For the first time, researchers have measured the toxicity of several types of PFAS substances when mixed.
In the study, published in Environmental Science & Technology, University at Buffalo researchers determined that while most of the tested chemicals had relatively low cytotoxicity and neurotoxicity, the chemicals became toxic when mixed.
“Though they are structurally similar, not all forever chemicals are made equal — some are more potent, others less. When mixed, all components contributed to the mixture’s cytotoxicity and neurotoxicity,” said Karla Ríos-Bonilla, a chemistry PhD student at the University at Buffalo.
“In the laboratory assays we used in this study, most of the types of PFAS that we tested did not appear to be very toxic when measured individually. However, when you measure an entire sample with multiple PFAS, you see the toxicity,” added Diana Aga, Professor in the UB Department of Chemistry.
Earlier this year the EPA issued the first-ever drinking water standards for six PFAS substances. However, researchers estimate that there are currently over 15,000 varieties of PFAS present in the environment, and nearly 45% of the nation's drinking water is already contaminated.
“There are six PFAS that can be regulated because we know a lot about them and their toxicity. Unfortunately, we cannot regulate other forms of PFAS until their toxicities are known,” added Aga. “We need to set maximum contamination levels for each PFAS that is proportional to their toxicity. To regulate contaminants, it is crucial to know their relative potencies when they occur as mixtures in the environment along with their predicted environmental concentrations.”
Through the research, the team discovered that the effect of PFAS is concentration-additive, which makes a toxicity prediction algorithm possible in the future.
“As up to 12 PFAS in the mixtures acted concentration-additive for cytotoxicity and specific neurotoxicity, it is likely that the thousands of other PFAS that are in commerce and use are also acting in the same manner,” said Beate Escher of the Helmholtz Centre for Environmental Research (UFZ). “Mixtures pose more of a risk than individual PFAS. As they act and occur in mixtures, they ought to be regulated as mixtures.”