Variation in cadmium content of caribou tissues from northern Québec.

Samples of kidney, liver, skeletal muscle, heart, mesentery and rumen wall were collected during 1985-1986 in northern Québec from 121 caribou belonging to the Rivière George herd. Significant seasonal variations were found for cadmium concentration in kidneys, liver and skeletal muscles, the level being higher in winter than in autumn. The concentration in liver and kidneys increased with age, while the effect of this factor was complex in skeletal muscles. Sex-related differences were found in muscle and liver levels of cadmium. According to season, sex and age, mean dry-weight concentrations varied between 5.6 and 51.3 micrograms g-1 in kidneys, 1.7 and 4.0 micrograms g-1 in liver and 0 and 0.27 microgram g-1 in skeletal muscles. Season and sex-related differences could be explained by seasonal variation in cadmium intake and by the annual weight cycle exhibited by caribou kidneys and liver. Because of the relatively high cadmium content, it was recommended not to consume liver and kidneys of free-ranging caribou in Québec; this restriction did not apply to meat, heart, mesentery or rumen wall that contained limited concentrations of this heavy metal.