Study: California salmon face deadly threat from car tires.
A highly toxic chemical used in the production of millions of tires every year is killing salmon in the Pacific Northwest, and it is being detected in streams across Northern California, a new study finds.
Scientists have known for decades that stormwater runoff from roads, highways and other urban areas has been linked to high rates of coho salmon deaths in Washington state, where as many as 90% of salmon in the Puget Sound area have died before they could spawn.
The new study published in the research journal Science on Thursday has identified a culprit chemical for the first time — a commonly used preservative called 6PPD used to give tires longer life.
“I think the broader impact is as we have already found this in San Francisco (Bay) creek water as well as the road runoff,” said the study’s lead author, Zhenyu Tian, a researcher at the University of Washington Tacoma. “We believe this thing is a prevalent contaminant. Wherever you have a busy highway, you have runoff
from there and you probably will detect it. Our detection rate for this chemical in runoff is almost always 100%. For coho salmon, it’s definitely a threat.”
As part of the study, stormwater running into four Bay Area waterways and creeks tested positive for deadly concentrations of the toxin known as 6PPDquinone. The creeks that tested for high toxicity included Rodeo Creek in Contra Costa County, Elmhurst Creek near Oakland and two locations near Coyote Creek near San Jose.
As tiny pieces of tire break off on roads and highways, the preservative 6PPD interacts with ground-level ozone to create 6PPD- quinone, which in turn washes into creeks and rivers when it rains, according to the study. The study led by the University of Washington and Washington State University found the toxin was highly deadly, killing some young coho salmon in just four hours when they were exposed to it.
Estimated to have once numbered in the hundreds of thousands, coho salmon numbers in California have been devastated since the mid-20th century by human development, damming, habitat loss and changing climate and ocean conditions. Coho have been federally listed as an endangered species and are at risk of extinction on the central California coast, where only 1% of the historic population remains.
State agencies and environmental groups have been working for decades to restore coho salmon populations between Santa Cruz County and the CaliforniaOregon border, including remaining coho strongholds on Lagunitas Creek, in San Mateo and farther north in the Klamath and Eel rivers.
The discovery of the toxin could help to inform further recovery efforts throughout the state, researchers said.
“Here in the tributaries that discharge into San Francisco Bay, we no longer have coho,” said Rebecca Sutton, a study coauthor and senior scientist with the San Francisco Bay Estuary, which tested Bay Area stormwater as part of the research. “But up north, we still have coho, and we want those populations to thrive. So removing stressors like this particular chemical could actually be pretty important.”
The findings also could inform state regulators
such as those in the California Department of Toxic Substances Control, which can mandate manufacturers to research greener alternatives to certain chemicals if they’re found to be harmful.
“This is a real opportunity to reformulate tires and make them greener because certainly we didn’t know about this toxicity problem before,” Sutton said. “But now that we know, we can improve the products that we use every day.”
Karl Palmer, a San Rafael native who serves as acting deputy director of California’s Safety Consumer Products program, said he has discussed the study’s findings with the researchers, tire manufacturers and his counterparts in the state of Washington on Thursday morning. Similar to how his department already is reviewing how zinc from tires is affecting the environment and aquatic wildlife, the new findings on 6PPD will begin what could be a lengthy assessment on whether the chemical poses a significant threat and whether safer alternatives are available, he said.
“The broad issue with today’s publishing of this paper is important because it highlights that there is this very specific chemical of concern that has been linked to really specific and pretty significant harm to coho salmon and perhaps other aquatic organisms as well,” Palmer said. “That sort of smoking gun, as you will, will point those at the water quality control boards and folks like us to ask, ‘ What is the problem and what do we do about it?’ ”
The U. S. Tire Manufacturers Association, based in Washington, D.C., provided tire samples and manufacturing information to the Washington researchers as part of the study. Sarah Amick, the association’s vice president of environmental health, safety and sustainability, states the study’s findings are preliminary and said it is premature to discuss potential alternatives to 6PPD.
“Our industry is committed to sustainability, and we are committed to understanding our products’ impact not only on the environment and wildlife but also on human health,” Amick said, adding that the association will continue to collaborate on future research.
Tian disagrees with his study’s findings being described as preliminary.
“Whatever we have written in the paper is peer-re
viewed, and those are very real,” Tian said. “We spent more than two years working on this. We are confident in what we put in there. I agree to say this is new, but I’m not sure preliminary is a correct word.”
Lagunitas Creek contains the largest population of endangered coho left in central California and runs parallel for many miles along well- traveled Sir Francis Drake Boulevard.
Todd Steiner, executive director of the Salmon Protection and Watershed Network or SPAWN in Olema, said the network’s salmon monitoring efforts so far have not shown the high death rates being experienced in Washington state.
“Clearly, that is a more urbanized area than we have here but we’re on the path to that,” Steiner said.
SPAWN plans to immediately begin looking at how to begin testing for the toxin to determine what threat Lagunitas salmon face.
In the meantime, working to capture stormwater runoff before it reaches creeks by using tools such as rain gardens and bioswales are necessary to prevent further harm to coho and other fish, Steiner said. Studies have shown that soils act as a natural filter for stormwater runoff as long as the water sinks into the ground before it reaches the creeks and streams.
“It’s basically urbanization that is causing impacts to the creek,” Steiner said. “When you lose the habitat along the creek, that is a natural biofilter.”
Coho salmon require clean, cool and pristine waters to survive, said CalTrout Bay Area Regional Director Patrick Samuel, which is often why they are the first to go when conditions worsen or pollutants are introduced. The Bay Area is fortunate to still have coho runs on its creeks such as Lagunitas when they are so rare in other parts of the state.
“It’s amazing that we have that in this major metropolitan area. The fact that we have these fish says that something is working and we can get them back if we’re able to intervene,” Samuel said. “Maybe this study will have some meaningful impact.”
The study ends by stating that further studies into the toxins’ impacts on other wildlife and potentially on humans also should be pursued.
Researchers from California, Washington and Canada and the National Marine Fisheries Service contributed to the study.