Tests of air around homes near natural gas drilling wells and other production equipment in five US states have found sometimes grossly elevated levels of chemicals linked to cancer. Some samples, all taken off site in the community, were in excess of occupational standards. These included both benzene and formaldehyde, chemicals rated as group 1 human carcinogens by the UN’s International Agency for Research on Cancer (IARC). Exposures faced by some fracking workers closer to the source of the chemicals are likely to be significantly higher. Studies by US government safety agencies have already confirmed high exposures to carcinogenic and toxic chemicals including benzene during some fracking operations, with some related poisoning deaths also confirmed.
Gregg Macey, David Carpenter and others. Air concentrations of volatile compounds near oil and gas production: a community-based exploratory study, Environmental Health, volume 13, page 82, 2014.