Toxicology. Drugs and Poisons

Transcription

1 Toxicology Drugs and Poisons

2 What is Poison? Anything can be a poison A poison is any substance that, when taken in sufficient quantities, causes a harmful or deadly reaction

3 In other words A poison is basically a substance that either harms you or kills you The key: Sufficient Quantities Example: arsenic, water intoxication, oxygen doping

4 LD 50 LD 50 for 150 pound person Botulism ng/kg, a few hundred billionths of one gram Water 90 ml/kg six liters Caffeine Alcohol Radiation Heroin 620 mrem per year average 118 cups of coffee 13 shots 500,000 mrem 30 milligrams 4

5 Toxicology: Poisons and Alcohol Aspects of Toxicity Dosage The chemical or physical form of the substance The mode of entry into the body Body weight and physiological conditions of the victim, including age and sex The time period of exposure The presence of other chemicals in the body or in the dose Chapter 8 Kendall/Hunt Publishing Company 5 5

6 Toxicology: Poisons and Alcohol Lethal Dose LD 50 refers to the dose of a substance that kills half the test population, usually within four hours Expressed in milligrams of substance per kilogram of body weight Chapter 8 Kendall/Hunt Publishing Company 6 6

7 Toxicology: Poisons and Alcohol Toxicity Classification LD 50 (rat,oral) Fatal Dose (taken all at once) Toxicity <1 mg/kg a taste to a drop extreme 1 50 mg/kg to a teaspoon high mg/kg to an ounce moderate 500 5,000 mg/kg to a pint slight 5 15 g/kg to a quart practically nontoxic Over 15 g/kg more than 1 quart relatively harmless Chapter 8 Kendall/Hunt Publishing Company 7 7

8 Intoxicant vs. Poison Intoxicant: requires that you ingest a rather large amount to be lethal Poison: only requires you ingest a small amount

9 Toxicology Toxicology deals with drugs, poisons, and other toxic substances, and how these substances alter or harm living organisms (particularly humans)

10 Forensic Toxicology A forensic toxicologist: analyzes biological samples for the presence of drugs, chemicals, or other toxins

11 Toxicologist Examples Assess the state of inebriation of an automobile or industrial accident victim Determine whether someone died from a poison or from natural causes Assess whether drugs played a role in a criminal s actions

12 Looking for toxins Type of Poison Caustic poison (lye) Carbon monoxide Sulfuric acid Hydrochloric acid Nitric acid Phosphorus Cyanide Arsenic, mercury Methyl (wood) or isopropyl (rubbing) alcohol Symptom/Evidence Characteristic burns around the lips and mouth of victim Red or pink patches on the chest and thigh, unusually bright red lividity Black vomit Greenish-brown vomit Yellow vomit Coffee-brown vomit, onion or garlic odor Burnt almond odor Extreme diarrhea Nausea and vomiting, unconsciousness, possibly blindness

13 Looking for toxins However, most toxins don t change the exterior of the body Therefore, the toxicologist must look for other evidence in body fluids

14 Looking for Toxins Biotransformation When one chemical changes into another in the body Also called metabolism Metabolites The new chemicals that happen when the body tries to break down/get rid of a toxin

15 Metabolite Example: Opium is found in poppies Morphine is extracted from opium Heroin is made from morphine When someone ingests heroin, their body turns it into morphine What should a toxicologist look for?

16 Where are the best places to collect samples? 1. Where the chemical enters 2. Where the chemical concentrates 3. Along the route of elimination

17 What are the clues? Ingested toxins show up in the stomach, intestines, or liver Inhaled gases are concentrated in the lungs Toxins that are injected intramuscularly concentrate themselves around the injection site Drugs that are given intravenously are directly absorbed into the blood bypassing the stomach and liver. Concentrations are found throughout the body, are low in the stomach and liver and high in the blood stream.

18 Best Tissues to Sample for Poisons Blood most useful tool will show chemical and its metabolites blood levels show what was going on in the body at the time of death Urine easy to obtain high concentrations kidneys are along the elimination route. Doesn t show how much or when the toxin/drug was ingested Stomach contents Are removed, washed, and tested. Digestion stops at the moment of death, so can give time of death. Doesn t relate to how much was in the blood

19 Best Tissues to Sample for Poisons Liver the toxin sponge of your body can reflect levels of toxins that even the blood may not reveal. Level of toxins moments before death Vitreous Humor eyeball fluid very slow to decay so will retain toxins even longer than most other organs Hair chemicals take about 5 days to show up in the core of a hair shaft natures timeline Insects toxins can accumulate (bioaccumulation) in the bodies of insects that feed off of decomposed bodies.

20 Check for Understanding: What is the difference between metabolism and metabolite?

21 A note on metals: Metallic elements also cause disease and death Iron, mercury, lead, and copper all lead to serious health problems Mercury, lead, arsenic, antimony, selenium, and other metals can kill

22 Levels of drugs in the body: Normal Level expected in the normal population Therapeutic Level a doctor wants a patient to reach on prescription medicine

23 Levels of drugs in the body: Toxic A level that may cause harm (nausea, vomiting, etc.) Lethal Level that consistently causes death

24 In a paragraph, describe the job of a forensic toxicologist. Then explain why you would or wouldn t want to do that job. Use specific information from today s lecture and at least 3 new vocabulary words from the worksheet. Finish forensics.rice.edu CSI Adventure - Toxicology