Beauty products

Chemicals in Hair, Cosmetics May Interfere With Hormones During Pregnancy


Pregnant women who use hair dyes or straighteners may have relatively lower levels of pregnancy-promoting hormones, a recent study suggests.

The researchers found that among the more than 1,000 pregnant women they followed, those who used certain hair products – dyes, bleaches, relaxers or mousse – had lower levels of several hormones, including estrogen and progesterone.

This is a concern because during pregnancy the levels of these hormones are expected to rise, said lead researcher Zorimar Rivera-Nunez, an assistant professor at the Rutgers School of Public Health in Piscataway, NJ.

Previous research, she noted, has linked disruptions in pregnancy hormones to an increased risk of problems such as impaired fetal growth, premature birth and low birth weight.

How would hair care fit in? Personal care products, including lotions, cleansers, makeup, shampoo, and nail polish, often contain many chemicals. And they include the so-called “endocrine disruptors,” chemicals that can interact with the body’s hormonal system.

Endocrine disruptors are everywhere, and people can be exposed through the food, water or even the air they breathe, according to the Endocrine Society.

When it comes to personal care products, some of the common hormone disrupting chemicals include parabens, phthalates, bisphenol-A, and toxic metals.

Researchers are still trying to understand how exposure can affect human health, Rivera-Nunez said. It’s complicated, in part because people are usually exposed to many chemicals.

But studies have shown, for example, that when pregnant women have high levels of certain endocrine disruptors in their bodies during pregnancy, their offspring are more likely to become overweight or go through precocious puberty.

Likewise, there is some evidence linking personal care products, in particular, to health risks.

A US government study found that women who frequently used chemical straighteners had a higher risk of breast cancer than non-users. Hair dye was also linked to an increased risk of disease, especially in black women.

Regarding pregnancy, a recent study of pregnant women in China found that those who frequently used makeup or skin care products were more likely to have a baby that was small for gestational age – a sign of growth restriction in the uterus.

The new study “fits well” with this body of research, said Alexis Temkin, toxicologist with the nonprofit Environmental Task Force in Washington, DC.

It links the use of hair products to hormonal differences that are consistent with some of the health effects that have been linked to these products, according to Temkin.

The results – published in the journal Environmental Research – are based on 1,070 pregnant women in Puerto Rico who made up to three study visits during their pregnancy.

They filled out questionnaires about the personal use of the products and gave blood samples to measure their hormone levels.

Overall, estrogen, progesterone, and testosterone levels were lower in women who reported using “other” hair products, compared to non-users. This category included dyes, straighteners, bleaches and foams, but not shampoos, conditioners, hairspray or hair gels.

It is not clear, according to Rivera-Nunez, whether women who use these hair products could be exposed to particular chemicals that are problematic, or have a higher level of exposure to endocrine disruptors.

Beyond that, there are many factors that can influence pregnancy hormones.

The researchers took into account variables they could, such as the women’s body weight before pregnancy, their income and education level, as well as their history of smoking and alcohol use.

But it’s not possible to explain everything, Rivera-Nunez said.

For now, she has recommended that women who are pregnant or planning to become pregnant read labels and be aware of what they are putting on their bodies. At the same time, she recognized that these labels are not necessarily consumer friendly.

“Lack of proper labeling is a problem,” Rivera-Nunez said.

Temkin advised researching the word “perfume” – a harmless term that actually includes a wide range of undisclosed chemicals, some of which can be endocrine disruptors.

More information

The environmental task force has more information on the ingredients of personal care products.

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