The neonatal and childhood neurological effects of severe maternal or fetal thyroid deficiency, which may be caused by low dietary iodine, are well established. Independently, exposure to pesticides can also reduce thyroid hormone, and may exacerbate the effects of low iodine. The combination of these environmental insults may lower thyroid hormone to the extent that fetal neurobehavioral development is significantly impacted. Although Thailand has made great advances in decreasing pesticide poisoning and reducing iodine deficiency disorders (IDD), there are still many pregnant women who experience exposure to pesticides through maternal agricultural work and maternal intake of pesticide contaminated drinking water, and all of the provinces in Thailand have newborns born with iodine deficiency disorders. Considering the importance of thyroid hormones in neurobehavioral development, our main hypothesis is that pesticide exposure increases the impact of iodine insufficiency on neurodevelopment as measured in newborns by the Brazelton Newborn Behavioral Assessment Survey (BNBAS) and in 3-4 month olds by EEG/ERP (Electroencephalogram/Event Related Potential) testing. The main objectives of this planning grant are: 1) to develop and strengthen a partnership of multi-disciplinary, international researchers in Thailand and the U.S. focused on the recognition, prevention and treatment of environmental and nutritional causes of neurobehavioral deficits among Thai infants and young children;2) to demonstrate the feasibility of conducting a prospective epidemiologic study to assess the impact of maternal/fetal sub-optimal iodine levels and pesticide exposures on thyroid hormone levels and neonatal neurobehavioral development. As part of our capacity building efforts we will establish a joint research Center for Work Environment and Nutrition in Human Development at the Mahidol Faculty of Public Health to facilitate researcher and student exchanges and collaboration. For our pilot research project, 108 pregnant women will be recruited from provincial hospitals in 3 provinces. They will be asked for information on nutrition, pesticide exposures and other potential confounders. The women will provide urine and blood samples and at birth a placental cord blood sample will be collected. Samples will be analyzed for iodine, pesticide and thyroid hormone levels. Newborns will undergo neurobehavioral testing with the BNBAS. When they return for routine 3-4 month immunizations, infants will undergo neurobehavioral testing using an EEG/ERP test battery. Breast milk will be collected from mothers for pesticide and iodine measurements. Our objective is to use this pilot study to launch a prospective study of the impact of iodine insufficiency, pesticide exposure and other potential nutritional and environmental influences, on Thai children's neurodevelopment. Additionally, a long term goal of this research is to work with the Thai Ministry of Health to develop and test prevention programs focused on prenatal care settings.
Not only is it of scientific interest to examine the role of environmental conditions (iodine availability and pesticide exposures) on the thyroid and subsequent fetal development, but it also may have important policy implications for public health. Developing countries have limited resources available to address a wide range of public health problems including IID and pesticide hazards. Better knowledge of the adverse effects of the interaction of pesticide exposures and iodine insufficiency will allow for more informed decisions by doctors, individuals and government public health officers and regulators.
|Kongtip, Pornpimol; Nankongnab, Noppanun; Woskie, Susan et al. (2014) Organophosphate urinary metabolite levels during pregnancy, delivery and postpartum in women living in agricultural areas in Thailand. J Occup Health 55:367-75|