Fish consumption and bioindicators of inorganic mercury exposure

摘要

Background: The direct and close relationship between fish consumption and blood and hair mercury (Hg) levels is well known,rnbut the influence of fish consumption on inorganic mercury in blood (B-IHg) and in urine (U-Hg) is unclear.rnObjective: Examine the relationship between fish consumption, total, inorganic and organic blood Hg levels and urinary Hgrnconcentration.rnMethods: A cross-sectional study was carried out on 171 persons from 7 riparian communities on the Tapajos River (BrazilianrnAmazon), with no history of inorganic Hg exposure from occupation or dental amalgams. During the rising water season in 2004,rnparticipants responded to a dietary survey, based on a seven-day recall of fish and fruit consumption frequency, and socio-rndemographic information was recorded. Blood and urine samples were collected. Total, organic and inorganic Hg in blood as wellrnas U-Hg were determined by Atomic Absorption Spectrometry.rnResults: On average, participants consumed 7.4 fish meals/week and 8.8 fruits/week. Blood total Hg averaged 38.6±21.7 μg/L, andrnthe average percentage of B-IHg was 13.8%. Average organic Hg (MeHg) was 33.6± 19.4 μg/L, B-IHg was 5.0±2.6 μg/L, whilernaverage U-Hg was 7.5±6.9 μg/L, with 19.9% of participants presenting U-Hg levels above 10 μg/L. B-IHg was highlyrnsignificantly related to the number of meals of carnivorous fish, but no relation was observed with non-carnivorous fish; it wasrnnegatively related to fruit consumption, increased with age, was higher among those who were born in the Tapajos region, andrnvaried with community. U-Hg was also significantly related to carnivorous but not non-carnivorous fish consumption, showed arntendency towards a negative relation with fruit consumption, was higher among men compared to women and higher among thosernborn in the region. U-Hg was strongly related to I-Hg, blood methyl Hg (B-MeHg) and blood total Hg (B-THg). The Odds Ratiorn(OR) for U-Hg above 10 μg/L for those who ate >4 carnivorous fish meals/week was 4.00 [1.83-9.20].rnConclusion: This study adds further evidence to a positive relation between fish consumption and IHg in both blood and urine, whichrnmay result from absorption of IHg from fish or from demethylation of MeHg. The findings support the importance of assessing IHgrnexposure in fish-eating communities. Further studies should examine the potential toxicity of IHg in heavy fish consumers.