Researchers at George Mason University, in Virginia, discovered links between chemicals widely used in cosmetic and personal care products, and changes in reproductive hormones.
The team analysed the urine samples of 143 women aged 18 to 44 who had no known chronic health conditions and did not use birth control.
Those with chemicals such as parabens (a preservative widely used in cosmetic products), benzophenones (used as UV filters) and bisphenol A in their urine were found to have abnormal amounts of the reproductive hormones oestrogen and progesterone.
Excessive oestrogen has been linked to fibroids and irregular menstrual periods, while too little prevents eggs maturing and being released from the ovary.
Too much progesterone is associated with both breast cancer and unusual vaginal bleeding, while it is thought bisphenol A (BPA), known as the 'gender-bending' chemical for its effects on male breast growth, could cause fertility problems.
Dr Anna Pollack, assistant professor of global and community health at George Mason University, said: “This study is the first to examine mixtures of chemicals that are widely used in personal care products in relation to hormones in healthy, reproductive-age women, using multiple measures of exposure across the menstrual cycle, which improved upon research that relied on one or two measures of chemicals.
“What we should take away from this study is that we may need to be careful about the chemicals in the beauty and personal care products we use.
“We have early indicators that chemicals such as parabens may increase oestrogen levels.
“If this finding is confirmed by additional research, it could have implications for oestrogen dependent diseases such as breast cancer.”
The study, titled Exposure to bisphenol A, chlorophenols, benzophenones, and parabens in relation to reproductive hormones in healthy women: A chemical mixture approach, was recently published in the science journal Environment International.