The effects of phthalates on steroid hormones in pregnant women

What are phthalates?

Phthalates are environmental chemicals. Some are classified as endocrine disruptors because of their ability to interfere with the functioning of hormones. Phthalates are commonly used in various types of plastics, including polyvinyl chloride (PVC). They are found in many food packaging materials and also in cosmetics.

What are steroid hormones?

Hormones are like "messengers" in the body that provide information to cells, telling them what to do and how to operate certain organs. In the study, we focused on steroid hormones, which include several types of hormones (progesterone, testosterone, cortisol, etc.). For example, testosterone is a hormone that plays an important role in the growth of male genital organs or the production of sperm. Thus, a malfunction of these hormones could have an effect on the growth or development of genital organs.

How were phthalates and steroid hormones measured in the Sepages study?

Phthalates were measured in urine samples collected during pregnancy (42 samples). Right after delivery, mothers provided hair samples. Steroid hormones were measured in hair samples (progesterone, testosterone, cortisol, cortisone, and 11-dehydrocorticosterone). The interest in conducting these measurements in hair is to obtain information on hormonal levels from previous weeks. In previous studies, hormones have been measured in blood or urine samples, and the issue is that these samples only provide short-term hormonal information (representing hormonal levels during the previous minutes/hours).

Results

Results showed that:

• 1) higher maternal third trimester exposure to certain phthaltes (mono-benzyl phthalate (MBzP), the metabolite of benzyl-butyl phthalate (BBzP)), was associated with higher levels of all the hormones investigated, including stress-related hormones such as cortisol ;
• 2) higher maternal second trimester exposure to di-isononyl phthalate (DiNP) was associated with lower testosterone levels, but only among mothers carrying male fetuses. The observed results could be caused by an anti-androgenic effect, meaning something that blocks or reduces the effects of male hormones in the body.

What’s next?

These findings need to be validated by future studies. However, this work supports that pregnancy exposure to some phthalate can have adverse effects on the functioning of steroid hormones, which play a central role in fetal development. Alterations in these hormones could explain associations reported in previous studies before Sepages, such as increased risk of preterm births in mothers exposed to higher MBzP concentrations during pregnancy.