Phthalates and BPA linked to altered reproductive hormones in women

A study of 90 women found that higher levels of these chemicals were associated with changes in estrogen and progesterone.

Editorial illustration — not from the study.

Researchers compared 50 women classified as exposed to phthalates and bisphenol A with 40 women in a control group. They analyzed 11 urinary phthalate breakdown products and BPA alongside blood levels of estrogen and progesterone.

Higher levels of BPA, monobutyl phthalate and combined diethylhexyl phthalate metabolites were associated with higher estrogen levels. Monobutyl phthalate, monoethyl phthalate and BPA were also positively associated with progesterone. The researchers additionally reported that smoking, bottled water and beverage consumption, ready-to-eat foods and cosmetics use were associated with exposure to combined diethylhexyl phthalate metabolites and BPA.

Hormone links found

The study found positive associations between estrogen and BPA, monobutyl phthalate and combined diethylhexyl phthalate metabolites. Each one-unit increase in the natural-log-transformed exposure measure was associated with a 0.045 log-unit increase in estrogen for BPA, a 0.042 log-unit increase for monobutyl phthalate and about a 0.04 log-unit increase for combined diethylhexyl phthalate metabolites. Monobutyl phthalate, monoethyl phthalate and BPA were also significantly and positively associated with progesterone. An analysis of the chemical mixture found a significantly positive overall association with both hormones at high exposure levels, including some non-linear relationships.

Why the links matter

Phthalates and BPA are endocrine-disrupting chemicals, meaning they can interfere with the body’s hormone signaling. The reported associations suggest that exposure to these chemicals may be relevant to hormone balance in women, a group the researchers identify as potentially vulnerable to their effects. The study also points to everyday behaviors associated with exposure, including use of cosmetics and consumption of bottled drinks and ready-to-eat foods.

Evidence and caveats

This was a cross-sectional study of 90 women, with 50 in an exposed group and 40 in a control group. The researchers used urine measurements, blood hormone concentrations and several statistical analyses, including a method for examining the combined effect of chemical mixtures. Because exposure and hormone levels were assessed at the same point in time, the study shows associations rather than cause and effect. The sample was also small, and the abstract does not establish whether the findings apply to women in other populations or whether the hormone changes lead to health outcomes.

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