Occupational and Environmental Health Midterm

Biological agents

Microorganisms—including bacteria, viruses, fungi, and parasites—or toxins produced by living organisms that can cause disease, infection, or death in humans, animals, or plants

Potential agents

chemical (solvents, heavy metals, pesticides), biological (bacteria, viruses, fungi), physical (noise, radiation, vibration), and ergonomic factors

Morbidity

state of being ill, diseased, or injured

mortality

the state of being dead, specifically the number of deaths caused by a disease or condition in a population

Sources of Data

Key data sources for occupational health include government agencies like OSHA and the Bureau of Labor Statistics (BLS), which track injuries, illnesses, and fatalities through surveys and reporting systems. Other critical sources are the CDC/NIOSH (surveillance, research)

Occupational Safety and Health Administration (OSHA)

U.S. Department of Labor agency established in 1970 to ensure safe working conditions by setting, enforcing standards, and providing training

Bureau of Labor Statistics (BLS)

principal fact-finding agency for the Federal Government in the broad field of labor economics and statistics

National Institute for Occupational Safety and Health (NIOSH)

United States federal agency responsible for conducting research and making recommendations for the prevention of work-related injury, illness, disability, and death

Categories of hazards

• Safety hazards: which result in injuries through the uncontrolled transfer of energy to vulnerable recipients 

• Health hazards, which result in acute illness or chronic disorders

  • Chemical hazards 

  • Physical hazards 

  • Biochemical hazards (heavy lifting, forceful movements)

  • Biological hazards 

  • Psychosocial hazards 

Levers of change

key intervention points or strategic actions within a system (like a business or society) that, when activated, create significant, widespread transformation, moving it towards a desired new state, much like a physical lever moves a heavy object with less force

Underreported

It is likely that injuries and illnesses related to jobs and the environment are underreported.

Reasons: hidden due to worker fear of reprisal, complex reporting processes, and economic incentives to undercount

Occupational and environmental health

comprises the recognition, diagnosis, treatment, and prevention of illnesses, injuries, and other adverse health conditions resulting from hazardous environmental exposures in the workplace, the home, and the community

Many hazardous exposures occur simultaneously in the workplace and the ambient environment,

• Contamination of ambient air and surface water near a chemical factory, whose workers are also exposed to hazardous substances

• Application by agricultural workers of pesticides that may contaminate surface water and groundwater

• Inadvertent transport of lead, asbestos, and other hazardous substances from the workplace to home on workers’ clothes, shoes, skin, and hair.

Relationship between Occupational Health and Environmental Health

Occupational health and environmental health evolved along separate—but often related—track

During the past 50 years, extraordinary developments in science, technology, legislation, public health, and social empowerment have led to much progress in both occupational health and environmental health

Historically, knowledge about adverse health effects of toxic environmental exposures in people has primarily resulted from research on occupational exposures.

By contrast, nonoccupational exposures to community residents have been more difcult to characterize and track, and individuals move from one community to another.

However, scientic ndings from occupational health research alone cannot protect the general population from environmental exposures.

Safety hazards

injuries through the uncontrolled transfer of energy to vulnerable recipients from sources such as electrical, thermal, kinetic, chemical, or radiation energy. Examples include unsafe playground equipment; loaded rearms in the home; causes of motor-vehicle or bicycle crashes; unprotected electrical sources and equipment; work at heights without fall protection; cluttered homes, leading to slips, trips, and falls; unguarded machinery in operation; and work in unshored trenches

Health hazards

result in acute illnesses or chronic disorders

Chemical hazards

including heavy metals, such as lead and mercury; pesticides; organic solvents, such as benzene and trichloroethylene; and many other chemicals. Since 1979, approximately 85,000 chemicals have been, at some point, in commercial use in the United States; however, the vast majority have not been adequately tested for adverse health effects

Physical hazards

excessive noise, vibration, extremes of temperature and pressure, and ionizing and non-ionizing radiation

Biomechanical hazards

heavy lifting and repetitive or forceful movements, that cause musculoskeletal disorders, such as chronic low back pain and carpal tunnel syndrome

Biological hazards

hepatitis B virus and hepatitis C virus, the tubercle bacillus, and many other microorganisms that may be transmitted through direct contact, air, water, or food

Psychosocial hazards

(i) socioeconomic stressors, such as discrimination, income inequality, migration or immigration status, and unemployment, and (ii) job and organizational stressors, such as excessive demands on and low control by workers, job insecurity, and inadequate job training and retraining opportunities

Accuracy of Data

population-based data on fatal injuries are generally thought to be more accurate than data on chronic occupational and environmental illnesses

What trend is reshaping workplace risks?

