Risk assessment of methylmercury from fish consumption in Oahu, Hawaii using hair as a biomarker of exposure

Includes bibliographical references (p. 72-78).The main purpose of this study was to assess the risk of methylmercury exposure from fish consumption in adults living in Oahu, Hawaii and to determine if demographic variables, fish consumption frequency, and fish parts eaten were associated with methylmercury body burden assessed through hair. The ultimate goal was to inform any guidelines on fish consumption, with consideration of cultural and lifestyle factors for populations that are susceptible to exposure. Persons were recruited at public areas from 5 areas of the island of Hawaii which included 110 adults (57 men and 53 women) during December, 2010 and January, 2011. Hair samples were obtained in order to measure methylmercury body burden concentrations, and a questionnaire assessed their fish consumption, demographic information, and general awareness about methylmercury and fish consumption. Hair samples were analyzed for total mercury through the Milestone Direct Mercury Analyzer (Milestone, Shelton, CT). Older men had the highest hair mercury levels, as compared to younger men and women of all age groups. Men > 45 years had a median hair mercury level of 2.00 ug/g as compared to younger men with a median 0.97 ug/g (p<0.05). Hair concentrations from older women had a median of 1.22 ug/g of mercury, as compared to 0.57 ug/g for younger women. Risk indices were calculated, and the average HI value among male residents was 1.61, which is above the safety criteria of 1.0. Among women, the average HI value was 0.92, however, among women of childbearing age, 38% had a HI > 1.0, indicating that both men and women were potentially at risk. Fish consumption was a significant contributing factor to increased hair mercury concentrations; significant variables included frequency of fish consumption, portion size of fish meal, frequency of fish consumption in conjunction with portion size, amount of fish parts consumed, and whether or not target organs (brain, head, heart) were consumed. This present study addressed methylmercury exposure among a population of healthy adults, which is uncommon for methylmercury studies since usually only susceptible populations, such as women of childbearing age and children, are examined. Although we did demonstrate that women were a susceptible population, as evidenced by values over 1.0 for a third of the women of childbearing age, men also appeared as a susceptible population, with the highest methylmercury values. Recent studies have established that cardiotoxicity is an adverse health effect of methylmercury exposure for the men at body burden levels found in this study. Since fish is an important staple for Oahu residents, proper guidelines for safe fish consumption should include consuming less than ?? pound of fish per meal at a frequency of less than one day per week, along with primarily consuming fish meat and discarding all other organs due to high methylmercury content. The benefits of fish consumption should also be highlighted, and if safe fish consumption practices are followed, residents can reap the health benefits without excessive toxicant exposure