Testing for IntoxicationTesting for Intoxication

Why is it not practical to Why is it not practical to measure an individual’s BAC measure an individual’s BAC by measuring a sample of by measuring a sample of blood?blood?

Breath TestingBreath Testing Field Sobriety TestsField Sobriety Tests

Breath Testing for AlcoholBreath Testing for Alcohol

Remember: Remember: The alcohol in breath The alcohol in breath samples is proportional to the alcohol samples is proportional to the alcohol concentration in bloodconcentration in blood

BreathalyzerBreathalyzer-developed in 1954; -developed in 1954; alcohol is reacted with several alcohol is reacted with several reagents; the reactions are reagents; the reactions are measured by a spectrophotometer.measured by a spectrophotometer.

Breathalyzer replaced by fuel cell Breathalyzer replaced by fuel cell and infrared detectors in the 1970’sand infrared detectors in the 1970’s

Breath Testing for AlcoholBreath Testing for Alcohol

The key to The key to accurate accurate measurements in measurements in breath testing is to breath testing is to obtain alveolar obtain alveolar breathsbreaths

Field Sobriety TestingField Sobriety Testing

A portable breath tester can be used A portable breath tester can be used to establish probable cause.to establish probable cause.

Psychophysical testsPsychophysical tests

-Horizontal-gaze nystagmus-Horizontal-gaze nystagmus

Divided-attention tasksDivided-attention tasks

-walk and turn-walk and turn

-one-leg stand-one-leg stand

The Analysis of Blood for AlcoholThe Analysis of Blood for Alcohol

Gas Chromatography is often used Gas Chromatography is often used by forensic labs to measure BACby forensic labs to measure BAC

Medical professionals often use Medical professionals often use spectrophotometric methodsspectrophotometric methods

Collection and Preservation of Collection and Preservation of BloodBlood

Blood samples must be stored in an Blood samples must be stored in an airtight containerairtight container

Anticoagulants Anticoagulants (EDTA, potassium (EDTA, potassium oxalate) must be added to prevent oxalate) must be added to prevent the blood from clottingthe blood from clotting

Preservatives Preservatives (sodium fluoride) must (sodium fluoride) must be added to inhibit the growth of be added to inhibit the growth of microorganisms.microorganisms.

Blood Alcohol LawsBlood Alcohol Laws

In 1992, the US DOT recommended In 1992, the US DOT recommended that states adopt 0.08 BAC as the that states adopt 0.08 BAC as the legal measure of drunk driving.legal measure of drunk driving.

The standard is 0.04 BAC for The standard is 0.04 BAC for commercial truck and bus driverscommercial truck and bus drivers

Constitutional IssuesConstitutional Issues

Implied consent law – a person must Implied consent law – a person must consent to a test for alcohol intoxication consent to a test for alcohol intoxication or be subject to loss of license for a or be subject to loss of license for a designated period of timedesignated period of time

Courts have ruled that the 5Courts have ruled that the 5thth amendment only applies to testimonial amendment only applies to testimonial evidenceevidence

Courts have also ruled that alcohol tests Courts have also ruled that alcohol tests do not violate 4do not violate 4thth amendment rights. amendment rights.

The Role of the ToxicologistThe Role of the Toxicologist

Beyond alcohol, toxicologists analyze Beyond alcohol, toxicologists analyze a wide variety of drugs and poisonsa wide variety of drugs and poisons

Some possible clues include:Some possible clues include:

-the victim’s symptoms-the victim’s symptoms

-postmortem pathological examination-postmortem pathological examination

-examination of personal items-examination of personal items

-nearby presence of drug containers, -nearby presence of drug containers, household chemicals, etc.household chemicals, etc.

Challenges Facing the Challenges Facing the ToxicologistToxicologist

Drugs and poisons may be present in Drugs and poisons may be present in tiny amounts/concentrationstiny amounts/concentrations

Few substances leave the body in the Few substances leave the body in the same form that they entered; they same form that they entered; they are metabolized (Example: heroin)are metabolized (Example: heroin)

When a drug or poison is detected, When a drug or poison is detected, its toxicity must be determinedits toxicity must be determined

Collection of Toxicological EvidenceCollection of Toxicological Evidence

For a deceased person, all body For a deceased person, all body fluids and tissues may be examinedfluids and tissues may be examined

For a living person, blood and urine For a living person, blood and urine samples are analyzedsamples are analyzed

Drugs: detectable in blood for 24 Drugs: detectable in blood for 24 hours; detectable in urine for 72 hours; detectable in urine for 72 hourshours

Hair samples may also be takenHair samples may also be taken

Techniques Used in ToxicologyTechniques Used in Toxicology

ScreeningScreening tests tentatively identify a tests tentatively identify a drug/poison or narrow down the drug/poison or narrow down the possibilities (TLC, GC, possibilities (TLC, GC, immunoassays)immunoassays)

ConfirmationConfirmation tests definitively tests definitively confirms the identity of a poison or confirms the identity of a poison or drug (GC/Mass spectrometry)drug (GC/Mass spectrometry)

Detecting Non-drug PoisonsDetecting Non-drug Poisons

Heavy metals – Lead, arsenic, Heavy metals – Lead, arsenic, mercury, thalliummercury, thallium

CyanideCyanide Carbon monoxideCarbon monoxide

Significance of Toxicological Significance of Toxicological TestingTesting

There are legal guidelines correlating There are legal guidelines correlating Blood alcohol concentrations and physical Blood alcohol concentrations and physical impairmentimpairment

No such guidelines exist regarding all No such guidelines exist regarding all other drugs.other drugs.

Toxicologists must judge the manner in Toxicologists must judge the manner in which a drug affects an individual’s which a drug affects an individual’s performance or physical state.performance or physical state.

For a deceased individual, toxicologists For a deceased individual, toxicologists work with medical examiners to determine work with medical examiners to determine the cause of deaththe cause of death

Significance of Toxicological Significance of Toxicological TestingTesting

Factors which affect drug-induced Factors which affect drug-induced behavior:behavior:

-age-age

-physical condition-physical condition

-tolerance of the drug user-tolerance of the drug user

-interaction between multiple drugs -interaction between multiple drugs (i.e. alcohol & barbiturates/narcotics(i.e. alcohol & barbiturates/narcotics