September 3, 2024
The California Department of Toxic Substances Control (DTSC) recently issued a notice of compliance approving the Preliminary Alternatives Analysis (AA) for motor vehicle tires containing the antiozonant N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine (6PPD), which was co-authored by Gradient scientists. 6PPD is an antiozonant used in motor vehicle tires sold worldwide and is critical to their safe use and longevity. Starting in 2021, scientific studies reported that a degradation product of 6PPD, found in tire and road wear particles, can cause pre-spawn mortality in certain sensitive fish species, particularly coho salmon native to the West Coast of the United States (US). The mechanism for this toxicity is currently unknown. At the request of the U.S. Tire Manufacturers Association (USTMA), DTSC listed motor vehicle tires containing 6PPD as a Priority Product under the Safer Consumer Products (SCP) program to facilitate the search for an acceptable 6PPD alternative. Over 70 candidate alternatives were evaluated in this robust process. As a result of the Stage 1 AA process, Gradient scientists identified seven possible 6PPD alternatives that warrant a deeper evaluation in terms of their performance and health effects:
The seven possible alternatives will now be evaluated in Stage 2, with the goal of identifying at least one replacement chemical with a better hazard profile and acceptable performance within two years. As part of the process, USTMA and Gradient scientists had detailed conversations with DTSC staff to help ensure that the submitted Preliminary AA could be approved by DTSC within the 30-day final review period. The Preliminary AA for 6PPD represents the third successful AA Gradient has prepared under the SCP program.
Gradient’s work was carried out on behalf of a global consortium of tire manufacturers mobilized by USTMA. A copy of the approved Preliminary AA is available on the USTMA website.
Gradient Experts:
Tom Lewandowski, Ph.D., DABT, ERT, ATS
Principal
Tom.Lewandowski@gradientcorp.com
Jiaru Zhang, M.P.H., DABT
Principal Scientist
Jiaru.Zhang@gradientcorp.com