Characteristics and findings of completed NIOSH HHEs of workplace cancer cluster concerns—the USA, 2001–2020
| Characteristic | No. (%)* |
| Requested and completed cancer cluster HHEs | 174 (100) |
| Industry sector | |
| Public administration | 56 (32) |
| Healthcare and social assistance | 28 (16) |
| Educational services | 25 (14) |
| Manufacturing | 16 (9) |
| Transportation and warehousing | 12 (7) |
| Information | 5 (3) |
| Other† | 24 (14) |
| Unknown | 8 (5) |
| Requestor type | |
| Employees | 69 (40) |
| Management | 61 (35) |
| Union | 33 (19) |
| Government‡ | 9 (5) |
| Joint | 2 (1) |
| Number of cancer sites | |
| Single | 39 (22) |
| Multiple | 123 (71) |
| Unknown | 12 (7) |
| Cancer site§ | |
| Breast | 93 (53) |
| Lung/bronchus | 53 (30) |
| Colon/rectum | 50 (29) |
| Brain | 46 (26) |
| Prostate | 41 (24) |
| Lymphoma | 34 (20) |
| Thyroid | 25 (14) |
| Uterine | 24 (14) |
| Bladder | 22 (13) |
| Leukaemia | 22 (13) |
| Ovarian | 21 (12) |
| Melanoma | 19 (11) |
| Pancreas | 18 (10) |
| Oropharyngeal | 17 (10) |
| Cervical | 16 (9) |
| Kidney | 15 (9) |
| Stomach | 14 (8) |
| Oesophagus | 13 (7) |
| Multiple myeloma | 13 (7) |
| Skin (not melanoma) | 12 (7) |
| Skin (not specified) | 10 (6) |
| Liver/bile duct | 9 (5) |
| Mesothelioma | 2 (1) |
| Other cancer site | 43 (25) |
| Unknown cancer site | 35 (20) |
| Investigative procedures§ | |
| Interview/questionnaire | 25 (14) |
| Sampling | 13 (7) |
| Site visit | 22 (13) |
| Rate calculations (eg, PMR, SIR, SMR) ¶ | 14 (8) |
| Record review | 63 (36) |
| Type of records reviewed§ | |
| Cancer registry | 10 (6) |
| Environmental records** | 53 (30) |
| Medical records | 19 (11) |
| Unspecified | 98 (56) |
| Individual criteria determination | |
| Individual criteria determination available§ | 128 (74) |
| Excess number of cases†† | 4 (2) |
| Unusual distribution of cancer | 8 (5) |
| Carcinogenic exposure present | 11 (6) |
| HHEs meeting≥1 criterion | 18 (10) |
| No excess no of cases and no unusual distribution and no exposure present | 110 (63) |
| Individual criteria determinations unknown | 46 (26) |
| Final determination | |
| Cluster exists, but work-related exposure unknown or unclear | 7 (4) |
| No evidence of a cluster | 151 (87) |
| Final determination unknown‡‡ | 16 (9) |
*Denominators for percentages in parenthesis are 174.
†Other industries include construction; finance and insurance; professional, scientific and technical services; other serves (except public administration); mining; retail trade; real estate rental and leasing; arts, entertainment and recreation; utilities; wholesale trade; and administrative support, waste management and remediation services.
‡Government includes federal, state and county agencies (eg, work locations such as health departments, public safety agencies and courthouses).
§Categories are not exclusive.
¶Abbreviations represent proportional mortality ratio (PMR), standardised incidence ratio (SIR) and standardised mortality ratio (SMR).
**Environmental records include industrial hygiene assessments of the facility, regulatory files, environmental data or information, maps and building schematics, records, drawings and reports regarding environmental matters.
††Of four HHEs where excess number of cancer cases was found, three were also determined to have an unusual distribution of cancer.
‡‡Final determination was not available in documents extracted for 16 of 174 HHEs.
HHE, Health Hazard Evaluation; NIOSH, National Institute for Occupational Safety and Health.