Background Organochlorine pesticides are still used for vector control, and there is evidence of their recent illegal use in agriculture in several tropical and subtropical areas of South America, including Bolivia.

Objectives To determine concentrations of three selected organochlorine pesticides (p,p’-DDT, p,p’-DDE, HCB) in adipose tissue and serum samples in several Bolivian population sub-groups.

Results We found relatively high exposure levels in several Bolivian population groups, influenced by different factors from those observed in Europe and North America due to their specific occupational, lifestyle and dietary patterns. Especially elevated p,p’-DDE (main DDT metabolite) exposure levels were found in agricultural farmers from three rural communities in eastern Bolivia (subtropical area), with median serum concentrations of 19.7 ng/mL, which were 20-fold higher than those found in Bolivian urban dwellers. This is an alarming finding considering that this pesticide has been prohibited in the country since 1996. Additionally, multivariate models revealed a positive correlation between residence in the study area and exposure levels.

Conclusion Our results point to the existence of heavily-polluted and previously unidentified hotspots in the region, underlining the need for the continuous monitoring of these populations given the potential associated health risks.