"Although our results need to be confirmed in more studies, they do support the hypothesis that certain environmental chemicals can contribute to the development of diabetes," says Monica Lind, associate professor of environmental medicine at the Section for Occupational and Environmental Medicine, Uppsala University.
Together with Lars Lind, professor of medicine at Uppsala University, she has analysed new information from the so-called PIVUS study, which covers more than 1 000 70-year-old women and men in Uppsala.
In a physical examination participants were examined for fasting blood sugar and various insulin measures. They submitted blood samples for analysis of various environmental toxins, including several substances formed when the body breaks down so-called phthalates. Most people come into daily contact with phthalates as they are used a softening agents in plastics and as carriers of perfumes in cosmetics and self-care products.
As expected, diabetes was more common among participants who were overweight and had high blood lipids. But the researchers also found a connection between blood levels of some of the phthalates and increased prevalence of diabetes, even after adjusting for obesity, blood lipids, smoking, and exercise habits. Individuals with elevated phthalate levels had roughly twice the risk of developing diabetes compared with those with lower levels. They also found that certain phthalates were associated with disrupted insulin production in the pancreas.
"However, to find out whether phthalates truly are risk factors for diabetes, further studies are needed that show similar associations. Today, besides the present study, there is only one small study of Mexican women. But experimental studies on animals and cells are also needed regarding what biological mechanisms might underlie these connections," says Monica Lind.
Facts about phthalates:
Mono-methyl phthalate (MMP), Mono-ethyl phthalate (MEP) and mono-isobutyl phthalate (MiBP) are all metabolites of the chemicals dimethylphthalate (DMP), Diethyl phthalate (DEP) and Di-isobutyl phthalate (DiBP), respectively, and are used in, among other things, cosmetics, self-care products, solid air fresheners, and scented candles. DMP is also used in ink and as a softening agent in cellulose plastics.
Phthalate studies point to several health problems
Researchers from Brigham and Women's Hospital published a report in Environmental Health Perspectives which revealed that women with high phthalate levels in their urine have a considerably higher risk of developing diabetes, compared to those with the lowest levels. (Link to article)Researchers from the Children's Environmental Health Center at The Mount Sinai Medical Center found a link between obesity in young children and exposure to phthalates. (Link to article)
Scientists from the University of Rochester Medical Center found in a pilot study that young boys whose mothers had high phthalate urine levels when they were pregnant were less likely to "play like boys" - engage in boyish banter, play fighting, and use masculine toys. (Link to article)
Phthalate concentrations were found in infants' urine by researchers from the CDC in Atlanta and the University of Rochester School of Medicine and Dentistry. The investigators said phthalates are widely used in baby care products, such as lotion, talc and shampoo. (Link to article)
At Columbia University's Mailman School of Public Health, scientists found "prenatal exposure to phthalates may adversely affect child mental, motor and behavioral development during the preschool years". (Link to article)
Scientists from the University of Michigan, in a large-scale study, confirmed a link between phthalate and BPA concentrations and thyroid hormone levels. Thyroid hormones play a key role in reproduction, metabolism, energy balance and other body functions. (Link to article)