From the Boston Globe:

[Upstream Contributor] Dr. Ana Soto won’t use plastic in the microwave.

R. Thomas Zoeller uses an iPhone application that flags products with potentially dangerous chemicals to help him make wise choices at the grocery store.

Dr. Perry E. Sheffield washes her hands often — as much to get rid of potentially dangerous chemicals as germs.

It’s nearly impossible to prove scientifically that certain diseases are caused by household chemicals, such as bisphenol-A, phthalates, and flame retardants, which are found in everything from kitchen cleaners to baby creams, carpeting to tin cans.

But as research accumulates about their potential dangers, and rates of diseases that are plausibly caused by these chemicals rise, these three scientists are anxious enough to make changes in their own homes.

“Effectively, we’re conducting experiments on our population,’’ said Sheffield, an assistant professor of preventive medicine and pediatrics at Mount Sinai School of Medicine in New York.

Researchers long ago proved that chemicals like bisphenol-A and phthalates can disrupt development in animals by interfering with their hormones. Now, scientists are increasingly demonstrating that these chemicals, known as endocrine disruptors, might be harmful to people, too.

“What’s happening to rats and mice is an indicator of what’s happening to humans,’’ said Soto, professor of cellular biology at Tufts University School of Medicine.

In one study of 427 men published in December, those who had the most bisphenol-A — known commonly as BPA — in their urine reported the highest levels of sexual problems, from decreased desire to lower satisfaction with their sex lives. In a 2009 study of 250 toddlers, girls (but not boys) were more likely to act aggressively if their mothers had high urine levels of BPA during pregnancy.

And a national survey of more than 1,400 adults showed that people with higher concentrations of BPA in their urine were more likely to have been diagnosed with heart disease or diabetes, according to a 2008 study in the Journal of the American Medical Association.

None of these studies are conclusive evidence of harm, the researchers said, because they do not meet the gold standard of medical research. To do that, scientists would have to study two large populations of people — one exposed to a chemical and one not — potentially for decades, to see if there are health differences between the two. Since virtually everyone is exposed to the major chemicals, and since our lifestyles differ in so many different ways, it would be nearly impossible to conduct such a study. Instead, researchers look to animal studies and weaker human studies to build a case.

The scientists interviewed for this story said enough data has accumulated to suggest that these chemicals might be harmful — and that we should take precautions as if they were.

It’s scientifically plausible that these chemicals account for some cases of autism, ADHD, learning disorders, and autoimmune problems like allergies and asthma, said Zoeller, a biology professor at the University of Massachusetts-Amherst and chairman of the Environmental Protection Agency’s Exposure and Human Health Committee.