😷Environmental and Occupational Health Unit 1 – Environmental Health Fundamentals

Key Concepts and Definitions

• Environmental health focuses on the study of how the natural and built environments affect human health and well-being
• Hazards are agents or factors that have the potential to cause harm or adverse health effects
  • Can be classified as biological (bacteria), chemical (pesticides), physical (radiation), or psychosocial (stress)
• Exposure refers to contact with a hazard through inhalation, ingestion, dermal absorption, or injection
• Dose-response relationship describes how the likelihood and severity of health effects change with varying levels of exposure to a hazard
• Risk assessment is the process of estimating the probability and magnitude of adverse health effects from exposure to hazards
• Environmental epidemiology studies the distribution and determinants of health outcomes in populations, particularly in relation to environmental factors
• Toxicology is the study of the adverse effects of chemical, physical, or biological agents on living organisms
• Environmental justice addresses the disproportionate environmental risks and burdens faced by disadvantaged communities

Environmental Health Hazards

• Air pollution includes outdoor (ambient) and indoor air pollutants such as particulate matter (PM), ozone, and volatile organic compounds (VOCs)
  • Major sources are transportation, industrial emissions, and household activities (cooking)
• Water pollution involves contamination of surface water and groundwater by pathogens, chemicals, and nutrients
  • Can result from sewage, agricultural runoff, and industrial discharges
• Soil contamination occurs when hazardous substances (heavy metals) accumulate in soil, posing risks to human health and the environment
• Hazardous waste includes solid, liquid, or gaseous materials that are toxic, flammable, corrosive, or reactive
  • Improper disposal can lead to environmental contamination and health risks
• Pesticides are chemicals used to control pests in agriculture and urban settings, but they can have unintended effects on human health and ecosystems
• Radiation hazards include ionizing (X-rays) and non-ionizing (UV) radiation, which can cause DNA damage and increase cancer risk
• Occupational hazards are specific to workplace settings and can include chemical exposures, physical hazards (noise), and ergonomic risks
• Climate change is a global environmental health threat, with impacts on air quality, water availability, food security, and infectious disease patterns

Exposure Pathways and Assessment

• Exposure pathways describe the route a hazard takes from its source to the target population
  • Includes the source, environmental media (air), point of exposure, route of exposure (inhalation), and receptor population
• Direct exposure occurs when individuals come into immediate contact with a hazard (dermal absorption)
• Indirect exposure involves contact with a hazard that has been transported or transformed through environmental media (ingestion of contaminated fish)
• Biomonitoring is the measurement of hazardous substances or their metabolites in human biological samples (blood) to assess exposure
• Environmental monitoring involves sampling and analysis of environmental media (air) to determine the presence and concentration of hazards
• Personal monitoring uses devices worn by individuals to measure their exposure to specific hazards (noise dosimeters)
• Exposure assessment is the process of estimating the magnitude, frequency, and duration of exposure to a hazard
  • Considers factors such as exposure pathways, exposure scenarios, and population characteristics
• Exposure modeling uses mathematical equations to predict exposure levels based on environmental concentrations and human activity patterns

Health Effects and Risk Assessment

• Acute health effects occur immediately or shortly after exposure to a hazard and are often reversible (respiratory irritation)
• Chronic health effects develop over a long period of time, often after repeated or continuous exposure, and may be irreversible (cancer)
• Dose-response assessment characterizes the relationship between the dose of a hazard and the incidence or severity of health effects
  • Threshold effects have a dose below which no adverse effects are observed (non-carcinogenic chemicals)
  • Non-threshold effects assume that any level of exposure carries some risk (carcinogenic substances)
• Hazard identification is the process of determining whether a substance or agent can cause adverse health effects
• Exposure-response assessment quantifies the relationship between the level of exposure and the probability or magnitude of health effects
• Risk characterization combines information from hazard identification, dose-response assessment, and exposure assessment to estimate the likelihood and severity of adverse health effects in a population
• Uncertainty analysis evaluates the limitations and variability in risk assessment data and assumptions
• Risk management involves decision-making to control or mitigate environmental health risks based on risk assessment results and other factors (economic)

