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Disrupting Hormones in the Name of Beauty

Epidemiologist Kim Harley ’92 is concerned about the ways that hormone-disrupting chemicals affect our health. "We are exposed to many different chemicals every day, including pesticides in our food, and chemicals in plastics, in our homes, and in our cosmetics and personal care items," says Harley, associate director of the UC Berkeley Center for Environmental Research and Children's Health and an associate professor in Maternal and Child Health at UC Berkeley's School of Public Health.

"These chemicals aren't very well regulated in the U.S., where there are thousands of chemicals on the market that haven't been tested for toxicity," she says. Harley's research is focused on learning how these substances impact our health and making that information available to the public so that the compounds can be better regulated.

The results of the recent Health and Environmental Research in Make-up of Salinas Adolescents (HERMOSA) study, led by Harley, were published in March in the journal Environmental Health Perspectives. The study—which enrolled 100 Latina teenage girls in the Salinas Valley of California—showed that taking even a three-day break from certain personal care products can lead to a marked drop in the levels of hormone-disrupting chemicals in the body.

"We know that there are chemicals in certain make-up and personal care products that interfere with naturally occurring hormones," says Harley. "Since hormones are the chemical messengers of our body, regulating many aspects of health and development, these compounds can have a wide ranging impact on our health." Harley says that hormone-disrupting chemicals seem to be a bigger problem during critical windows of exposure while human bodies are growing and developing, namely during pregnancy, in early childhood, and throughout adolescence.

The HERMOSA study focused on teenage girls because they use more make-up and personal care products than women do and women use more than men. "We wanted to focus on a group with a high exposure to hormone-disrupting chemicals at a time when they are undergoing rapid reproductive and brain development," says Harley.

In place of their regular products, the participants used low-chemical make-up, conditioner, soap, and body lotion provided by the researchers. Urine testing done pre- and post-participation found that the levels of four chemicals—phthalates, parabens, triclosan, and oxybenzone—decreased between 25 percent and 45 percent. "In animal studies, these four chemicals have been shown to interfere with or mimic hormones like estrogen and testosterone," says Harley. "We are still learning about how these chemicals affect humans, but we know enough to be concerned."

Since there is research showing that these chemicals may increase the risk of cancer, affect brain development and behavior, and impact immune function, among other health concerns, Harley is eager to spread the word about the impact that some simple changes can make.

"I think most people are unaware that there are hormone disrupting chemicals in products we are putting all over our bodies," she says. "But we have evidence to show that the chemicals that we are putting on our bodies are getting into our bodies." She says that people who are concerned about reducing their exposure to these chemicals should read product labels. "It can be intimidating to read the list of chemicals but look for shorter labels with fewer ingredients, or products that specifically advertise that they contain no parabens, phthalates, or artificial fragrance," she advises. The Environmental Working Group ( and Campaign for Safe Cosmetics ( are also good resources for greener products, she notes.

The HERMOSA study did more than prove the concept that making a change in personal care products makes a difference in the body. It also strengthened community-university collaboration in the Salinas Valley, a northern California agriculture region with a large Latino farmworker population.

Kim Harvey '92 with members of HERMOSA study team.

Seven years ago, Harley helped create the CHAMACOS youth council, a joint project of UC Berkeley and Clinica de Salud del Valle de Salinas, which meets every two weeks, with the goal of empowering local high school students and growing the next generation of environmental health leaders. "We train these young people in environmental health literacy and environmental justice and make them aware of issues in the community," she says. "We use community-based participatory research (CBPR) in which we have the youth tell us what the issues are in their community, what research is important, and what information we need to give back to the community."

In fact, CBPR led to the creation of the HERMOSA study. "At a meeting of the youth council, we talked to them about the hormone-disrupting chemicals in products that get into their bodies; it was eye opening for them," she says. Harley and her colleagues worked with the teens to design the study. The teens designed the logo, came up with the study's name, pilot-tested the questionnaire and the replacement products, and conducted all the data collection.

"We hired some of the teens as UC Berkeley research assistants to conduct the study. They did everything, from recruiting participants, conducting interviews, and collecting urine samples," says Harley. "The youth in this area don't typically have a lot of opportunities; they are largely low-income Latino kids in a community with high rates of teen violence and teen pregnancy." Harley says that if the young people hadn't been hired as research assistants, many of them would have been working in the fields.

Of the 15 students hired as research assistants, 5 are currently attending community college while 10 are at four-year colleges. All of the students are first-generation college students. Harley stays in touch with many of the former research assistants, including the five currently attending UC Berkeley. Two of those students are pre-med, two plan to major in public health, and one is interested in environmental policy.

"This project certainly sparked an interest in public heath and the environment for many of the participants, which is very fulfilling to see," says Harley. "During the research study, some of the students were interviewed on the news and said things such as, 'I always thought scientists were people in white lab coats.' and 'Before this, I never thought science was relevant to my life and my community.' Our work is about involving community members in research that is relevant to them."

—Michele Lynn P'19