What's in Those Plastics?

Phthalates levels in teen urine linked to higher insulin resistance

(RxWiki News) It can often take a while for researchers to learn more about the effects of different substances in the environment on our bodies. Phthalates are one of those substances we're learning more about.

A recent study found that teens with high levels of phthalates in their urine were also more likely to be insulin resistant.

Phthalates are compounds added to plastics to increase their flexibility and durability. For example, they are often added to PVC to soften it.

Insulin resistance can be a risk factor or a sign of type 2 diabetes.

This study did not show that phthalates cause insulin resistance or similar problems. More work is needed to understand the relationship between phthalates and insulin resistance.

"Look for phthalate-free products."

This study, led by Leonardo Trasande, MD, of the Department of Pediatrics at New York University's School of Medicine, looked at whether insulin resistance was linked to teens' exposure to phthalates.

Insulin resistance means the body's cells do not properly respond to the hormone insulin, which is used to process sugars in the body. Increased insulin resistance can increase the risk of type 2 diabetes.

A wide range of products may contain phthalates, including household goods, electronics, toys, medical devices, personal care products, textiles and pharmaceuticals.

Concerns about the safety of phthalates have been increasing, but there is still more research needed to understand their possible effects on the body.

Phthalate usage is decreasing due to regulations, such as a 2008 law which made it illegal to manufacture, import or sell a child's product with more than 0.1 percent of DEHP, DBP or BBP — three different phthalates.

This study focused on DEHP, which stands for di-2-ethylhexylphthalate and is often found in processed foods.

The researchers used data from the 2003-2008 National Health and Nutrition Examination Survey, which included urine sample analyses from 766 teens aged 12 to 19.

The researchers compared the amount of phthalates in the urine with standard measures of insulin resistance in the urine samples. They adjusted their analysis to account for the age, sex, gender, race/ethnicity, diet, weight, behavioral activities and smoking habits of each participant.

The researchers found that for each amount the DEHP concentration markers increased three times, there was a small increase in the individual's marker of insulin resistance.

For example, among the teens in the lowest third for phthalate exposure, 14.5 percent were insulin resistant.

Among the teens in the highest third for phthalate exposure, 21.6 percent were insulin resistant.

The researchers also made adjustments to account for the amount of bisphenol A (BPA) in the teens' urine. BPA is another chemical known to interfere with human's endocrine systems, the body system that manages hormones.

The results did not change after adjustments for BPA, which can be found in some foods and food packaging.

The researchers also found that the types of phthalates found in cosmetics and other personal care products did not appear to be linked to insulin resistance in any way.

The findings cannot show that phthalates cause insulin resistance. It may be, for example, that teens who are already insulin resistant already eat more food that contains phthalates or otherwise have more exposure to them.

"This study cannot rule out the possibility that insulin-resistant children ingest food with higher phthalate content, or that insulin-resistant children excrete more DEHP," the researchers wrote.

More research will be needed to understand the link better and whether phthalates are having an effect on the teens.

This study was published August 19 in the journal Pediatrics. The research was funded by the KiDS of NYU Foundation. The authors declared no conflicts of interest.

Review Date: 
August 18, 2013