Biological Hazards in the Workplace

Biological hazards in the workplace are living organisms or their products—bacteria, viruses, fungi, parasites, and biologically derived materials such as endotoxins and allergens—that can cause infection, allergy, toxicity, or other disease through work. They are central in health care, laboratory work, agriculture, food processing, and waste management.

Definition

A biological hazard in the workplace is a microorganism, including those genetically modified, a cell culture, a human or animal endoparasite, or a biologically derived agent that, through occupational contact, can provoke infection, allergy, or toxicity in a worker.

Scope

The topic covers the classes of biological agents encountered at work, the routes by which they reach workers (inhalation of bioaerosols, percutaneous injury, mucous-membrane and direct contact, and ingestion), and the occupational settings in which they predominate. It treats biological hazards as a reference and public-health topic—including occupationally acquired infection in health-care workers—rather than as infection-control or treatment guidance.

Core questions

• Which biological agents are present in a given occupation, and by what route do they reach workers?
• Which occupational groups carry the greatest exposure to biological hazards?
• How are infectious, allergic, and toxic effects of biological agents distinguished?
• How is exposure to bioaerosols and bloodborne agents assessed?

Key concepts

• Bacteria, viruses, fungi, and parasites as occupational agents
• Bloodborne pathogens and percutaneous (needlestick) injury
• Bioaerosols, endotoxins, and respiratory exposure
• Occupational allergens and hypersensitivity
• Zoonoses in agriculture and animal handling
• Risk-group classification of biological agents
• Occupationally acquired infection

Mechanisms

Biological agents reach workers through inhalation of bioaerosols (droplets, dusts, spores, and endotoxin-laden particles), percutaneous inoculation from sharps and needlestick injuries, contact with mucous membranes or broken skin, and ingestion. Once contact occurs, effects follow the agent's biology: infection when a viable pathogen establishes itself, allergic or hypersensitivity reactions to proteins and spores, and toxic effects from microbial products such as endotoxins and mycotoxins. The likelihood of harm depends on the agent's infectivity and pathogenicity, the inoculum, the route, and host susceptibility. In health care, bloodborne agents transmitted by needlestick exposure exemplify the percutaneous route, as reviewed by Sepkowitz (1996).

Clinical relevance

Recognizing which biological agents and transmission routes characterize an occupation underpins the understanding of occupational infectious and allergic disease and the appraisal of related evidence. This entry describes how biological workplace hazards are classified, transmitted, and studied at the reference level; it does not provide individual diagnostic, post-exposure, or infection-control instructions.

Epidemiology

Health-care, laboratory, agricultural, and waste workers carry elevated exposure to biological hazards. Occupationally acquired infections in health-care workers—including bloodborne viruses transmitted by percutaneous injury and airborne pathogens such as tuberculosis—are a long-documented occupational risk, reviewed comprehensively by Sepkowitz (1996); agricultural and animal-contact work carries additional risk of zoonoses and bioaerosol-related respiratory disease.

History

Occupational infections such as anthrax in wool sorters and tuberculosis among health-care and laboratory staff were recognized in the nineteenth and early twentieth centuries. The emergence of HIV and hepatitis B and C as bloodborne occupational risks in the late twentieth century sharpened attention to percutaneous exposure and prompted systematic reviews of occupationally acquired infection in health-care workers.

Seminal works

• sepkowitz-1996-part1
• sepkowitz-1996-part2

Frequently asked questions

Which workers face the greatest biological hazards?

Health-care and laboratory workers, agricultural and animal-contact workers, and those in food processing and waste management are among the most exposed, each to a characteristic set of agents and routes.

How do biological agents reach workers?

Principally by inhalation of bioaerosols, by percutaneous injury such as needlesticks, by contact with mucous membranes or broken skin, and by ingestion.