Assaying organochlorines in archived serum for a large, long-term cohort: implications of combining assay results from multiple laboratories over time.

Conserving irreplaceable, archived serum samples may sometimes conflict with the objective of minimizing measurement error due to laboratory effects. We sought to determine whether we could successfully combine assay results for DDT-related compounds and polychlorinated biphenyls (PCBs) in serum from the same birth cohort obtained from different laboratories over time. Using the Child Health and Development Studies (CHDS) serum archive, we compared variability for assays of a quality control pool to variability for assays of subject serum.

Polychlorinated biphenyl (PCB) exposure in mothers and time to pregnancy in daughters.

Developmental exposure to polychlorinated biphenyls (PCBs) disrupts reproduction in animals. Human data are lacking. We measured PCBs in preserved mothers' serum samples collected during 1960-1963, 1-3 days after their daughters' birth.

DDT and breast cancer in young women: new data on the significance of age at exposure.

Background: Previous studies of DDT and breast cancer assessed exposure later in life when the breast may not have been vulnerable, after most DDT had been eliminated, and after DDT had been banned.

Objectives: We investigated whether DDT exposure in young women during the period of peak DDT use predicts breast cancer.

Methods: We conducted a prospective, nested case-control study with a median time to diagnosis of 17 years using blood samples obtained from young women during 1959-1967.

DDT and DDE exposure in mothers and time to pregnancy in daughters.

Reproductive-tract anomalies after administration of the potent oestrogen, diethylstilboestrol, in pregnant women raised concerns about the reproductive effects of exposure to weakly oestrogenic environmental contaminants such as bis[4-chlorophenyl]-1,1,1-trichloroethane (p,p'-DDT) or its metabolites, such as bis[4-chlorophenyl]-1,1-dichloroethene (p,p'-DDE). We measured p,p'-DDT and p,p'-DDE in preserved maternal serum samples drawn 1-3 days after delivery between 1960 and 1963. We recorded time to pregnancy in 289 eldest daughters 28-31 years later.