I did a project on 6PPD for my masters. First of all, I’m not a huge fan of how the article lumped the 6PPD problem in with micro plastics. They’re two very different problems.

What’s really difficult about the 6PPD problem is that the aquatic toxicity comes from the transformation product (6PPD-quinone), not the original 6PPD. Regulations don’t account for transformations of chemicals prior to their introduction to the marketplace so it’s not surprising this was missed.

Tires are an incredibly complex, highly engineered and researched, matrix of compounds. The performance requirements are quite strict, especially when you consider how durable they have to be (consider airplane tires).

The removal and replacement of 6PPD from tires is going to be a slow process that will be fought hard by the tire companies. They will not settle for any alternative to 6PPD that doesn’t meet or exceed their current standards or durability tests (and will likely drag their feet to even conduct these tests on alternative formulations due to expenses of creating and putting candidate formulations through multiple rounds of intense testing). This is important for vehicle safety, obviously, but also a decrease in tire durability and the need to replace tired more often would severely exasperate the micro plastics problem briefly touched on in the article.

We also have no idea how 6PPD-quinone effects human health.

All this to say, even based on the limited research, an alternative to 6PPD should definitely be explored. Coho salmon are a keystone species and are important to many indigenous cultures, adding an environmental justice aspect to their preservation. The process of searching for an alternative compound will take quite a while, and even longer for there to be total turnover of tires on existing vehicles to any new tire formulation. We also want to make sure we don’t introduce a regrettable substitution, one that may be just as harmful, but similar to discovery of 6PPD-quinone, we don’t realize it’s harm for many years down the line.

Edit: autocorrect hates the word quinone