FORENSIC SCIENCE Toxicology

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TOXICOLOGY

DEFINITIONS

: • Toxicology = study of the marriage of chemistry & physiology that deals with drugs, poisons, and other toxic substances, and how they alter living organisms.

• Toxin = naturally occurring poison.

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TOXICOLOGY

DEFINITIONS : • Toxicity = the degree of toxicity of any substance depends on how much enters the body and over how long a period of time. • Drug = any substance causing physiologic or behavioral changes for medicinal 3

TOXICOLOGY

DEFINITIONS : • Intoxicant = such as alcohol or carbon monoxide, typically requires that a

large amount required

to cause death • Poison = any substance that, when taken in sufficient quantities, causes a harmful or deadly reaction:

small amount

required.

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TOXICOLOGY

Classes of Controlled Substances

:  Stimulants -amphetamines & cocaine  Depressants -alcohol & barbiturates  Hallucinogens -marijuana & LSD & PCP  Narcotics -opiates……………………….

 Anabolic Steroids -testosterone like 5

TOXICOLOGY

Other Organic Toxins:

are usually proteins made by one organism that will interfere with the metabolism of another organism. Venoms & Defenses : - Reptiles - Amphibians - Insects - Fish - Plants - Corals - Mammals - Arachnids - Others ? Bacterial Toxins - Botulism - Tetanus - Anthrax : - Salmonella - E. coli 6

TOXICOLOGY

Heavy Metals:

are also naturally occurring and are very poisonous. They have been used for suicides, homicides and accidental deaths.  Arsenic  Lead  Mercury 7

TOXICOLOGY

Pesticides:

some are naturally occurring and others are man-made . Both types are very poisonous. They have been used for suicides, homicides and accidental deaths. - Cyanide - Strychnine - DDT - Dioxin 8

TOXICOLOGY

Forensic Toxicology Applications

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Postmortem : medical examiner or coroner Criminal : motor vehicle accidents (MVA), assault, etc.

Workplace drug testing Sports : human and animal 9

TOXICOLOGY

Why do Toxicology?

Toxicology can: • Be a cause of death • Contribute to death • • Cause impairment Explain behavior 10

TOXICOLOGY

Looking For Poisons - Most poisons don’t visibly change the body / tissues.

- M.E. won’t notice poisoning in most cases…need to collect fluids and tissues to send to toxicology lab.

- Biotransformation = conversion or transformation of one chemical into another by the body. This happens during metabolism. The new products are called metabolites. Ex. heroin  morphine *Toxicologists most often test for metabolites.

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TOXICOLOGY

Best places of the body to collect samples… - Where chemical entered - Where chemical concentrates - Along body’s route of chemical’s elimination 12

TOXICOLOGY

Best tissues to sample…    blood urine will show chemical and its metabolites blood levels correlate with effects on body will show chemical at higher concentrations than in the blood because body is trying to return to homeostasis.

stomach contents body not known : concentrations won’t correlate with blood levels so effect on 13

TOXICOLOGY

Best tissues to sample…  liver : many chemicals will concentrate in the liver even if none is found in the blood. it is the body’s detox factory. Ex  = eyeball fluid. Real slow a 2 hour delay for diffusion from blood.

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TOXICOLOGY

Best tissues to sample…   hair : chemicals take about 5 days to drugs show up in hair. Certain heavy known growth rate ( ½ mm per day) insects : are used in cases of severely decomposed bodies. Certain chemicals 15

TOXICOLOGY

Screening tests or presumptive tests…..

Street Drugs • Vital signs • • Injection sites Basic Chemistry Analysis • • • Color Tests Immunoassay Chromatography (s) 16

TOXICOLOGY

Basic Chemistry Analysis



Solubility

 

pH Chemical reactivity

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TOXICOLOGY

Color tests

Marquis - turns purple in the presence of opium derivatives and orange-brown with amphetamines Dillie-Koppanyi - turns violet-blue if barbiturates Duquenois-Levine - turns purple in the presence of marijuana Van Urk - turns a blue-purple in the presence of LSD Scott test - turns blue in the presence of cocaine 18

TOXICOLOGY

Immunoassay tests

Antigen-antibody reactions will show the “family” that an unknown drug belongs to.

Remember blood typing?

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TOXICOLOGY

Chromatography tests Paper , Thin layer belongs to.

Documents?

, Gas an unknown drug …. will show the “family” that Remember Questioned 20

TOXICOLOGY

Confirmatory tests Gas Chromatography-Mass Spectrometry The mixture is separated where ( GCMS ) first in a gas chromatograph. The GC column is directly attached to the mass spectrometer a beam of electrons is shot through the sample molecules.

The electrons cause the molecules to lose electrons and become positively charged. These are unstable and decompose into many smaller fragments an electric or magnetic field and are separated according to their masses.

. These fragments pass through NO TWO SUBSTANCES PRODUCE THE SAME FRAGMENTATION PATTERN.

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TOXICOLOGY

Example of GCMS unit 22

Toxicology of Alcohol

The BIOLOGY of Alcohol…

    

Alcohol is a depressant Extent of depression which acts on the CNS is proportional to the concentration of alcohol in nerve cells Blood carries alcohol to all cells of the body ** blood alcohol conc. = brain alcohol conc.

**Henry’s law Alcohol is absorbed thru stomach and small intestine

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  

Toxicology of Alcohol

• • • • • • • •

Many factors determine rate of absorption Consumption time Alcohol content of beverage Amount consumed Amount of food in stomach Type of food in stomach Mixers used with alcohol Time to peak effect varies 30 min to 3 hours Elimination is accomplished thru 2 mechanisms Oxidation into carbon dioxide & water in liver Excretion via the breath, urine & perspiration

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Toxicology of Alcohol

•Excreted alcohol (unchanged) in breath is directly

proportional to BAC

•BAC can be measured via blood or breath •“Breathalyzer” since 1954 is a spectrophotometer •Other breath testers work on….

-Infrared light absorption -Fuel cell types measure oxidation ion (most PBT’s)

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Toxicology of Alcohol

How much alcohol is “One Drink”??

  ½ ounce of pure ethyl alcohol 10 oz. to 12 oz. of 4% to 5% BEER     8 oz. to 12 oz. of 4% to 6% WINE COOLER 4 oz. to 5 oz. of 9% to 12% TABLE WINE 1.2 oz. of 40% (80 proof) ALCOHOL 1 oz. of 50 % (100 proof) ALCOHOL ( PER HOUR ) 26

TOXICOLOGY

Screening tests or presumptive tests…..

Alcohol-(ethanol=is the most abused drug) 

Breath alcohol test

  • •

Interview with officer Eye examination Horizontal gaze nystagmus Pupil dilatation

  • • •

Divided attention psycho-physical tests Walk and turn One legged stand Motor Skills Finger to nose

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TOXICOLOGY

DETERMINING CAUSE AND MANNER OF DEATH

Medical Examiner’s job, but needs toxicology report Natural ex. Heart attack. May be influenced by chemicals.

Amphetamines or other drugs like cocaine in the body need to be weighed as to were they the cause of death or contributing to the death.

Accidental -Most often happens at home and involves children putting things in their mouth.

-When adult it is usually due to mislabel, miscalculation, or dangerous mixtures like ammonia & bleach or alcohol & sedatives.

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TOXICOLOGY

DETERMINING CAUSE AND MANNER OF DEATH

Medical Examiner’s job, but needs toxicology report Suicidal This is the most common death by poison.

#1 is carbon monoxide #2 is prescription overdose Homicidal More common further back in history. Why?

We now know how to detect. It used to go unnoticed Technological advances in weapons…..GUNS 29