Bisphenol A causes sex-specific changes in metabolism and the immune system, study reveals

Even small amounts of bisphenol A can lead to long-term health effects. When researchers studied adult rats exposed in the fetal stage, they found that females had developed a more masculine and males a more feminine gene expression pattern. This led to females progressing towards a cancer-like state, while males progressed towards metabolic syndrome, which can increase the risk of diabetes and heart disease.

Bisphenol A is a synthetic chemical with estrogen-like properties that is commonly used in food packaging materials. The substance is banned in many products, but is still present in some packaging. Levels of bisphenol A in people’s bodies are often above levels considered safe, with previous research showing that the substance can cause adverse health effects.

Females masculinized and males feminized

In the current study, published in Communications Medicine, researchers investigated how bisphenol A affects the body during the fetal stage.

Pregnant rats were given drinking water containing bisphenol A. Two doses of bisphenol A were studied, one corresponding to the daily human exposure (0.5 micrograms per kilogram of body weight per day) and a higher dose considered safe in 2015 (50 micrograms per kilogram of body weight per day). The researchers then analyzed gene expression in the bone marrow and biological markers in the blood of the adult offspring.

“We saw lasting effects in the adult rat,” says Thomas Lind, the study’s first author. “Even very low doses changed how the genes were expressed. Females were masculinized and males were feminized. Both sexes experienced metabolic changes—females progressed towards a cancer-like state while males showed signs of progression towards metabolic syndrome, which can increase the risk of diabetes and heart disease.”

Strengthens the link between bisphenol A and PCOS

The researchers also saw an impact on the immune system. The activity of some immune cells, the T cells, increased in males but decreased in females. This finding confirms what previous studies have shown, namely that these immune cells are involved in changes caused by bisphenol A exposure.

The analysis of the blood markers showed several sex-specific changes. In males, a disturbed lipid profile was observed, with signs of increased metabolism and thyroid-related hyperactivity. In females, there were reduced glucose levels, elevated insulin levels and signs of increased testosterone activity, a pattern reminiscent of polycystic ovary syndrome (PCOS).

“The results also corroborate previous human studies, where women with the hormone disorder PCOS have exhibited higher levels of bisphenol A in the blood, which correlates with an increased influence of male sex hormones. This reinforces the findings of other studies linking bisphenol A exposure to declining fertility in women,” says Lind.

Study confirms need for stricter regulation

The results suggest that reducing the use of bisphenol A in food packaging could help prevent health risks.

“The study shows that even very small amounts of bisphenol A can affect health later in life. Although the results are based on experimental data, they support the European Food Safety Authority’s decision to significantly lower the tolerable daily intake of the substance by 20,000 times to 0.2 nanograms per kilogram of body weight per day.”