Toxicology is the study of the adverse effects of toxic substances on living organisms. It examines the toxic mechanisms of action, effects, occurrence, and risk assessment of toxicants. There are three main categories of toxicology: descriptive toxicology conducts toxicity testing, mechanistic toxicology identifies toxic mechanisms of action, and regulatory toxicology decides if chemicals pose low risks. There are also four specialized areas: forensic toxicology aids in determining causes of death, clinical toxicology addresses substance-induced diseases, environmental toxicology focuses on pollutant impacts on human and environmental health, and ecotoxicology examines impacts on ecosystem population dynamics.

1. TOXICOLOGY

2. Toxicology: Study the adverse effects of toxicants in
living organisms, and examine the toxic effects
1.cellular
2.biochemical
3.molecular mechanism of action
4.occurrence
5. risk assessment

3. • Areas of Toxicology: Three main categories:
1.Descriptive toxicology Direct conduct testing, and provide
information for safety evaluation and regulation
⇒e.g., acute oral toxicity test, LD50levels
2.Mechanistic toxicology :Identifying and understanding the
mechanisms of toxicants exert toxic effect on living organisms
⇒e.g., organophosphate pesticides inhibit AChE
3.Regulatory toxicology: The responsibility for deciding whether
a drug or chemical poses a low risk to be marked
1)Environmental Protection Agency (EPA)
⇒Chemicals and other toxicants
2)Department of Health (DOH)
⇒Food and Drugs
Occupational Safety and health Administration (OSHA)

4. • Four specialized areas of toxicology
1.Forensic toxicology : Forensic toxicology is a hybrid of
analytic chemistry and fundamental toxicology
♣ Concerned with the medico-legal aspects of the
harmful effects of
Chemicals on human and animals
♣To aid in establishing the cause of death in a
postmortem investigation
2.Clinical toxicology: Clinical toxicology is concerned with
disease caused by or uniquely associated with toxic
substances
♦Physicians
♦Special training in emergency medicine and poison
management

5. • 3.Environmental toxicology :Environmental
toxicology focuses on the impacts of chemical
pollutants in the environment on biological
organisms
♠ the effects on human health
• non human organisms, fish, birds and terrestrial
animals
• 4. Ecotoxicology : Ecotoxicology is a specialized
area within environmental toxicology .The impacts
of toxic substances on population dynamics in an
ecosystem .The transport, fate, and interactions of
chemicals in the environmental and ecotoxicology ./