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Toxicology

Toxicology. Hormesis. Substances that kill at high doses are actually beneficial at low doses Arsenic – growth deficiency without it, syphilus, cancer Clostridium botulinum - Botox. History of Poisons. Earliest use of poison was for Socrates’ execution in 339 BC

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Toxicology

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  1. Toxicology

  2. Hormesis • Substances that kill at high doses are actually beneficial at low doses • Arsenic – growth deficiency without it, syphilus, cancer • Clostridium botulinum - Botox

  3. History of Poisons • Earliest use of poison was for Socrates’ execution in 339 BC • Arsenic was most common because it left no trace and resembled death by natural causes. • “Traite des poisons” by Mathieu Orfila in 1814 gave first systematic approach to identifying poisons in the body. • James Marsh developed test to detect arsenic in body tissues and fluids.

  4. Things That Affect Toxicity • Dosage • Chemical or physical form of substance • How it enters the body • Body weight and physiological conditions of the victim, age, and sex • Time period of exposure • Whether other chemicals are present (synergism and antagonism)

  5. Measuring Toxicity • Use animals to get estimates • LD50 is the lethal dose for half of the population within 4 hours (mg substance/kg body weight) • Regulatory agencies • FDA, EPA, Consumer Product Safety Commission, DOT, OSHA

  6. Lead Poisoning • Subtle brain damage, memory loss, faulty thought processes • Most common exposure is through lead-based paints (banned in 1978) • 2 tests for lead • Reaction of dissolved lead with sulfide ion to form insoluble, brown-black lead sulfide • Reaction with an organic complexing agent, sodium rhodizonate, to make a pink color • Other sources: lead pipes, soil, leaded gas (banned in 1995)

  7. Murder By Poison • Less than one half of 1% of all homicides are a result of poison • Common poisons today are arsenic, cyanide, and strychnine • Acute poisoning – high dose over short period of time • Chronic poisoning – low dose over long amount of time

  8. Accidental Drug Overdoses • More common than poisonings • John Belushi, Chris Farley, River Phoenix, Janis Joplin, Jim Morrison, Jimi Hendrix, Marilyn Monroe, Heath Ledger, Anna Nicole Smith

  9. Other Toxins • Organic - Venom • Snakes, bees • Alcohols • Bacterial Toxins • Botulism (neurotoxin), Clostridium tetani • Heavy Metals and Pesticides • Bioterrorism Agents • Ricin (waste product of castor oil) • Anthrax (Bacillus anthracis)

  10. Alcohol • Most abused drug in America • 40% of all traffic deaths are alcohol related • Ethanol affects the CNS • BAC ist he amount of alcohol in the blood • Present BAC limit is 0.08% so .08 grams of alcohol for every 100 mL of blood • Average removal rate is 0.015% per hour

  11. BAC Calculations • BAC (male) = 0.071 x (volume consumed, oz) x (% alc.)/body weight • BAC (female) = 0.085 x (volume consumed, oz) x (% alc.)/body weight

  12. Breathalyzer Test • 1 mL of blood contains as much alcohol as 2,100 mL of breath (based on Henry’s Law)

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