Bisphenol-A (BPA), a chemical used in plastics, including food packaging, is associated with a higher risk of obesity in girls aged between 9 and 12 years, researchers from the Kaiser Permanente Division of Research in Oakland, California, reported in the journal PLoS ONE.

The authors wrote that girls in the beginning and middle of puberty whose BPA urine levels are above average have double the risk of being obese/overweight, compared to their counterparts with lower levels.

Lead researcher, De-Kun Li, MD, PhD, said:

"This study provides evidence from a human population that confirms the findings from animal studies - that high BPA exposure levels could increase the risk of overweight or obesity."

BPA is an industrial chemical that has been used since the 1960s to make certain plastics and resins, it is found in polycarbonate plastics and epoxy resins. Polycarbonate plastics are commonly used in food and drink containers, such as water bottles, as well as other consumer goods. Epoxy resins are used to coat the inside of food and drink cans, bottle tops, and water supply pipes. Some dental sealants also contain BPA.

There has been concern over the last few years that BPA can seep into foods or drinks from containers that contain the chemical. BPA exposure has been associated with undesirable health effects on the brain, and the prostate gland of fetuses, babies and children. One study showed that BPA exposure in the womb raised the risk of behavioral and emotional problems later on.

According to the FDA, after reviewing hundreds of studies, BPA in foods and drinks is harmless to human health as long as levels are low.

The authors in this latest study explained that BPA is a known endocrine disruptor with estrogenic properties - it can mimic estrogen, a female hormone.

Dr. Li said that in children and teenagers BPA typically enters the body mainly through foods and beverages that have been ingested - foods that have come into contact with materials that contain BPA.

Dr. Li added:

"Girls in the midst of puberty may be more sensitive to the impacts of BPA on their energy balance and fat metabolism."

Studies have demonstrated that BPA interferes with how the body distributes and deals with fat.

Dr. Li and team set out to determine whether BPA exposure influences body mass index (BMI) in school-age children. They carried out their study in Shanghai as part of a major study of puberty and adolescent health.

The researchers gathered and examined data on 1,326 boys and girls in grades 4 to 12 from one elementary, one middle and one high school, all of them in Shanghai. Urine samples were collected with BPA-free materials. They also collected information on other factors which can raise the risk of obesity, such as physical activity (or inactivity), mental health, dietary habits, and family history.

After separating the data into nine groups (one for each school grade from 4 to 12), girls with at least 2 micrograms per liter of BPA in their urine were twice as likely to be in the top 10th percentile regarding body weight.

Girls aged 9 to 12 years with at least 10 micrograms per liter of BPA in their urine (extremely high level) were five times as likely to be in the top 10th percentile. In other words, their risk of being overweight/obese was five times greater compared to girls with average or lower levels.

The BPA effects on all the boys and girls over 12 years of age were much smaller, the authors pointed out - no significant BPA effects were identified.

Among the girls in the 9 to 12 year old age group, the investigators found that:
  • 36% of those with higher-than-average BPA urine levels were overweight/obese
  • 21% of those with lower-than-average BPA urine levels were overweight/obese
The authors concluded:

"Our study suggests that BPA could be a potential new environmental obesogen, a chemical compound that can disrupt the normal development and balance of lipid metabolism, which can lead to obesity. Worldwide exposure to BPA in the human population may be contributing to the worldwide obesity epidemic."

Eating canned soup every day can raise BPA rapidly - in 2011, researchers from the Harvard School of Public Health carried out a study showing how consuming one can of soup per day can raise your BPA levels. They divided their volunteers into two groups: one group consumed a can of soup per day for five days while the other group ate freshly made soup each day for five days.

By the end of the five days, those on the canned soups had BPA levels 1,221% higher, compared to the other group. Their study was published in JAMA (Journal of the American Medical Association).

95% of dollar bills were found to have BPA, according to one study conducted by the Safer Chemicals, Healthy Families coalition.

Written by Christian Nordqvist