TOXICOLOGY - PowerPoint PPT Presentation

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TOXICOLOGY

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TOXICOLOGY The study of chemical or physical agents and their interaction with biologic systems to produce a response in a organism. The dose makes the poison! – PowerPoint PPT presentation

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Title: TOXICOLOGY


1
TOXICOLOGY
  • The study of chemical or physical agents and
    their interaction with biologic systems to
    produce a response in a organism.
  • The dose makes the poison!

2
TOXICOLOGY
  • DOSE AMOUNT
  • Units
  • mg/Kg (per unit weight)
  • mg/cm2 (per area of skin surface)
  • ppm (per unit volume of air inhaled (gas/vapor))
  • mg/m3 (for solids inhaled in air)

3
TOXICOLOGY
  • Types of Exposure
  • Acute
  • amount of substance which is capable of causing
    an immediate reaction (less than 24 hours)
  • Chronic
  • small amount which does not cause an immediate
    reaction but is accumulated in the body to cause
    a delayed reaction over a longer period of time.

4
TOXICOLOGY
  • Routes of Exposure
  • oral
  • dermal
  • inhalation
  • injection

5
TOXICOLOGY
  • Toxicity Tests
  • goal is to select a test species that is a good
    model of humans, a response that is not
    subjective and can be consistently determined,
    and a test period that is relatively short.

6
TOXICOLOGY
  • Dose-Response Curve

test organisms responding
Dose
7
TOXICOLOGY
  • DOSE - RESPONSE TERMS
  • Toxic dose low (TLlo) lowest dose introduced by
    any route (except inhalation) reported to produce
    any toxic effect in humans or to produce
    tumorigenic or reproductive effects in animals.

8
TOXICOLOGY
  • DOSE - RESPONSE TERMS
  • - Toxic Concentration Low (TClo) - Lowest
    concentration of substance in air to which humans
    or animals have been exposed and has produced any
    toxic effect

9
TOXICOLOGY
  • DOSE - RESPONSE TERMS
  • Lethal Dose low (LDl0) Lowest dose of a substance
    introduced by any route (except inhalation) which
    has been reported to have caused death in humans
    or animals.

10
TOXICOLOGY
  • DOSE - RESPONSE TERMS
  • Lethal Dose 50 (LD50) - Calculated dose of a
    substance which is expected to cause death of 50
    of the entire defined experimental population.

11
TOXICOLOGY
  • DOSE - RESPONSE TERMS
  • Lethal Concentration 50 (LC50) Calculated
    concentration of a substance in air to which is
    expected to cause the death of 50 of an entire
    defined experimental population.
  • (Table 1.)

12
TOXICOLOGY
  • USING DOSE - RESPONSE INFORMATION
  • Can compare LD50 of chemicals gives a relative
    rating of toxicity (Table 2.)
  • Use LD50 (mg/Kg) and multiply by 70 gives a rough
    estimate of toxic potential for humans.

13
TOXICOLOGY
  • DOSE - RESPONSE
  • AND SAFETY FACTORS

LD50
TLV
ED50
Percent Response
Dose
14
TOXICOLOGY
  • FACTORS INFLUENCING TOXICITY
  • ROUTE OF EXPOSURE
  • Route determines how much is absorbed and
    which organs are exposed to the highest
    concentrations.

15
TOXICOLOGY
  • FACTORS INFLUENCING TOXICITY
  • GENDER
  • Some substances are more toxic to one gender
    than another.

16
TOXICOLOGY
  • FACTORS INFLUENCING TOXICITY
  • AGE
  • Older people have different blood, hepatic
    systems, musculature, metabolism, and excretory
    patterns than younger people. This can influence
    disposition and toxic effects of chemicals.

17
TOXICOLOGY
  • FACTORS INFLUENCING TOXICITY
  • SYNERGISM - 1 1 3
  • ANTAGONISM - 1 1 1/2
  • POTENTIATION - Type of Synergism

18
TOXICOLOGY
  • FACTORS INFLUENCING TOXICITY
  • GENETICS
  • Not all people are created equal genetically!

19
TOXICOLOGY
  • FACTORS INFLUENCING TOXICITY
  • SPECIES VARIATION
  • Physiological differences between species can
    lead one to over or under estimate toxic effects
    of a chemical when comparing results from one to
    another species.

