Environmental Chemistry Part IV: Toxic Organic Compounds

General Overview

• Discuss the prevalence of synthetic organic compounds as environmental pollutants.
• Highlight major classes: pesticides, dioxins, furans, PCBs, and other toxic organics.
• Emphasize their origins, uses, environmental persistence, and health impacts.

Chapter 13: Pesticides

• Introduction to Pesticides
  • Define synthetic chemicals and their reliance on petroleum as a carbon source.
  • Categories of pesticides:
    • Insecticides, herbicides, fungicides, and others (e.g., bactericides, nematicides).
    • Table of pesticides and their targets (e.g., acaricides for mites, piscicides for fish).
• Environmental and Health Concerns
  • Bioaccumulation and biomagnification of organochlorines (e.g., DDT).
  • Case studies:
    • Historical use of DDT and its ecological impact (e.g., bird population declines).
  • Explore alternatives like methoxychlor and organophosphates.
• Mechanisms and Toxicology
  • Acute vs. chronic toxicity: Effects on organisms at different exposure levels.
  • Dose-response relationships:
    • LD50 (lethal dose for 50% of test subjects) and its implications.
  • Bioconcentration and biomagnification:
    • Partition coefficients (Kow) as predictors of environmental and biological behavior.
• Risk Assessment and Regulation
  • Discuss the process of evaluating toxicity and setting maximum allowable doses.
  • Examples:
    • WHO and U.S. EPA pesticide categorization.

Chapter 14: Dioxins, Furans, and PCBs

• Understanding Persistent Organic Pollutants (POPs)
  • Chemical structures and characteristics.
  • Sources and industrial applications of PCBs and related compounds.
  • Long-range transport and global persistence.
• Environmental and Health Impacts
  • Accumulation in fatty tissues.
  • Links to cancer, endocrine disruption, and immune system damage.
• Strategies for Mitigation
  • International agreements like the Stockholm Convention.
  • Bioremediation and other cleanup methods.

Chapter 15: Other Toxic Organic Compounds

• Emerging Contaminants
  • Flame retardants, hormone mimics, and combustion by-products.
  • Transport mechanisms for long-distance pollution.
• Case Studies
  • Highlight specific incidents of contamination (e.g., oil spills, industrial leaks).
• Future Directions
  • Green chemistry approaches to reduce environmental impact.
  • Innovations in detection and remediation technologies.

Teaching Suggestions

• Use visual aids: molecular structures, distribution maps, and dose-response curves.
• Incorporate case studies for real-world applications.
• Assign problem-solving exercises to explore toxicity calculations and risk assessments.
• Encourage class debates on regulation vs. economic impact of chemical use.