In a new report, a consortium of US tire manufacturers assessing possible replacements for N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine (6PPD), an antiozonant used by the tire industry for a half century, has eliminated 38 chemicals from consideration. The group is still evaluating 39 molecules as part of its review, which is scheduled to conclude in 2029.
In 2020, a team of scientists published conclusive evidence that 6PPD-quinone, a transformation product of 6PPD, is responsible for unexplained die-offs of coho salmon long observed in the Pacific Northwest. Further studies showed that less than 0.1 μg/L of 6PPD-quinone is enough to kill 50% of a salmon population within 24 h.
