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By Pamela Ferdinand
Propylparaben, a widely used preservative found in shampoos, lotions, packaged foods and pharmaceuticals, may harm ovarian function and reduce fertility across generations, according to new research.
The findings, published in Nature Communications on Sept. 16, show that pregnant mice exposed to propylparaben, a known endocrine disruptor, passed fertility problems to their daughters, granddaughters and great-granddaughters.
Earlier research by the same team found that mice exposed to propylparaben before birth showed effects resembling diminished ovarian reserve in women, meaning they had fewer and lower-quality eggs.
This latest study, however, is the first to link propylparaben exposure to multigenerational fertility decline through biological changes that “reprogram” sperm or eggs and pass impacts down to offspring without changing DNA.
It also adds to growing evidence that everyday exposure to common industrial and household chemicals may cause reproductive and other health harms, now and for future generations.
“This biological process emphasizes the profound and enduring impact that environmental stressors can exert on the epigenetic landscape of descendants,” the study’s authors noted, “and reveals the potential origins of many diseases.”
Parabens, a class of chemicals used to prevent bacterial growth in a wide range of consumer products, are endocrine-disrupting chemicals (EDCs) that can mimic or interfere with hormones.
Absorbed through the skin, scientists have detected parabens in blood, urine, hair, breast milk and even the placenta. Studies suggest parabens and other EDCs may be linked to reproductive problems, breast cancer, obesity and thyroid disorders.
In this study, scientists gave pregnant mice doses of propylparaben that, when adjusted for body weight, were comparable to the levels humans are typically exposed to through consumer products. Human exposure, however, usually occurs through skin contact, food or air.
The female offspring showed several reproductive changes:
- Fewer ovarian follicles, which contain immature egg cells.
- Increased follicular atresia, meaning more follicles die or break down before they can release a mature egg.
- Lower quality egg cells, which aren’t as healthy or work as well as they should to mature and promote normal embryo growth.
- Lower levels of anti-Müllerian hormone, a key marker of a woman’s fertility and egg supply (ovarian reserve).
- More death of specialized ovarian cells (granulosa cells) is essential for egg development, contributing to lower anti-Müllerian hormone levels and fewer healthy eggs.
Researchers traced the initial fertility changes to reduced DNA methylation of the Rhobtb1 gene. Methylation involves a chemical change that silences genes or causes them to be less active.
But in this case, reduced methylation (hypomethylation) did the opposite, triggering cell death in ovarian tissue and depleting egg reserves. Strikingly, the researchers said, those same problems persisted through two more generations of mice — even though those animals were never directly exposed to propylparaben.
Diminished ovarian reserve, or low egg count, affects about one in four women undergoing fertility treatment. While genetics, medical treatments and aging play a role, environmental chemical exposures, especially in early development, are increasingly recognized as key factors amid steadily declining fertility rates in the U.S.
When researchers tested blood samples from women with diminished ovarian reserve or primary ovarian insufficiency, they found the same Rhobtb1 pattern seen in mice. Both groups showed excessive gene activity at key sites, suggesting a common inherited link to ovarian decline and potential biomarkers for identifying women at risk of diminished ovarian reserve.
To explore possible interventions, some mice were given a diet including folic acid and vitamin B12 during pregnancy and nursing.
Their offspring showed healthier ovaries and hormone levels, suggesting that nutrition may help offset some effects of paraben exposure. The study also found lower birth weights in male mice exposed to propylparaben across three generations.
While the authors caution that more research is needed, other studies support the idea that environmental exposures can shape reproductive health for generations.
For instance, premature birth, or prenatal exposure to air pollution (PM2.5) and alcohol, have been linked to high blood pressure, developmental issues and weakened immune function that can be inherited.
Similarly, studies show exposure to chemicals such as the plasticizer di(2-ethylhexyl) phthalate (DEHP) during pregnancy and lactation may reduce egg numbers and fertility across multiple generations. Pesticides and other toxins may also cause inherited ovarian disease.
Parabens remain common in personal-care products, though regulations vary. In the U.S., the U.S. Food and Drug Administration considers them safe at low levels but notes data gaps on cumulative and prenatal exposure.
Propylparaben is among the chemicals targeted for expedited agency review. California became the first state to ban propylparaben in 2023 from food and personal care products, while West Virginia prohibited it in foods.
The European Union has banned propylparaben as a food preservative and tightly regulates its use in cosmetics.
Among the study’s limitations, the injection method used in mice ensured precise dosing but differs from typical human exposure routes such as skin contact, ingestion or inhalation, limiting direct comparison.
The authors also noted that real-world exposure involves multiple chemicals and lifestyle factors, which should be addressed in future research.
Comprehensive epidemiological studies are needed to determine population-level exposure and guide evidence-based safety standards, the authors said. They stress the need for stricter controls on paraben exposure during pregnancy.
“From a policy perspective, it is imperative to restrict the use of certain EDCs and to modernize preservative systems to mitigate daily exposure risks,” they said. “Such measures are critical for preventing ovarian aging and other health conditions linked to paraben exposure.”
To limit exposure to propylparaben, choose paraben-free, organic-certified products, reduce ultraprocessed and packaged foods and avoid plastics. Avoid water-based products containing propylparaben, including hair care, body wash, sunscreen, lip balm, and moisturizers and other skin care products.
Originally published by U.S. Right to Know.
Pamela Ferdinand is an award-winning journalist and former Massachusetts Institute of Technology Knight Science Journalism fellow who covers the commercial determinants of public health.
