Very low exposure to bisphenol A can have lasting effects on health. In a study of adult rats that were exposed before birth, researchers observed long-term changes in gene activity that differed by sex. Females showed gene expression patterns typically associated with males, while males showed patterns more commonly seen in females, Sci Tech Daily reported Saturday.
Source: Sci Tech Daily, By Sandra Gunnarsson, Uppsala University.
These shifts were linked to females moving toward a cancer-like biological state and males toward metabolic syndrome, a condition associated with higher risks of diabetes and heart disease.
Bisphenol A is a man-made chemical with estrogen-like effects that is widely used in food packaging. Although it has been banned from many products, it is still found in some types of packaging. Measurements show that levels of bisphenol A in many people exceed what is considered safe, and earlier research has already connected the chemical to a range of harmful health outcomes.
Females masculinized and males feminized
In this study, scientists focused on how bisphenol A influences the body during the fetal stage. Pregnant rats were given drinking water containing bisphenol A.
The researchers tested two exposure levels, one matching typical daily human exposure (0.5 micrograms per kilogram of body weight per day) and a higher dose that was considered safe in 2015 (50 micrograms per kilogram of body weight per day). When the offspring reached adulthood, the team examined gene expression in bone marrow as well as biological markers in the blood to assess long-term effects.
“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.”
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