Toxicology: Drugs and Poisons Forensic Science

Toxicology Toxicology - Mix of Chemistry and Physiology that deals with drugs, poisons, and other toxic substances. –Began in 1775 when Swedish chemist Karl Scheele discovered a way to prove arsenic was the culprit in a suspicious death.

Toxins ANY substance that when taken in sufficient quantities causes a harmful or deadly reaction. (Sufficient quantities – how much enters the body, over what period of time) 1. Intoxicant requires an ingestion of large quantities before it is lethal -Ex: Carbon Monoxide, Alcohol, heavy metals (mercury, lead, selenium) 2. True Poison – requires only a tiny amount - Ex: Cyanide

The Forensic Toxicologist Finds toxins and determines the likely effect on the individual who ingested or came in contact with it. Examples: –Inebriation in an automobile accident or industrial accident –Whether a person died from poison or from natural cause? –Whether drugs played a role in a perpetrator’s actions or in seizures or coma?

Effects of Toxins Effects of toxins do not cause VISIBLE changes in the body in living people or during an autopsy. Medical Examiner will collect fluids and tissues for testing –Toxins are sneaky! Biotransformation can change one chemical into another within the body due to metabolism. –The toxicologist may have to look for a different sign of the toxin. –Ex: Heroin will change into morphine in the bloodstream so looking for heroin is fruitless

Best Places for Sample Testing 1.Blood – most useful… tells what is going on at the time of death. 2.Urine – Easily obtained… Urine can’t determine whether a drug was exerting any effect at time it was collected. 3.Stomach Contents – survivors are sampled by way of a gastric tube. Still no correlation between effects at time it was collected but will determine if in the body 4.Liver – important in metabolism (destruction) of undesirables in the body. Many drugs concentrate in the liver, so no signs may be in the blood but the liver will reveal if a toxin is present. -Amounts in liver determine hours before death -Amount in bile determines past 3-4 days of exposure

Sampling Continued… 5. Vitreous Humor – EYE BALL WATER… resists decay…may be the only fluid left in a decaying body… levels in this fluid lag behind the blood levels by 1 to 2 hours. 6. Hair – absorbs heavy metals and provides timeline of ingestion… can determine if a poisoning was quick (acute) or drawn out (chronic) -Arsenic will kill whether given all at once or slowly administered 7. Insects – that feed on the corpse will have elevated levels of certain drugs and may provide information if the drug was present at death.

Common Drugs Categorized by physiological and psychological effects. Can effect structure and/or function of tissues via chemical reactions Legal or illegal Addictive (Narcotics) or non-addictive Drugs covered by law are “controlled substances” and taken in excess may cause death or illness. 75% of evidence analyzed is drug-related Pharmaceutical companies send samples of new drugs to the FBI to be categorized for future comparisons

Depressants Make you sleepy and lethargic Considered “downers” –Ex: Alcohol most commonly abused drug Suppresses respiration - potentially lethal + addictive Blood levels correlate to degree of intoxication –Ex: Opiates Derived from poppies Sleep producing and produces euphoria and lethargy –Barbiturates - sleeping pills

Stimulants “Uppers” Increases alertness Lessens fatigue – suppresses appetite Irritability, anxiousness, aggressive behavior, paranoia, fatigue, depression The body will get used to the drug and require more for an affect, so the person is taking ever increasing doses HIGHLY ADDICTIVE! Ex: Amphetamines, Cocaine

Other Drugs Hallucinogens –Alter perception and mood –Leads to delusional thinking and hallucinations. –Ex: Marijuana, cacti, mushrooms, LSD, PCP, Ecstasy, Rohyphonol (Date rate drug) Narcotics –Pain reducers –Ex: morphine, methadone, codeine, heroin Anabolic Steroids –Increase testosterone –Aggressive behavior and diminished sex drive –Liver cancer