Epidemiologist Joseph Braun is interested in the “environmental determinants of children’s health — in particular, the effects of chemical exposures early in life,” when the developing brain is most vulnerable.

Braun, who holds a Master of Science in Public Health as well as a Ph.D. in epidemiology, is investigating whether prenatal exposure to chemical pollutants is increasing the risk of problems like ADHD, conduct disorder, and autism, as well as affecting intelligence, memory, and learning in children.

Currently, Braun is focusing on the influence of endocrine disrupting compounds (EDCs) like bisphenol A (BPA) and phthalates, chemicals found in everything from personal care products to plastic bottles and canned and packaged foods. These pollutants are present in the bodies of virtually all people who live in industrialized countries.

“Some researchers think that the fetus’s exposure to hormones like testosterone and estradiol might influence the risk for developing autism and ADHD. This is, of course, a very controversial theory,” Braun says. “Endocrine disrupting compounds like BPA and phthalates may act on hormonal systems, either affecting the metabolism of the fetus’s hormones or acting on the receptors that the natural hormones were intended for. So if BPA, which looks a lot like estradiol, fits into the receptor, but does it at the wrong time, that could actually lead to abnormal development.” Braun’s work is supported by a five-year National Institutes of Health “Pathway to Independence Award.”

In one study still in its early stages, Braun is following a cohort of women and children in the Cincinnati area. His team measured BPA and phthalate levels in the mother’s urine and then followed up on the children three years later.

“So far, we have found that the daughters of women with higher BPA exposure during pregnancy tend to have more ADHD-like and anxious behaviors. They also have difficulty with emotional and behavioral regulation — problems with what we refer to as executive function,” Braun says. He plans to check on the children again at ages 5 and 8.

One criticism of this type of research is that the measured effects can be subtle — a couple points in behavior or IQ. “You and I wouldn’t notice if we lost three IQ points, although I hope I don’t lose any,” Braun says. “But if you imagine a population of a million people, and they each lose three IQ points, you have now increased the proportion of people with intellectual disabilities, and you've also reduced the number of people who could be considered gifted. So even if these chemicals have subtle effects on the individual, they can have very profound effects on populations.”

Braun comes to the field of epidemiology via an unusual route. A Wisconsin native, he worked in a lab after graduating from the University of Wisconsin–Madison with a degree in biochemistry, but he felt uninspired by laboratory research. “I just wasn’t interested in the art of mixing colorless liquids,” he says. “I wanted to join the front lines of the health care field.”

So he got a nursing degree from the University of Wisconsin–Milwaukee and worked as a school nurse in two inner-city elementary schools in Milwaukee for a year.

“The number of children I saw who were diagnosed with either ADHD or autism was quite staggering,” he says. “This experience solidified my interest in working with kids and finding ways of reducing the burden of environmentally caused diseases in children.”

Braun went on to earn his M.S.P.H. (2008) and Ph.D. (2010) in epidemiology from the University of North Carolina, then joined the Department of Public Health at the Harvard School of Public Health as a postdoctoral fellow.

Braun was drawn to Brown’s Program in Public Health by the University’s commitment to interdisciplinary research and by the opportunity to work with students at all levels, from doctoral students in epidemiology to undergraduates interested in environmental hazards. He will be teaching a graduate class on environmental epidemiology in his first year.

He and his wife, Kerry Hanson, an attorney, have settled into their new place on the East Side. A marathon runner — he has run six and qualified for the Boston marathon — Braun plans to keep up his training.

How does he do it all? “We don’t have any kids yet,” he says.

“We are very excited to have Joe on our faculty,” says Stephen Buka, chair of the Department of Epidemiology. “Biomedicine and epidemiology are challenging and exciting fields right now and they need pioneers who can forge cross-disciplinary paths that largely don’t exist yet. With his clinical background in children’s health and behavior, his knowledge of environmental pollutants, and his experience conducting epidemiological studies, Joe is poised to be such a pioneer. His energy and enthusiasm will serve him well in the classroom.”

Braun hopes his research will encourage policymakers to take action. “Regulations are supposed to protect the most vulnerable members of society. The developing fetus, infant, and young child are more susceptible to environmental chemicals because they are rapidly developing and not as efficient at detoxifying these chemicals as adults are,” he says. “Bringing this information to policymakers should, theoretically, help them make good decisions.”