Health Hazard Evaluations of occupational cancer cluster concerns: the USA, January 2001-December 2020

To describe recent investigations of potential workplace cancer clusters.

We identified Health Hazard Evaluations (HHEs) of cancer concerns during 2001-2020. We described information about industry, requestors, cancer characteristics, investigative procedures, and determinations about the presence of a cluster (ie, presence of excess cases, unusual case distribution or exposure).

Of 5754 HHEs, 174 included cancer concerns, comprising 1%-5% of HHEs per year. In 123 HHEs, the cancer cluster concerns involved different cancer primary sites. Investigation procedures varied but included record review (n=63, 36%) and site visits (n=22, 13%). Of 158 HHEs with a cluster determination by investigator(s), 151 (96%) were not considered cancer clusters. In seven HHEs, investigators found evidence of a cluster, but occupational exposure to a carcinogen was not identified.

The proportion of HHEs on workplace cancer cluster concerns remained steady over time; most did not meet the definition of a cluster or uncover an occupational cause. Public health practitioners can use this information to provide updated context when addressing workplace cancer cluster concerns and as motivation to refine investigative approaches. More broadly, this review highlights an opportunity to identify best practices on how to apply community cluster investigation methods to the workplace.