1

FORENSIC SCIENCEToxicology

2

TOXICOLOGYDEFINITIONS:

•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.

3

TOXICOLOGYDEFINITIONS:

• 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 purposes.

4

TOXICOLOGYDEFINITIONS:

• 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.

5

TOXICOLOGYClasses of Controlled Substances: Stimulants-amphetamines & cocaine Depressants-alcohol & barbiturates Hallucinogens-marijuana & LSD & PCP Narcotics-opiates………………………. Anabolic Steroids-testosterone like

6

TOXICOLOGYOther Organic Toxins: are usually proteins

made by one organism that will interfere with the metabolism of another organism.

Venoms & Defenses : Bacterial Toxins : - Reptiles - Amphibians - Botulism - Insects - Mammals - Tetanus - Fish - Arachnids - Anthrax - Plants- Others ? - Salmonella - Corals - E. coli

7

TOXICOLOGYHeavy Metals: are also naturally occurring

and are very poisonous. They have been used for suicides, homicides and accidental deaths.

Arsenic Lead Mercury

8

TOXICOLOGYPesticides: 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 - DDT - Strychnine - Dioxin

9

TOXICOLOGYForensic Toxicology Applications

1. Postmortem : medical examiner or coroner2. Criminal : motor vehicle accidents (MVA),

assault, etc.3. Workplace drug testing4. Sports : human and animal

10

TOXICOLOGYWhy do Toxicology? Toxicology can:

• Be a cause of death• Contribute to death• Cause impairment• Explain behavior

11

TOXICOLOGYLooking 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.

12

TOXICOLOGYBest places of the body to collect

samples…

- Where chemical entered- Where chemical concentrates

- Along body’s route of chemical’s elimination

13

TOXICOLOGYBest tissues to sample… blood will show chemical and its

metabolites blood levels correlate with effects on body

urine will show chemical at higher concentrations than in the blood because body is trying to return to homeostasis.

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

14

TOXICOLOGYBest 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 opiates.

vitreous humor = eyeball fluid. Real slow to decay. Water soluble chemicals will be detectable here for a long time. There is a 2 hour delay for diffusion from blood.

15

TOXICOLOGYBest tissues to sample… hair : chemicals take about 5 days to

show up in core of hair shaft. All illicit drugs show up in hair. Certain heavy metals (arsenic and lead) concentrate here. Timelines can be established due to known growth rate ( ½ mm per day)

insects : are used in cases of severely decomposed bodies. Certain chemicals are concentrated in insect bodies due to bioaccumulation.

16

TOXICOLOGYScreening tests or presumptive tests…..Street Drugs

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

17

TOXICOLOGYBasic Chemistry Analysis Solubility pH Chemical reactivity

18

TOXICOLOGYColor testsMarquis--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

19

TOXICOLOGYImmunoassay tests

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

Remember blood typing?

20

TOXICOLOGYChromatography tests

Paper, Thin layer, Gas…. will show the “family” that an unknown drug belongs to.

Remember Questioned Documents?

21

TOXICOLOGYConfirmatory tests

Gas Chromatography-Mass Spectrometry (GCMS)The mixture is separated first in a gas chromatograph.

The GC column is directly attached to the mass spectrometer where 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. These fragments pass through an electric or magnetic field and are separated according to their masses.

NO TWO SUBSTANCES PRODUCE THE SAME FRAGMENTATION PATTERN.

22

TOXICOLOGYExample of GCMS unit

23

Toxicology of AlcoholThe BIOLOGY of Alcohol… Alcohol is a depressant which acts on

the CNS Extent of depression 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

24

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

25

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)

26

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 )

27

TOXICOLOGYScreening 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

28

TOXICOLOGYDETERMINING CAUSE AND MANNER OF DEATHMedical Examiner’s job, but needs toxicology reportNatural 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.

29

TOXICOLOGYDETERMINING CAUSE AND MANNER OF

DEATHMedical Examiner’s job, but needs toxicology

report

SuicidalThis is the most common death by poison.#1 is carbon monoxide#2 is prescription overdose

HomicidalMore common further back in history. Why?We now know how to detect. It used to go unnoticedTechnological advances in weapons…..GUNS