Distribution and retention of some chlorinated hydrocarbons and a phthalate in the mouse brain during the pre-weaning period.

In a quantitative retaining study and a whole-body autoradiographic study 5 14C-labelled compounds, bis-(4-chlorophenyl)trichloroethane (DDT), 2,2',4,4',5,5'-hexachlorobiphenyl (6-CB), hexachlorophene (HCP), polychlorohexadecane (PCHD) and diethylhexylphthalate (DEHP) were each administered to mice at the age of 3, 10 and 20 days. The mice were killed 24 h or 7 days after treatment and the amount of radioactivity in the whole brain was measured and its distribution studied. The retention of radioactivity was most pronounced in mice receiving DDT, PCHD, and 6-CB during the tenth day of life. Here the level of radioactivity 7 days after treatment was nearly as high as that observed after 24 h (ratio between 0.86 and 0.74). In contrast, HCP showed a rapid elimination from the brain and was hardly retained at all in the 20-day-old mouse brain. The retention of DEHP in the brain was minimal. Some of the autoradiographic sections were also subjected to myelin staining. Large amounts of radioactivity were found in the myelinated areas of the brain after HCP and PCHD administration. DDT and 6-CB showed a more even distribution within the brain and were not particularly concentrated in the myelin. There was no obvious relationship between the lipophilicity of the parent compounds and their retention in the brain.