Elevated urinary concentration of bisphenol A (BPA) and di-2-ethylhexyl phthalate (DEHP), two chemicals commonly used in food packaging, have been associated with obesity in kids and insulin resistance in teens, results from two studies show.
In one study, higher urinary BPA concentrations were significantly associated with higher risk for BMI ≥ 95th percentile and abnormal waist circumference-to-height ratio, Joyce Lee, MD, of the Child Health Evaluation and Research Unit at the University of Michigan in Ann Arbor, and colleagues reported.
In a second study, adolescents with three-fold increased urinary concentrations of DEHP had a 27% increased risk for insulin resistance, according to Leonardo Trasande, MD, of New York University’s Langone Medical Center in New York City, and colleagues. Both studies appeared in Pediatrics.
Both BPA and DEHP are chemical compounds used in the manufacture of food and drink containers. Previous studies have linked BPA exposure with obesity in kids, altered thyroid function in pregnant women and behavioral problems in toddlers. In July 2013, the FDA banned the use of BPA in infant formula packaging.
In the most recent studies, Lee and colleagues examined the relationship between urinary concentrations of BPA and adiposity measures, cholesterol, insulin and glucose in a population of 3,370 children and adolescents aged 6 to 18 years who were included in the 2003-2010 National Health and Nutrition Examination Survey (NHANES).
Children were grouped into four quartiles based on urinary BPA concentrations: first quartile, less than 1.3 ng/mL; second quartile, 1.3 to 2.6 ng/mL; third quartile, 2.6 to 4.9 ng/mL; fourth quartile, greater than 4.9 ng/mL
Compared with those with the lowest concentrations of urinary BPA, children with moderate or greater exposure were at significantly increased risk for obesity, the researchers found:
- Second quartile had 74% increased odds for obesity (odds ratio 1.74, 95% CI 1.17-2.60, P=0.008)
- Third quartile had 64% increased odds (OR 1.64, 95% CI 1.09-2.47, P=0.02)
- Fourth quartile had a two-fold greater risk (OR 2.01, 95% CI 1.36-2.98, P=0.001)
The likelihood of having abnormal waist circumference-to-height ratio was also significantly greater for those in the third (OR 1.41, 95% CI 1.07-1.87, P=0.02) and fourth quartiles (OR 1.55, 95% CI 1.12-2.15, P=0.01).
Lee and colleagues pointed out the possibility of reverse causality, noting that obese people may store BPA differently than those who are not obese.
In the study by Trasande and colleagues, the researchers examined associations between DEHP metabolites and insulin resistance among a population of 5,829 adolescents aged 12 to 19 years included in the 2003-2008 NHANES data.
For each log unit increase in DEHP metabolites, there was a 0.19 increase in score for homeostatic model assessment of insulin resistance (HOMA-IR; P=0.005). This association was stronger among girls, Hispanics and blacks, and in households with poverty-income quartiles less than 1.3.
Those with the highest concentrations of urinary DEHP had a 21.6% prevalence on insulin resistance (95% CI 17.2%-26.0%, P=0.017).
Trasande and colleagues pointed out that lower molecular weight phthalates commonly used in cosmetics and other personal care products have not been associated with insulin resistance.
In an accompanying editorial, Robert Brent, MD, PhD, of the Alfred I. DuPont Hospital for Children in Wilmington, Del., urged caution when interpreting the study results because “using urine as a marker of an environmental toxin is not necessarily reflective of a significant exposure.”
“Most BPA articles in humans use the urine content of BPA as a surrogate of exposure, when in reality it is a measure of the intake of BPA from diet,” he noted, adding that “actual serum levels are extremely low and in many instances not detectable.”
“Therefore, the studies that determine the effect of BPA by using urinary BPA levels areunlikely to be valid,” Brent wrote.
Both Lee and Trasande’s groups called for further longitudinal studies to confirm the associations between BPA, DEHP and metabolic affects.