May 2006: (I)250 –256 Brief Critical Review Awareness of Fish Advisories and Mercury Exposure in Women of Childbearing Age Sohyun Park, PhD, and Mary Ann Johnson, PhD Methylmercury crosses the placenta and increases the risk of impaired neurodevelopment in the fetus. Fed- eral guidelines for ﬁsh intake and ﬁsh advisories are in place to help people of all ages limit their exposure to mercury from ﬁsh. However, recent studies suggest that the awareness of ﬁsh advisories is low among women of childbearing age. Fish intake is strongly correlated with hair mercury concentrations. In women in states with ﬁsh advisories, hair mercury concentrations were 7-fold higher in women who consumed 20 or more servings of ﬁsh than in those who reported no ﬁsh consumption in the past 3 months (0.59 vs. 0.08 g/g). Among this high ﬁsh con- sumption group, the 75th and 95th percentile of hair mercury concentrations were 0.99 and 2.29 g/g, respectively. This is of concern because the US Envi- ronmental Protection Agency (EPA) recommends that hair mercury be less than 1 g/g. Public health campaigns to reduce mercury exposure need further reﬁnement to reach women of childbearing age. © 2006 International Life Sciences Institute doi: 10.1301/nr.2006.may.250 –256 INTRODUCTION Mercury is a toxic heavy metal that can be found in ﬁsh, thermometers, dental amalgams, vaccine preserva- tives, and in the atmosphere. The primary mercury source in humans is methylmercury-contaminated ﬁsh. 1,2 Methylmercury in ﬁsh muscle is bound to protein; there- fore, skinning, trimming, and cooking do not reduce the content. 3 Methylmercury toxicity is associated with se- rious health problems such as mental retardation, cere- bral palsy, deafness, blindness, and dysarthria due to prenatal exposure in infants and children, as well as sensory impairment, motor impairment, and adverse ef- fects on the cardiovascular system in adults. 2,4 Methyl- mercury has profound adverse effects on the immature central nervous system of the fetus and infant and fewer effects on the mature central nervous system of adults. 2,5,6 Almost all methylmercury (90%–100%) is rapidly absorbed after ingestion and spread throughout the human body. 4 An amino acid carrier may transport methylmercury across the blood-brain barrier and result in accumulation of methylmercury in the fetal and adult brain. 7 In humans, the half-life of methylmercury is about 50 days (range, 48 –53 days) in the blood measured in blood and hair samples and 70 to 80 days in the whole body. 4 The major excretory pathways of methylmercury are bile, feces, urine, and breast milk. 4 During pregnancy, methylmercury traverses the pla- centa and is amassed in the blood, brain, and other tissues of the fetus. 2,3 Therefore, women of childbearing age are one of the special populations targeted for ﬁsh advisories to minimize their exposure to methylmer- cury. 8 Despite the critical effects of methylmercury on neurodevelopment in the fetus and in infants, the prev- alence of awareness of ﬁsh advisories related to mercury was low (20%) in women of childbearing age. 1,9 BIOMARKERS OF MERCURY EXPOSURE There are several biomarkers for measuring mercury concentration in the body, such as hair, blood, cord blood, and breast milk. 2,4 Among those biomarkers, both hair and total blood mercury concentration are reason- able biomarkers for methylmercury concentration in the blood. 4,10 Total mercury in blood reﬂects the most recent exposure of both methylmercury and inorganic mercury; however, methylmercury is the dominant form of total mercury in blood. 4 There is a high correlation between blood mercury concentration and estimated mercury in- take. 10 In contrast, hair mercury concentration reﬂects relatively long-term mercury exposure according to the hair length analyzed, and indicates history of blood mercury concentration. 10 Methylmercury is about 90% of total mercury in hair. 4 The average head hair growth Drs. Park and Johnson are with the Department of Foods and Nutrition, Faculty of Gerontology, The Uni- versity of Georgia, Athens, Georgia, USA. Please address all correspondence to: Dr. Mary Ann Johnson, Department of Foods and Nutrition, The University of Georgia, Dawson Hall, Athens, GA 30602; Phone: 706-542-2292; Fax: 706-542-5059; E-mail: mjohnson@fcs.uga.edu. 250 Nutrition Reviews, Vol. 64, No. 5