Indeed, the Environmental Protection Agency chose not to label electromagnetic fields as a human carcinogen due to the fact that the association between cancer and electromagnetic fields was not strong enough to prove a causal relationship, largely because the relative risks in the published reports have seldom exceeded 3.0.
EPA External Review Draft, October 1990, Evaluation of the Potential Carcinogenicity of Electromagnetic Fields, p. 6-2
How interesting, then, that the Envrionmental Protection Agency saw fit to label
secondhand smoke as a human carcinogen based on a relative risk of only 1.19.