Growth of nonstandard work (temporary, part‑time, subcontracted)

Provide examples of ergonomic hazards

Repetitive motion risks for garment workers; assembly‑line work

Why are many occupational/environmental illnesses underrecognized?

Long latency periods, nonspecific symptoms, limited reporting, and lack of surveillance

Clean Air Act

comprehensive U.S. federal law, primarily enacted in 1970 and amended in 1977 and 1990, designed to control air pollution from stationary and mobile sources. It authorizes the EPA to establish National Ambient Air Quality Standards (NAAQS) to protect public health and welfare

The U.S. Environmental Protection Agency (EPA)

federal agency that protects human health and the environment by enforcing regulations, conducting research, and providing environmental education.

Risk of Children

Children are at increased risk for many environmental health problems because (a) their neurological and other systems are still in development, (b) they absorb substances and metabolize them differently than adults, and (c) they may be at risk for increased exposure from hand-to-mouth activity or improper storage of chemicals.

How is occupational health inequity defined?

Disparities in work-related risks and exposures among marginalized groups (minorities, immigrants, women, low‑income workers)

What groups are disproportionately overrepresented in high‑risk jobs?

Women, racial/ethnic minorities, immigrants, temporary workers

What is environmental injustice?

Unequal distribution of environmental hazards to minority or low‑income communities.

How does the built environment influence health?

Through access to amenities, exposure to pollution, transportation patterns, housing conditions, and zoning decisions

How does climate change influence occupational/environmental health?

Increases heat stress, changes disease vectors, worsens air quality, and contributes to extreme weather impacts

What is “export of hazard”?

Shifting hazardous jobs, waste, and risks to low‑ and middle‑income countries due to globalization.

Under-recognition or Underreporting of Illnesses and Injuries

1. Many problems do not come to the attention of health professionals, employers, and others and therefore are not included in data collection systems

2. Many health problems that do come to the attention of physicians, employers, and others are not recognized as occupationally and environmentally related

3. Some health problems that are recognized by health professionals, employees, or others as occupationally or environmentally related are not reported because the association with the workplace or other environments is not certain or because reporting requirements are not enforced.

Prevention

Prevention consists of:

• Primary prevention: Preventing illnesses and injuries before they occur

• Secondary prevention: Identifying and treating health problems as early as possible, often before symptoms have developed or permanent impairment has occurred

• Tertiary prevention: Implementing interventions to arrest the progress of established diseases, injuries, or their consequences, including disability.

Recognition

The first and most important step in diagnosis and treatment of an occupational or environmental illness or injury is the recognition that it is potentially caused by an occupational or environmental exposure. Recognition focuses both on (a) detecting occupational and environmental illnesses and injuries in symptomatic and asymptomatic individuals and (b) conducting public health surveillance in populations to detect individual cases and overall trends of illness and injury

public health model of host, agent, and environment

First, some preventive measures focus on a host or hosts— workers or community residents; these measures include education and training, providing immunizations or post-exposure prophylaxis, monitoring personal exposures, screening for early detection of disease, and use of personal protective equipment. Second, some preventive measures focus on the agent (hazard), such as an asbestos-containing product, and restricting or banning its production or use in order to reduce exposure. And third, some preventive measures focus on the environment, including engineering measures, such as local exhaust ventilation to remove airborne hazards in the workplace, placement of sound-barrier walls alongside highways to reduce noise in adjacent neighborhoods, and urban planning to create more green space or bicycle lanes

Mine Safety and Health Administration

U.S. Department of Labor agency that prevents mining-related deaths, injuries, and illnesses. It develops and enforces safety standards, conducts mandatory inspections of all U.S. mines, investigates accidents, and provides training and technical assistance to ensure a safe work environment

Toxic Substances and Disease Registry

federal public health agency within the U.S. Department of Health and Human Services. The agency focuses on minimizing human health risks associated with exposure to hazardous substances

Key approaches to preventing occupational/environmental health problems?

