Presentation on theme: "Toxicology: Drugs and Poisons Forensic Science. Toxicology Toxicology - Mix of Chemistry and Physiology that deals with drugs, poisons, and other toxic."— Presentation transcript:
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.
Poisons 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 (chromic) -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 Testing Procedures 1.Color Tests – a reagent is added to the substance to be tested and a color change will represent the presence of the suspected chemical. -CHEAP, EASY, and QUICK 2. Immunoassays – Antigen-antibody reaction… substance being sought is the antigen-testing reagent is the antibody. -An antibody will react only with antigens and ignores all other chemicals
Testing Procedures Continued… 3. Gas Chromatography – Separates compounds according to size, shapes, and chemical properties… will determine class of compounds but not exact makeup -can be used to separate a large mixed sample for further analysis 4. Ultra-Violet Spectroscopy – different compounds absorb and reflect light differently… indicates the concentration of a drug in a sample 5. Mass Spectrometry (MS) – high energy bombards the sample and breaks it into tiny fragments. They are passed through a magnetic field and separated by molecular weight…Produces the same pattern… can be used to ID.
Points of Administration Toxins will be most concentrated at the point of entry: a. Ingested Toxins – show up more in the stomach, intestines, and liver b. Inhaled Toxins – show up in the lungs c. Injected Toxins – linger in tissues around point of injection… muscle slows down the transfer to the bloodstream. d. Intravenously (IV) – will bypass the stomach and liver going directly into the bloodstream therefore quickly distributed… very little remains in the IV site. May find high concentrations in tissues but none in stomach or intestines.
Testing Continued… Once testing is done, the toxicologist evaluates what toxins are present, identifying routes of administration, and determining whether the concentration is sufficient to play a role in the subject’s death or behavior. Route of entry is EXTREMELY important in cases of injection where the person had no means to inject or no physical capabilities… homicide is a stronger consideration.
Be Aware… Finding a large quantity of toxin in the stomach does not meant it is the cause of death! The toxin may not have entered the bloodstream yet. Blood concentration is the MOST important!
Concentration Categories by the Toxicologist 1.Normal – expected in the general population under normal circumstances 2.Therapeutic – The level your doctor wants in your bloodstream for medical reasons 3.Toxic – a level that may cause harm- nausea, vomiting, change in heart rhythm 4.Lethal – Level at which the toxin consistently cause death –LD50 – means the toxin at that level will cause 50% of people to die. Wiggle room between categories – everyone reacts differently based on age, sex, body size, genetics, and health.
Responsibilities of the Toxicologist 1.Know the chemical make-up, physiological actions, and by- products of the drug 2.Understand how the drug is metabolized by the body and the potential of the metabolites 3.Know how the chemicals will effect healthy people and people with various illnesses and addictions. 4.Recognize the symptoms and signs produced by the chemicals.
Familiar Poisons Cyanide – very lethal –Can enter by inhalation, ingestion, or direct skin contact –Used for executions –Damages internal workings of the cell –ME will notice a BRIGHT cherry red color to the victim’s blood. Strychnine – plant based rat poison –Extremely bitter taste: hard to disguise –Causes a LOT of pain: Not typical in suicides –Causes convulsions –Death is caused by asphyxia –Rigor mortis is quick because of the depletion of ATP during convulsions Mushrooms – easily confused with the edible type –Implicated in accidental suicides and homicides –Causes severe damage to liver and extremely low blood sugar level
Poisons Continued… Ethylene Glycol – antifreeze –Alcoholics sometimes will consume it to satisfy the urge to drink –Causes deadly breakdown of oxalic acid reacting with calcium in the blood and crystallizes in the brain and kidneys –ME will find crystals in tubules of kidney Oxalic Acid – raw rhubarb –Powerful irritant to gastrointestinal track –May cause bleeding –ME will find irritation of mouth, esophagus, stomach, and low levels of calcium in the blood Heavy Metals – Arsenic, Mercury, Lead, Antimony, Bismusth, Thallium –All behave slightly different but cause gastrointestinal injury –Leads to nausea, vomiting, diarrhea (bloody) –Damages kidneys, liver, brain, and nerves
More Poisons… Insulin – drops blood sugar level –Robs brain of nutrients: death is quick –If the ME finds high levels of insulin he will look for a tumor in the pancreas to rule out natural death –If there is NO tumor… suspects homicide Succinyl Choline – injectable drug –paralyzes all the muscles of the body –Lethal injections –Leaves behind little evidence of presence –ME looks for metabolites Corrosive Chemicals – Strong alkalis bases (lye) and acids –When ingested…corrode and burn tissues of digestive track –Causes bleeding, shock, and death –Rarely used in homicides…mostly accidental children ingestion.
Case Study – Carl Coppolino Physician Anesthesiologist August 1965 Carl called his friend Dr. Karow to report that his wife had died. She signed the death certificate and no autopsy was preformed. Carl had been having an affair with a neighbor. When the affair ended, she went to Dr. Karow with her story. She had been given a syringe and Coppolino had instructed her on how to kill her husband, so they could continue the affair. She did not go through with it, but Coppolino came and strangled her husband and signed the death certificate. Investigations and autopsies were preformed – Coppolino was acquitted in the death of the husband. However, the ME knew that Coppolino had access to succinyl choline and that this drug would not be present in the corpse but the metabolite succinic acid would be. Large quantities were found and Coppolino was convicted of 2 nd degree murder of his wife.
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 Increases alertness Lessens fatigue – suppresses appetite Irritability, anxiousness, aggressive behavior, paranoia, fatigue, depression The body will get use to the drug and require more for an effect, 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