The findings from a new study by researchers from the Netherlands has shown bisphenol A, at levels commonly found in people, may slow foetal growth. Babies whose mothers had higher levels of BPA had smaller heads and weighed 20 percent less at birth compared with babies born to women with the lowest BPA levels. BPA is used to make polycarbonate plastic and is found in the lining of metal food cans and some thermal receipts. California recently announced it intends to list BPA as a reproductive hazard. The study is one of only a few that has examined the link between prenatal BPA exposure and growth in humans. It is unique because BPA was measured multiple times during the pregnancy, which provides more accurate estimates of exposure and stronger results than prior studies based on only one sample. The babies born to women with higher amounts of BPA had smaller heads and grew slower in the womb than babies whose mums had the lowest amount of BPA. Head sizes were 11 percent smaller and growth rates 20 percent lower in babies whose mothers had the highest exposures. The exposure levels found in the women were typical of levels reported in the United States and Canada by national health surveys. BPA is an endocrine-disrupting chemical that can act like oestrogen in the body. Experts are especially concerned about exposures in pregnant women, the developing foetus and growing children. Human and animal studies have linked the ubiquitous chemical to reproductive, behaviour and endocrine effects. The few studies that have examined maternal BPA exposure and foetal weight gain are inconsistent. One reason for this may be that BPA is difficult to measure in people because it is quickly eliminated from the body. A unique aspect of this study was that it addressed that concern. Urine BPA levels were measured 1 to 3 times during pregnancy. More measurements improves the accuracy of estimating BPA exposure by smoothing out the fluctuations that occur over time, as levels in people vary and can change frequently. Interestingly, the relationships between maternal BPA and foetal growth were only observed in the group that had the mothers’ urine measured three times. BPA is used to make polycarbonate plastics and resins and is commonly found in some plastic food and beverage containers, the lining of metal cans, thermal receipts and dental sealants. Because of the widespread use of BPA-containing products, nearly everyone has small quantities in their bodies. In recent years, concern about the harmful health effects of BPA has led to a reduction in use, particularly in products used by infants and children. In addition, California announced in late January that it intends to declare BPA a reproductive hazard. The study group consisted of 219 pregnant women from Rotterdam in the Netherlands. Urine was collected from the pregnant women between February 2004 and November 2005. Urine BPA was measured once in 99 women, twice in 40 women and three times in 80 women. Foetal size was determined from ultrasound images in the second and third trimesters. At birth, weight, length and head circumference were measured. Growth rate was calculated from these before and after birth measures. The researchers accounted for personal and socioeconomic factors, such as maternal age, smoking, education and ethnicity. A limitation of the study was that only BPA exposure was considered and other endocrine-disrupting chemicals in the womens bodies were not measured. Future work should investigate the effects of BPA replacements such as bisphenol S and bisphenol AF on foetal growth.
Environmental health News, 5 March 2013 ;