Chemicals in Popular Consumer Products Associated with Increased Risk of Diabetes in Women

By: Almas Eftekhari

According to a recent ADA-funded study, chemicals commonly found in beauty and hygiene products may increase the risk of diabetes in women. Phthalates are a class of industrial chemicals often used in the manufacturing of consumer products, especially cosmetics, perfumes, nail polishes, soaps, and even food packaging and toys. More than 75 percent of people in the US have detectable amounts of phthalate metabolites in the body. Women, however, have significantly higher levels than men, which may be owed to increased exposure through greater use of personal care products.  

The study’s lead investigator, Tamarra James-Todd, PhD, and her mentor Janet Rich-Edwards, PhD, from Brigham and Women’s Hospital suggest that exposure to phthalates may be partially to blame for the growing prevalence of diabetes in women. Phthalates are known to be endocrine disrupting chemicals, which can interfere with hormones in the body related to metabolism and insulin sensitivity.

The research team analyzed urine samples from 2,350 women between the ages of 20 and 80 years old, collected from the National Health and Nutrition Examination Survey over an eight-year period. They found that women with the highest concentrations of mono-benzyl and mono-isobutyl phthalates were almost twice as likely to have diabetes compared to women with the lowest levels. Those with elevated levels of mono-n-butyl and di-2-ethylhexyl phthalates showed a 70% increased odds of diabetes, and those with high levels of mono-(3-carboxylpropyl) phthalate were at 60% greater odds.

The researchers also evaluated women without diabetes to determine whether phthalates altered precursors of diabetes, such as blood glucose levels and insulin resistance.  Among women without diabetes, those with high concentrations of mono-isobutyl and di-2-ethylhexyl phthalate had elevated fasting blood-sugar levels and were more insulin resistant in comparison to women with lower levels of these phthalates.

Published online in the July 13, 2012 edition of Environmental Health Perspectives, the study is the first to examine the association between phthalates and diabetes in a large, representative sample of women living in the US. These findings suggest the need to further examine the role phthalates, and other endocrine disrupting chemicals, as potential risk factors for diabetes.  If future studies find a causal link between phthalates and diabetes, reducing exposure to these chemicals could prevent or delay the onset of diabetes in women at high risk or with pre-diabetes. “Individuals with diabetes could benefit from this research indirectly through learning about those exposures that could further increase the risk of diabetes among family members who may already be at an increased risk,” Dr. Rich-Edwards expanded.  

While the study accounted for sociodemographic, dietary, behavioral, and anthropometric factors, women self-reported their diabetes status and researchers caution against reading too much into the study due the possibility of reverse causation.  “This is an important first step in exploring the connection between phthalates and diabetes,” said Dr. James-Todd. “We know that in addition to being present in personal care products, phthalates also exist in certain types of medical devices and medication that are used to treat diabetes. So overall, more research is needed."

While the commercial use of phthalates is declining due to concerns of their potentially negative impact on health, including cancer and male sterility, avoiding overexposure can be difficult, since companies are not required to label whether a product contains phthalates.  However, most products containing “fragrance” on their ingredients list contain phthalates, as well as many food items packaged and stored in plastics. It is possible that avoiding or reducing the use of these items could decrease phthalate exposure, but this remains unclear.  In their future work, Drs. Rich-Edwards and James-Todd plan to further explore whether avoiding phthalates through lifestyle interventions will help reduce the risk of developing diabetes.

(James-Todd T, Stahlhut R, Meeker JD, Powell S-G, Hauser R, Huang T, et al. 2012. Urinary Phthalate Metabolite Concentrations and Diabetes among Women in the National Health and Nutrition Examination Survey (NHANES) 2001-2008. Environ Health Perspect:-. http://dx.doi.org/10.1289/ehp.1104717)