PAHs are a known human carcinogen. Smol and his colleagues took sediment core samples from 6 lakes around the mines, even as far away as 90km, for this study. “We show clearly the timing of the change and the type of contamination, and the ones increasing are ones closely related to the tar sands industry.”
The sediment cores date back as far as 1960, 20 years before the mining activities began. Though the levels of PAHs are increasing they have not yet reached the levels found in more urban streams and lakes. The study also shows that there have been no noticeable impacts to the fish or other aquatic life in the lakes.
Photo Credit: Peter Essick (National Geographic)