Expression of CYP1A1 mRNA in milk cells serves as a biomarker for dioxins exposure?

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Samples of breast milk and blood were obtained from 50 women at U Obstetrics and Gynecology Clinic within one week of childbearing with informed consent. The milk cells and cream layer were separated by centrifugation. Dioxins (PCDD/F, coplanar PCBs) and noncoplanar PCBs in the cream layer were analyzed by HRGC/HRMS. Genotyping of CYP1Alm1,CYP1A1m2 and GSTM1 null was performed from the genomic DNA extracted from peripheral blood. CYP1A1 mRNA expression in the milk cells was analyzed by real-time RT-PCR. The geometric mean concentrations of PCDDs,PCDFs, coplanar-PCBs and their sum were 7.3,3.8,5.2, and 16.8 pg TEQ/g fat, respectively. The levels of PCDF and DFCo (PCDD+PCDF+CoPCB) were significantly lower in the CYP1A1 m2 genotype than in others (hetero or wild). This might be explained by the increased microsomal enzyme activity. The expression of CYP1A1 mRNA in the milk cells was low and there was no significant correlation between dioxinconcentration in breast milk and CYP1A1 mRNA expression in the milk cells. CYP1A1 mRNA expression in the milk cells did not serve as a biomarker for dioxin exposure in the present study.