This topic will provide an overview of environmental toxicology, including the sources of environmental contaminants, their impact on ecosystems and human health, and the principles of toxicology.
Introduction to Environmental Toxicology
Key concepts, terminology, and foundational principles
| Aspect | Description |
|---|---|
| Definition | The scientific study of the adverse effects of chemical, physical, or biological agents on living organisms and ecosystems. |
| Scope | • Human health (occupational, community, and consumer exposure) • Wildlife and plant health • Ecosystem functions (soil, water, air) |
| Goal | Identify hazardous substances, understand exposure pathways, assess risk, and develop strategies to prevent or mitigate damage. |
| Term | Meaning |
|---|---|
| Toxin | A poisonous substance produced by a living organism (e.g., venom, mycotoxins). |
| Toxicant | A man‑made or naturally occurring chemical that can cause toxicity (e.g., pesticides, heavy metals). |
| Dose/Exposure | Amount of a substance that reaches an organism (often expressed as mg/kg body weight). |
| Concentration | Amount of a substance per unit volume or mass (e.g., µg/L in water). |
| Bioaccumulation | Build‑up of a chemical in an organism over time faster than it can be metabolized or excreted. |
| Biomagnification | Increase in contaminant concentration as it moves up the food chain. |
| LD₅₀ / LC₅₀ | Lethal dose or concentration that kills 50 % of a test population; a standard toxicity metric. |
| NOAEL / LOAEL | No‑Observed‑Adverse‑Effect Level; Lowest‑Observed‑Adverse‑Effect Level. |
| Ecotoxicology | Sub‑discipline focusing on effects of pollutants on ecosystems and non‑human species. |
| Risk Assessment | Process that combines hazard identification, dose‑response, exposure assessment, and risk characterization. |
| Pathway | Typical Sources | Example Contaminants |
|---|---|---|
| Inhalation | Airborne gases, vapors, dust, aerosols | Volatile organic compounds (VOCs), asbestos fibers |
| Ingestion | Food, water, soil, contaminated hands | Pesticide residues, lead, mercury |
| Dermal Contact | Direct skin contact with liquids, solids, or gases | Industrial solvents, oil spills, sunscreen chemicals |
| Injection (rare in environment) | Bites, stings, contaminated needles | Venoms, pathogen‑laden blood |
Graphical tip: Plot dose (x‑axis) vs. response (y‑axis); identify NOAEL, LOAEL, and LD₅₀ points.
| Endpoint | What It Measures | Typical Tests |
|---|---|---|
| Acute Toxicity | Immediate effects (hours–days) | LD₅₀, LC₅₀ assays (rodents, fish) |
| Chronic Toxicity | Long‑term effects (months–years) | Cancer incidence, organ pathology |
| **Reproductive/Developmental Toxicity |