Hazard recognition, substitution, engineering controls, policy interventions, worker training, and surveillance systems

What is the link between workplace and home environments?

Industrial hygiene, toxicology, epidemiology, environmental science, engineering, public health, ergonomics, and occupational medicine

What is occupational health equity?

Ensuring that all workers have equal protection from workplace hazards, regardless of race, ethnicity, gender, immigration status, income, or job type. Equity means eliminating disparities in exposures, injuries, illnesses, and protections

What is environmental health equity?

Fair distribution of environmental benefits and burdens across all communities, so that no racial or socioeconomic group is disproportionately exposed to harmful environmental hazards

How are work and environmental equity connected?

Communities facing environmental injustice often also face inequitable work conditions, and the same social forces (racism, segregation, poverty) create both workplace and environmental disparities

What groups are overrepresented in the most hazardous, lowest-wage jobs?

Minority workers, immigrants, women, and temporary/contingent workers

What trend is increasing inequity in workplace health?

Growth of nonstandard work arrangements—including temporary, part‑time, subcontracted, gig, and contingent work. These roles often lack benefits and safety protections

Why are temporary and immigrant workers at higher risk?

They face employer abuse, unstable employment, language barriers, discrimination, and fear of retaliation or deportation, which reduces reporting of hazards and injuries

How does discrimination contribute to occupational health disparities?

Discrimination leads to stress, limited job opportunities, assignment to more dangerous tasks, harassment, and reduced access to compensation or protections

What is workplace injustice?

Practices such as harassment, bullying, underpayment, assignment to hazardous jobs, or denial of safety equipment, disproportionately harming marginalized workers

What major historical studies documented environmental injustice?

• 1983 U.S. GAO report on hazardous waste sites and race

• 1987 UCC Toxic Wastes and Race report
  Both revealed racial disparities in siting of hazardous facilitie

What is residential segregation’s role in health?

Segregation concentrates economic disadvantage and environmental risks, increasing exposures to air pollution and toxic substances in minority communities

How does zoning contribute to environmental injustice?

It places undesirable land uses (waste sites, industrial facilities) in minority neighborhoods while restricting access to green spaces and amenities

built environment inequities

Lack of access to sewer and water services, absence of safe green spaces, traffic and pollution burdens, and inequitable placement of industrial facilities in communities of color

What strategies help decrease occupational/environmental health inequities?

• Community-based participatory research

• Advocacy and organizing

• Improved regulatory enforcement

• Worker education programs

• Equity-focused policy reform

What groups support workers in addressing health inequities?

• Labor unions

• Worker centers

• COSH groups (Committees/Coalitions on Occupational Safety & Health)

• Public health associations

• Community empowerment organizations

What social determinants of health are tied to workplace/environmental inequity?

Income, housing, education, immigration status, racism, and neighborhood infrastructure. These shape exposure and vulnerability

How do occupational and environmental inequities reinforce each other?

Workers harmed at work often live in polluted neighborhoods, creating cumulative exposure burdens

Triangle Shirtwaist Factory

The Triangle Shirtwaist Factory fire occurred in the Greenwich Village neighborhood of Manhattan, a borough of New York City, on Saturday, March 25, 1911. The fire was the deadliest industrial disaster in the history of the city, and one of the deadliest in U.S. history.^[1] The fire caused the deaths of 146 garment workers

workplace discrimination and segregation

Workplace discrimination is the unfavorable treatment of individuals based on protected characteristics (race, gender, etc.), while segregation is a specific form of discrimination involving the physical or functional separation of employees based on these characteristics (ex. one group of workers disproportionately works certain jobs with greater risk of psychosocial stress)

Smart growth

community-driven planning approach that creates, healthy, sustainable, and economically vibrant, neighborhoods by encouraging, compact development, mixed land uses, and diverse, transport options

Emerging contaminants

Natural or man-made substances in water and the environment that are suspected to pose risks to human or ecological health but aren't yet regulated or fully understood due to new detection, new research on effects, or increased usage, including PFAS

