Causal Agent-Cancer Links in Haz-Map

Click here to see the occupational cancers covered in the Haz-map database. When first published in 2001, Haz-Map followed the rule that an agent causes occupational cancer if the agent is listed as a Group 1 carcinogen (known human carcinogen) and the evidence is based on epidemiology studies of workers developing cancer after exposures at work. Click here to see the IARC monographs. Later, the chemical-disease links in Haz-Map regarding occupational cancer were based on Cancer Epidemiology and Prevention, 3rd Edition. See Table 18-3 "Substances and Mixtures That Have Been Evaluated by IARC as Definite (Group 1) Human Carcinogens and Are Occupational Exposures." This book was last published in 2006. The authors of the chapter on Occupation are Jack Siemiatycki, PhD,  Lesley Richardson, MSc, and Paolo Boffetta, MD, MPH. Dr. Siemiatycki's book, Risk Factors for Cancer in the Workplace, describes decades of research in Montreal of nearly 300 occupational exposures and 20 types of cancer in which detailed job exposure information was collected in case control studies. The author of the chapter on "Ionizing Radiation" is John D. Boice, Jr. who has master's degrees in Nuclear Engineering and Medical Physics and a doctoral degree in Epidemiology at Harvard.

IARC Changes in 2018

1. See "Identifying occupational carcinogens: an update from the IARC Monographs." This 2018 document from IARC provides three important tables: 1.) Group 1 agents excluded from occupational carcinogens; 2.) List of Group 1 agents showing which ones were included in Siemiatycki et al.; and 3.) List of Group 1 agents sorted by occupational disease. 

2. Agents are considered causal of occupational cancers in Haz-Map when they are Group 1 based on occupational epidemiology.

3. The occupational carcinogens in Haz-Map conform to the ones shown in Table 3 with a few exceptions.

4. Outdoor air pollution is not listed in Haz-Map as an occupational carcinogen.

5. As shown in the following table from "Ionizing Radiation" by John D. Boice, Jr. in Cancer Epidemiology and Prevention, 3rd Ed., workers are not considered to be at risk for certain cancers (breast, thyroid, brain, colon, kidney, esophagus, salivary gland, stomach, and bladder) caused by exposure to ionizing radiation.

Derived from: Figure 15-1. Distribution of various types of cancer associated with radiation in different populations
Occupation Breast Thyroid Brain Colon Kidney Esophagus Salivary Stomach Bladder
Ra dial painter
Radiologists ++------
Miners U. ------
Nuclear W. --------
Uranium P. -------
Chernobyl C. -
Mayak W. +
+ = suggested but unconfirmed or questionable association; - = no significant association found, although study reasonable powerful;
Blank = no or minimal data; U. = underground; W. = workers; P. = processors; C = cleanup;

6. Haz-Map shows that workers are at risk for the following cancers after exposure to high doses of ionizing radiation: leukemia, bone, lung, and skin.

7. "The observed association between exposure in arsenic in drinking-water [not an occupational exposure] and bladder cancer cannot be attributed to chance or bias. There is evidence of dose-response relationships within exposed populations." [IARC Monograph 100C] Note that arsenic is not listed as an occupational cause of bladder cancer in the "Occupation" chapter of Cancer Epidemiology and Prevention, 3rd Ed. See Table 18-3.

8. "Welding fumes (not otherwise specified)" are now linked to lung cancer. "Polychlorinated biphenyls" are linked to melanoma. "Acheson process, occupational exposure" is linked to lung cancer. Vinyl chloride is now linked to both Angiosarcoma of the liver and Liver cancer to comply with IARC Monograph 100F. Benzo(a)pyrene is no longer linked to cancers of the bladder, lung, skin. This is because the IARC classification is based on mechanistic data, not occupational epidemiology.

9. For questions about the IARC classifications, see the following two pages:

    Do Polychlorinated Biphenyls Cause Malignant Melanoma after Occupational Exposure?  

    Do Welding Fumes Cause Lung Cancer?

The Intersection of Epidemiology and Toxicology

Please read this paper published in the summer of 2011, a beautiful analysis of what it takes to translate the enormous amount of toxicological and epidemiological information into a rational method for determining the causes of occupational cancer. "The causal relationship grid provides a clear view of how epidemiological and toxicological data intersect, permits straightforward conclusions with regard to a causal relationship between agent and effect, and can show how additional data can influence conclusions of causality." [Toxicology and epidemiology: improving the science with a framework for combining toxicological and epidemiological evidence to establish causal inference]

For more information about occupational cancer in Haz-Map, see the "Occupational Cancer" page on the archived website of Haz-Map.