Environmental health Study Guide

📖 Core Concepts Environmental health: Study of how natural and built environments affect human health; focuses on physical, chemical, and biological external factors plus related behaviours. WHO definitions: 1989 – health determined by environmental factors; 1990 – adds direct effects of chemicals/radiation & indirect social‑cultural effects; 2016 – excludes genetics and non‑environmental behaviours. Core disciplines: Environmental epidemiology – links exposures to health outcomes (observational). Toxicology – determines how agents cause disease (often animal studies). Exposure science – measures how much of a contaminant people encounter. Environmental engineering – designs solutions to protect people and ecosystems. Environmental law – statutes & treaties governing environmental protection. Risk assessment & management – combines data to decide if an exposure is unacceptable and guides policy. Major exposure categories: Air (outdoor & indoor), water, soil, noise, hazardous waste, micro‑plastics, climate‑related hazards. Health impact metrics: DALYs, deaths attributable to environmental causes (≈4.9 M deaths worldwide; 5–10 % of DALYs in Europe). 📌 Must Remember Air pollution deaths: >6.5 M worldwide annually; indoor pollution ≈4.3 M deaths. Fine particulate matter (PM₂.₅) is the leading environmental DALY driver in Europe. Safe water gap: >2 B people lack safe drinking water; 22 M U.S. people consume water violating standards. Lead in school water → neurodevelopment loss (lower IQ, attention deficits). Microplastic ingestion: >50 000 particles/year per person; 5 g/week (≈credit‑card weight). Environmental racism: Minority groups live nearer to major roadways, waste sites, and have higher PM₂.₅ exposure. Noise health effects: Hearing loss, hypertension, sleep disruption, 20 % lower memory development in children near traffic noise. Risk assessment integrates epidemiology, toxicology, and exposure data to set standards (e.g., emissions limits, sanitation rules). 🔄 Key Processes Risk Assessment Workflow Hazard Identification → Is the agent toxic? Dose‑Response Assessment → Relationship between exposure level and effect. Exposure Assessment → Quantify how much, how often, and who is exposed. Risk Characterization → Combine dose‑response & exposure to estimate health risk. Environmental Surveillance (services) Monitoring (air, water, soil) → Collect data. Control Activities → Apply engineering or regulatory controls. Promotion → Public education & technology incentives. Air‑Quality Exposure Pathway Source → Ambient concentration → Personal exposure (activity patterns) → Health outcome. 🔍 Key Comparisons Outdoor vs. Indoor Air Pollution Sources: traffic, industry vs. coal/kerosene burning, mold, ETS. Deaths: 6.5 M vs. 4.3 M annually. Vulnerable groups: outdoor – children playing outside; indoor – elderly, children at home. Direct vs. Indirect Environmental Effects (WHO 1990) Direct: chemical, radiation, biological agents causing pathology. Indirect: housing, urban design, transport influencing health via psychosocial pathways. Microplastics vs. Traditional Plastic Pollution Micro: particles <5 mm, ingested/inhaled, found in human tissues. Traditional: larger debris, visible environmental litter. ⚠️ Common Misunderstandings “All pollution is chemical” – Noise, heat, and psychosocial stressors are also health‑relevant pollutants. “Genetics matters in environmental health” – WHO 2016 explicitly excludes genetics from the definition. “Indoor air is always cleaner” – Indoor sources (solid‑fuel cooking, ETS) cause >4 M deaths annually. “Microplastics are harmless because they’re tiny” – They can carry chemicals and trigger inflammation; found in blood & placenta. 🧠 Mental Models / Intuition “Exposure = Dose × Time” – Visualize a person’s daily routine as a path through a polluted “cloud”; longer time in high‑concentration zones = higher dose. “Risk Pyramid” – Bottom: ubiquitous low‑level exposures (e.g., PM₂.₅); middle: occasional high‑impact events (e.g., chemical spill); tip: rare catastrophes (e.g., nuclear accident). “Environmental Justice Map” – Imagine a heat‑map overlay of pollutant sources and demographic data; hotspots reveal systemic inequities. 🚩 Exceptions & Edge Cases Fluoride & Arsenic – Low, controlled levels can be beneficial, whereas high levels are toxic. High‑income “super polluters” – Wealthy households may own carbon‑intensive assets despite living in cleaner neighborhoods. Occupational vs. General Population Exposure – Workers may face orders of magnitude higher doses; risk assessments must use different exposure scenarios. 📍 When to Use Which Epidemiology vs. Toxicology – Use epidemiology to describe real‑world health outcomes; use toxicology for mechanistic insight and dose‑response curves when human data are lacking. Exposure Science vs. Risk Assessment – Apply exposure science to obtain accurate concentration data; feed those data into a full risk assessment for policy decisions. Engineering Controls vs. Regulatory Controls – Engineering for immediate source reduction (e.g., filtration); regulatory for long‑term population‑wide standards (e.g., PM₂.₅ limits). 👀 Patterns to Recognize Cluster of health effects around a single exposure (e.g., PM₂.₅ → respiratory + cardiovascular mortality). Disproportionate burden: whenever a question mentions minority or low‑income groups, think of environmental racism and higher pollutant exposure. Triad of “source → pathway → receptor” in any environmental health problem (e.g., landfill leak → groundwater → drinking water). Dual‑impact pollutants: many agents (e.g., noise) have both auditory and non‑auditory health outcomes. 🗂️ Exam Traps “Genetics is part of environmental health” – Wrong; WHO 2016 excludes genetics. Confusing “indoor air pollution deaths” with “outdoor” – Remember the separate figures (4.3 M vs. 6.5 M). Assuming all microplastics are harmful – While pervasive, the outline only states potential inflammation and chemical vectoring; the exam may ask for known vs. hypothesized effects. Mixing up “environmental medicine” and “environmental health” – Medicine is a specialty within the broader field; not synonymous. Attributing DALYs to a single pollutant – Only fine particulate matter is identified as the leading factor in Europe; other pollutants contribute but are not the top driver. --- Use this guide to quickly recall definitions, key numbers, and decision pathways. Focus on the relationships between exposure sources, vulnerable populations, and health outcomes—those are the high‑yield links most exam questions test.