Toxicology for presentation power point

7/28/2019 Toxicology for presentation power point

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Forensic Toxicology

Definition:

The science of detecting and

identifying the presence of drugsand poisons in body fluids, tissues,

and organs.


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Controlled Substances Act Federal Law established 5

schedules of classification ofcontrolled substances based on

Drugs potential for abuse Potential to physical and

psychological dependence

Medical Value

Note: Federal law also controlsmaterials that are used in makingdrugs and those that are manufacturedto resemble drugs


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Drug Schedules Schedule I:

Drugs with high potential for abuse andaddiction, NO medical value

Ex: Heroin, LSD, Ecstasy, Marijuana Schedule II:

Drugs with high potential for abuse andaddiction, have some medical value withrestrictions

Ex: PCP, Cocaine, Amphetamines, MostOpiates, Some Barbiturates


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Drug Schedules Schedule III:

Drugs with less potential for abuse andaddiction, currently acceptable formedical use

Ex: Some Barbiturates, Codeine, Steroids

Schedule IV:

Drugs with low potential for abuse andaddiction, currently acceptable formedical useEx: Tranquilizers like Valium, Xanax,Librium


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Drug Schedules

Schedule V:

Drugs with low potential abuse,

medical use, lowest potentialdependency

Ex: Some Opiates with Non-Narcotic

Ingredients


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Role of the Toxicologist

Must identify one of thousands ofdrugs and poisons

Must find nanogram to microgramquantities dissipated throughout theentire body

Not always looking for exact

chemicals, but metabolites ofdesired chemicals (ex. heroinmorphine within seconds)


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Toxicology Procedures

10mL of blood in airtight container

Add anticoagulant

Add preservative 2 consecutive urine samples

Some drugs take a while to show up in

urine (1-3 days)

Vitreous humor

Hair samples


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Toxicology Procedures

Screening-

quick test to narrow down possibilities

color tests, TLC, GC, immunoassay Confirmation-

determines exact identity

GC/Mass Spec

Note: TLCthin layer

chromatography


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Color Tests

Marquis Test:

Turns purple in the presence of Heroin,

morphine, opium

Turns orange-brown in presence ofAmphetamines

Scott Test:Three solutions

Blue then pink then back to blue in the

presence of Cocaine

Duquenois-Levine:

Test for marijuanaturns purple


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More Analytical Tests

Microcrystalline Tests: Identifies

drug by using chemicals that reacts

to produce characteristic crystals

Chromatography: TLC, HPLC and

gas separate drugs/tentative ID

Mass Spectrometry: chemicalfingerprint no two drugs fragment

the same


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Why?

Think of all the people that you have

heard do drugs.

US drug manufacturers produce enough

barbiturates and tranquilizers each yearto give every person in the US 40 pills

(thats about 12 billion pills)

18,000 out of 44,000 annual traffic deathsare alcohol related and send over 2

million people to the hospital


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Toxicology of Alcohol

Alcohol is absorbed through the

stomach and intestine

Once absorbed, alcohol is: Oxidized- in liver by alcohol

dehydrogenaseturned into acidic

acid

Excreted- by breath, perspiration, andkidneysturned into carbon dioxide

and water


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Factors that Affect Alcohol

Absorption

Time of

consumption

Type of alcoholic

beverage

Presence of food

in stomach


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Toxicology of Alcohol

Alcohol intoxication depends on

Amount of alcohol consumed

Time of consumption

Body weight

Rate of alcohol absorption


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Fate of Alcohol

Alcohol is absorbed into the

bloodstream

Distributed through-out the bodyswater

And finally eliminated by oxidation

and excretion


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Fate of Alcohol Cont

Note:

A. Oxidation is the combination of

oxygen and alcohol to producenew products by the liver

B. Elimination is removing alcoholfrom the body in an unchangedstate; normally excreted in breathand urine


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Alcohol in the Circulatory

System

Measuring the quantity of alcohol in

the blood system determines the

degree to which someone is drunk

Two methods of making this

measurement

Measurement of alcohol content in

blood

Measurement of alcohol in breath


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Circulation and Alcohol


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Circulation and Alcohol


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Circulation Definitions

Arterya blood vessel that carries blood

away from the heart

Veina blood vessel that transports

blood toward the heart

Capillarya tiny blood vesselwalls

exchange materials between blood and

tissues Alveolismall sacs in lungsexchange

vapors between breath and blood


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Circulation Cont

Note: If alcohol is present, it will be

passed from the blood into the alveoli

where it will be passed on to the mouth

and nose during the act of breathing. Evidence has shown that the ratio of

alcohol to alveoli air is approx. 2100 to

1This is a basis for relating breath to

blood-alcohol concentration.


