American girls are now going through puberty significantly earlier than in prior decades and this trend has been linked to physiological and psychological risks. Factors thought to drive early puberty include: obesity, toxic stress, and environmental elements.

A recent landmark study focused on one particular type of environmental element — chemicals in household items. A long-running study on mothers and children published in Human Reproduction determined that the onset of female puberty is associated with exposure to commonly used chemicals like phthalates, parabens, and the antibacterial agent triclosan.

These products can be found in personal care products, some brands of perfumes, cosmetics, and toothpaste. The same result was not found in populations of boys, whose timing of puberty was also examined in this study.

University of California, Berkeley associate professor Kim Harley, Ph.D reported that researchers have known for the past 15 to 20 years that girls are entering puberty at an earlier age than they used to in the past. Obesity certainly plays a role in that, but now science has shown that the hormone-disrupting chemicals that are in our homes and in our environment could be an additional factor that’s contributing to this.

While it’s too soon to say conclusively whether these widely used chemicals are definitively causing early puberty, we need to pay attention to these chemicals and studies are starting to have enough information about them to certainly be concerned.

Discovering the cause of early puberty is important to scientists because the phenomenon is linked to a higher risk of developing depression, a greater risk for teen pregnancy, and an increased likelihood of developing diseases like breast cancer and heart disease.

The new study’s conclusions are based on data on pregnant women and the children they gave birth to who were enrolled in the Center for the Health Assessment of Mothers and Children of Salinas study between 1999 and 2000. When the women were at around 14 and 27 weeks’ gestation they gave the scientists consent to examine their urine samples for concentrations of phthalates, parabens, and phenols.

After the women gave birth, the team collected urine samples and evaluated the pubertal development of the resulting 179 girls and 159 boys. Every nine months between the ages of 9 and 13, scientists checked in to see how puberty was affecting the children. Overall, 90 percent of the urine samples showed concentrations of all the tested compounds. That was only detected in the 73 percent of the samples of pregnant mothers and 69 percent of samples taken from the nine-year old girls.

Mothers whose samples contained diethyl phthalate and triclosan had daughters that entered puberty earlier. For every doubling of triclosan in the mother’s urine, the timing of the girls’ first menstrual period shifted by just under a month and for every doubling in the samples for an indicator for phthalates, the development of girls’ pubic hair shifted by 1.3 months earlier. The urine samples taken from 9-year old girls revealed that, for every doubling in concentrations of parabens, the timing of the breast and pubic hair development, as well as their first period, happened one month earlier on average.

One reason these chemicals may affect puberty is because all of them are known endocrine disruptors. Previous studies on animals and humans have demonstrated that endocrine disruptors have the capacity to mimic, block, or otherwise interfere with the body’s hormones. They can bind to hormone receptors, such as estrogen receptors, and influence changes in our bodies. These chemicals can impact development, particularly if the exposure is happening in utero, and t research from human studies show that they may also impact development.

The difficulty in sharing the study’s results is that for now all they can say is that these are “chemicals of concern.” The Centers for Disease Control and Prevention readily acknowledges that there’s widespread exposure to phthalates and parabens, with the majority of Americans who are tested containing evidence of these chemicals in their urine. However, the agency states that finding a measurable amount of these chemicals does “not imply that they cause an adverse health effect.”

Harley hopes that regulators look at studies like hers when they move forward in conducting policy decisions and regulations. As of now, she explains, there’s no established benchmark level that states when it’s no longer safe to be exposed to these chemicals. It’s not illegal to have them in personal care products because the science isn’t strong enough to say that they absolutely cause adverse health effects. They are controversial chemicals, and about 70 percent of Americans have them inside their bodies.

These chemicals are basically ubiquitous. Regulation isn’t really there, but for people who are concerned, there are things that can be done. The advice is simple: Reduce exposure to chemicals of concern by changing the personal care products that you use and by purchasing products that don’t contain them.

So if you’re like me and pay attention to labels and ingredients, you may be concerned about the health and well being of your families, and arre careful about what you bring into your home. Switching to products that are formulated with natural, biodegradable ingredients and contain no harsh chemicals means they’re safer for your children, family, your home, and the environment.