A major new study suggests that everyday exposure to chemicals found in plastics, personal-care products, household items and the environment can lead to an earlier menopause.

Scientists at Washington University School of Medicine in St. Louis found that women whose bodies have high levels of endocrine-disrupting chemicals experience menopause two to four years earlier than women with lower levels of these chemicals.

The study, published in the journal PLOS ONE, does not prove that chemical exposure caused earlier menopause. But the authors believe the associations they found warrant further research.

"Chemicals linked to earlier menopause may lead to an early decline in ovarian function, and our results suggest we as a society should be concerned," commented senior author Amber Cooper, MD, an assistant professor of obstetrics and gynecology.

As well as adversely affecting fertility, a decline in ovarian function can also lead to earlier development of heart disease, osteoporosis and other health problems.

Cooper recommends that people microwave food in glass or paper containers instead of in plastic and try to learn more about the ingredients in cosmetics, personal-care products and food packaging they use every day.

The researchers used a nationally representative sample of patients across the United States and looked at levels in blood and urine of 111 mostly man-made chemicals that are suspected of interfering with the natural production and distribution of hormones in the body.

Many of the chemicals are banned in the United States but are still are produced elsewhere and are pervasive in the environment.

The chemicals analyzed included: dioxins/furans (industrial combustion byproducts); phthalates (found in plastics, common household items, pharmaceuticals and personal-care products including lotions, perfumes, makeup, nail polish, liquid soap and hair spray); phytoestrogens (plant-derived estrogens); polychlorinated biphenyls (PCBs, coolants); phenolic derivatives (phenols, industrial pollutants); organophosphate pesticides; surfactants; and polycyclic aromatic hydrocarbons (combustion products).

In particular, the researchers identified 15 chemicals — nine PCBs, three pesticides, two phthalates and a furan (a toxic chemical) — that were significantly associated with earlier ages of menopause and potentially have detrimental effects on ovarian function.

Endocrine-disrupting chemicals have previously been linked to certain cancers, metabolic syndrome and, in younger females, early puberty.

"Understanding how the environment affects health is complex. This study doesn't prove causation, but the associations raise a red flag and support the need for future research," Cooper said.