Evaluation of the potential cancer risk of obsolete organochlorine pesticides in abandoned storehouses throughout the Almaty oblast, Kazakhstan

Abstract Kazakhstan is facing environmental problems with the large amounts of residual prohibited obsolete pesticides. More than 1500 tons of banned, obsolete pesticides and mixtures of unknown composition have been disclosed distributed throughout Kazakhstan in store houses that are abandoned, in partially or completely demolished states. However, these locations still contain significant amounts of these banned substances that have been (and presumably still are) widely used. The present study focusses on potential problems associated with former pesticide storehouses in the Almaty oblast (region) that due to significant agricultural activities is of particular concern. DDTs and HCHs are found in samples from storehouses in 9 districts of the Almaty oblast. Variations in concentrations are associated with different degradation pathways that have been studied applying ternary plots. The highest concentrations of p,p′-DDT, p,p′-DDD, and p,p′-DDE in soil samples exceed the Kazakh maximum allowable concentration (MAC) by factors of 65, 19, and 21, respectively, whereas for the HCHs isomers, α-HCH, β-HCH, and γ-HCH in soil samples the Kazakh MAC value was exceeded by factors of 12, 45, and 4.4, respectively. Analyses of the cancer risk showed that for both DDTs and HCHs the risk mainly occurs from ingestion of soil, whereas inhalation and dermal contact exposure contributes to a minor extent only. The implication to the local population is discussed.