SHANGHAI, China/OAKLAND & SAN FRANCISCO, Calif., USA/NICE, France: A study of Shanghai schoolchildren has shown that bisphenol A (BPA), a chemical used in producing plastics and dental resins, may affect metabolic processes and increase the risk of obesity, especially in pubescent girls. Yet another study has linked the substance to undescended testicles, the most frequent congenital malformation in male newborns.
Researchers at Kaiser Permanente, a U.S.-based integrated managed care consortium researching safer alternatives to products that contain potentially harmful chemicals, have suggested that girls in the midst of puberty are most susceptible to the impacts of BPA on fat metabolism. In 2011, they analyzed 1,326 urine samples provided by male and female children from the three largest elementary, middle and high schools in the Jiading district of Shanghai.
Among other findings, they found that girls with urinary BPA levels higher than 2 µg/L had a twofold risk of being overweight. While 36 percent of all girls aged 9 to 12 with elevated urinary BPA levels were overweight or obese, only 21 percent of those with lower levels exhibited the same characteristics. In addition, girls with extremely high levels (over 10 µg/L) were five times more likely to be overweight. However, no such relation was observed in older girls or boys of the same age.
The researchers concluded that widespread exposure to BPA may contribute to increasing obesity rates worldwide.
The study, titled “Urine Bisphenol-A Level in Relation to Obesity and Overweight in School-Age Children,” was published online on 12 June in the PLOS ONE journal.
In addition, a study of 180 boys born between 2003 and 2005 conducted by researchers at the university hospital of Nice in France has suggested that fetal exposure to BPA contributes to cryptorchidism, a condition that occurs in 2 to 5 percent of male newborns and may cause infertility and testicular cancer if left untreated.
Fifty-two of the boys in the study had one or two undescended testicles when they were born, and 26 of them still had the condition at three months of age. The researchers found that high levels of BPA were associated with lower levels of insulin-like peptide 3, an important hormone produced mainly in gonadal tissues.
The findings, which were presented at the Endocrine Society’s annual meeting in San Francisco on Monday, are in line with prior studies in animals, which have linked fetal BPA exposure to an increased risk of reproductive disorders.