Contaminated diet contributes to exposure to endocrine-disrupting chemicals: Phthalates and BPA

According to a study published February 27 in the Nature Journal of Exposure Science and Environmental Epidemiology, we may be exposed to these chemicals in our diet, even if our diet is organic and we prepare, cook, and store foods in non-plastic containers. Children may be most vulnerable.

"Current information we give families may not be enough to reduce exposures," said Dr. Sheela Sathyanarayana, lead author on the study and an environmental health pediatrician in the UW School of Public Health and at Seattle Children's Research Institute. She is a physician at Harborview Medical Center's Pediatric Environmental Health Specialty Unit, and a UW assistant professor of pediatrics.

Phthalates and bisphenol A, better known as BPA, are synthetic endocrine-disrupting chemicals. Previous studies have linked prenatal exposure to phthalates to abnormalities in the male reproductive system. Associations have also been shown between fetal exposure to BPA and hyperactivity, anxiety, and depression in girls.

The researchers compared the chemical exposures of 10 families, half of whom were given written instructions on how to reduce phthalate and BPA exposures. They received handouts prepared by the national Pediatric Environmental Health Specialty Units, a network of experts on environmentally related health effects in children. The other families received a five-day catered diet of local, fresh, organic food that was not prepared, cooked or stored in plastic containers.

When the researchers tested the participants' urinary concentrations of metabolites for phthalates and BPA, they got surprising results. The researchers expected the levels of the metabolities to decrease in those adults and children eating the catered diet.

Instead, the opposite happened. The urinary concentration for phthalates were 100-fold higher than the those levels found in the majority of the general population. The comparison comes from a study conducted by the National Health and Nutrition Examination Survey. This is a program of studies managed by the Centers for Disease Control and Prevention and designed to assess the health and nutritional status of adults and children in the United States.

The concentrations were also much higher for children as compared to the adults. The researchers then tested the phthalate concentrations in the food ingredients used in the dietary intervention. Dairy products -- butter, cream, milk, and cheese -- had concentrations above 440 nanograms/gram. Ground cinnamon and cayenne pepper had concentrations above 700 ng/g, and ground coriander had concentrations of 21,400 ng/g.

"We were extremely surprised to see these results. We expected the concentrations to decrease significantly for the kids and parents in the catered diet group. Chemical contamination of foods can lead to concentrations higher than deemed safe by the US EPA," said Dr. Sheela Sathyanarayana.

Using the study results, the researchers estimated that the average child aged three to six years old was exposed to 183 milligrams per kilogram of their body weight per day. The U.S. Environmental Protection Agency's recommended limit is 20 mg/kg/day.

"It's difficult to control your exposure to these chemicals, even when you try," said Sathyanarayana. "We have very little control over what's in our food, including contaminants. Families can focus on buying fresh fruits and vegetables, foods that are not canned and are low in fat, but it may take new federal regulations to reduce exposures to these chemicals."

The other researchers in the study included Garry Alcedo (Seattle Children's Research Institute), Brian E. Saelens and Chuan Zhou (UW Department of Pediatrics, Seattle Children's Research Institute), Russell L. Dills and Jianbo Yu (UW Department of Environmental and Occupational Health Sciences) and Bruce Lanphear (BC Children's Hospital and Simon Fraser University).

Their paper is titled, "Unexpected results in a randomized dietary trial to reduce phthalate and bisphenol A exposure."

The study was supported through by the Center for Ecogenetics and Environmental Health in the Department of Environmental and Occupational Health Sciences in the UW School of Public Health. A grant from the National Institute of Environmental Health provides major support for the center.