Largest Global Tire Industry Consortium Releases Preliminary 6PPD Alternatives Analysis Report

The preliminary assessment identifies five possible alternatives to 6PPD in tires  for further evaluation from more than 60 initial candidates   

WASHINGTON, March 29, 2024 – A global consortium of 30 tire manufacturers, mobilized by the U.S. Tire Manufacturers Association (“USTMA”), and representing the world’s largest tire companies, has released a Stage 1 Alternatives Analysis (“AA”) report for 6PPD in tires in accordance with California’s Safer Consumer Product Regulations (“SCPR”). The report, submitted by each Consortium member to the Department of Toxic Substances Control (“DTSC”), meets SCPR requirements for each tire manufacturer selling tires in California to conduct an alternatives analysis to identify possible alternatives to 6PPD in tires. This Preliminary (“Stage 1”) AA Report establishes the basis for the further evaluation of possible alternatives in Stage 2, which will result in a final alternatives analysis report.  

As part of this robust assessment, over 60 candidate alternatives for 6PPD were evaluated, screened and scored for likely feasibility based on a new screening method developed expressly by the Consortium. Based on this initial review, 40 possible alternatives were identified which were then subjected to the detailed SCPR AA process. After reviewing the potential hazards, physical chemical properties and initial performance data for these 40 chemicals, the Consortium identified five possible alternatives that warrant further evaluation.  

6PPD is exceptional in terms of ensuring tire and passenger safety and has been used for decades. It serves an essential safety function, protecting the components of the tire from attack by ozone and oxygen. Tire composition cannot responsibly be modified without great care, including extensive and rigorous testing. Any material identified as a possible alternative must continue to ensure comparable performance in a tire and continued compliance with federal safety regulations.  

In late 2020, USTMA petitioned DTSC to list 6PPD in tires as a priority product under the SCPR due to recent studies suggesting environmental concerns from a newly identified 6PPD transformation product, 6PPD-quinone (“6PPDQ”). After a robust regulatory process, DTSC agreed with USTMA’s request and listed motor vehicle tires containing 6PPD as a priority product, effective October 1, 2023. USTMA sought the listing because California’s AA process provides a rigorous, transparent, and science-based regulatory framework to thoughtfully screen and analyze possible alternatives to 6PPD in tires.  

“The safety, performance and sustainability of our products remains our uncompromising priority, and there is important work to be done to ensure any potential alternatives meet that high standard,” said USTMA President and CEO Anne Forristall Luke. “This preliminary Alternatives Analysis marks an unprecedented milestone in the tire industry’s search for an alternative to 6PPD in tires. The depth and breadth of this work represents significant progress towards the identification of potential alternatives, and further demonstrates our industry’s commitment as a leading force in the search for solutions.”  

USTMA partnered with Gradient, a recognized leader in the alternatives analysis field, to conduct the Stage 1 AA. “This Stage 1 Alternatives Analysis report is notable for the large and diverse number of candidate alternatives identified and screened, the robust approach to considering potential impacts of possible alternatives across the entire product lifecycle, and the thoughtfulness, technical knowledge and high level of engagement by industry experts,” said Gradient project lead Dr. Tom Lewandowski.  

The chemicals selected for further evaluation in Stage 2 had sufficient data demonstrating suitable potential in the areas of performance and environmental impact. During Stage 2, as required by the DTSC process, the Consortium will confirm the “short list” of possible alternatives (in light of any new data that may emerge), assess the potential impacts of these options and initiate a more detailed review of the chemicals’ potential hazards and exposure-related chemical properties. The Stage 2 AA will allow further evaluation and a more definitive determination regarding suitable alternative(s). 

“The rigor, collaboration and transparency involved in this preliminary evaluation demonstrates our industry’s commitment to this alternatives analysis process,” said Tracey Norberg, USTMA Executive Vice President & General Counsel and USTMA project lead for the report. “Investigation of possible alternatives to 6PPD is a dynamic area of research.”  

At the end of the Stage 2 AA, USTMA is optimistic that the Consortium will have identified one or more possible alternatives that hold promise to replace or materially reduce 6PPD in motor vehicle tires, subject to future performance testing to ensure comparable tire safety and performance.