Bisphenol A (BPA) and phthalates, two types of chemicals in plastics that have been linked to a number of health effects, could still find their way into your body even if you avoid foods that are shipped, stored or cooked using plastic materials, new research suggests.
The findings are based on a small study that followed 10 families for five days. Half of the families got catered meals made with fresh, local ingredients that were not stored or prepared with plastics.
The other half got a handout on how to avoid BPA and phthalates in their diet, such as not microwaving foods and drinks in plastic containers and avoiding food in cans, which are often lined in BPA-containing material.
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"We fully expected to see reductions in the catered-diet group, and hoped the other group would also have reductions" in their levels of these chemicals, said study author Sheela Sathyanarayana, M.D., an assistant professor of pediatrics at the University of Washington in Seattle.
Instead, the researchers found that all but one person in the catered-diet group had a spike in phthalate levels in their urine during the five-day diet intervention, and a more modest increase in their BPA levels. In contrast, the group that got handouts had steady levels of these chemicals over the study period.
The researchers then tested the ingredients in the catered diet to track down the source of phthalate exposure and detected high levels in milk, butter and cream, and also in some of the spices, such as cinnamon and ground coriander.
"Several studies have found that high-fat dairy tends to contain high concentration of phthalates, maybe because of phthalates in the plastic tubing that milk goes through to get to the final containers, and it may be in animal products, such as feed," Dr. Sathyanarayana said.
Overall, the more processed the food, the more likely it could come into contact with materials that contain phthalates, and phthalates can easily leach from these materials into food, Dr. Sathyanarayana explained. Spices could be one type of highly processed food, she added.
Unfortunately, consumers have no way of knowing which products or brands contain phthalates because manufacturers themselves don't know whether their processing materials contain phthalates, Dr. Sathyanarayana added.
Brent Collett and his wife and kids were one of the families that received the catered diet for the study. At the end of the study, Collett and the other families received a letter telling them their phthalate and BPA levels and the foods that contained phthalates.
"To have ingredients [such as coriander] that is not a major part of diet lead to this increase was a bit of an eye-opener," said Collett, a psychologist at Seattle Children's Hospital. "There would be no way we as consumers could do any better" than the catered diet in this study at avoiding plastics, he added.
The American Chemistry Council, which represents the chemicals industry, had this to say about the findings:
"The study confirms that exposure to BPA is very low, regardless of the dietary choices made by the participants," said Steven Hentges, executive director of the Polycarbonate/BPA Global Group at the council. "The exposure values reported are below the typical values for the U.S. population . . . The study results are very reassuring, and don't raise any alarms for BPA."
But another expert had a different opinion.
Maida Galvez, M.D., an associate professor of pediatrics and preventive medicine at the Icahn School of Medicine at Mount Sinai University in New York City, said: "This study points to the need for comprehensive legislation, such as the Safe Chemicals Act, and for third-party certification that products are free [of phthalates and BPA]."
The Safe Chemicals Act is proposed legislation that would require manufacturers to provide safety data for chemicals in products that are already on the market, and help ensure that products are tested for safety before they enter the market.
Phthalates and BPA are found in a variety of other materials, including construction and automobiles, medical devices, perfumes and clothing.
The U.S. Food and Drug Administration approved phthalates for use in food packaging back in the 1960s, and has not reevaluated their safety since then, said Sarah Janssen, a senior scientist in the Health and Environment program of the Natural Resources Defense Council, an environmental action group.
Although the FDA has been reviewing the safety of BPA, its evaluation has depended heavily on studies funded by the chemical industry, Janssen said.
"The question is, 'Are these chemicals safe?' and I would argue that they are not," said Janssen, who has conducted research testing phthalate levels in foods.
Phthalates and BPA are known as "hormone disruptors" that can interfere with testosterone production and mimic estrogen, respectively.
Research suggests that phthalates can interfere with reproductive development in males, reduce male fertility and increase the risk of asthma in children. BPA has been linked to hyperactivity and aggression in children exposed as fetuses, and heart disease and diabetes in adults.
The current study was published in the Journal of Exposure Science and Environmental Epidemiology.
Dr. Sathyanarayana and her colleagues included five families with 10 adults and 11 children in the catered-diet group, and five families with nine adults and 10 children in the group that got a written handout.
Notably, children in the diet-intervention group had higher levels of the chemicals than the adults. "Children are not only vulnerable because of their increased body burden [due to their smaller bodies] but also because they are probably taking in a lot more dairy," Sathyanarayana explained.
Although the levels of phthalates and BPA in the group that received a handout did not change, they also did not drop, as the researchers had hoped. Dr. Sathyanarayana and her colleagues are currently working on creating educational materials that are more user-friendly with videos on how to grocery shop and prepare foods.
Even though "there's likely contamination higher up in the food chain, in growing and processing the food, there are still lots of things you can do to reduce your exposure," she said. These steps include avoiding plastics that could contain phthalates and BPA, storing food in glass containers and not heating foods in plastic containers.
"The same advice that your doctor gives you to eat a low-fat diet, less processed foods and more fruits and vegetables will probably also reduce your consumption of phthalates," Janssen said.