Little is known about the consequences of early life exposure to most common environmental chemicals, including arsenic. This constitutes a critical gap in knowledge, since our recent findings from Chile suggest that early life exposure to arsenic results in disturbing increases in young adult mortality from several cancers, including lung cancer, bladder cancer, kidney cancer, as well as non-cancer causes of death, including myocardial infarction, chronic renal failure and chronic respiratory disease. Arsenic is a remarkable toxicant already known to affect multiple organ systems in exposed adults, including increased incidence of several cancers, cardiovascular disease, chronic respiratory disease and diabetes. We have been following a cohort of 650 children in Bangladesh, approximately half of whom had a wide range of exposure to arsenic in drinking water in early life, up to 1000μg/L, while the other half were never exposed to more than 10 μg/L in water. To date, our focus has been on respiratory disease, and we have found a marked increase in respiratory symptoms in the exposed children at ages 7-17 years, including wheezing and shortness of breath. We propose to continue following this unique cohort of children, not only to look for progression of respiratory disease, but also to add additional markers of early life effects for several other important chronic diseases. These include early markers and risk factors for cardiovascular disease (blood pressure, serum lipids, body mass index, and hemoglobin), diabetes (fasting blood sugar and glycosuria), and chronic renal effects (creatinine and serum ß2-microglobulin). We also plan a pilot investigation of arsenic in deciduous teeth as a biological marker for in utero and early childhood exposure. Studying the effects of early life arsenic exposure is a public health priority, since millions of pregnant mothers and children in the US and worldwide are exposed to arsenic in drinking water above the current drinking water standard of 10 μg/L. If further study confirms our preliminary evidence that early life exposure is important to the long-term health of exposed children, then much more attention must be paid to preventing early life arsenic exposure.

Arsenic is a common environmental pollutant and associated with adverse health outcomes in humans including cancer. Less well known, but equally important, is evidence that arsenic is immunotoxic. This pollutant readily crosses the placenta and there is mounting evidence that the developing immune system is more sensitive to chemical insult than the immune system of adults. Yet few studies have examined the effect of early life exposure to either arsenic on children's immune functioning. We propose, therefore, to extend the follow-up of a birth cohort recruited in Bangladesh whose early life exposure to arsenic. We will utilize archived biospecimens to determine prenatal and early postnatal exposure to arsenic and collect additional blood samples that will be used to measure vaccine antibody levels in the children who are now 5 years of age. This will allow us to accomplish the following aims: 1) Determine the relationship between prenatal arsenic exposure and infectious diseases morbidity, 2) Determine the relationship between prenatal arsenic exposure and development of humoral immunity against human pathogens, and 3) Explore the association between prenatal arsenic and changes in immune profiles in peripheral leukocytes in paired cord-infant blood samples. Completion of the proposed research is expected to provide new insights into the immunomodulatory effects of environmental exposure during critical windows of development in children. This information addresses an important gap in our knowledge regarding the developmental toxicity of arsenic exposure at environmentally- relevant concentrations in susceptible populations. The outcomes from this research will be clinically relevant and help to inform public health interventions that can reduce the burden of disease in children.

While lead poisoning has been extensively studied, exposure levels remain elevated in many vulnerable populations. Other toxic metals such as arsenic and manganese are also elevated in the environment, but their effects on neurodevelopment are poorly understood. Perhaps more importantly, the effects of mixed metal exposures are poorly understood, yet this exposure scenario is most reflective of the real world. In this project we will pool the data and resources from 3 cohort studies of metals and neurodevelopment. One in a developing country-Bangladesh, where metal exposures are unusually high, one in Mexico, a middle income country where metal exposures are moderately high, and one in a developed Country-Tar Creek, OK, where exposures are representative of a community near a US toxic waste site. These cohorts allow us to overcome barriers that prevented research in both metal mixtures and the role of developmental windows in neurotoxicology. Our program will have a final sample size of 2600 children with prospective data on metal exposure, and repeated neurophenotype measures. This will give us sufficient power to model the effects of joint exposures to As/Pb, As/Mn and Mn/Pb and their 3 way interactions on neurodevelopment. In addition, as we have longitudinal exposure data, we can compare the effects of metal exposure during different developmental windows (i.e. pre vs post-natal exposure) on neurodevelopment. This project is also integrated with the nonbiomedical projects. For example, we will partner with projects 4 and 6 to test the effect of deep wells on As/Mn biomarker levels in Bangladesh. We will also partner with Projects 5 and 6 to validate statistical methods for site characterization and the incorporation of bioavailability/metal speciation data into geospatial models of exposure assessment at the Tar Creek Superfund site.

