If one word could describe the onslaught of chemicals that we’re exposed to every day, ubiquitous might be it. Nearly everything we touch—from food packaging to that comfy living room couch—presents us with chemicals that we can’t see and usually can’t smell.
One class of chemicals in particular, called endocrine-disrupting chemicals, are known to interfere with hormone (endocrine) functions, and have been associated with cancer, birth defects, diabetes, obesity, neurodevelopmental disorders and harm to reproductive systems—but are largely unregulated in the U.S. Bisphenol A, or BPA, is the chemical from this class that has received the most attention and scrutiny in recent years, ultimately leading the federal government to issue rare new restrictions on its use in consumer goods (mainly baby bottles, sippy cups and infant food packaging).
Yet as omnipresent as these chemicals are, researchers are finding that some minority and low-income populations experience even greater exposure to many of these substances than whites or the general population. A panel of health experts raised this and other questions around endocrine-disrupting chemicals during a Jan. 31 forum hosted by the Harvard T.H. Chan School of Public Health.
What is not yet clear is what this increased exposure means, exactly, for the populations affected, said Tamarra James-Todd, PhD, MPH, an epidemiologist and environmental health scientist at Harvard. That’s what she wants to bring more attention to, and see more research on.
“There are populations that are more vulnerable, be it due to their furniture quality or their housing quality, so they’re more exposed to flame retardants; or their diet, leaving them more exposed to phenols; or due to certain cultural practices because they use more fragrances and cosmetics,” James-Todd said during the forum. “How that tracks together gives people different risk profiles.”
She cited data from the Centers for Disease Control and Prevention’s ongoing National Health and Nutrition Examination Survey showing that African-Americans and Hispanics have higher body concentrations of many phthalates than white populations—one study traced phthalate exposure among African-American women to their more widespread use of vaginal douches and other feminine care products compared with white women—as well as phenols and parabens. The same research found that Hispanics had higher systemic levels of some flame retardants. Some of James-Todd’s own research has found that more black women use hair products containing endocrine-disrupting chemicals than white women.
James-Todd has focused much of her research on pregnant women, looking at impacts of chemical exposure on babies but also on women’s own long-term health. “Across the entire time-period of pregnancy, many of these chemicals maintain higher concentrations among these vulnerable women,” she said.
James-Todd noted that while gestational diabetes affects about 5 to 7 percent of pregnant women overall, that rate jumps to 14 percent in some Native American communities, and to around 10 percent among some Asian-American and Hispanic women. As evidence increases that endocrine-disrupting chemicals interfere not only with hormones but metabolic activity, so do concerns that higher chemical exposure could be to blame, at least partially, for the increase in gestational diabetes. James-Todd added that gestational diabetes ultimately increases the risk of these women developing type 2 diabetes later on.
There are disparities along socioeconomic lines, as well: A few years ago, researchers reported higher concentrations of BPA in people who were food-insecure than those who were not. The effect was even stronger among children, where those receiving emergency food aid had 54 percent higher BPA levels than children whose families did not.
“We don’t know how those sources of exposure play into the disparities we see with respect to the biomarkers that we use to measure exposure,” James-Todd said. “In the literature to date, that has simply been documented and described. People have posited as to why that may be, but there are very few, if any, studies that have looked at the why, and the implications of the differences.”