Environmental toxins are everywhere these days, from cosmetics to ocean water, and we probably only know a fraction of the health problems exposure to them causes over time. One of the things we do know, however, is that certain chemicals found in plastics or fungicides (frequently sprinkled over fruits and vegetables) may be harmful to children’s teeth, according to a new study presented at the European Congress of Endocrinology. The research focused primarily on how these chemicals affect tooth enamel, the tough outer layer on teeth that protects them from harm.

In the study, researchers examined rats that were given daily doses of Bisphenol A (BPA), either alone or in combination with vinclozoli n — a common fungicide that is often found on fruits and vegetables like raspberries, lettuce, kiwi, and onions. BPA is an industrial chemical that is frequently found in plastics like water bottles, and other food containers.

The doses were about equivalent to those a human would be exposed to every day from birth until 30 days old, as scientists know that it’s nearly impossible for us to avoid endocrine disruptors in the modern world, whether prenatally or as adults. After taking cell samples from the rats’ teeth, the researchers discovered that the expression of two genes had changed due to the BPA and vinclozolin exposure. The genes were involved in mineralization, which contributes to strengthening tooth enamel. Because BPA and vinclozolin impaired mineralization, it’s possible that children whose teeth are still in development may be at higher risk of experiencing molar incisor hypermineralization (MIH), which causes sensitive, painful spots of weakened tooth enamel and a higher risk of cavities, due to chemical exposure.

The second half of the study involved rat ameloblast cells, which deposit enamel during a baby’s tooth development. Sex hormones like estrogen and testosterone were shown to boost tooth enamel development, while exposure to BPA and vinclozolin had the opposite effect of impairing the hormones and thus indirectly weakening tooth enamel.

Kids’ tooth enamel begins developing inside the womb and continues for several years. “Tooth enamel starts at the third trimester of pregnancy and ends at the age of 5, so minimizing exposure to endocrine disruptors at this stage in life as a precautionary measure would be one way of reducing the risk of enamel weakening,” said Dr. Katia Jedeon, lead author of the study, in a statement.

Other endocrine disruptors are found in pesticides, plasticizers, metal food cans, detergents, toys, and cosmetics. Though research into the health effects of endocrine disruptors is ongoing, the NIH notes that they appear to pose the greatest risk during prenatal or early infant development.

Source: Jedeon K, et al. European Society of Endocrinology, 2016.