Associations of serum organohalogen levels and prostate cancer risk: Results from a case-control study in Singapore.

There is increasing evidence that elevated exposure to organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) may lead to an increased risk of prostate cancer. As part of a hospital-based case-control study of the Singaporean male population, we investigated associations between organohalogen exposure and risk of prostate cancer. Trace residue concentrations of 74 organohalogen contaminants, including several PCBs, OCPs and halogenated flame retardants (HFRs), were determined in serum samples (n = 120) using gas chromatography tandem mass spectrometry (GC-MS/MS). A variety of OCPs, PCBs and HFRs were detected in samples of both patients and controls. Mean concentrations of p,p' DDT, p,p' DDE, PCB 118, PCB 138, PCB 153 and PCB 187 were significantly higher (p < 0.05) in serum of patients. p,p' DDE measured in serum of patients was relatively high (mean:13,700 ng/g lipid, 95% CI:7000-26,800). Odds ratios (ORs) of OCPs and PCBs in many cases exceeded 1. ORs for p,p' DDE and PCB-153 at the highest tertile (>67th) were 5.67 (95% CI, 2.37-13.54) and 2.14 (95% CI, 0.99 to 4.66), respectively. The results suggest that exposure to DDTs and PCBs may be associated with prostate cancer risk in Singaporean males. No such association was observed for the organohalogen flame retardants studied, including polybrominated diphenyl ethers (PBDEs). The study provides novel information regarding the occurrence, levels and potential associations with prostate cancer risk for several organohalogen contaminants in the Singapore population. However, further investigation and analyses should be conducted to confirm these findings.