Toxic Roads

Vapors from coal-tar pavement are extremely toxic to breathe in. This outgassing includes toxic substances called polycyclic aromatic hydrocarbons (PAHs).

One recently released study that was done by the U.S. Geological Survey (USGS) and Milwaukee Metropolitan Sewerage District, identified coal-tar sealants as the primary source of PAHs and called them “a major source of contamination in urban and suburban areas and a potential concern for human health and aquatic life.”

Toxic coal-tar sealants were found to be responsible for up to 94% of the PAHs found in 40 samples of streambed sediment that was collected from 19 creeks and rivers, along with dust from six parking lots in metropolitan Milwaukee.

According to lead study author and USGS scientist Austin Baldwin, “Fully 78% of the samples contained enough PAHs to be considered toxic and capable of causing adverse effects in aquatic animals.”

As far back as 2007, Dane County, Wisconsin, banned both the sale and use of coal-tar sealants, but prior to the cut-off, 300,000 gallons of coal-tar sealants were estimated to have been used, every year, on driveways and parking lots in that county alone.

The problem in Milwaukee is not isolated. Besides the toxic materials used to build roadways and other surfaces, similar issues are emerging around the U.S. Another new study says stormwater runoff is so poisonous in parts of the Pacific Northwest, it can kill an adult coho salmon in just 2.5 hours.

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