are irreversible, may persist through life, and some of them may be induced by the mechanism of imprinting. Exposure to lead during the perinatal period of life may occur in mothers previously exposed to the metal, presenting increased concentration of lead in bones; fetuses and newborns are most vulnerable to the toxic effects of lead because the damage persists throughout life.

The various sources of lead exposure in Chile as well as the evolution of regulations and mitigation measures are reviewed. An important source of contamination with lead was the existence of paints with high lead content, used to paint house walls, children’s furniture, and toys, among other objects. The highest content of lead in paints was not in those bearing Chilean trademark names, but from a foreign trademark with formulas licensed to produce in Chile, although the same products in the country of origin (U.S.) did not present measurable lead levels. From 1997 on, new legislation regulated lead content in paints. Many houses, furniture, children’s toys, and other objects painted before 1997 are still an important source of exposure to lead, mainly for children.

Formerly, the widest source of lead contamination in Chile was the use of leaded gasoline, mainly in greatly populated cities. There has been a progressive decrease in lead content in leaded gasoline, which was banned in April 2001. Lead pollution still persists in highly populated cities as city soil, home soil, and as soil contamination near highways.

Clusters of different magnitude originated from point sources, of which the most relevant in magnitude was that which occurred in Ñuble with the use of wheat flour contaminated with lead, caused by the use of a mill whose stone was repaired by lead welding. Several other clusters of smaller magnitude are frequently caused by the widespread practice of battery repair and recovery by small enterprises or as a familial productive activity, affecting all the family group and occasionally persons living in the vicinity.

Two special cases of very important environmental contamination occurred, affecting the population of two major cities. The most dramatic case was the storage of powdered lead mineral concentrates at the ports or the railroad terminals within the cities of Arica and Antofagasta, where it usually remained until shipped to other countries. Lead from this source is the most relevant source of exposure in the cities of Arica and Antofagasta. Another source of lead, which affected the population of Arica, originated from toxic wastes imported by Promel from the Swedish company Boliden Metal, stored without protection in Arica suburbs, where a few years later new dwellings were constructed and residents were exposed for more than 10 years.

Occupational exposure frequently occurs in painters, welders, and mining or smelting workers. Various degrees of food lead contamination may increase exposure to the metal. Vegetables grown in or near highly populated areas, lead pipes in old dwellings or copper pipes welded with lead, and formerly lead from canned food, especially those that had been accidentally deformed or were opened and the food stored in those cans.

Little information exists on lead content in soil. There are sites where lead concentrations are increased from anthropogenic sources. In regions known to have abundant lead minerals, soil is not contaminated in the vicinity of rivers, suggesting that raw lead minerals do not dissolve in water and do not affect the soil.