Testing for Intoxication Why is it not practical to measure an individual’s BAC by measuring a sample of blood? Why is it not practical to measure an individual’s BAC by measuring a sample of blood? Breath Testing Breath Testing Field Sobriety Tests Field Sobriety Tests

Breath Testing for Alcohol Remember: The alcohol in breath samples is proportional to the alcohol concentration in blood Remember: The alcohol in breath samples is proportional to the alcohol concentration in blood Breathalyzer-developed in 1954; alcohol is reacted with several reagents; the reactions are measured by a spectrophotometer. Breathalyzer-developed in 1954; alcohol is reacted with several reagents; the reactions are measured by a spectrophotometer. Breathalyzer replaced by fuel cell and infrared detectors in the 1970’s Breathalyzer replaced by fuel cell and infrared detectors in the 1970’s

Breath Testing for Alcohol The key to accurate measurements in breath testing is to obtain alveolar breaths The key to accurate measurements in breath testing is to obtain alveolar breaths

Field Sobriety Testing A portable breath tester can be used to establish probable cause. A portable breath tester can be used to establish probable cause. Psychophysical tests Psychophysical tests -Horizontal-gaze nystagmus Divided-attention tasks -walk and turn -one-leg stand

The Analysis of Blood for Alcohol Gas Chromatography is often used by forensic labs to measure BAC Gas Chromatography is often used by forensic labs to measure BAC Medical professionals often use spectrophotometric methods Medical professionals often use spectrophotometric methods

Collection and Preservation of Blood Blood samples must be stored in an airtight container Blood samples must be stored in an airtight container Anticoagulants (EDTA, potassium oxalate) must be added to prevent the blood from clotting Anticoagulants (EDTA, potassium oxalate) must be added to prevent the blood from clotting Preservatives (sodium fluoride) must be added to inhibit the growth of microorganisms. Preservatives (sodium fluoride) must be added to inhibit the growth of microorganisms.

Blood Alcohol Laws In 1992, the US DOT recommended that states adopt 0.08 BAC as the legal measure of drunk driving. In 1992, the US DOT recommended that states adopt 0.08 BAC as the legal measure of drunk driving. The standard is 0.04 BAC for commercial truck and bus drivers The standard is 0.04 BAC for commercial truck and bus drivers

Constitutional Issues Implied consent law – a person must consent to a test for alcohol intoxication or be subject to loss of license for a designated period of time Implied consent law – a person must consent to a test for alcohol intoxication or be subject to loss of license for a designated period of time Courts have ruled that the 5 th amendment only applies to testimonial evidence Courts have ruled that the 5 th amendment only applies to testimonial evidence Courts have also ruled that alcohol tests do not violate 4 th amendment rights. Courts have also ruled that alcohol tests do not violate 4 th amendment rights.

The Role of the Toxicologist Beyond alcohol, toxicologists analyze a wide variety of drugs and poisons Beyond alcohol, toxicologists analyze a wide variety of drugs and poisons Some possible clues include: Some possible clues include: -the victim’s symptoms -postmortem pathological examination -examination of personal items -nearby presence of drug containers, household chemicals, etc.

Challenges Facing the Toxicologist Drugs and poisons may be present in tiny amounts/concentrations Drugs and poisons may be present in tiny amounts/concentrations Few substances leave the body in the same form that they entered; they are metabolized (Example: heroin) Few substances leave the body in the same form that they entered; they are metabolized (Example: heroin) When a drug or poison is detected, its toxicity must be determined When a drug or poison is detected, its toxicity must be determined

Collection of Toxicological Evidence For a deceased person, all body fluids and tissues may be examined For a deceased person, all body fluids and tissues may be examined For a living person, blood and urine samples are analyzed For a living person, blood and urine samples are analyzed Drugs: detectable in blood for 24 hours; detectable in urine for 72 hours Drugs: detectable in blood for 24 hours; detectable in urine for 72 hours Hair samples may also be taken Hair samples may also be taken

Techniques Used in Toxicology Screening tests tentatively identify a drug/poison or narrow down the possibilities (TLC, GC, immunoassays) Screening tests tentatively identify a drug/poison or narrow down the possibilities (TLC, GC, immunoassays) Confirmation tests definitively confirms the identity of a poison or drug (GC/Mass spectrometry) Confirmation tests definitively confirms the identity of a poison or drug (GC/Mass spectrometry)

Detecting Non-drug Poisons Heavy metals – Lead, arsenic, mercury, thallium Heavy metals – Lead, arsenic, mercury, thallium Cyanide Cyanide Carbon monoxide Carbon monoxide

Significance of Toxicological Testing There are legal guidelines correlating Blood alcohol concentrations and physical impairment There are legal guidelines correlating Blood alcohol concentrations and physical impairment No such guidelines exist regarding all other drugs. No such guidelines exist regarding all other drugs. Toxicologists must judge the manner in which a drug affects an individual’s performance or physical state. Toxicologists must judge the manner in which a drug affects an individual’s performance or physical state. For a deceased individual, toxicologists work with medical examiners to determine the cause of death For a deceased individual, toxicologists work with medical examiners to determine the cause of death

Significance of Toxicological Testing Factors which affect drug-induced behavior: Factors which affect drug-induced behavior:-age -physical condition -tolerance of the drug user -interaction between multiple drugs (i.e. alcohol & barbiturates/narcotics