Chemicals in early menopause link
Earlier menopause has been linked to common chemicals found in plastics, cosmetics, electrical appliances and industrial pollutants.
A large-scale study found that women with high levels of the substances in their blood and urine experienced the menopause two to four years sooner than those with lower levels.
The 111 chemicals investigated are believed to interfere with hormones in the body.
They include PCBs (polychlorinated biphenyls) whose manufacture is now banned in the UK and many other countries but which where once widely used in paints, electrical components and coolants.
US lead researcher Dr Amber Cooper, from Washington University School of Medicine in St Louis, said: "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.
"Many of these chemical exposures are beyond our control because they are in the soil, water and air. But we can educate ourselves about our day-to-day chemical exposures and become more aware of the plastics and other household products we use."
One simple safeguard people could take was to microwave food in glass or paper containers instead of plastic, said Dr Cooper.
Her team analysed data on 31,575 people collected from 1999 to 2008 as part of the US National Health and Nutrition Examination Survey.
Participants included 1,442 menopausal women with an average age of 61 who had been tested for levels of hormone-disrupting chemicals. None of these women was undergoing hormone replacement therapy (HRT) or had their ovaries removed.
The women's blood and urine were tested for the presence of 111 mostly man-made chemicals, including persistent substances that take more than a year to break down.
The scientists idenfied 15 chemicals - nine PCBs, three pesticides, two phthalates and a furan - that were significantly associated with earlier menopause and had the potential to harm ovarian function.
Phthalates are found in plastics and common household items as well as hair spray, cosmetics and soaps. Furans are industrial combustion by-products.
Dr Cooper added: "Earlier menopause can alter the quality of a woman's life and has profound implications for fertility, health and our society. 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."
The research is reported in the online journal Public Library of Science ONE.
Ashley Grossman, Professor of Endocrinology at Oxford University, said: "Although a relatively small change, this could have a significant impact on fertility. However, the authors investigated up to 111 chemicals and, as this was more of a pilot study, did not make any allowance for multiple comparisons; it is always possible that comparing lots of different things will suggest a statistically significant effect when it purely arises by chance.
"There is also evidence that many of these chemicals have already been removed from industrial processes. Even so, it would be sensible to try and reduce environmental contaminants even further, particularly plastic bottles. Perhaps many of those walking around and continually sipping (expensive) bottled water will decide it might be healthier to abandon this unnecessary habit altogether."
Dr Crispin Halsall, reader in environmental chemistry at the University of Lancaster, said: "The study includes a large number of chemicals with widely varying potency with regards to mimicking or disrupting hormones. To add to this the concentration ranges in the serum of these women also varies enormously, so while the study appears to reveal an association between chemical exposure and the onset of menopause, the underlying reasons are really quite obscure.
"We can't be complacent about long-lived synthetic chemicals that we are exposed to in our daily lives, but considerable research is required to tease out a mechanism to explain this effect."
Research published in the journal Human Reproduction yesterday suggested that sugary drinks may be causing girls to menstruate earlier.
A study of girls aged nine to 14 found that those drinking more than 1.5 sugar-sweetened beverages a day had their first period 2.7 months earlier than those consuming two a week or fewer.
The Harvard Medical School scientists said the discovery was important because earlier onset menstrual periods have been linked to an increased risk of breast cancer later in life.