Academic journal article Environmental Health Perspectives

The Importance of Weight-Normalized Exposure Data When Issuing Fish Advisories for Protection of Public Health. (Research Articles)

Academic journal article Environmental Health Perspectives

The Importance of Weight-Normalized Exposure Data When Issuing Fish Advisories for Protection of Public Health. (Research Articles)

Article excerpt

Public health protection from environmental contaminants requires an understanding of the extent of contamination and of the extent of exposure to the contamination. My argument here is that weight-normalized, species-specific, individual-consumption pattern data are vital for determining exposure levels used to ascertain health protection measures and impacts from consuming contaminated fish. This study demonstrates the importance of adequate consumption pattern data for determining exposure distributions used for public health protection by examining three populations exposed to methylmercury through fish consumption: one recreational angler population and two Native-American populations. I compared exposure distributions derived from empirically derived species-specific, individual-consumption data from the three populations and exposure distributions derived, in part, from summary statistics for populations. In so doing, I conducted sensitivity analyses and population-specific probabilistic assessments of exposure. Although the goals of present-day accepted practices--using exposure distributions derived partly from point-estimate-based consumption and body-weight values--are laudable, results presented here indicate that weight-adjusted intake values for a population of concern are warranted when determining exposure distributions and should not be neglected in a health assessment instigated by available data on contaminant concentrations. If individual intake data are unobtainable, raw data from similar populations or tabulated values providing contaminant intake normalized for body weight may be viable alternatives to default values, and can be used to adequately protect public health. Without weight-normalized consumption pattern data to determine exposure, health assessment conclusions can mislead the public and have diminishing protective value. Key words: consumption data, contaminant data, exposure data, fish, fish advisories, mercury, tolerable daily intake.

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When contaminants are found in fish, concern regarding the concentrations of these compounds in the fish can raise the question "Are these fish safe to eat?" In response, local health jurisdictions or other health and environmental agencies frequently use contaminant concentrations along with point estimate-based values for consumption and body weight to determine exposure levels to the population. However, actual rates and values for the population of concern may differ considerably from the default values used, especially when subpopulations, such as those who are more sensitive or high fish consumers, are considered.

Under certain circumstances, this approach may be acceptable because minimizing exposure to contaminants is the primary goal of an assessment. However, with respect to fish contaminants such as mercury, the reduction in exposure must be weighed against the impact on fish consumption patterns of populations that rely on fish as a protein source. Also, cultural, spiritual, and historical practices of the populations must be considered. Weighing these various aspects is not a trivial undertaking, because negative effects from mercury exposure have been well documented, as have positive effects from eating fish. Exposure through diet has resulted in increased body burdens of methylmercury in human populations (1,2). Catastrophic exposures in communities in Japan and Iraq produced severe toxic and teratogenic effects (3). Prenatal exposure of the fetus can lead to central nervous system damage, which can produce neurotoxic effects in children (1,2). These consequences from overexposure must be weighed against the benefits of fish consumption because it is an excellent source of protein that is low in saturated fats and high in essential nutrients, including vitamin D and [[omega].sub.3] fatty acids. Also, fish consumption has been linked to reduction of cardiovascular disease and osteoporosis. …

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