Interaction between sex and contaminant type attributable to males eliminating mercury at a faster rate

Abstract

The observed interaction between sex and contaminant type (polychlorinated biphenyls (PCBs) or mercury (Hg)) in adult teleost fishes is most likely due to adult males having a substantially higher Hg-elimination rate than adult females. In contrast, long-term elimination of PCBs by teleost fishes has been characterized as negligible for both sexes. In addition, the variation in the differences between the PCB ratio (ratio of whole-fish PCB concentration in males to whole-fish PCB concentration in females) and Hg ratio (ratio of whole-fish Hg concentration in males to whole-fish Hg concentration in females) across species appears to be attributable, at least in part, to variation in Hg-elimination rates of adult males across species. According to this proposed relationship, the difference between the two ratios increases with increasing Hg-elimination rate of adult males. Further, the variation in Hg-elimination rates of adult males across species appears to be partly explained by levels of certain androgens in the males. In mammals, the key androgen enhancing Hg-elimination rate in males is testosterone. Hg-elimination rate increases with increasing testosterone level. In teleost fishes, testosterone and 11-ketotestosterone are the agents likely responsible for enhanced Hg-elimination rate in adult males. I uncovered new evidence to indicate that the variability in Hg-elimination rates of adult males across strains of laboratory mice (Mus musculus) is explained, at least in part, by variability in testosterone levels in adult males across strains. Specifically, Hg-elimination rate of the adult males tends to increase with increasing testosterone level. This new evidence supported the abovementioned hypotheses.