Tyre makers have warned that designating PPD derivatives as a candidate chemical under California’s Safer Consumer Products (SCP) programme could impede an ongoing alternatives analysis (AA) for the antidegradant 6PPD.
In comments made on 15 November, the US Tire Manufacturers Association (USTMA) opposed a Department of Toxic Substances Control (DTSC) proposal to put PPD derivatives on the green chemistry scheme’s candidate chemicals list. The listing aims to enable agency efforts to prevent regrettable substitution as companies look for replacements for n-(1,3-dimethylbutyl)-n′-phenyl-p-phenylenediamine (6PPD) in motor vehicle tyres. The agency recently adopted 6PPD-containing tyres as an SCP priority product due to the adverse aquatic impacts of its transformation product 6PPD-quinone.
However, according to the USTMA, the agency’s plan could "have the unintended effect of slowing the evaluation of other potential candidate alternatives to 6PPD by diverting resources toward a separate, duplicative and unnecessary regulatory process for each PPD derivative.
The trade group emphasised that it already is coordinating an AA that "will yield the most effective and exhaustive review possible of whether a safer alternative to 6PPD in tyres currently exists".
Moreover, the DTSC’s belief that deeming PPD derivatives as a candidate chemical is needed for a rigorous AA "is inconsistent" with SCP regulations, which "do not prescribe any additional analysis" for candidate substances, the organisation said.
It called on the DTSC to at least "narrow the proposed listing to a discrete list of chemicals," after the agency determines which ones are hazardous and used in products sold in California.
Meanwhile, tyre additive manufacturer Lanxess noted that "it is too early to include all ‘PPD derivatives’ in one class for regulatory action". According to the firm, "not much is known yet about the wider class beyond a handful of substances, and more data will be available in a short time" from industry research into possible 6PPD replacements.
Support
Various entities responded positively to the DTSC’s move.
PPD maker Flexsys said the agency’s science-driven approach "will help to ensure that all potential [6PPD] alternatives and their degradation products are well-vetted and understood" prior to their implementation. The business noted that it is working with the US Department of Agriculture (USDA) to investigate 6PPD substitutes "and would welcome additional collaboration with DTSC".
NGO Safe Healthy Playing Fields Inc (SHPFI) urged the DTSC to finalise its proposal, saying the agency "has gone over and above to meet the criteria to list the PPD class".
Discarded tyres are used to create artificial turf, so permitting "detrimental replacement chemicals in the PPD class is not only playing whack-a-mole with chemicals, but also our most vulnerable children's lives", according to the group.
Earlier this month, the US EPA granted a TSCA section 21 petition requesting action under that statute on 6PPD-containing tyres.
The DTSC should still proceed swiftly, the SHPFI said, citing the EPA’s "history of slow to no progress" and the likelihood of policy shifts stemming from changing administrations.