Specialties
Early childhood development and PCB exposures in Slovakia
Hertz-Picciotto, Irva — Department of Epidemiology adn Preventive Medicine
Technical abstract
Polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorinated dibenzo-dioxin (TCDD) are neurodevelopmental and immunologic toxicants in experimental animals treated prenatally. Associations with neurobehavioral deficits are found in some but not all epidemiologic studies of environmental exposures, with data suggesting the prenatal period to be the most sensitive. Additionally, the risk of intrauterine growth retardation increases with higher environmental PCB exposures, and several reports suggest a more potent effect in male babies. The proposed study will therefore evaluate prenatal and postnatal PCB and dioxin exposures in relation to immune markers at birth and early childhood, to intrauterine and early childhood growth, and to early neurobehavioral development.
The study will be conducted in the Slovak Republic, where a chemical plant that manufactured PCBs improperly discharged large quantities of contaminated waste into the surrounding area. A total of 1200 births in years 2001-2003 will be enrolled in two districts, half from the district with high contamination of PCBs, and the other half from a district with lower contamination levels. The study will parallel a European Union-funded study of adults and school-age children in the same two districts.
The project will be one of the first to evaluate a wide battery of immune parameters in an epidemiologic study, including lymphocyte immunophenotypes, thymic size, post-vaccination antibody titers, and morbidity. It will also be the largest to date to evaluate neurobehavioral development. Other unique features include the evaluation of hearing loss at birth, the measurement of hydroxy and methylsulfone metabolites of PCBs, and a population which includes about 1/3 Gypsies.
Exposure levels in the contaminated district are higher than those in most environmentally exposed populations today, but are certainly lower than those resulting from accidental poisonings. Nevertheless, the wide variability within this population, the substantially lower PCB burdens in the control district, and the study size will enable a statistically powerful investigation of dose-response and interactions with factors influencing susceptibility such as heavy metals, gender, and ethnicity. Banking of specimens will allow for long-term follow-up and utilization of new technologies not yet available. If no associations are found, the lower US levels and the decline in countries such as the Slovak Republic could provide some reassurance.
The study will be conducted in the Slovak Republic, where a chemical plant that manufactured PCBs improperly discharged large quantities of contaminated waste into the surrounding area. A total of 1200 births in years 2001-2003 will be enrolled in two districts, half from the district with high contamination of PCBs, and the other half from a district with lower contamination levels. The study will parallel a European Union-funded study of adults and school-age children in the same two districts.
The project will be one of the first to evaluate a wide battery of immune parameters in an epidemiologic study, including lymphocyte immunophenotypes, thymic size, post-vaccination antibody titers, and morbidity. It will also be the largest to date to evaluate neurobehavioral development. Other unique features include the evaluation of hearing loss at birth, the measurement of hydroxy and methylsulfone metabolites of PCBs, and a population which includes about 1/3 Gypsies.
Exposure levels in the contaminated district are higher than those in most environmentally exposed populations today, but are certainly lower than those resulting from accidental poisonings. Nevertheless, the wide variability within this population, the substantially lower PCB burdens in the control district, and the study size will enable a statistically powerful investigation of dose-response and interactions with factors influencing susceptibility such as heavy metals, gender, and ethnicity. Banking of specimens will allow for long-term follow-up and utilization of new technologies not yet available. If no associations are found, the lower US levels and the decline in countries such as the Slovak Republic could provide some reassurance.