Bioconcentration of lipophilic organochlorines in ovine dentine

The bioconcentration of lipophilic organochlorines in ovine dentine in comp arison to adipose tissue was examined. Sheep were given a single dose (0.2- 1.4 mg/kg body wt) of individual polychlorobiphenyl (PCB) congeners (tetrac hlorobiphenyls IUPAC Nos. 54 and 80, and hexachlorobiphenyls IUPAC Nos. 155 and 169) and organochlorine pesticides 1,1-bis(4-chlorophenyl)-2,2-dichlor oethene) (4,4'-DDE) and hexachlorobenzene (HCB). They were killed 2 months after the dose and teeth and adipose tissue were collected. For the extract ion of organochlorines, dentine was treated ultrasonically with sulfuric ac id and hexane. The concentration of organochlorines in dentine and adipose tissue was determined by high-resolution gas chromatography with electron-c apture detection. The bioconcentration of 'planar' compounds (PCB-169, HCB) in dentine, compared to adipose tissue, was lower than that of 'non-planar ' (PCB-155, 4,4'-DDE). Ratios of the non-planar to planar compounds PCB-155 /-169 and 4,4'-DDE/HCB in dentine were 1.4 and 7.2, and in adipose tissue 0 .5 and 2.4, respectively. The dentine:adipose tissue bioconcentration ratio s (on a lipid basis) of PCB-54, -80, -155, -169, 4,4'-DDE and HCB were 47, 16, 0.3, 0.1, 3.2 and 1.0, respectively. The results indicate that the bioc oncentration of organochlorines in different tissues cannot be based on lip id content only. It is suggested that the physicochemical properties of ind ividual organochlorines, i.e. lipophilicity (K-ow), diffusivity, metabolism and tissue-specific interactions, play a part in the different bio concent rations of individual organochlorine pollutants in dentine compared to adip ose tissue. (C) 2001 Elsevier Science Ltd. All rights reserved.