Interrelationships among hair mercury levels, fish-eating habits and fatty acid composition of serum lipids

Abstract

Scalp hair and blood samples were collected from 151 persons who were living in several places in Kagoshima-prefecture and supposedly had no abnormal exposures to mercury compounds. Hair was analysed for total mercury and blood was analysed for serum lipid fatty acids. The study subjects were also individually questioned on the amounts of average fish intake in a day. Results obtained were as follows:1) Hair mercury levels were significantly higher in males than in females, the average values being 11.95±9.15ppm with a maximum of 45.5ppm for males and 7.05±5.36ppm with a maximum of 25.8ppm for females. The hair mercury levels increased with increases in the amount of daily fish consumption for both sexes with an indication that such increases might be attributable to the fish consumption.2) Serum concentrations of eicosapentaenoic acid (20:5, EPA) and docosahexaenoic acid (22:6, DHA) both of which belong to the ω-3 series of polyunsaturated fatty acid, and the value of EPA/AA (a ratio of 20:5 for arachidonic acid) also increased with an increase of daily fish consumption for both sexes, indicating that these values can give quite valuable information in the assessment of individual fish consumption.3) When comparison was made taking into account of the amount of daily fish consumption, however, there were no significant differences of hair mercury levels between the sexes, particularly for those having a low intake of fish.4) There were no significant differences between the sexes for the serum concentrations of eicosapentaenoic acid and docosahexaenoic acid but the value of EPA/AA was significantly higher in males than in females, suggesting that males have a partiality for a fish diet as compared with females.5) When the serm concentration of eicosapentaenoic acid or docosahexaenoic acid was used as an indicator for evaluation of the amount of fish consumption, the hair mercury levels showed a tendency to increase along with the values of these indicators for both males and females. However, the hair mercury levels were significantly higher in males than in females even when the comparison was made taking into account of the values of these indicators, which could not be explained only by the amount of fish consumption.