Persistent organochlorines (POCs), such as polychlorinated biphenyls (PCBs) and DDT, are present at relatively high concentrations in food and show estrogenic, anti-estrogenic or anti-androgenic activity in biological test systems. Because bone mineral density (BMD) in men is influenced by sex hormones, we looked for associations between BMD and serum concentrations of POCs in 115 men (mean age 63 years, range 40-75 years) from the general Swedish population. Ten PCB congeners, five DDT isomers, hexachlorobenzene, three hexachlorocyclohexane isomers, trans-nonachlor and oxychlordane were analyzed by gas chromatography. Quantitative bone measurements were performed by dual-energy X-ray absorptiometry at three sites: whole body, the L2-L4 region of the lumbar spine, and the neck region of the proximal femur, as well as by quantitative ultrasound on the left os calcis (broadband ultrasound attenuation (BUA) and speed of sound (SOS)). After adjustment for confounding factors in linear regression analyses we found no strong association between serum concentrations of single POCs and the five BMD and ultrasound variables. When POCs were grouped according to hormonal activity (estrogenic, anti-estrogenic, anti-androgenic) and the study subjects were divided into organochlorine concentration quartiles, a weak association was indicated between increased serum concentrations of p,p'-DDE (antiandrogenic) and decreased BMD, BUA and SOS. This may suggest that p,p'-DDE could cause negative effects on bone density, but the findings might also be due to chance since multiple comparisons were made in the statistical analysis. Overall our results do not suggest that the studied POCs caused major effects on bone density in our study group.
OBJECTIVE: To prospectively evaluate if repeated measurements of organochlorine exposure provide a more precise measure of breast cancer risk. METHODS: In the Copenhagen City Heart Study (CCHS) participants donated blood twice, in 1976-1978 and 1981 1983. Information on breast cancer risk factors was obtained through standardized questionnaires. A cohort nested case-control study of 155 cases and 274 matched breast cancer-free controls who had participated in both CCHS examinations was conducted. The average serum organochlorine concentration over the course of the two examinations was used, testing a possible association between organochlorine exposure and breast cancer risk. RESULTS: A high serum concentration of p,p'-DDT over the course of the two examinations was associated with a more than three-fold significantly increased risk of breast cancer, and a dose-response relationship was apparent. Furthermore, the risk of breast cancer increased with increasing serum concentrations of PCB congener 118 and 138 and the total amount of DDT isomers (sigmaDDT), but the trends were not significant. CONCLUSION: This study provides new evidence of the adverse effect of some organochlorines on breast cancer risk. Furthermore, repeated assessment of exposure during a relevant time period may provide a more precise risk estimate than a single measurement.