Assessing bioaccumulation of Pb, Cd, and As in Goats: Impacts of exposure to mine tailings in a polymetallic mining region

Abstract

Pb, Cd, and As concentrations were measured in blood, edible tissues, urine, feces, and hair samples from goats raised in the vicinity of the abandoned El Fraile mine tailings (Taxco de Alarcón, Mexico) to evaluate the bioaccumulation levels to Pb, Cd, and As. The goats were fed grains, grasses, and sprouts that grew on top of mine tailings and drank from the mine leachate for seven months, reproducing the natural conditions of goats raised around and on top of mine tailings. Blood showed the lowest Pb, Cd, and As concentrations, followed by edible tissues (leg muscle, brain, and lungs) whose concentrations were below Mexican permissible limits (NOM-004-ZOO-1994). However, urine showed higher concentrations of Pb and As, but feces showed even higher concentrations and hair and bezoars exhibited the highest Pb, Cd, and As values. Even though these data suggest that consuming edible tissues does not represent a risk to human health, the high Pb, Cd, and As concentrations in urine, feces, and hair suggest that goats were exposed to chronic poisoning. Additionally, isotope data indicate that Pb determined in blood, urine, and bezoars is related to the remanent mineralization present in the mine tailings, highlighting the hazard that mine tailings represent to the environment and settlers of the region.