Tires are an indispensable part of daily life. Without them, our vehicles would just be a bunch of assembled parts—convenient to sit in, but not effective for getting where you are going.

Tires are composite materials that have a lot of components in them, including a molecule known as 6PPD, which provides UV protection to help the rubber found in tires last longer. The 6PPD accomplishes this by absorbing the sun’s rays and preventing the material from breaking down due to reactions with ozone and other reactive oxygen species in the air.

As tires wear down through contact with road surfaces, however, they release particles of 6PPD into the environment. Stormwater runoff carries these toxic particles into freshwater systems and other bodies of water, where the chemical can quickly kill fish, even in small doses. Recently, tribes in the Pacific Northwest filed a petition asking the Environmental Protection Agency to consider establishing regulations prohibiting the use of this chemical.