It's an open secret that millions of tires have wound up in the oceans. However, a study has investigated the extent to which this was reality — and the results are alarming.

What did the study entail?

The study, published in the Journal of Hazardous Materials, was conducted by researchers in Norway. Specifically, they aimed to assess the difference between exposure from particles versus leached chemicals from car tire rubber (CTR).

To do this, researchers exposed young Atlantic cod specimens to three different groups of CTR 'treatments': i) pre-leached particles, ii) chemicals leached from CTR (CTR-LEACH), and iii) particles with both leached and unleached chemicals present (CTR-BOTH).

While exposing groups of the cod to various doses of the three treatments, researchers measured hatching success, developmental alterations, gene expression, and mortality.

What they found, they explain, is that the leachates alone, as well as the leachates with the particles (groups II and III), caused the most significant impacts. High concentrations of both CTR-LEACH and CTR-BOTH "significantly reduced" hatching success, as well as increasing larval mortality. High concentrations of the leachate-free particles (group I) did not produce the same effect.

However, high concentrations of all three groups were found to cause developmental alterations, with CTR-BOTH showing the most severe impact. They found the same outcome with the expression of stress genes.

In short, this means that the chemical components of tires are primarily responsible for toxic impacts on marine life, but particles enhance these impacts.

Why are these findings so concerning?

The research team explained the gravity of their findings in the study's conclusion. The observed impacts from CTR-BOTH, they explained, "suggest potential long-term implications for fish populations exposed to [tire wear particles] and their associated chemicals, which could influence ecosystem dynamics and services."

It's especially concerning, considering the number of tires already in the ocean. According to Yale's School of the Environment, the global market is projected to sell 3.4 billion tires annually by 2030. That's nearly enough tires to reach the moon and back when stacked on their sides.

And as these tires wear down, they release synthetic particles into the environment. Many of those particles end up washing from roadways into sewage systems, where they flow to the ocean. The Pew Charitable Trust estimates that 78% of all ocean microplastics come from synthetic tire rubber.

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And if the particles are increasing mortality and affecting the development of Atlantic cod larvae, it's certain they're negatively impacting other species, too.

"This is essential information for understanding the real environmental risk of plastic particles across a range of materials and consumer products and for providing the basis for effective mitigation actions to be developed and implemented," researchers concluded.

What can be done?

The team called for further research to understand the full extent of the ecotoxicological risk. This, they argued, could help researchers develop safer design approaches for manufacturers to limit the use of toxic chemicals.

However, the race against time to avert more damage is moving quickly, and few calls for change are heard quite as loudly as those made by consumers. To that end, any opportunity that individuals can take to reduce their use of plastic can build momentum.

And while few people will be able to stop using their car — and therefore stop generating CTRs completely — even swapping out driving for biking, walking, or using public transit once a week would make a big difference.

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