Exposure Assessment of Mercury in Fish from Kentucky Surface Waters

Consumption of fish contaminated with mercury is the primary exposure pathway by which humans are exposed to mercury. Mercury is known to be a neurological toxin that can cause attention and language deficits, impaired memory, and impaired visual and motor function, especially in children under the age of six. In addition, mercury exposure can lead to other health problems in adults, such as damage to the kidney and increased risk of coronary heart disease. This study assesses the exposure to mercury through consumption of fish from Kentucky surface waters. The exposure assessment is based on data collected by the Kentucky Department for Environmental Protection (KDEP), Division of Water, from different streams and lakes in Kentucky and average consumption rates defined by the U.S. Environmental Protection Agency (EPA). The design of this study is established to determine if people in Kentucky are at risk of mercury contamination and whether the Kentucky fish advisory protects the population from this threat. The exposure analysis presented examines mercury in different fish species from different streams and lakes in Kentucky. Fillet samples of fish were examined by KDEP and the quantity of methylmercury was determined in micrograms per kilogram (ppm). These data were used to estimate the exposure under various scenarios for methylmercury. Exposure assessment is a major component of the risk assessment process and is used here to assess the magnitude of methylmercury contamination for people in Kentucky that consume fish. EPA has been determined the maximum contaminant level of mercury in fish to be 1 ppm, and stated that the general consumer should be advised to eat no more than 1 meal/week of noncommercial fish in the U.S. at this level. Also, they determined the reference dose of methylmercury to be 0.1 (J.g/kg of body weight/day. The result of categorizing Kentucky fishes according to EPA monthly risk-based fish consumption limits indicated that 22.8% of the fishes caught from lakes and 31.44% of the fishes from streams had a greater risk than the current Kentucky advisory would indicate. The calculated daily intakes of methylmercury have shown that the consumption of certain types of fish from lakes and streams will lead to ingestion of methylmercury that exceeds the acceptable level as determined by EPA