Occupational Chemical Carcinogenesis

Abstract

Workers are exposed to carcinogens and carcinogenic exposure circumstances, as well as to many other agents considered probably, possibly, or reasonably anticipated to be human carcinogens. Covered herein are occupational carcinogens: chemicals, uncharacterized exposure circumstances, and occupations/workplaces known or suspected to cause cancer in workers, and agents causing cancers in animal bioassays, which are proven predictive for human cancers. Importantly, individuals differ in susceptibility for developing cancer due to exposure to a carcinogenic substance; factors influencing cancer outcomes include exposure circumstances, genetic differences, lifestyle, health condition, age, and gender. Identification of agents as carcinogens is based on information from epidemiological studies, long‐term animal studies, in vitro and in vivo evaluations, and assessments of mechanistic data and structure‐activity relationships. Various agencies, such as IARC, NTP, U.S. EPA, CalEPA, and others have developed classification schemes that categorize potential carcinogenicity of environmental and industrial agents in humans based on strength‐of‐evidence from human studies, animal studies, and mechanistic information. Categorizations formulated by authoritative bodies serve as the initial basis for standard's settings and regulatory actions. Several health and safety laws have been promulgated to protect workers from harmful effects of hazardous agents in the workplace. Risk characterization provides an integrative summary of available and relevant information on hazard identification, exposure assessment, and dose‐response relationships that have been used to estimate potential human cancer risks under various exposure circumstances. This information serves as the basis for risk management decisions on the extent to which workers' exposures to hazardous agents should be controlled. Likewise reducing or eliminating exposures to known and suspected carcinogens will reduce or prevent the incidences of occupational cancers. The World Health Organization reports occupational carcinogens are responsible for ∼152,000 cancer deaths per year and cancer prevention is essential because ∼40% of all cancer deaths can be prevented.