Research Blood Mercury Reporting in NHANES: Identifying Asian, Paciﬁc Islander, Native American, and Multiracial Groups Jane M. Hightower,1 Ann O’Hare,2 German T. Hernandez 3 1Department of Internal Medicine, California Paciﬁc Medical Center, San Francisco, California, USA; 2Department of Medicine, Veterans’s Administration and University of California San Francisco, San Francisco, California, USA; 3Department of Medicine, University of California San Francisco and San Francisco General Hospital, San Francisco, California, USA INTRODUCTION: Asians, Paciﬁc Islanders, and Native Americans are a potentially high-risk group for dietary exposure to methylmercury through ﬁsh consumption. However, blood mercury levels in this group have not been identified in recent reports of the National Health and Nutrition Examination Survey (NHANES) for the years 1999–2002. METHODS: We used NHANES data from 1999–2002 to obtain population estimates of blood mer- cury levels among women of childbearing age classiﬁed as belonging to the “other” racial/ethnic group (Asian, Paciﬁc Islander, Native American, and multiracial; n = 140). Blood mercury levels in this group were compared with those among all other women participants, classiﬁed as Mexican American, non-Hispanic black, non-Hispanic white, and “other” Hispanic. RESULTS: An estimated 16.59 ± 4.0% (mean ± SE) of adult female participants who self-identiﬁed as Asian, Paciﬁc Islander, Native American, or multiracial (n = 140) had blood mercury levels ≥ 5.8 µg/L, and 27.26 ± 4.22% had levels ≥ 3.5 µg/L. Among remaining survey participants (n = 3,497), 5.08 ± 0.90% had blood mercury levels ≥ 5.8 µg/L, and 10.86 ± 1.45% had levels ≥ 3.5 µg/L. CONCLUSIONS: Study subjects in NHANES who self-identiﬁed as Asian, Paciﬁc Islander, Native American, or multiracial had a higher prevalence of elevated blood mercury than all other racial/ethnic participants in the survey. Future studies should address reasons for the high mercury levels in this group and explore possible interventions for lowering risk of methylmercury exposure in this population. KEY WORDS: Alaskan Natives, American Medical Association, Asians, Centers for Disease Control, fish, mercury, methylmercury, multiracial, National Health and Nutrition Examination Survey, Native Americans, Paciﬁc Islanders, reference dose, women. Environ Health Perspect 114:173–175 (2006). doi:10.1289/ehp.8464 available via http://dx.doi.org/ [Online 21 September 2005] There is growing public awareness of risk of methylmercury exposure associated with ﬁsh consumption (Hightower and Moore 2003; Knobeloch et al. 2005). Although omega-3 fatty acids in fish have been associated with healthful beneﬁts, there is increasing evidence that the methylmercury content in some ﬁsh, if consumed too frequently, can lead to adverse health effects. The predominant concerns at this time include cardiovascular disease (Frustaci et al. 1999; Guallar et al. 2002; Rissanen et al. 2000; Salonen et al. 1995, 2000; Sørensen et al. 1999; Virtanen et al. 2005), autoimmune disease (Bagenstose et al. 1999; Bernier et al. 1995; Bigazzi 1994; Nielsen and Hultman 2002; Silva et al. 2004; Stejskal and Stejskal 1999; Stejskal et al. 1999; Via et al. 2003), infertility (Choy et al. 2002; Dickman and Leung 1998; Leung et al. 2001; Sheiner et al. 2003), neuropsychiatric effects (Beuter and Edwards 2004; Yokoo et al. 2003), and subjective complaints (Fukuda et al. 1999). Furthermore, many of these adverse health effects may occur at mercury levels previously thought to be safe. The fetus has been the greatest concern because permanent damage to the developing brain can occur with methylmercury expo- sure. The U.S. Environment Protection Agency’s reference dose for mercury was based on a cord blood concentration of 5.8 µg/L and corresponds to a maternal intake of 0.1 µg Hg/kg body weight/day. However, it has been argued that this concentration should be low- ered to 3.5 µg/L, based on more recent obser- vations showing that cord blood mercury concentrations are approximately 70% higher than maternal concentrations (Stern and Smith 2003). It is of importance to note that mercury concentration across the placenta was not considered when the reference dose was established (Mahaffey 2005; Rice 2004; Rice et al. 2003). Fish consumption accounts for most of the daily intake of mercury compounds in the United States, with lesser contributions from elemental mercury from mercury vapor in den- tal amalgams. Urine mercury is a reﬂection of inorganic or elemental exposure, as occurs with dental amalgams, magical uses of elemental mercury, and herbs and medicines adulterated with inorganic mercury. Only small amounts of methylmercury, which is consumed primar- ily through ﬁsh consumption, is metabolized to inorganic mercury and excreted in the urine (Dye et al. 2005). There is also growing recognition within the medical community of the clinical impor- tance of methylmercury exposure and of the connection between blood mercury levels and consumption of ﬁsh and shellﬁsh products that are high in mercury. The American Medical Environmental Health Perspectives • VOLUME 114 | NUMBER 2 | February 2006 Association (AMA) has advocated that physi- cians “assist in educating patients about the relative mercury content of ﬁsh and shellﬁsh products and make patients aware of the advice contained in both national and regional consumer ﬁsh consumption advisories” (AMA 2004). Since 1999, the National Health and Nutrition Examination Survey (NHANES) has reported total whole-blood mercury levels in children 1–5 years of age and in women 16–49 years of age. Recent reports based on NHANES data for 1999–2002 have examined blood mercury levels among the major racial/ethnic groups but have not examined blood mercury levels among those classified as “other” racial/ethnic group. The “other” group is of interest because it includes people at potentially high risk for methylmercury exposure through fish consumption, such as Asians, Paciﬁc Islanders, and Native Americans (including Alaskan Natives) [Centers for Disease Control and Prevention (CDC) 2004, 2005; National Center for Health Statistics 2005; Sechena et al. 2003]. Materials and Methods This study complies with all applicable require- ments of the U.S. human subject and research regulations. This project was reviewed by the Institutional Review Board of the California Pacific Medical Center and was declared exempt. Data were obtained from public access databases and contained no identiﬁers. Data sources. NHANES is a complex, stratiﬁed, multistage probability cluster survey of a representative sample of the noninstitu- tionalized civilian population (CDC 2005; National Center for Health Statistics 2005). We used data from the most recent NHANES (1999–2002) to compare blood mercury levels among women 16–49 years of age in the “other” racial/ethnic group (this Address correspondence to J.M. Hightower, 2100 Webster St., Ste. 418, San Francisco, CA 94115 USA. Telephone: (415) 923-3025. Fax: (415) 749-5722. E-mail: jhightowermd@aol.com G.T.H. is supported by the W.K. Kellogg Scholars in Health Disparities Program. A.O. is supported by a Research Career Development Award from the Health Services Research and Development Service, Department of Veterans Affairs. The authors declare they have no competing ﬁnancial interests. Received 4 July 2005; accepted 21 September 2005. 173