Metals such as manganese and arsenic are of increasing public health concern since recent data demonstrates their neurotoxicity to the developing brain. However, the role of genetic susceptibility to these toxic metals is unknown. Furthermore, while lead poisoning has been studied extensively, genetic susceptibility to its toxicity is not well understood. A systematic approach to studying gene-environment interaction would have immediate impact on our understanding of how metals induce toxicity and provide biological insight for potential treatment and prevention measures. In this project we will assess data from 3 cohort studies of metals and neurodevelopment. One in a developing country-Bangladesh, where metal exposures are unusually high, one in Mexico, a middle income country where metal exposures are moderately high, and one in a developed Country- (United States) in Tar Creek, OK, where exposure are representative of a community near a US toxic waste site. Tar Creek is a Superfund Megasite and former metal mining community. The success in assembling these cohorts has laid the groundwork for further research in genetic susceptibility to metals. Our 3 cohorts combined yield a sample of 2600 children with prospective data on metal exposure, and repeated neurophenotype measures; sufficient power to discover and to validate genetic susceptibility genes/SNPs. Using a genome-wide approach, we will discover susceptibility variants in a Discovery phase, and then Validate our findings in an independent sample of children while controlling for multiple comparisons. Furthermore, we will integrate with Project 3 (Genetic Mechanisms of Metal Neurotoxicity) to determine other biological pathways relevant to metal toxicity using state of the art siRNA technology to identify genes/pathways which promote/inhibit metal toxicity. This project represents perhaps the first large scale coordinated study of genetic susceptibility to metal toxicity and will provide biological insight into the mechanisms by which metals produce toxicity.

Dr. Maitreyi Mazumdar is Assistant In Neurology at Children's Hospital Boston and Instructor In Neurology at Harvard Medical School. The candidate's long-term goal is to develop an Independent research career focusing on the role of environmental contaminants in the development of neurological Injury and disease In children. Dr. Mazumdar's Interests in this field developed during her Fellowship in neurodevelopmental toxicology, when she became aware of Investigations of the effects of environmental arsenic exposure on children in Bangladesh. The proposed career development plan incorporates a multi-disciplinary program designed to provide an Intense, closely mentored, patient-oriented research experience, associated with a comprehensively structured didactic curriculum In environmental epidemiology, exposure assessment, advanced biostatistics, and risk assessment. Under the mentorship of Dr. David Christiani, Professor of Environmental Health at the Harvard School of Public Health, the candidate will investigate the effect of prenatal and early childhood arsenic exposure on neurodevelopment of children In Bangladesh, a country with high levels of arsenic contamination In groundwater. This research will examine epidemiological associations of arsenic exposure with measures of neurological development In infants and children, including 1) head circumference, 2) hearing impairment, 3) motor dysfunction, and 4) formal neurocognitive testing. The studies will be conducted in a cohort of 600 infants who are participating In a current study of reproductive health effects of arsenic. Additional children between the ages of 12 and 24 months will also be recruited neurodevelopmental assessment. The superb clinical, research, and teaching facilities of Children's Hospital Boston, Harvard Medical School, and the Harvard School of Public Health will support Dr. Mazumdar in meeting the objectives of her career development and research plans. RELEVANCE (See instructions): Studies have linked chronic exposure to arsenic with adverse health outcomes in adults, but its effect on children is unknown. The proposed work will examine the neurodevelopmental effects of prenatal and early- life arsenic exposure on Infants and young children in Bangladesh, an area with extremely high groundwater arsenic concentrations. Findings from this work will directly inform ongoing environmental risk assessment.

Inorganic Arsenic is a toxic compound with significant public health impact. The Environmental Protection Agency (EPA) has identified 1,300 sites on its National Priorities List (NPL), and arsenic has been found in at least 781 of these sites. Arsenic is also a by-product of coal combustion, as well as a naturally occurring water contaminant in many regions of the world, including the USA, Exposure may occur by a variety of pathways including inhalation of dusts in air, ingestion of contaminated soil or water, or through the food chain. Arsenic has been associated with a number of adverse health effects. However, the precise relation of arsenic to pregnancy outcomes has not been established. Thus, we wish to extend the previous work we conducted in Taiwan and Bangladesh to an assessment of birth outcomes in a prospective, repeated measures study of expectant mothers and their newborns in Bangladesh. Currently, an estimated 133 million people in Bangladesh are at risk of disease from drinking arsenic-contaminated drinking water. The proposed studies will evaluate standard birth outcomes at exposure levels that are relevant not only to the U.S. population, but also globally. The proposed studies will assess this risk in a population with a wide range of exposure, from low to high. Together, these data will add substantially to the existing risk assessment information by elucidating birth outcomes after arsenic exposure; the role of methylated forms of arsenic in the urine as biomarkers of exposure and risk; and an evaluation of a new potential marker of adverse outcome (proteomic profiles), as well as the influence of candidate genetic susceptibility traits as risk modifiers. This project is relevant to the overall strategic plan of the NIEHS in several ways. Firstly, we will examine a range of health effects of a significant environmental toxicant, arsenic. Secondly, we will define human biomarkers of exposure, early effects, and genetic susceptibility to arsenic exposure. Thirdly, we will examine exposure-response relationships for arsenic-induced birth outcomes. Fourthly, we will incorporate new, sensitive toxicogenomic technology (proteomics) to assess potentially novel biomarkers of exposure and effect in a molecular epidemiologic setting. Lastly, the study is international, sited in the developing world. The proposed human studies will fill important research gaps in our knowledge of arsenic toxicity and inform clinical and public health interventions.