Environmental Hazards and Human Health; Waste Management

Module 12 (11/17–11/23) · Environmental Hazards and Human Health; Waste Management · Blueprint Pillar 3 · PGCC Outcomes 4–5 · Download .docx

Objectives

Interpret a dose-response curve and define LD50.
Distinguish carcinogens, mutagens, and teratogens.
Apply the waste hierarchy.
Define environmental justice and identify examples.

Key terms

Toxicology: The study of the adverse effects of chemicals on living organisms.
Dose-response curve: Graph showing the relationship between the amount of a chemical exposure and the biological effect.
LD50: Lethal dose for 50% of a test population; used to compare chemical toxicity.
Carcinogen: Substance that causes or promotes the development of cancer.
Mutagen: Substance that causes mutations in DNA, potentially heritable.
Teratogen: Substance that causes birth defects when a developing fetus is exposed.
Environmental justice: Principle that all communities deserve equal protection from environmental hazards and equal access to environmental benefits.
Waste hierarchy: Priority order for waste management: Reduce → Reuse → Recycle → Recover → Dispose.
Sanitary landfill: Engineered solid waste disposal site with liners and leachate collection to minimize environmental contamination.
Leachate: Liquid that has percolated through solid waste and may contain dissolved contaminants.
RCRA (Resource Conservation and Recovery Act): U.S. law governing disposal of solid and hazardous waste.
Superfund (CERCLA): U.S. law (1980) authorizing cleanup of the nation's most contaminated hazardous waste sites.

The concept

Toxicology studies the adverse effects of chemicals on living organisms. The foundational principle is 'the dose makes the poison' — almost any substance is harmful at a sufficient dose. A dose-response curve plots biological effect against dose; the LD50 is the dose lethal to 50% of a test population and is used to compare relative toxicity.

Chemicals cause harm in different ways: carcinogens cause cancer (benzene, asbestos, tobacco), mutagens alter DNA (potentially causing heritable changes), and teratogens cause birth defects in developing fetuses (thalidomide, alcohol). Routes of exposure — inhalation, ingestion, and dermal contact — affect how quickly and severely a toxin acts. Environmental justice holds that all communities, regardless of race or income, deserve equal protection from environmental hazards.

The waste hierarchy prioritizes: Reduce → Reuse → Recycle → Recover (energy) → Dispose (landfill or incineration). Reduction is always best. Modern sanitary landfills use impermeable liners and leachate collection to prevent groundwater contamination. Superfund (CERCLA, 1980) funds cleanup of the most contaminated abandoned hazardous waste sites in the U.S.

Self-check

Try each one before you look. A miss here costs nothing and tells you exactly what to reread.

1. The phrase 'the dose makes the poison' means that:

2. The LD50 of a chemical is the dose that:

3. A substance that causes birth defects when a fetus is exposed during development is called a:

4. Environmental justice is most directly violated when:

5. In the waste hierarchy, which action is the HIGHEST priority?

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