Section 10.3 Other Endocrine Glands

A potential biomarker of exposure to PBDEs relates to their effect on the thyroid gland. As discussed in Sections 3.2.2.2, Endocrine Effects, thyroid changes in rats and mice include reduced serum thyroxine (T4) levels w itli no changes in scrum TSH (Damerud and Sinjari 1996 Fowles et al. 1994 Hallgren and Damemd 1998 WIL Research Laboratories 1984 Zhou et al. 2001, 2002). Additional studies are needed to characterize thyroid effects of PBDEs in humans and develop specific correlations between levels and duration of exposure and alterations in senun levels of T4. This potential biomarker is not specific to PBDEs because PBBs and other antithyroid agents can have similar effects. 

Developmental Effects. This section summarizes effects of PCBs on anthropometric measures at birth as well as physical growth during infancy. Effects of perinatal exposure to PCBs on other end points in the offspring, such as the thyroid gland and thyroid hormone status, end points known to be very important for structural and functional aspects of normal development of the brain and sexual organs, are discussed in the Endocrine Effects and Reproductive Effects sections, respectively. Neurodevelopmental effects of PCBs are summarized in the Neurological Effects section. 

Cathro and Coyle (C4) have described the second pregnancy of a woman who had already given birth to an infant with adrenal hypoplasia. The first infant died of respiratory failure 18 hours after birth and postmortem examination revealed very small adrenal glands but no other detectable endocrine abnormality. During the latter part of the second pregnancy, the maternal estriol excretion was low (1 mg/24 hours), an expected finding since 16a-OH-DHA produced by the fetus is an important precursor of estriol (D6, D9) (Section 4.1.1.). Evidence for adrenocortical insufficiency in the infant was obtained from the low level of cortisol in the umbilical cord blood. The infant was satisfactorily treated at birth with steroid therapy. 

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