20
TOXICOLOGY
  • EXPOSURE GUIDELINES
  • ACGIH - American Conference of
  • Governmental Industrial
    Hygienists
  • Develop and Publish - Threshold Limit

  • Values (TLVs)

21
TOXICOLOGY
  • TLV - based on the concept that there is a
    threshold dose or concentration below
    which there is no adverse effects.
  • - Developed for use in the workplace

22
TOXICOLOGY
  • TLVs
  • Refer to airborne concentrations
  • Represent conditions under which nearly all
    workers may be repeatedly exposed day after day
    without adverse effects.
  • Limited healthy working age individuals

23
Toxicology
  • TLV TYPES
  • TLV-TWA Time Weighted Average
  • time weighted average concentration for a
  • normal eight-hour work day
  • TLV-STEL Short Term Exposure Limit
  • 15 minute time weighted average exposure
    repeated exposure no more than four times
    per 8 hour work shift

24
TOXICOLOGY
  • TLV TYPES
  • TLV-C Ceiling
  • Concentration that should not be exceeded,
    even instantaneously.

25
TOXICOLOGY
  • EXPOSURE GUIDELINES
  • OSHA - PELs Permissible Exposure Limits
  • PELs are legally enforceable and apply to all
    private industries and the Federal government.
  • 29 CFR 1910.1000 lists PELs for specific
    compounds

26
TOXICOLOGY
  • EXPOSURE TYPES
  • IDLH - Immediately Dangerous to Life and Health
  • represent maximum concentrations from which one
    could escape within 30 minutes without any
    irreversible health effects

27
TOXICOLOGY
  • BODY RESPONSE
  • TO TOXIC CHEMICALS
  • Respiratory Tract
  • upper - nasopharyngeal
  • middle - tracheobronchial
  • lower - pulmonary acinus

28
TOXICOLOGY
  • BODY RESPONSE
  • TO TOXIC CHEMICALS
  • Types of inhaled toxicants
  • Asphyxiants gases that deprive the body of
    oxygen
  • Simple asphyxiants (nitrogen, helium, methane)
  • Chemical asphyxiants (cyanide, Carbon Monoxide)

29
TOXICOLOGY
  • BODY RESPONSE
  • TO TOXIC CHEMICALS
  • Irritants
  • chemicals that irritate the air passages, causing
    constriction of airways and edema (liquid in the
    lungs) and infection.
  • (ammonia, chlorine, HF, HCl)

30
TOXICOLOGY
  • BODY RESPONSE
  • TO TOXIC CHEMICALS
  • Necrosis Producers
  • chemicals that result in cell death and edema.
  • (ozone, nitrogen dioxide)

31
TOXICOLOGY
  • BODY RESPONSE
  • TO TOXIC CHEMICALS
  • Fibrosis producers
  • chemicals that produce fibrotic tissue which if
    massive, block airways and decrease lung
    capacity.
  • (asbestos, silicates, beryllium)

32
TOXICOLOGY
  • BODY RESPONSE
  • TO TOXIC CHEMICALS
  • Allergens
  • chemicals that induce allergic response
    characterized by bronhoconstriction and pulmonary
    disease.
  • (isocyanates, sulfur dioxide)

33
TOXICOLGY
  • BODY RESPONSE
  • TO TOXIC CHEMICALS
  • Carcinogens
  • chemicals associated with lung cancer
  • (cigarette smoke, coke emissions,
  • asbestos, arsenic)

34
TOXICOLOGY
  • BODY RESPONSE
  • TO TOXIC CHEMICALS
  • SKIN
  • natural barrier prevents absorption
  • Sebaceous glands secrete fatty acids
  • Melanocytesprotects from UV
  • Sweat galnds regulate heat

35
TOXICOLOGY
  • BODY RESPONSE
  • TO TOXIC CHEMICALS
  • EYES
  • CENTRAL NERVOUS SYSTEM
  • LIVER
  • KIDNEYS
  • BLOOD

36
TOXICOLOGY
  • TERATOGENS
  • MUTAGENS
  • CARCINOGENS
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