Toxicology

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Toxicology

• Forensics
• Foster

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Toxin

• Substance that can cause injury to the health of
  a living thing on contact or absorption
• Usually reserved for naturally produced
  substances that kill in small quantities

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Factors affecting Toxicity

1. Dosage- amount and frequency
2. The chemical or physical form of the substance
3. The mode of entry into the body
4. Body weight and physiological conditions of the
   victim, including age and sex
5. The time period of exposure
6. The presence of other chemicals in the body or in
   the dose

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Example

• Arsenic is a metal
• Rather insoluble in stomach acid
• As2O3 and extremely toxic As2O5
• Arsine AsH3 is a gas that can kill
• Small amounts of arsenic are good for you and you
  are exposed to all the time

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Factors (cont.)

• Lethal Dose
• LD50 refers to the dose of a substance that kills
  50 of the test population, usually within 4
  hours
• Expressed in mg of substance per kg of body
  weight
• Chemical or physical form of the substance
• Solid, liquid
• How it enters the body
• Blood, absorption
• Body weight and physiological conditions of the
  victim, including age and sex
• Larger doses are required for a big person

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Factors (cont.)

• Time period of exposure
• Chronic exposure- exposure over a long period of
  time
• Acute toxicity- effects almost immediately (hrs.
  or days)

Violin markings
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Factors (cont.)

• Presence of other chemicals in the body
• Synergism- combined effect of substances exceeds
  sum of individual effect
• Antagonism- combined effect decreases individual
  effects
• Chelating agent- stabilize or prevent the
  precipitation of damaging compounds

Red Hourglass
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Measuring ToxicityHumans based on animal
LD50 (Rat, oral) Correlation to Ingestion by 150-lb Adult Human Toxicity
lt1 mg/kg a taste to a drop extreme
150 mg/kg to a teaspoon high
50500 mg/kg to an ounce moderate
5005,000 mg/kg to a pint slight
515 g/kg to a quart practically nontoxic
Over 15 g/kg more than 1 quart relatively harmless
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To Prove a Case
Prove a crime was committed Motive Intent Access
to poison Access to victim Death was
homicidal Death was caused by poison
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Alcohol

• Most abused drug in US
• 40 of accidents related to alcohol
• Tests
• Field
• One leg stand
• 9 step walk turn
• Nystagmus
• jerky eye
• Breath Analysis
• Blood Analysis