Polychlorinated biphenyls in blood plasma among Swedish female fish consumers in relation to time to pregnancy.

The purpose of this study was to assess the association between 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) in plasma, a biomarker of exposure to polychlorinated biphenyls (PCB), and time to pregnancy (TTP) in a group of women with a varying dietary exposure to PCB. For 121 Swedish east coast fishermen's wives (median year of birth 1956, range 1945-1968), information on selt-reported TTP for the first planned pregnancy (median 2 mo, range 0-48) and CB-153 concentrations from blood samples drawn in 1995 (median 144 ng/g lipid, range 16-566) were available. Each woman's CB-153 concentration in plasma at the time immediately preceding her pregnancy was estimated, taking into account reduction of body burden of CB-153 due to lactation, the yearly reduction of PCB in Baltic Sea fish, as well as the biological half-life of CB-153. Based on the estimated CB-153 concentrations, subjects were categorized into tertiles as low (37-206 ng/g lipid), medium (207-330 ng/g lipid), and high (331-,1036 ng/g lipid) exposure groups. TTP in the medium- and high-exposure groups were then compared to TTP in the low-exposure group by estimating the corresponding success rate (i.e., the number of pregnancies per person month) ratios (SuRR) using discrete Cox regression, taking into account essential confounders. No obvious association between estimated CB-153 concentration and TTP was observed (medium vs. low: SuRR 0.77 [95% CI 0.47-1.28] and high vs. low: SuRR 0.95 10.74-1.23]). The present data give no support for a negative association between the plasma CB-153 concentrations observed in the present study and TTP. It should, however, be borne in mind that the study group was rather small and mainly included relatively young women, likely to have been only moderately exposed.