An industrial chemical most Americans already have in their bodies is back under the microscope.
New research suggests that even low-level exposure in the womb can disrupt fetal development, feminizing males and masculinizing females.
Worse yet, scientists found these prenatal changes may permanently alter metabolism, immunity and disease risk — potentially setting the stage for cancer and a wide range of chronic illnesses later in life.
The culprit? Bisphenol A, better known as BPA, a man-made chemical commonly used to make plastics tougher and more heat-resistant.
Previous research shows that BPA can leach into food and drinks from the containers they are stored in, quietly sneaking into our bodies. In fact, government scientists estimate that more than 90% of Americans have detectable levels in their blood.
Once inside, BPA acts as an endocrine disruptor, mimicking the body’s natural hormones and throwing their normal functions off balance — particularly estrogen, the primary female sex hormone, though it’s also found in men.
Some studies suggest babies and children are the most vulnerable to BPA exposure. Over the years, scientists have linked the chemical to a long list of developmental and health problems, including ADHD, anxiety, depression, early puberty, immune system dysfunction, diabetes, obesity and heart disease.
Despite bans in some products, BPA can still be found in food and beverage packaging and other consumer goods. The FDA maintains that, based on current evidence, the small amounts that leach from these products aren’t enough to cause harm.
Still, scientists at Uppsala University in Sweden wondered what BPA exposure does before birth.
To find out, they gave pregnant rats drinking water containing BPA. The team tested two doses: one matching typical human exposure (0.5 micrograms per kilogram of body weight per day) and a higher dose once considered safe in 2015 (50 micrograms per kilogram per day).
When the offspring reached adulthood, researchers analyzed gene expression in their bone marrow and checked blood markers to see whether BPA exposure in the womb had long-term effects.
“We saw lasting effects in the adult rat,” Thomas Lind, the study’s first author, said in a press release. “Even very low doses changed how the genes were expressed. Females were masculinized, and males were feminized.”
Those changes weren’t just cosmetic.
Both sexes showed metabolic shifts, but in very different directions. Female rats drifted toward a cancer-like biological state, while males showed signs of metabolic syndrome, a condition tied to higher risks of diabetes and heart disease.
The immune system also took a hit. The activity of their T cells — white blood cells that help fight infection — increased in males but dropped in females, echoing earlier research linking BPA exposure to immune dysfunction.
When the team analyzed the mice’s blood, they found even more sex-specific changes.
The males showed a disturbed lipid profile, along with signs of increased metabolism and thyroid-related hyperactivity.
The females, meanwhile, had lower glucose levels, higher insulin levels, and signs of increased testosterone activity, a pattern similar to polycystic ovary syndrome, or 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,” Lind explained.
“This reinforces the findings of other studies linking bisphenol A exposure to declining fertility in women,” he continued.
The authors say their findings strengthen the case for cutting BPA out of food and beverage packaging.
Last year, the European Union banned BPA from being used in nearly all food-contact materials, with a phase-out period currently underway.
But the US is lagging behind. While the FDA has barred the chemical from baby bottles, sippy cups and infant formula packaging, there’s no nationwide ban.
Still, pressure is building. More than 30 states and local governments have enacted rules limiting BPA’s production, use or distribution.
In New York, state law prohibits the manufacture or sale of BPA-containing childcare products intended for children under 3, including pacifiers, bottles and other beverage containers.
