Chemicals used in food packaging can increase the risk of obesity and pre-diabetes in children, a new study reported.

The study found that phthalates could raise the risk of insulin resistance in teens and bisphenol A or BPA could up the risk of obesity. According to estimates by Centers for Disease Control and Prevention, a third of all people living in the U.S are obese. 

 Earlier studies have found that women exposed to phthalate had a higher risk of developing diabetes. Also, research conducted on rhesus monkeys showed that BPA could lead to birth defect and even shorten reproductive lifespan.

A person unable to use insulin (a hormone required to break down sugar) is Insulin resistant. Detecting pre-diabetes in children is especially difficult as it usually has no symptoms. Risk factors for insulin resistance and pre-diabetes include excess weight, lack of physical activity, hormonal and sleep-related problems.

For the study, Trasande and colleagues looked at data on 766 adolescents aged 12 to 19. They were all part of a nutrition and health survey conducted between 2003 and 2008.

They found that exposure to a certain phthalate called Di-2-ethylhexylphthalate (DEHP) was associated with the child's risk of developing insulin resistance. DEHP is used to soften plastics.

However, the scientists added that the study didn't show a cause-effect relationship between food packaging material and health complications. It is possible that already obese children are eating more packaged products and are increasing their exposure to the chemicals.

"Clearly unhealthy diet and lack of physical activity are the drivers of this epidemic ... but increasingly environmental chemicals are being identified as possible contributors," Dr. Leonardo Trasande, a pediatrician from New York University told Reuters Health.

Another related study by University of Michigan researchers found that kids exposed to BPA didn't have any diabetes risk, but had an increased risk of obesity and larger waist circumference. This study was based on data of over 3,300 children and teens between age 6 and 18 years.

The research is published in the journal 'Pediatrics.'