Distribution of organochlorine pollutants in ovine dental tissues and bone

The distribution of selected lipophilic organochlorine pollutants, including two pairs of tetra- and hexa-chlorobiphenyl isomers (PCB-54, -80, -155, -169) and organochlorine pesticides [hexachlorobenzene (HCB) and 1,1-bis(4-chlorophenyl)-2,2-dichloroethene (4,4'-DDE)], in ovine dental pulp, dentine, enamel and mandibular bone was examined. Sheeps were given a single dose of individual organochlorine (1-4μmol/kg) in olive oil by intramuscular injection and sacrificed 2 months later. Organochlorine residues were determined by gas chromatography. The highest levels of organochlorines were found in bone. The lipid adjusted levels varied significantly between tissues. Lower chlorinated, metabolically unstable, non-planar PCB-54 was enriched in enamel, while higher chlorinated, metabolically resistant, planar PCB-169 was preferentially retained in pulp. The ratio of planar to non-planar PCB homologues and pesticides (PCB-169/-155, PCB-80/-54, HCB/4,4'-DDE) decreased in the order pulp>dentine>enamel, suggesting that besides compound's lipophilicity and the tissue's lipid content, other physicochemical properties of organochlorines and tissue specific characteristics affect their distribution.