The U.S. Tire Manufacturers Association (USTMA) announced on November 14, 2023, that it will partner with the U.S. Geological Survey (USGS) on a research project “to assess and refine methods of evaluating potential alternatives to [N-(1,3-Dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD)] for use in tires.” As reported in our November 3, 2023, blog item, the U.S. Environmental Protection Agency (EPA) has granted a petition filed under Section 21 of the Toxic Substances Control Act (TSCA) to address the use of 6PPD in tires. According to USTMA, 6PPD “serves critical safety and performance functions that protect motor vehicle tires from degradation upon exposure to ozone and oxygen in the air,” as well as “provid[ing] critical needs for endurance and product safety.”

In the study, USTMA and the USGS Western Fisheries Research Center are working to establish a new method for in vitro toxicity testing of 6PPD alternatives through a Collaborative Research and Development Agreement. According to USTMA, the study will expose fish cell lines to rubber containing three possible alternatives to 6PPD and their transformation products. Researchers will assess the toxicity of each proposed alternative and compare it to the toxicity levels of 6PPD-quinone. USTMA notes that although the initial research is not expected to identify an alternative immediately, each of the three alternatives represent a different class of chemical compounds and will inform future research.

USTMA states that the partnership with USGS is set to run through September 2024. The organizations expect initial toxicological results to be available in March 2024.