IARC evaluations in the light of limitations of human epidemiologic data

Considerable human data are available that would causally associate human cancer with occupational exposures through the identification of substantial workplace risks. Much additional data are available, indicating lesser risks, that have not achieved widespread acceptance because of the limitations of epidemiologic techniques. Limitations of epidemiologic techniques also limit the associations that can be made, using general population data, between cancer mortality and occupation. These same uncertainties, however, also affect assertions of absence of effect. Apparently "negative" results must be evaluated with the same critical view as are most "positive" results.