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Analysis of BAC

Breath Tests

Field Sobriety Tests

Blood Tests


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Breath Tests

A breath test reflects the alcohol

concentration in the pulmonary

artery.

One instrument used for breath tests

is called TheBreathalyzer.

The Breathalyzer is a device for

collecting and measuring the alcohol

content of alveolar breath.


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The Breathalyzer


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The BreathalyzerCont

The Breathalyzer traps 1/40 of 2100milliliters of alveolar breath.

Since the amount of alcohol in 2100

milliliters of breath approximates theamount of alcohol in 1 milliliter ofbloodthe Breathalyzer in

essence measures the alcoholconcentration present in 1/40 of amilliliter of blood.


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Breathalyzer Cont

Once the alveolar breath is trapped it is

allowed to undergo a chemical reaction:

2K2Cr2O7 + 3C2H5OH + 8H2SO4 2Cr2(SO4)3 + 2K2SO4 + 3CH3COOH + 11H2O

The Breathalyzer indirectly determines the quantity of alcohol

consumed by measuring the absorption of light by potassium

chromate before and after its reaction with alcohol, using the

principle of spectrophotometry

Potassiumdichromate

Ethylalcohol

Sulfuricacid

Chromiumsulfate

Potassiumsulfate

Aceticacid

Dihydrogeoxide


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Other Breath Tests

Infrared breath-testing instrument

Fuel cell

Note: These instruments are usedmore recently because they dont

depend upon chemical reagents and

are entirely automated.


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Infrared-Breath Test

Uses the principle that infrared light is

absorbed when shined on alcohol

Essentially, the infrared light passes

through a chamber where it will interactwith the alcohol and cause the light

density to decrease.

The decrease in light intensity isproportional to the concentration of

alcohol present in the captured breath


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Fuel CellBreath Test

A fuel cell converts a fuel and anoxidant into an electrical current.

In this test, the breath alcohol is the

fuel and atmospheric oxygen acts asthe oxidant.

Alcohol is converted, generating a

current that is proportional to thequantity of alcohol present in thebreath.


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Infrared and Fuel Cell

Breath Tests

Infrared Breath Test

uses infrared

wavelengths to test for

alcohol or other

interferences in thebreath

Fuel Cell Test

converts fuel

(alcohol) and

oxygen into ameasurable electric

current


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Field Sobriety Testing

Two reasons for the field sobriety

test:

1. Used as a preliminary test to

ascertain the degree of the suspects

physical impairment

2. To see whether or not an evidential

test is justified.


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Field Sobriety Testing

Methods

Field sobriety testing consists of aseries of psychophysical tests and apreliminary breath test (typically

done with a handheld fuel cell tester) These tests are preliminary and

nonevidential in naturethey only

serve to establish probable causerequiring a more thorough breath orblood test.


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Field Sobriety Tests

Horizontal Gaze Nystagmus Involuntary eye jerk as eye moves horizontally

Walk and Turn (divided attention tasks)

One-Leg Stand


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Parts of the brain affected

by Alcohol

Alcohol 1st

affects the

forebrain

and movesbackward

Last

affected is

medulla

oblongata


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Alcohol

and the Law

1939-1964:

intoxicated =

0.15% BAC

1965: intoxicated =

0.10% BAC 2003: intoxicated =

0.08% BAC

At least we dont live in

France, Germany, Ireland,or Japan (0.05%) orespecially Sweden (0.02%)!


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Alcohol and the Law

Try the drink wheel:

http://www.intox.com/wheel/drinkwheel.asp
http://www.intox.com/wheel/drinkwheel.asphttp://www.intox.com/wheel/drinkwheel.asp


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