Environmental Health Sciences
Core concepts
Environmental health links exposures to health effects through source → pathway → receptor models. Know the exposure routes (inhalation, ingestion, dermal) and dose–response relationships. Understand hazard identification, dose-response assessment, exposure assessment, and risk characterization-the four steps of risk assessment-followed by risk management and risk communication.
Master key agents: lead (neurodevelopmental harm, no safe threshold in children), asbestos (mesothelioma, asbestosis), radon (lung cancer), particulate matter (cardiopulmonary effects), carbon monoxide (binds hemoglobin), nitrates (methemoglobinemia in infants), and waterborne pathogens (e.g., Legionella, Cryptosporidium). Know air quality standards, drinking water treatment (coagulation, filtration, disinfection), and vector control.
Traps
- Confusing hazard (potential to harm) with risk (probability of harm under exposure).
- Assuming any detection equals harm-dose matters, and thresholds exist for many agents.
- Mixing primary (source control) with secondary (screening) prevention.
- Forgetting vulnerable populations: children, pregnant women, elderly, immunocompromised.
Worked rule of thumb
For a contamination scenario, trace the pathway: source (well, air, soil) → route (ingestion/inhalation) → dose → population at risk → control (engineering, administrative, PPE-in that order of preference in the hierarchy of controls).
Key principle
Environmental justice questions emphasize disproportionate exposure of low-income and minority communities.