Human exposure to persistent organic pollutants and health risk : current knowledge and perspectives

Purpose: Persistent organic pollutants (POPs) are organic compounds of anthropogenic origin that have an intrinsic resistance to natural degradation processes. These compounds include pesticides (DDT, heptachlor, etc.), and other chemical compounds, such as hexachlorobenzene, polychlorinated biphenyls, polychlorinated dibenzodioxins and polychlorinated dibenzofurans. Although their production and use are now banned in many countries, they are still a matter of great concern due to their persistence and ability to concentrate through the food chain. Since humans are at the top of the food chain, they accumulate lipophilic, persistent compounds in their blood, in adipose tissue, and in breast milk. Humans can be exposed to POPs through diet, occupational accidents, and the environment. Both acute and chronic exposure to POPs may be associated to a wide range of adverse health effects, including cancer, endocrine disruption, immunotoxicity, neurobehavioral and developmental disorders, and birth defects. Body burden data, have been obtained from biological monitoring all over the world. Yet, much has still to be done. In order to collect additional information about human health risks, it is necessary to identify early biomarkers of adverse effects in the general population. Effect-biomarker studies on exposed subjects should therefore be performed. Methods: a systematic bibliographic research has been conducted on the main international toxicological and medical databases. Key words were “organochlorine compounds AND endocrine disruption, cancer, neurological impairment; PCB AND thyroid hormones, immune system”. Results: The most commonly used biomarker of body burden of POPs is one of the most abundant PCB congener, CB-153, whereas p,p’-DDE is considered to be a good indicator of non-recent exposure to DDT. Both biomarkers can be measured in serum samples, and correction for serum fat content is recommended. Moreover, our study has pointed out the possibility of measuring, in a pre-clinical phase, estrogenic effects, impairment of thyroid hormones synthesis and of glucose metabolism. Conclusion: it is recommended to carry out biological monitoring activities in which, together with biological indicators of dose, the following pre-clinical effect indicators are measured: T3, T4, TSH; 17beta-Estradiol; Testosteron; Luteinizing Hormone, Follicle-Stimulating Hormone; Sexual Hormone Binding Globulin; Prolactine; Serum Glucose and Glycate Haemoglobine. A pilot experience of such an approach is being prepared by our group, and will be carried out in the next future in an Asian developing country.