摘要：National fish consumption advisories that are based solely on assessment of risk of exposure to contaminants without consideration of consumption benefits result in overly restrictive advice that discourages eating fish even in areas where such advice is unwarranted. In fact, generic fish advisories may have adverse public health consequences because of decreased fish consumption and substitution of foods that are less healthy. Public health is on the threshold of a new era for determining actual exposures to environmental contaminants, owing to technological advances in analytical chemistry. It is now possible to target fish consumption advice to specific at-risk populations by evaluating individual contaminant exposures and health risk factors. Because of the current epidemic of nutritionally linked disease, such as obesity, diabetes, and cardiovascular disease, general recommendations for limiting fish consumption are ill conceived and potentially dangerous. BOTH THE US ENVIRONMENTAL Protection Agency (EPA) and the US Food and Drug Administration (FDA) have issued national fish consumption advisories that recommend women of childbearing age restrict their consumption of fish to avoid excessive exposure to methylmercury. These advisories were issued on the basis of methylmercury levels found in fish in specific locations across the country and estimates of dietary consumption, and they were issued across the country regardless of actual levels of mercury found among human populations. Thus, we question the wisdom and the validity of the scientific basis of these advisories. First, by ignoring the benefits associated with consuming fish and the potentially decreasing fish consumption among women of childbearing age, these advisories may violate the ethical principles of beneficence: do not harm, and maximize possible benefits and minimize possible risks. 1 Second, the advisories ignore the evolution of public health’s ability to measure actual exposure to environmental contaminants among specific populations. Both advisories, which were issued in 2001 and reissued in 2004, restrict the fish consumption of women of childbearing age: the EPA’s advisory restricts consumption of recreationally caught fish to no more than 6 ounces a week; the FDA’s advisory restricts consumption of commercially caught fish to no more than 12 ounces a week. 2– 4 These consumption levels seem overly cautious after reviewing the 1999–2000 National Health and Nutrition Examination Survey (NHANES), which found that 92% of women of childbearing age (n=1709) had blood total mercury concentration levels that were below 5.8 μg/L, which is the blood level that corresponds with the EPA’s conservative reference dose. The EPA’s reference dose—the safe dose that can be consumed every day during a 70-year lifetime without any adverse health effects—was derived from the “benchmark dose” blood mercury concentration of 58 μg/L divided by a 10-fold uncertainty factor. 5 The 95th percentile geometric mean from the NHANES study was 7.13 μg/L (95% confidence interval [CI] = 5.79, 8.48), which was well below the EPA’s “benchmark dose” level of 58 μg/L. 5 Many Alaskans have no readily available alternative to fish. In fact, a large number of Alaskans rely on locally caught fish as their primary protein source. 6 Thus, for Alaska public health officials, the EPA/FDA advisories have been particularly problematic. Even though available data show methylmercury concentrations in the most frequently consumed Alaska fish (e.g., chinook, coho, sockeye, chum, and pink salmon) are among the lowest of all fish species (average < 0.05 mg/kg), 7 many Alaskans, particularly Alaska Natives, have begun questioning the safety of their traditional diets. The adverse effects on public health in communities that have moved away from traditional foods have been well documented. 8, 9 In Alaska, there is now evidence that Alaska Natives are replacing their traditional diets with foods that are far less healthy, 10, 11 and Alaska Natives are experiencing a significant increase in the prevalence of diabetes 9 and overweight/obesity. 12 Additionally, many Alaskans have serious problems with alcohol use and lack of physical exercise, 13 conditions that may be partially attributed to the abandonment of a traditional diet and lifestyle. 14 Alaska’s public health response to the EPA/FDA advisories has been to recommend unrestricted consumption of fish caught in Alaska waters. 15 Furthermore, a biomonitoring program has been implemented to determine actual exposure levels of environmental contaminants among concerned populations. The program tests methylmercury exposure among pregnant women, with limited testing among women of childbearing age. It is expected to expand and eventually include all women of childbearing age; it also will test exposure to other chemicals of concern, such as polychlorinated biphenyls (PCBs), pesticides, and heavy metals. Exposure is determined by analyzing total mercury concentrations in hair, which is both noninvasive and relatively inexpensive. Hair mercury is a well-established biomarker for determining methylmercury exposure among fish-eating populations. 16– 20 The Alaska Division of Public Health (ADPH) began its Statewide Mercury Hair Biomonitoring Program during June 2002, when it offered free, confidential testing to all pregnant women in Alaska. 21 The initial results of this program and the utility of targeted screening when recommending specific local-consumption advice are described in this article.
