A study recently published in the peer-reviewed journal Kidney International, a publication of Nature, stirred debate as it suggested that bisphenol A (BPA) may increase the risk of chronic conditions including metabolic syndrome and cardiovascular diseases (Trasande et al.). The researchers from the New York University School of Medicine linked urinary BPA (uBPA) to increased albumin-to-creatinine ratio (ACR), a marker of oxidative stress. Their analysis was based on the BPA and albumin content of spot urine samples taken from 667 children from US population.
The study was criticized by Steven Hentges, spokesman of the American Chemistry Council (ACC), as it based its analysis on only one spot sample of uBPA. Further, the ACC criticized in its statement that associations between BPA and kidney and heart disease were only inferred, and based on the measurement of indirect markers. The ACC pointed to earlier studies carried out by the US National Center for Disease control, which had argued that is BPA is unlikely to pose a thread, because it is rapidly metabolized.
Trasande et al. had investigated the link between uBPA and urinary albumin, a biomarker of oxidative stress. Oxidative stress is marked by increasing production of free radicals, whose presence may lead to cell damage and eventually cell death. Oxidative stress has been associated with the promotion of a variety of chronic conditions, including cardiovascular diseases.
The researchers analyzed spot samples uBPA and albumin levels of 667 children aged 6-19 from the 2009-2010 NHANES population. Upper quartile uBPA levels were found to be significantly associated with a 0.91mg/g increase urinary ACR and each log unit increase in uBPA with a 0.28ng/g increase in ACR. Low grade albuminuria has previously been associated with systemic complications, like obesity and metabolic syndrome, endothelial dysfunction, an early sign of atherosclerotic changes, and is understood to be an early and sensitive marker of cardiovascular diseases including chronic kidney disease (CKD).
The study also found associations of uBPA with two other chemicals, namely triclosan, an additive in plastics, soaps and toothpaste, and benzophenone-3, which is used as a UV-absorber in sunscreens and especially PVC food packaging. However, these chemicals could not be linked to the ACR. According to the authors, this supports the specificity of the link between ACR and BPA.
Trasande, L., Attina, T.M. and Trachtman, H.. “Bisphenol A exposure is associated with low-grade urinary albumin excretion in children of the United States.” Kidney Int, 2013 (published online January 9, 2013). doi:10.1038/ki.2012.422.