Endocrine disruptors are chemicals that can interfere with estrogen, testosterone, thyroid hormone, insulin, or other hormones. At very low levels, they can turn on, shut off, or alter the signals that the hormones send throughout our bodies. And that can spell trouble.
Endocrine-disrupting chemicals can end up in what we eat and drink because they’re used in food processing equipment and food packaging.
Here’s what we know about one key disruptor—phthalates—and how to avoid them.
“Chemical in macaroni and cheese tied to birth defects,” announced the foxnews.com headline in July.
What was behind that bombshell? When consumer groups tested 30 cheese products, including boxed macaroni and cheese, for traces of a family of chemical plasticizers called phthalates, all but one of the 30 tested positive.1
Among other things, phthalates are linked to birth defects in boys.
Phthalates (THAL-ates) increase the flexibility of plastics in everything from vinyl flooring and shower curtains to IV tubes, food processing equipment, and food packaging. They’re also used in some adhesives, detergents, shampoos, and nail polishes.
“Phthalates are everywhere, and virtually all Americans have traces of these chemicals in their bodies,” says Ami Zota, a professor of environmental and occupational health at George Washington University. “You can even find them in household dust.”
The young may be the most vulnerable. In one study, seven-year-olds whose mothers had the highest levels of phthalates in their urine during pregnancy had IQs that averaged seven points lower than the IQs of seven-year-olds whose mothers had the lowest phthalate levels.2
How do phthalates affect adults?
Phthalates may also put adults at risk. “Researchers are finding that exposure to phthalates in adulthood may be linked to diabetes, obesity, and the metabolic syndrome,” notes Zota.
In the National Health and Nutrition Examination Survey, people with higher levels of certain phthalates weighed more and had larger waists and higher blood sugar and insulin levels than those with lower levels.3,4
But those studies were snapshots in time. They couldn’t show whether higher phthalate levels increased blood sugar or weight or vice versa. So researchers monitored nearly 1,000 nurses for 10 years after the women provided urine samples.
Those with the highest phthalate levels gained an average of one more pound every three years than those with the lowest levels.5 And middle-aged nurses with the highest phthalate levels were twice as likely to later be diagnosed with type 2 diabetes as those with the lowest levels.6 But there was no increase in diabetes risk for nurses in their 60s and 70s.
“We’re still trying to figure out why,” says Qi Sun, an assistant professor in the department of nutrition at the Harvard T.H. Chan School of Public Health. Older women may be less sensitive to phthalates because they have lower estrogen levels, he notes. “And endocrine disruptors exert their effects primarily through disturbing estrogen’s effects.”
Phthalates in food
“Phthalates are commonly found in food, and avoiding them is really hard,” says Sheela Sathyanarayanan, an associate professor of pediatrics at the University of Washington.
“We have some general ideas about which foods are more likely to be contaminated with them, such as poultry, red meat, butter, margarine, cooking oil, cream, and cheese. But we don’t know which specific oils, cheeses, or other foods to target.”
Making the challenge even harder: phthalates can leach into food from processing equipment and plastic packaging long before the food reaches us. And there’s no way we’d ever know.
When Sathyanarayana and her colleagues fed five families catered meals of local, fresh organic foods, they were stunned by the results.
Phthalate levels in the families’ urine were 33 times higher than levels in the urine of five similar families who ate their usual diets and were simply given advice about how to reduce phthalates.7
Two unexpected sources of phthalates in the special diet: coriander, which the caterer used liberally, and milk.
“We were not able to trace the sources of the contamination,” says Sathyanarayana. Odds are, it occurred before the food reached the caterer.
“We don’t know a lot about how our food is being contaminated with phthalates,” she points out. “The only way we can know that our food is free of phthalates is if the government does something about it.”
In 2016, a coalition of consumer and environmental groups—including the Center for Science in the Public Interest, Nutrition Action’s publisher—petitioned the FDA to ban phthalates in food packaging.8 The agency agreed to review the petition, but so far hasn’t declared what, if anything, it plans to do.
In the meantime, Sathyanarayana recommends eating more fresh foods. “The more fresh it is, the less likely it is to be contaminated with phthalates, though that’s no guarantee.”
Evidence also suggests that phthalates affect fertility. Stay tuned for details in an upcoming post.
2 PLoS One 9: e114003, 2014.
3 Int. J. Obes. 39: 994, 2015.
4 Environ. Health 13: 6, 2014.
5 Int. J. Obes. 38: 1532, 2014.
6 Environ. Health Perspect. 122: 616, 2014.
7 J. Expo. Sci. Environ. Epidemiol. 23: 378, 2013.
Photo: © Ezume Images/fotolia.com
Find this article interesting and useful? Nutrition Action Healthletter subscribers regularly get sound, timely information about staying healthy with diet and exercise, delicious recipes, and detailed analyses of the healthy and unhealthy foods in supermarkets and restaurants. If you don’t already subscribe to the world’s most popular nutrition newsletter, click here to join hundreds of thousands of fellow health-minded consumers.