Toxic PFAS "forever chemicals" used in lithium ion batteries essential to the clean energy transition present a dangerous source of chemical pollution that new research finds threatens the environment and human health. The multipronged, peer-reviewed study zeroed in on a little-researched and unregulated subclass of PFAS called bis-FASI that are used in lithium ion batteries. Researchers found alarming levels of the chemicals in the environment near manufacturing plants, noted their presence in remote areas around the world, found they appear to be toxic to living organisms, and discovered that waste from batteries disposed of in landfills was a major pollution source. PFAS are a class of about 16,000 human-made compounds most often used to make products resistant to water, stains and heat. They are called "forever chemicals" because they do not naturally break down and have been found to accumulate in humans. The chemicals are linked to cancer, birth defects, liver disease, thyroid disease, plummeting sperm counts and a range of other serious health problems. The paper notes that few end-of-life standards for PFAS battery waste exist, and the vast majority ends up in municipal dumps where it can leach into waterways, accumulate locally or be transported long distances. It looked at the presence of the chemicals in historical leachate samples and found none in those from prior to the mid-1990s, when the chemical class was commercialized.