| || || Kumar, Maureen Christina.|
| || || Human mercury exposure in relation to fish consumption in Fiji |
Author:Kumar, Maureen Christina.
Institution: University of the South Pacific.
Call No.: Pac RA 1231 .M5 K86 2006
Copyright:Under 10% of this thesis may be copied without the authors written permission
Abstract: Fish is the major source of mercury exposure in humans and data on mercury levels in fish and other seafoods from the Pacific Islands are scarce. Mercury (Hg) and its compounds pose a significant threat to human health, particularly to women who are pregnant or of childbearing age and young children. The aim of the initial study was to measure total Hg content in several types of seafoods, which are commonly consumed in the Fiji Islands and calculate from the results whether there is a significant health risk arising from fish consumption. Total Hg in the edible tissues of 200 seafood samples of different types (whole fish, fish steaks, shellfish, and canned fish) and species was analysed. Total Hg was determined by strong acid (HNO3/H2SO4/HCl) digestion, addition of bromine chloride, reduction with sodium borohydride and analysis via flow injection cold vapour atomic absorption spectroscopy. The total Hg levels in some of the large predatory fish species (marlin and swordfish) exceeded the Food and Agriculture Organization (FAO)/World Health Organization (WHO) Codex Alimentarius guideline level of 1 mg/kg. Other types of fish steaks, smaller reef fish, shellfish, canned tuna and mackerel had average levels below the guidelines. Although a limited amount of analyses were conducted on some fish species, it is clear that health risks, particularly to pregnant women, exist from consuming relatively small quantities (<1-2 portions per week) of a number of the larger fish species, such as shark, marlin, swordfish, sunfish, large albacore tuna (canned and fresh), bigeye tuna, sailfish and large walu. For the marlin, swordfish, shark and sunfish the calculated safe level of human consumption is less than 1 portion size/week and for bigeye tuna it is about 1 portion per week. Frequent consumption of more than the recommended amount of these fish could lead to health problems. Issuing of fish consumption advisory is recommended since the total Hg levels in predatory fish are high and these fish are sold cheaply, more people tend to buy and consume these fish species. The mercury in hair study confirmed this need, however, careful risk communication is needed as fish consumption has many health benefits. A follow-up study was initiated to determine human mercury exposure in the fish consuming population of Fiji. Hair was used as a biomarker of exposure. A total of 92 participants who volunteered their consent were part of this study of which 82 were fish consumers and 10 were a vegetarian control group. The fish consumers were from the Suburban Suva-Lami area included the participants from USP, Kalekana Settlement and Muaivuso village and Outer Island dwellers included participants from Dravuni and Daku villages of Kadavu. The method used for the determination of total Hg in human hair used was similar to that for fish tissue digestion mentioned earlier. The background total Hg in hair was 0.17 μg/g determined in the control group. In the total fish consuming population the men (n = 20) had total hair [Hg] of 5.06 μg/g and consumed an average of 7 serves of fish meals/week, women (n = 56) had hair [Hg] of 2.73 μg/g and consumed an average of 5 serves of fish meals/week and children (n = 6) had hair [Hg] of 3.09 μg/g and consumed average of 5 serves of fish meals/week. The mean total [Hg] in hair of the overall fish consuming population (n = 82) was 3.33 μg/g consuming an average of 5.5 servings of fish meals/week. The total hair [Hg] in all men exceeded the USEPA safety limit of approximately 1μg/g in hair and 85% of them exceeded the recommended FAO/WHO safety limit of 3μg/g in hair. Only 69% of the childbearing age women had total hair [Hg] below the FAO/WHO safety limit and 6% of the childbearing age women had hair [Hg] above WHO safety limit of 10 μg/g, an earlier safety limit derived from the Iraqi data which estimated level at which health effects occur but did not include some uncertainty factors included in later safety limit. In the total fish consuming population 44% of the participants have exceeded the FAO/WHO safety limit.