POP levels in breast milk and maternal serum and thyroid hormone levels in mother–child pairs from Uppsala, Sweden

Abstract

In experimental studies, it has frequently been observed that the homeostasis of thyroid hormones (THs) is affected by exposure to persistent organic pollutants (POPs), such as dioxins and PCBs. In man, similar effects have been indicated in several epidemiological studies. In order to investigate the possible effect on THs at low background exposures found among the Swedish population the following study was performed. Primiparous women (n=395) in the Uppsala region were recruited between 1996 and 1999. Of these, 325 mothers agreed to donate a serum sample in late pregnancy and breast milk was obtained from 211 women 3 weeks after delivery. Babies were sampled for blood at 3 weeks (n=150) and 3 months (n=115) after birth. In connection to the sampling, questions on personal characteristics were asked. Levels of low (tri- to penta-) chlorinated PCB, di-ortho PCB, p,p'-DDE, (mono-ortho) PCB TEQ and PCDD/DF TEQ were monitored in breast milk and in mother's blood (not PCDD/DF). The results showed that the measured TH levels (thyroid-stimulating hormone - TSH, total tri-iodothyronine - TT3, free thyroxine - FT4) in mothers and children were within the reference range. Some significant associations were seen between POP exposures and TH levels in mother or child after simple regression analysis. Following adjustment for important confounding factors, the significant associations mostly disappeared. However, significantly decreasing TT3 levels with increasing prenatal low-chlorinated PCB exposure were still seen in 3 week old children, and on TT3 in mothers exposed to PCDD/DF. In conclusion, the study clearly shows the importance of adjustment for important confounding factors in the analysis of possible associations between POP exposure and hormonal effects. The remaining associations are weak in both children and mothers and the clinical consequences of these alterations are uncertain. When comparing studies that investigate associations between TH levels and POP levels during the perinatal stage, no obvious between-study concordance was seen regarding the critical dose for hormonal effects to occur.

Serum levels of hydroxylated PCBs, PCBs and thyroid hormone measures of Japanese pregnant women

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Estimation of human body concentrations of DDT from indoor residual spraying for malaria control

“…Consequently, lipid-normalized concentrations will be similar between different body compartments. Empirical measurements support this assumption (Darnerud et al 2010;Sapbamrer et al, 2008;Waliszewski et al, 2000Waliszewski et al, , 2001.…”

High levels of DDT in breast milk: Intake, risk, lactation duration, and involvement of gender

“…Cao et al, 2011;Cohn, 2011;Fromberg et al, 2011;Glynn et al, 2011) and its continued use in malaria vector control (Eskenazi et al, 2009;van den Berg, 2009;Darnerud et al, 2010;Bouwman et al, 2011). The problems with the use of DDT stems largely from its persistence, bioaccumulation, toxicity, and physical-chemical capacity for long-range transport (Mackay et al, 2006;Stockholm Convention, 2012).…”