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PRINCIPLES OF TOXICOLOGY

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Title: PRINCIPLES OF TOXICOLOGY


1
PRINCIPLES OF TOXICOLOGY
  • ...a discussion of the fundamental means by which
    toxicological properties are determined.

2
DEFINITIONS
  • Toxicology
  • Science that studies the harmful or toxic
    properties of substances

3
TOXICITY vs HAZARDan important distinction
  • Toxicity
  • The ability of a substance to have an adverse
    effect on the health or well-being of a human
  • The toxicity of a chemical depends on the degree
    of exposure and absorption
  • Hazard
  • The probability that the concentration will occur
    at that site in the body

4
Toxicity vs. Hazard
  • Two chemicals can possess the same degree of
    toxicity, but present different degrees of
    hazard.
  • Ex. Odorless and non-irritating vs. pungent odor
  • The chemical with warning properties may present
    a lesser degree of hazard.

5
TOXICOLOGY
  • Early interest was in how to poison
  • In 1800s, tests to identify poisons were
    developed (i.e., forensic medicine)
  • Only in 20th century has toxicology been applied
    to defining safe work conditions

6
TOXICOLOGY IS MULTIDISCIPLINARY
  • CHEMISTRY
  • BIOCHEMISTRY
  • PHYSIOLOGY
  • PATHOLOGY
  • IMMUNOLOGY
  • PHYSICS
  • ENGINEERING
  • STATISTICS

7
ROUTES OF EXPOSURE
  • Inhalation
  • Ingestion
  • Skin contact
  • Injection

8
EFFECTS OF EXPOSURE
  • ACUTE - a one-time event
  • rapid absorption of material
  • exposure sudden severe
  • critical period for death/survival
  • CHRONIC - small doses over long time
  • rate of intake gt rate of elimination
  • material remains in tissue injures

9
Comparison of Chemical ExposuresIndustrial vs
Non-Industrial
  • Route of Exposure inhalation ingestion
    skin absorption
  • Type of Contact acute chronic
  • Number of Agents
  • Other Aspects

10
TYPES OF TOXIC EFFECT
  • mortality
  • pathological change
  • growth rate change
  • physiological injury
  • biochemical change
  • behavioral effects
  • reproductive system damage
  • mutagenic, etc.

11
Toxic Effect by Target Organ
  • irritant
  • asphyxiant
  • anesthetic
  • hepatotoxic
  • nephrotoxic
  • neurotoxic
  • pulmonary

12
Factors Influencing Intensityof Toxic Action
  • route of entry
  • rate of exposure
  • age of host
  • prior exposure
  • environment
  • host factors gender, genetics
  • other factors

13
Dose-Response Relationship
  • Correlation between the amount of exposure and
    the resulting effect

14
Lethal Dose/Lethal Concentration
  • LD50 - Dose required to kill 50 of population
  • LC50 Concentration required to kill 50 of
    population

15
How is toxicological data obtained?
  • animal toxicological studies
  • accidental human overexposures
  • controlled exposures of human volunteers
  • epidemiological studies
  • descriptive retrospective
    (conventional) prospective (cutting edge)

16
Sources of Toxicological Information
  • Material Safety Data Sheet
  • Identity
  • Hazardous Ingredients/Identify Information
  • Physical/Chemical Characteristics
  • Fire and Explosion Hazard Data
  • Reactivity Data
  • Health Hazard Data
  • Precautions for Safe Handling and Use
  • Control Measures

17
Information Resources
  • http//msds.ehs.cornell.edu/msdssrch.asp
  • http//hazard.com/msds/index.php
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