As a key component in polycarbonate plastics such as those used for reusable water bottles, baby bottles, canned-food liners, and some building materials, bisphenol-A (BPA) has become the new chemical to fear. Despite that, I had to track down a paper from the Transactions of the Wessex Institute on research conducted at Dresden University to understand better what may be the next problem area to emerge for BPA: toilet paper. Backing up, it's really about the thermal paper that has become ubiquitous in the form of credit card receipts and other point-of-sale printouts. Thermal paper is a very smooth type of paper with a thin coating of leuco dye, and a phenol developer such as BPA. This chemical cocktail is like an invisible ink that reveals a message under application of heat, usually with a laser. The heat causes the chemicals to melt and react; as they do, the dye changes form and is able to reflect visible light. According to a source in Denmark, about 1,500 tons of BPA was produced in Europe for thermal paper in 2003. I'm sure it's a lot more now, and much more in the U.S. When that thermal paper is recycled, a lot of it goes into toilet paper, in which high recycled content has become quite common. And when that toilet paper is flushed, and digested in municipal wastewater plants, that BPA is released into surface water and groundwater. According to the Dresden research, the concentration of BPA in toilet paper can be 430 mg/kg dry mass. The researchers conclude:

Toilet paper, thus, was shown being an important source of xenoestrogen emissions to wastewater. Thermal paper again is assessed as being a major source for the contamination of recycled paper products with BPA. Because of the distinct contamination with xenoestrogens, both paper waste and recycled paper products should not be mixed with biological waste e.g. for co-composting or co-fermentation in order to derive organic fertilisers.

Pay in cash and bring out the bidets? (The photo above came from zigzag zombie.)