Your Thyroid on Plastic
Phthalates, which are widely used to make plastic products soft and bendable, have prompted concern among scientists for their adverse human health effects. They are found just about everywhere in a wide variety of household products, including shower curtains, plastic water bottles, food storage containers, perfumes and lotions. Already a cause for concern because of their association with reproductive abnormalities and asthma, a recent study by University of Michigan School of Public Health associated phthalates with changes in thyroid hormones as well.
This blog entry written by WTC Intern Allison Camp
Phthalates, which are widely used to make plastic products soft and bendable, have prompted concern among scientists for their adverse human health effects. They are found just about everywhere in a wide variety of household products, including shower curtains, plastic water bottles, food storage containers, perfumes and lotions. For more info, check out our blog on the villain Thoughtless Phthalates or our Chemicals of Concern page.
Phthalate exposure is already a cause for concern because of its association with reproductive abnormalities and asthma, and a recent study by University of Michigan School of Public Health scientists associated phthalates with changes in thyroid hormones as well. The thyroid gland is critical for regulating metabolism, especially during pregnancy, when altered levels can hamper brain development in the fetus. The study looked at how phthalate exposure is related to thyroid function by comparing the levels of phthalate metabolites in urine with those of thyroid hormone levels in blood.
Researchers examined two phthalates, DEHP and DBP. Their subjects, including 1,346 adults and 329 adolescents (12-19), were part of the National Health and Nutritional Examination Survey (NHANES) during 2007 and 2008.
The results of their study: indeed, evidence suggests that phthalates are able to affect thyroid hormones. Researchers found that adult individuals who had more exposure to DEHP had lower thyroid hormone levels, while adolescents with higher exposure had higher thyroid hormone levels, possibly due to puberty. On the other hand, one of three DBP metabolites was associated with decreased hormone levels in both adults and adolescents.
Since the data used for this study was purely observational, more controlled studies are necessary to understand the cause of the relationships between thyroid hormones and phthalates. However, with many studies confirming phthalates’ other nasty effects, why would anyone want them around?