• The emerging part of “emerging contaminant” refers to substances recently discovered or recognized as having potentially harmful, poorly understood, or previously undocumented impacts on human health and the environment

Susceptibility

state of being easily affected, influenced, or harmed by external factors like diseases, pathogens, or drugs, indicating a lack of resistance

• Influences include: age, sex, race, preexisting health conditions (co-morbidity= the simultaneous presence of two or more diseases or medical conditions in a patient)

• Behaviors can also alter susceptibility – ex. Frequent contact with a chemical agent, vaccinations, wearing masks 

host

a living organism—animal, plant, or microbe—that harbors another organism (a parasite, pathogen, or symbiont), providing it with nourishment, shelter, and a, suitable environment for surviva

Vector

An organism (usually an arthropod) that acts as an intermediary, transmitting parasites or pathogens from one host to another.

Known existence vs. presumptive PFAS and PFOA

While "known" sites are verified through sampling, "presumptive" contamination assumes presence near specific industrial, military, or waste sites

In situ remediation

treats contaminated soil and groundwater directly in place without excavation, using techniques like chemical oxidation, biodegradation, or thermal treatment. It minimizes site disruption, reduces costs compared to excavation, and treats contaminants like petroleum hydrocarbons or solvents via injected reagents or, for example, activated carbon

PFAS toxicity: Zebra Fish Model

The zebrafish (Danio rerio) is an established model for rapid toxicity screening and provides predictive insights into human health risks to PFAS. any PFAS alter larval behavior, such as swimming patterns and reactions to light (photomotor response), even at non-lethal concentrations (Early warning system for humans)

Per- and polyfluoroalkyl substances (PFAS)

a group of over 15,000 synthetic "forever chemicals" used since the 1950s in products like non-stick cookware, stain-resistant fabrics, and food packaging. They persist in the environment and human body, linked to health issues including cancer, liver damage, and reduced fertility

• Structure of PFAS: PFAS (Per- and Polyfluoroalkyl Substances) have a core structure featuring a chain of carbon atoms, with most or all hydrogen atoms replaced by fluorine, creating a super-strong carbon-fluorine bond, and ending with a functional group (like -COOH or -SO3H) that determines its properties

  • Up to 5,000 species, most without standards or toxicity 

  • Surface active, accumulate at interfaces (air-water, oil-water)

  • Repel both water and oil (Gire-Tex, Scotch Guard, Stainmaster)

  • Resistant to degradation (chemical, biological, thermal)

  • Some of these properties that make them attractive, also make them a problem 

DuPont

DuPont has a long, controversial history with PFAS ("forever chemicals"), being a major manufacturer for products like Teflon, leading to widespread environmental contamination and lawsuits alleging the company concealed health risks associated with these persistent chemicals, resulting in massive settlements and ongoing remediation efforts

What health effects have PFAS exposure been associated with?

Cancers, hypertension, elevated cholesterol, reproductive issues, and reduced vaccine effectiveness

What major regulatory change occurred in 2024?

The U.S. EPA finalized enforceable drinking water MCLs for six PFAS and designated PFOA & PFOS as hazardous substances under CERCLA

What is “presumptive contamination”?

A model identifying likely PFAS contamination sites where systematic testing is lacking, based on land use and known PFAS emission industries

What major categories are used to classify known contamination sites?

Municipal fire activity, airports, industrial facilities, military facilities, waste facilities, and unknown

Which site categories make up the largest proportions of known PFAS contamination?

• Waste sites: 40%

• Industrial sites: 29%

• Military facilities: 20%

Why does AFFF use matter?

Aqueous Film-Forming Foam (AFFF) is a highly effective, PFAS-containing firefighting foam used for extinguishing fuel fires

• AFFF sites show significantly higher PFAS concentrations than other site types in groundwater

What do “high‑high clusters” represent in spatial analysis?

Counties with consistently high site densities surrounded by similarly high‑density counties

How do PFAS exposures relate to environmental justice?

PFAS contamination and source proximity are elevated in communities with higher proportions of people of color

How do urban areas factor into PFAS exposure risk?

Urban land use is positively correlated with PFAS detections and often corresponds to historically disadvantaged communities

What populations are excluded from federal PFAS drinking water protections?

