Differences in elimination rates of methylmercury between two genetic variant strains of mice.

This study demonstrates an intraspecies difference in elimination of methylmercury between two genetic variant strains of mice. Following a single non-toxic dose of 203Hg labeled methylmercury (0.5 mg Hg/kg i.p.), the half-time of 203Hg elimination in the CBA/J inbred strain was 7.4 days compared to 3.0 days in the CFW strain. The fecal excretion rate of 203 Hg was the same for both strains, whereas urinary excretion rate was 5-fold higher in the CFW strain than in the CBA/J strain. The higher excretion rate in the CFW strain accounted for significant lowering of mercury concentrations in terminal tissue samples. The mercury burden in the pelt relative to the terminal body burden was similar for the two strains suggesting that elimination via the fur plays no significant role in the difference in overall excretion rate. Intraspecies differences in methylmercury elimination has direct implications for human exposures where a wide variation in kinetics has been observed. This animal model will be useful in studying the mechanism of urinary excretion of methylmercury and provide insight into more effective antidotal procedures.