in recent years, studies have suggested that polycarbonates, made from bisphenol a (bpa) and phosgene (), such as the ones nalgene used, may leach endocrine disruptors including bpa. nalgene denies that the quantity leached from their products posed a significant threat to health. among the secreted chemicals, bpa is a concern, as it binds to estrogen receptors, thus altering gene expression. other research has found that fixatives in polycarbonate plastics can cause chromosomal error in cell division called aneuploidy. nalgene claims these chemicals are only potentially released from nalgene products when used at temperatures outside of the designed range.