People using private wells, who still face high potential exposures

What upstream actions could reduce contamination from Wastewater Treatment Plants (WWTPs)?

Reducing PFAS production, use, and emissions from industries sending waste to treatment plants

Health equity

means everyone has a fair and just opportunity to achieve their highest level of health, removing obstacles like poverty, discrimination, and lack of access to resources, ensuring health isn't dependent on social, economic, or demographic factors like race, gender, or location

• CDC: “Every person has the opportunity to attain his or her full potential and no one is disadvantaged from achieving this potential because of social position or other socially determined circumstances”

Concentrated animal feeding operations (CAFO)

large-scale, industrial agricultural facilities that confine thousands of animals (meat, dairy, or egg) without access to pasture for 45+ days in a 12-month period

• Many children from a poor rural area in North Carolina near industrial hog operations were having diarrhea (especially after heavy rains)

• Found high levels of E. coli and fecal coliforms in residential well water 

• Found that the hog operations were near poor and African American neighborhoods 

Mesothelioma

a rare, aggressive cancer of the tissue lining organs (mesothelium), almost exclusively caused by inhaling or swallowing asbestos fibers

asbestos

a group of naturally occurring fibrous silicate minerals known for heat resistance, used heavily in construction and insulation until the 1970s. Inhalation of fibers causes severe health issues, including mesothelioma, lung cancer, and asbestosis

built environment

refers to all human-made surroundings, including buildings, roads, parks, and infrastructure, that provide spaces for living, working, and recreation, significantly impacting public health, social interaction, and sustainability, by shaping activities, access to resources, and exposure to pollutants

noise pollution

the propagation of noise or sound with potential harmful effects on humans and animals. The main sources of outdoor noise worldwide are machines, transportation, and propagation systems.

Informal workers

individuals engaged in economic activities not regulated, taxed, or protected by the state

Essential workers

individuals in critical sectors, such as healthcare, agriculture, grocery, and delivery services, whose roles are vital for society's functioning

Guest workers

foreign nationals permitted to work temporarily in a host country to fill labor shortages, primarily in agriculture, hospitality, and construction, typically under non-immigrant, employer-specific visas

Surveillance

continuous, systematic collection, analysis, and interpretation of health data to plan, implement, and evaluate public health practices

risk assessment

a systematic process to identify hazards, analyze the risk (likelihood and severity of harm), evaluate the risk level, and determine control measures to eliminate or reduce it, ensuring safety in workplaces, projects, or decisions

• qualitative risk assessment = risks are compared between agents in a relative non-quantitative manner

  • Virtually the same thing as “hazard evaluation” step of Quantitative Risk Assessment 

  • Is the material harmful to humans under any circumstances 

  • Codified by agencies, especially for cancer 

• quantitative assessment = a numerical estimate of the risk of a specific agent is generated based on the findings of other studies

  • A formal process with four steps:

    • Hazard identification 

    • Exposure assessment 

    • Dose-response assessment 

    • Risk characterization 

Control of occupational and environmental hazards

Prevent exposure of susceptible hosts to the agents of concern

Obstacles

Lack of “perfect” information ? Sufficient resources?- fiscal, political will? Creation of appropriate incentives for action?

What is an exposure metric in occupational/environmental health?

A method for characterizing and quantifying exposure, including intensity, frequency, and duration

What is biological monitoring?

Measurement of chemicals, metabolites, or biological changes in workers to assess internal exposure levels

What is incidence?

The number of new cases of a disease occurring in a defined population over a specified time period.

Incidence = (number of new cases) / (total population at risk during the specified time period)

Incidence rate = (number of new cases during time period)/ (total number at risk) —> assesses the frequency of disease onset

Prevalence

Measure of disease status. Refers to the number of existing cases in the population

Point prevalence identifies the prevalence estimated at a given time

point prevalence = (number of cases) / (population at risk)

Person-years

A measure combining the number of persons and the amount of time each contributes to a study

Risk ratio (RR)/relative risk

measures the likelihood of an event occurring in an exposed group compared to an unexposed group, calculated as (ratio of two probabilties)

RR = (incidence of the disease among exposed)/(incidence of the disease among unexposed)