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During much of the twentieth century, Jersey City, New Jersey was the leading center of chromate production in the United States. Chromate production produced huge volumes of chromium ore-processing residue containing many parts per million of hexavalent chromium. Starting in the 1990s, we undertook a series of studies to identify exposed populations, sources and pathways of exposure and the effectiveness of remediation activities in Jersey City. These studies revealed the effectiveness and success of the remediation activities. The sequence of studies presented here, builds on the lessons learned from each preceding study and illustrates how these studies advanced the field of exposure science in important ways, including the use of household dust as a measure of exposure to contaminants originating in the outdoor environment; development of effective and reproducible dust sampling; use of household dust to track temporal changes in exposure; understanding of the spatial relationship between sources of passive outdoor particulate emissions and residential exposure; use of focused biomonitoring to assess exposure under conditions of large inter-individual variability; and utility of linking environmental monitoring and biomonitoring. For chromium, the studies have demonstrated the use of Cr+6-specific analytical methods for measuring low concentrations of Cr+6 in household dust and understanding of the occurrence of Cr+6 in the background residential environment. We strongly recommend that environmental and public health agencies evaluate sites for their potential for off-site exposure and apply these tools in cases with significant potential as appropriate. This approach is especially important when contamination is widespread and/or a large population is potentially exposed. In such cases, these tools should be used to identify, characterize and then reduce the exposure to the off-site as well as on-site population. Importantly, these tools can be used in a demonstrable and quantifiable manner to provide both clarity and closure to concerned stakeholders. [ABSTRACT FROM AUTHOR]

The paper builds on existing literature, highlighting current understanding and identifying unresolved issues about MeHg exposure, health effects, and risk assessment, and concludes with a consensus statement. Methylmercury is a potent toxin, bioaccumulated and concentrated through the aquatic food chain, placing at risk people, throughout the globe and across the socioeconomic spectrum, who consume predatory fish or for whom fish is a dietary mainstay. Methylmercury developmental neurotoxicity has constituted the basis for risk assessments and public health policies. Despite gaps in our knowledge on new bioindicators of exposure, factors that influence MeHg uptake and toxicity, toxicokinetics, neurologic and cardiovascular effects in adult populations, and the nutritional benefits and risks from the large number of marine and freshwater fish and fish-eating species, the panel concluded that to preserve human health, all efforts need to be made to reduce and eliminate sources of exposure. [ABSTRACT FROM AUTHOR]

In 2001, the U.S. Environmental Protection Agency (EPA) adopted a revised reference dose (RfD) for methyl mercury (MeHg) of 0.1 μg/kg/day. The RfD is based on neurologic developmental effects measured in children associated with exposure in uztero to MeHg from the maternal diet. The RfD derivation proceeded from a point of departure based on measured concentration of mercury in fetal cord blood (micrograms per liter). The RID, however, is a maternal dose (micro- grams per kilogram per day). Reconstruction of the maternal dose corresponding to this cord blood concentration, including the variability around this estimate, is a critical step in the RID derivation. The dose reconstruction employed by the U.S. EPA using the one-compartment phar-macokinetic model contains two areas of significant uncertainty: It does not directly account for the influence of the ratio of cord blood:maternal blood Hg concentration, and it does not resolve uncertainty regarding the most appropriate central tendency estimates for pregnancy and third- trimester-specific model parameters. A probabilistic reassessment of this dose reconstruction was undertaken to address these areas of uncertainty and generally to reconsider the specification of model input parameters. On the basis of a thorough review of the literature and recalculation of the one-compartment model including sensitivity analyses, I estimated that the 95th and 99th percentiles (i.e., the lower 5th and 1st percentiles) of the maternal intake dose corresponding to a fetal cord blood Hg concentration of 58μg/L are 0.3 and 0.2 μg/kg/day, respectively. For the 99th percentile, this is half the value previously estimated by the U.S. EPA. [ABSTRACT FROM AUTHOR]