Trends in the levels of some chlorinated hydrocarbon residues in adipose tissue of Canadians.

Trends in the levels of hexachlorobenzene, hexachlorocyclohexanes, oxychlordane, t-nonachlor, heptachlor epoxide, dieldrin, DDTs and polychlorinated biphenyls in adipose tissue of the Canadian population were followed from 1969 to 1985. Residues of lindane, dieldrin and p,p'-DDT continuously and significantly (P<0.025) decreased during that time, coinciding with restrictions on their use. Other residues also decreased significantly between 1969 and 1985, although not always continuously, while t-nonachlor levels did not change significantly since 1972. In general no consistent and/or significant differences were observed between the sexes, but in some instances differences were found for a particular residue in a given year. Three arbitrarily chosen age groups (0-25; 26-50 and > or =51 years) showed a downward trend in residue levels with time. The results of the surveys also indicate an increase in adipose tissue burden of chlorinated hydrocarbons with age, but this increase became apparently less significant with increasing age.