Understanding Environmental Toxicology and Toxins

Sep 16, 2024

Lecture Notes: Environmental Toxicology

Introduction

  • Discussion on toxins and chemicals in the environment from natural and human sources.
  • Focus on understanding types, sources, and effects of toxins and chemicals.

Environmental Toxicology

  • Study of environmental toxins including:
    • Sources and residency time
    • Impact and removal methods
  • Exposure pathways:
    • Inhalation
    • Ingestion
    • Skin contact (more acute)

Agency for Toxic Substances and Diseases

  • Tracks environmental toxins and publishes annual reports.
  • Top 10 toxins list based on danger, exposure, and abundance.

Key Toxins Discussed

Arsenic

  • Naturally occurring in geological sources.
  • Exposure mainly from groundwater.
  • Health effects: carcinogenic, cardiovascular disease, diabetes, birth defects.

Mercury

  • Natural and from human activities (coal, waste burning).
  • Bioaccumulates in fish (higher trophic levels higher risk).
  • Health effects: central nervous system damage, speech/vision impairments.

Bisphenol A (BPA)

  • Produced in plastic manufacturing.
  • Known as an endocrine disruptor affecting fertility, puberty, etc.
  • Widespread presence (found in 93% of tested individuals).

Phthalates

  • Used in making flexible plastics.
  • Similar exposure pathways as BPA.
  • Potentially linked to asthma, ADHD, cancer, obesity.

Lead

  • Sources: fossil fuels, industrial practices, old house paints.
  • Primarily affects children through inhalation of dust.
  • Health effects: central nervous system damage.

Formaldehyde

  • Found in wood products, cosmetics, carpets.
  • Health effects: skin irritation, carcinogenic.

Polycyclic Aromatic Hydrocarbons (PAHs)

  • From burning fossil fuels, trash, plastics.
  • Health impacts: cancer, organ damage.

Generalized Terms and Health Effects

Acute vs Chronic Effects

  • Acute: single, large dose exposure.
  • Chronic: long-term, low-dose exposure.

Lethal Dose Concepts

  • Lethal Dose (LD): amount required to kill.
  • LD50: dose to kill 50% of the test subjects.

Types of Contaminants

  • Carcinogens: Cause cancer.
  • Teratogens: Affect embryos.
  • Mutagens: Cause DNA mutations.
  • Neurotoxicants: Affect the nervous system.
  • Endocrine Disruptors: Mimic/messengers in the body causing wide-ranging effects.

Conclusion

  • Next discussions will focus on removal of toxins and disease ecology.