The importance of weight-normalized exposure data when issuing fish advisories for protection of public health.

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.