Environmental Regulations and Policies

• Clean Air Act (CAA) regulates air pollutant emissions from stationary and mobile sources to protect public health and welfare
  • Establishes National Ambient Air Quality Standards (NAAQS) for criteria pollutants (ozone)
• Clean Water Act (CWA) regulates discharges of pollutants into surface waters and sets water quality standards
  • Requires permits for point source discharges (wastewater treatment plants) and addresses nonpoint source pollution (stormwater runoff)
• Safe Drinking Water Act (SDWA) establishes standards for contaminants in public drinking water systems and regulates underground injection of fluids
• Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), also known as Superfund, provides for the cleanup of hazardous waste sites and emergency response to releases of hazardous substances
• Resource Conservation and Recovery Act (RCRA) regulates the generation, transportation, treatment, storage, and disposal of hazardous and non-hazardous solid waste
• Toxic Substances Control Act (TSCA) grants EPA authority to regulate the production, importation, use, and disposal of chemicals that pose risks to human health and the environment
• Occupational Safety and Health Act (OSH Act) requires employers to provide a safe and healthful workplace and sets standards for occupational exposure to hazards
• National Environmental Policy Act (NEPA) mandates environmental impact assessments for major federal actions that may significantly affect the environment

Prevention and Control Strategies

• Source reduction aims to prevent or minimize the generation of pollutants or hazards at their origin
  • Includes process modifications, material substitution, and product redesign
• Pollution control involves the use of technologies or practices to reduce or eliminate emissions or discharges of pollutants
  • Examples are air pollution control devices (scrubbers) and wastewater treatment systems
• Exposure control focuses on reducing human contact with hazards through engineering controls (ventilation), administrative controls (work practices), and personal protective equipment (respirators)
• Environmental remediation is the process of cleaning up contaminated sites to restore them to a safe and usable condition
  • Techniques include soil excavation, groundwater pump-and-treat, and bioremediation
• Risk communication is the process of informing and educating the public about environmental health risks and engaging them in decision-making
• Community-based participatory research (CBPR) involves collaboration between researchers and communities to address environmental health issues and develop interventions
• Health impact assessment (HIA) is a tool for evaluating the potential health effects of a policy, plan, or project before implementation
• Precautionary principle states that when an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause-and-effect relationships are not fully established

Emerging Issues in Environmental Health

• Climate change impacts on health include heat-related illnesses, respiratory diseases from air pollution, waterborne diseases from flooding, and vector-borne diseases from changing habitats
  • Adaptation strategies are needed to reduce vulnerability and increase resilience to climate-related health risks
• Environmental health disparities refer to the disproportionate burden of environmental hazards and adverse health outcomes faced by certain populations (low-income)
  • Addressing these disparities requires attention to social determinants of health and environmental justice
• Endocrine-disrupting chemicals (EDCs) are substances that interfere with the body's hormone system and can cause developmental, reproductive, and other health effects
  • Examples include bisphenol A (BPA) and phthalates found in consumer products
• Nanotechnology involves the manipulation of matter at the nanoscale (1-100 nm) and has potential applications in environmental remediation and drug delivery
  • However, the health and environmental risks of nanomaterials are not yet fully understood
• Antibiotic resistance is a growing public health threat, partly due to the use of antibiotics in animal agriculture and the release of antibiotic residues into the environment
• Electronic waste (e-waste) contains hazardous substances (lead) that can pose risks to human health and the environment if not properly managed
• Urban green space provides environmental and health benefits (improved air quality), but access to green space is often inequitable
• One Health recognizes the interconnections between human, animal, and environmental health and promotes a holistic approach to addressing health challenges

Practical Applications and Case Studies

• Flint, Michigan water crisis involved lead contamination of the city's drinking water supply due to a change in water source and inadequate treatment
  • Highlights the importance of proper water quality monitoring and the disproportionate impact on vulnerable populations
• Love Canal, New York was a neighborhood built on a former industrial waste dump, resulting in exposure to hazardous chemicals and adverse health effects
  • Led to the creation of the Superfund program for cleaning up hazardous waste sites
• Air pollution in Beijing, China has reached hazardous levels, with major contributors being coal combustion, vehicle emissions, and industrial activities
  • Demonstrates the need for comprehensive air quality management and public health interventions
• Occupational exposure to asbestos has been linked to lung cancer and mesothelioma among workers in construction and shipbuilding industries
  • Emphasizes the importance of workplace exposure assessment and control measures
• Zika virus outbreak in the Americas was associated with microcephaly in infants born to infected mothers, highlighting the role of environmental factors (mosquito vectors) in infectious disease transmission
• Deepwater Horizon oil spill in the Gulf of Mexico had significant ecological and human health impacts, including exposure to oil and dispersants among cleanup workers and coastal communities
• Pesticide exposure among farmworkers has been associated with acute poisoning and chronic health effects, underscoring the need for worker protection and integrated pest management
• Neighborhood greenness and access to parks have been linked to improved mental health outcomes and reduced health disparities in urban populations