Previous studies of phthalates have mainly focused on how they affect reproductive health and child development. These chemicals are believed to act as endocrine disrupters in the body, meaning they may have an impact on sex hormones.
The new study, however, looks at their potential health effects among people over age 65.
Critics of the new study are quick to point out that it does not show that exposure to these chemicals causes diabetes in any way, shape, or form. The study just shows an association, not a cause-and-effect relationship.
Researchers measured fasting blood sugar (when a person has not eaten for at least eight hours) and other factors associated with the hormone insulin in more than 1,000 70-year-old women and men from Uppsala, Sweden. Their blood was also analyzed for evidence of environmental toxins, including several substances formed when the body breaks down phthalates.
Diabetes Risk Doubles in the Presence of Phthalates
Overall, diabetes was more common among participants who were overweight and had high blood cholesterol levels. That said, risk was also elevated among those who had higher blood levels of some of the phthalates.
According to the new study, individuals with higher phthalate levels had roughly twice the risk of developing diabetes compared to those with lower levels.
"There is a connection between phthalates found in cosmetics and plastics and the risk of developing diabetes among seniors," says researcher P. Monica Lind, PhD, via email. Lind is an associate professor of occupational and environmental medicine at Uppsala University in Sweden. "Even at relatively low levels of phthalate metabolites in the blood, the risk of getting diabetes begins to rise."
Exactly how, or even if, phthalates may increase diabetes risk is not known. "Further studies are needed that show similar associations," Lind says. "Experimental studies are also needed regarding what biological mechanisms might underlie these connections." One theory is that phthalates may interact with important players in the fat metabolism process.
The findings appearinDiabetes Care.
It is hard -- if not impossible -- to avoid phthalates. Most people come into daily contact with them, as they are used as softening agents in everyday plastics and as carriers of perfumes in cosmetics and self-care products. "The implications of our findings must be to cut down on plastics, and choose self-care products without perfumes," Lind says in an email.
A Cause for Concern?
"There are chemicals in our environment including phthalates that may be able to interact with the body that changes the way we metabolize and regulate fat," says Johanna Congleton, PhD. She is a senior scientist for Environmental Working Group in Washington, D.C.
Many companies are phasing these chemicals out of their products, but others still rely on them to make plastics more flexible and durable. And "they are doing a good job of getting into our bodies and could affect metabolic processes," she says.
Concerned consumers should call on manufacturers and legislators to phase out phthalates and other potentially endocrine-disrupting chemicals such as the controversial plasticizer BPA, Congleton says.
Jill Stein, MD, a candidate for the Green Party's presidential nomination, reviewed the study for WebMD. "This study adds to a very powerful growing body of evidence that implicates these endocrine-disrupting chemicals in very pervasive diseases."
She says there "is real cause for concern." But "we can fix this; it is not as though the damage is done." Stein says these chemicals leave our body quickly if we avoid exposure.
"The burden should not be on consumers."
What can we do? A lot, she says. Choose products that don't contain these chemicals, urge manufacturers to phase these chemicals out, and let your state and local legislators know how you feel.
The movement to ban BPA had a setback, though, in late March when the FDA said it will not ban this chemical.
Critics: Phthalates Are Safe, Study Is Flawed
Members of the American Chemistry Council (ACC), which represents the chemical industry, point to flaws in the research, as well as to phthalates' extensive safety record.
"The authors over-state the conclusions and, most important for the public to know, the study does not show any cause-and-effect relationship between phthalate exposure and diabetes," says Steve Risotto, senior director of the ACC Phthalate Esters Panel, in a written statement. "Phthalates have a long history of safe use and have been extensively reviewed by governments around the world including the CDC, which found that average phthalates exposure levels are actually far below those set by the government to be protective of human health."
What's more, the levels of phthalates seen in the study are based on one blood sample and were analyzed five to eight years following collection. "This single sample is meaningless for characterizing long-term exposure, as phthalates are rapidly metabolized and eliminated from the body within 24 hours," he says.