Opinion: Who cares if cars are killing coho in Cascadia?

Car (left) and the coho killing chemical (right). (Source: KGW video stills)

Every once in a while the news cycle will hit me over the head with the simple fact that cars are the most violent and destructive force in our society. They enable drive-by shootings, smash-and-grab thefts, rage-induced violence, social isolation, inhumane urban sprawl, and so many other terrible things.

Now the story I can’t get out of my head is the one about how the rubber used in car tires is responsible for mass die-offs of Coho salmon in the Pacific Northwest. This isn’t a new story, but it was just covered this week by local NBC station KGW. I admit that I didn’t take time to let this story sink in until it was covered in-depth by a local outlet. Now I can’t stop thinking about it.

If this new to you, here’s the gist (via KGW):

[Scientists] discovered a toxin called 6PPD-quinone produced when the common tire preservative 6PPD mixes with oxygen. As tires age, the rubber starts to peel off leaving bits and pieces in their path. When it rains anything that doesn’t soak into soil becomes stormwater pollution, eventually ending up in local waterways where every fall Coho salmon return to spawn.

(Source: US Tire Manufacturers Assocation)

I’m no expert, but I can tell from a cursory bit of research that the science around this finding is not in dispute. It is 100% clear that little bits of car tires (and other major rubber sources) are killing coho and damaging our water sources. The fact that there isn’t more urgency around the issue is not surprising, since most people have accepted every other negative trade-off that comes with our car-centric system.

The responses to the problem are very telling. There’s a lot of talk about how to make the tires less toxic and about the need for tougher environmental regulations for makers and sellers of them. What about the tire industry? They can’t refute the science (although I’m sure they have tried), so they’ve got websites and other PR messaging to keep the profits coming. They admit the chemical they use, 6PPD, kills fish and pollutes streams and rivers, but they want you to know that it also keeps drivers safe (see image at right). And hey, it makes your tires last longer so you save money! Isn’t that great? Dead fish be damned.

Unfortunately, most of the news stories I’ve read about this mass coho die-off never mention the one thing that would solve it: less driving and/or bans on driving in watersheds. (And last time I checked, electric car tires have tires too.)

Another innocent victim of car dependency. (Photo: Puget Sound Institute)

This is an immense problem that will take decades to solve if we go about it through the standard procedure of incremental reforms. It’s the duty of policymakers and city leaders to muster the political support and courage to quicken the pace of change. If we address the root problem of car dependency and driving abuse, we can save much more than coho.


— Learn more about 6PPD and 6PPD-Quinone at PugetSoundInstitute.org.

Jonathan Maus (Publisher/Editor)

Jonathan Maus (Publisher/Editor)

Founder of BikePortland (in 2005). Father of three. North Portlander. Basketball lover. Car driver. If you have questions or feedback about this site or my work, contact me via email at maus.jonathan@gmail.com, or phone/text at 503-706-8804. Also, if you read and appreciate this site, please become a paying subscriber.

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Granpa
Granpa
2 years ago

Thank you for covering this. The chemical kills fish before they can spawn and roads with tire residue are everywhere.
Stunters , “sideshows” drifting and smoking burn-outs deposit huge amounts of the toxins onto roadsides where stormwater will carry the poison into streams. Sigh

Hippodamus
Hippodamus
2 years ago

The average car drops about 10 pounds of tire material each year while driving around. EVs are poised to make this worse. Heavier vehicles mean greater tire wear and thus more pollution. I saw a recent study that tires are the leading cause of microplastics in the San Francisco Bay – not really a surprise because my collection of fleece jackets doesn’t weigh 10 pounds combined.

Jim Calhoon
Jim Calhoon
2 years ago

Just an easy solution, ban driving in the watershed that salmon live in. So, no more driving in California, Oregon, Washington, Idaho, Montana and Alaska. Also, we will need to include our neighbors to the north, Alberta, British Columbia and the Yukon. I am confused why that would be easier than say remove 6PPD from the tires. The biggest problem is that it has been used in tires for over 50 years. It wasn’t until the 1990s that researchers documented the impacts of stormwater toxicity on salmonids. 6PPD was not identified as the specific chemical until December of 2020. The problem has a huge head start. Along with a change in tire manufacturing, we need to change how stormwater drains from streets straight to water. Researchers found that stormwater discharged through soil with plants (garden type basis) solved the problem and protected salmon. You can try the driving ban, but I don’t think it will gain much traction.

Harth
Harth
2 years ago

We need bigger cars – I’m sorry, I mean trucks – to drive daily, transporting only ourselves. Those cars…trucks…need bigger tires. I mean BIG tires, like 18-24 inches in diameter, and they must be wide, with big knobs, so they look tough while I drive to work or get groceries. It also helps if the truck weighs at least 4000lbs, but more is always better.

Sorry, my sarcasm got away from me. Smaller cars with smaller wheels and tires would go a long way to stemming this issue.

But we all know that ain’t happening.

Takethelane
Takethelane
2 years ago
Reply to  Harth

Your estimated truck weight may be low. My Astro mini van weighs 5,000 lbs. empty, according to two different scales.

Watts
Watts
2 years ago

“the one thing that would solve it”

There are many ways to address this problem. Getting rid of vehicles with tires is one of the least likely to work in any practical sense. You might as well suggest we all travel by hover car. That’s another thing that would solve it.

Watts
Watts
2 years ago

Well, it is like what you said, as those “specific areas” are quite large.

My point is that not driving in any watershed that feeds the Columbia is a complete non-starter in the Pacific Northwest.

Takethelane
Takethelane
2 years ago

Last time I looked, bicycles have tires too.

Pete S.
Pete S.
2 years ago

One possible solution would be for people to engage in autonomous deflation of automobile tires in their neighborhoods.

Though people did get pretty mad around here the last time that came up…

Granpa
Granpa
2 years ago
Reply to  Pete S.

Letting air out of tires does nothing about tire toxicity. It does infuse discourse with anger, bordering on toxicity. Nicely done, keeping that anger fed.

wheelwing
wheelwing
2 years ago

I think I found the source of that 10 pounds of rubber per year figure and it seems quite legit: https://www.mdpi.com/1660-4601/14/10/1265/htm

Thing is, that’s actually the “per capita” estimate for the US — the per vehicle estimate for the US is actually closer to 15 lbs/yr (6.8 kg)

That should take some of the air out of the “bikes have tires, too” strawman, as my two tires together don’t weigh much more than a pound brand-new, and there’s still plenty of rubber left after a year of riding ’em daily.

soren
soren
2 years ago
Reply to  wheelwing

The average passenger motorvehicle tire weight is ~20 lbs. If this oft-repeated urban legend were accurate, in 4 years the average tire would weigh 0 lbs.

The 10-15% value in the review you cited is for mass loss after tires are disposed.

Lassen and colleagues [12] also calculated the amount of wear and tear by multiplying the number of tyres sold with the mass difference between new and disposed tyres. The weight loss of new tyres was estimated by several studies to vary between 10% and 15%.