Monitoring Tire Wear Toxins in Local Streams
It was a dark and stormy night … sounds like a gloomy, pull the covers over your head scenario for some except for the Beaufort Watershed Stewards (BWS) tire toxin sampling crew — it is a weather forecast that sounds a call to action.
Why are BWS volunteers out in the rain?
Rain events, preceded by a dry spell, signal the flushing of toxic tire dust buildup on highways, parking lots and bridges into water courses that all too often lead to salmon bearing streams. This discharge, specifically containing 6PPD-Q in the tire dust can be acutely toxic to both coho salmon and cutthroat trout with exposure to extremely low levels of concentration particularly in their vulnerable juvenile stages.
What does acutely toxic mean? Approximately one half of a teaspoon of 6PPD-Q in the volume of an Olympic sized pool will cause mortality with 24 – 48 hours of exposure.
Toxic tire dust is a result of tire wear — it is a global problem. How many of us have given much thought when replacing tread-worn tires as to where the worn-out part went? Since the mid 1960s tire manufacturers have dealt with tire wear by adding a rubber preservative 6PPD to all tires to slow down degradation and cracking. This compound makes up 1-2% of all tires by weight.
What are local stewardship groups doing?
Under the leadership of BC Conservation Foundation’s Tire Wear Toxin Program BWS are working to identify tire wear toxin sources by collecting water samples from specific streams before, during and after rain events.
In Bowser, Thames and Nile Creeks were sampled from Fall 2024 to Spring 2025 for a total of 7 rain events. The Fall 2025 sampling season has begun with four events already logged on Nile and Annie Creeks.
When a rain event is predicted, a ‘before sample’ is taken midstream, about 15 metres downstream from bridges. During the rainfall we collect storm water discharge from the downspouts under the bridge deck; this is our ‘point source’ sample. Once the rain has stopped, an ‘after sample’ is obtained at the downstream location.
Vancouver Island University’s Centre for Health & Environmental Mass Spectrometry (CHEMS) analyzes the samples. Here is a graphic example of the results for Nile Creek after an unseasonably lengthy summer dry spell, August 14-16, 2025. The red lines indicate lethal concentrations for fry and smolt. You can explore results for all Vancouver Island locations at the Tire Wear Toxins Data dashboard.
What do the experts say about our findings?
We asked Haley Tomlin, BCCF Biologist to explain the significance of the results for this event, and whether the data collected to date on Nile Creek indicates the need for future mitigation:
“Grab samples provide us with a snapshot in time of how much 6PPDQ is in a given creek. That said, 6PPDQ’s presence is very dynamic – it can flush in and out of a system relatively quickly, so the timing of the sampling is important. Unfortunately, there are many times when rain starts in the middle of the night, and sampling doesn’t start until the next morning. These grab samples give an indication that 6PPDQ is present in the roadway runoff and reaching detectable levels in Nile Creek downstream of Hwy19A. These preliminary results show that in-stream concentrations are below the 10 ng/L, which is the BC Acute Water Quality Guidelines for 6PPDQ. Further sampling in the area is warranted to capture peak concentrations and duration of elevated levels.
The concentrations detected in the point source samples (bridge downspouts) themselves are 2 – 7 times the lethal concentration for juvenile (~ 3-week-old) coho salmon and coastal cutthroat trout and ~ 1- 3 times the lethal concentrations for smolts and adults. However, those concentrations are diluted when they enter into the creek, which is likely why the concentrations detected in the creek were much lower (~ 6 – 8 ng/L). That said, the detection of any concentrations supports further monitoring of the creek to gain a better understanding of the impact.
At this point, these concentrations wouldn’t put this site at the top of our list for major green infrastructure projects, as sites in more urban areas are showing much higher in- stream concentrations. However, this could be a good candidate for smaller scale projects to direct the runoff away from the creek.”
Haley was also asked: As Nile Creek is frequented by fishers, surfers and walkers what kind of fish in distress symptoms could they be looking for during rain events? And what could they do to report it?
“Yes, it’s definitely always useful to have more eyes on the creek – that is a large reason why the impacts of tire wear toxicants were discovered. The signs and symptoms of what is referred to as ‘urban runoff mortality syndrome’ (i.e. exposure to 6PPDQ) are loss of equilibrium, circular swimming, gasping at the surface, and ultimately loss of buoyancy. There isn’t currently a central database to report potential urban runoff mortality syndrome observations. One avenue to take is to take is to email us (htomlin@bccf.com) and we can see if anyone in the area would be able to collect a sample and document any other water quality parameters (because we want to understand that the mortality couldn’t be linked to any other circumstances such as low dissolved oxygen).”
One last question for Haley: Other than conservation mitigation of runoff, are there any provincial/federal actions in the works towards policy/regulation changes to reduce/remove 6PPDQ from the tire industry?
In February 2023, a request to the Minister of Environment and Climate Change was put forth by Ecojustice on behalf of the Pacific Salmon Foundation, Watershed Watch Salmon Society, and Raincoast Conservation Foundation to prioritize 6PPD for investigation to state that it is a toxic substance. Once listed as a toxic substance under Schedule 1 of the Canadian Environmental Protection Act, it can then be regulated more rigidly. In May 2024, Environment & Climate Change Canada committed to reviewing 6PPD, 6PPDQ and other PPDs. It is currently listed under their Plan for Priorities for investigations to begin in winter 2025.
On the US side of the border, the US Tire Manufacturers’ Association is currently working along California State’s Department of Toxic Substances Control (DTSC) to take part in DTSC’s alternative’s approval process, which requires manufacturers to identify and compare other potential alternative chemicals. They’re currently in phase 2 of this process and that report is due to the DTSC in August 2026.
Overall, it’s hoped that a safe alternative with no detrimental environment impacts is found and used as a replacement in tires and other rubber products, sooner than later.”
What can you do?
We’ll keep you posted as results continue to come in from the 6PPD-Q sampling program. In the meantime, your eyes on our watershed streams are extremely important. It was observations of abnormal salmon behaviour that raised the initial concerns about tire wear toxins. A healthy environment equals healthy communities.
Is there something here that resonates with you? Visit BWS Website for more information on ongoing programs, and please connect with us at info@beaufortwater.org if you’d like to join us stream side — the more the merrier!