Consortium identifies five potential alternatives to 6PPD

 Consortium identifies five potential alternatives to 6PPDA global consortium of 30 tyre manufacturers, mobilised by the US Tire Manufacturers Association (USTMA), and representing the world’s largest tyre companies, has released a Stage 1 Alternatives Analysis (AA) report for 6PPD in tyres 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 tyre manufacturer selling tyres in California to conduct an alternatives analysis to identify possible alternatives to 6PPD in tyres. 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 tyre and passenger safety and has been used for decades. It serves an essential safety function, protecting the components of the tyre from attack by ozone and oxygen.

Tyre 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 tyre and continued compliance with federal safety regulations.

In late 2020, USTMA petitioned DTSC to list 6PPD in tyres 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 tyres 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 analyse possible alternatives to 6PPD in tyres.

“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/CEO Anne Forristall Luke.

USTMA partnered with Gradient, a recognised 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).

Tracey Norberg, USTMA Executive Vice President & General Counsel and USTMA project lead for the report, added, “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 tyres, subject to future performance testing to ensure comparable tyre safety and performance.