Human Performance Toxicology Cheat Sheet

Human Performance Toxicology 3 Types of Forensic Toxicology ● Human Performance ● Forensic Drug Testing ● Postmortem Forensics • Behavioral effects of drugs • Enhance performance — (steroids, sports, etc) • Impair performance—(usually of more interest to toxicologists) • Interest: Human Performance Toxicology • Human Performance: Evaluation of a person’s ability to perform routine, yet • Both illicit and therapeutic drugs • antidepressants, muscle relaxants, alcohol complex psychomotor tasks • Benzodiazepines - anxiolytics • Tasks that occur daily - Low doses - improve driving behavior • Monitored frequently - High doses - impact driving behavior • Highway, workplace, etc • Human Performance Toxicology: Behavioral Toxicology Specimen collected for Human Performance • How a person behaves under the influence of drugs and alcohol • Blood – most commonly used for establishing dose/concentration and effect relationships • Different from Post-mortem Toxicology • Why? – most intimately in contact with CNS • Provides best info concerning how a drug, its active metabolites and their concentrations are Behavioral Toxicology related to performance impairment at that moment in time • Goal: To determine and quantify the dose-effect relationship between • Negative effects on CNS = performance impairment drugs that elicit behavioral changes and those changes • Urine, sweat and hair can be tested although it is difficult to make a direct connection between • Combines psychology, toxicology and pharmacology concentration and behavior • Behavior – the manner of one’s conduct and one’s response to environmental stimuli • Performance – the execution of an action, the manner of reacting to stimuli and the carrying out of an action or behavior • Human Performance Toxicology – the study of human response to environmental conditions and stimuli under the influence of drugs/alcohol Human Performance Evaluation • Justification: • Inability to perform may affect safety of other persons • May have economical and legal implications Why Forensic Toxicologists? • Natural extension of the interest in the medicolegalI implications of drug use, misuse and abuse • Broad social and economical implications on the road and in the workplace History of Alcohol and Driving • Early 1800s – invention of steam locomotive and railway transportation • Concerns arose over high-speed travel and alcohol • 1843 – law to prevent drinking while working Railway and steam locomotives • 1904 – editorial about drinking before driving and automobile accidents • 1910 – NYC identified alcohol as a traffic safety factor • 1924 – National Safety Council formed • Interests highway safety alcohol effects on driving • Erik Widmark (1920s) – 1st to quantify amount of alcohol in various fluids and correlate concentration to measures of impairment • Developed protocol for physicians to evaluate drivers suspected of DUI. • Rolla Harger – Drunkometer • Used to evaluate BAC in drivers • Measured alcohol in the breath • No blood or urine needed • Less invasive • Richard Holcomb —Study of 270 drivers hospitalized following automobile accidents in Evanston, IL • Chances of having an accident increased geometrically with the presence of alcohol • each 0.02g/dL BAC increase = double risk of accident • March 1939 – 1st DUI law passed in Indiana • < 0.05 g/dL – presumptive evidence of no guilt • > 0.15 g/dL – presumptive evidence of guilt • 0.05 – 0.15 g/dL – supportive evidence of DUI • 1953 – Implied Consent legislation passed in New York. • As a condition precedent to being issued a driver’ s license, an applicant agrees, by implication, to submit to a chemical test in any case in which he is suspected of DUI. Refusal to submit to the test results in loss of driving privileges. • 1954 Robert Borkenstein • Breathalyzer • More portable than the drunkometer • 1958 – Symposium on Alcohol and Road Traffic BAC of 0.05 g/dL – impairs driving ability of some individuals BAC of 0.10 g/dL – all individuals impaired 1964– Grand Rapids Study: BAC of 0.04 g/dL – as likely to have accident as if sober BAC of 0.06 g/dL – twice as likely BAC 0f 0.10 g/dL – six times as likely BAC of 0.15 g/dL – 25 times as likely 1971 – legal limit of driving while impaired set at 0.10 g/dL All states have lowered this number to 0.08 g/dL, including Louisiana Behavioral effects of Alcohol • decreased visual acuity and peripheral vision n decreased sensitivity to taste and smell • altered sense of time • choice reaction time impaired • hand-eye coordination effects n impairment of vigilance tasks • All depends on BAC: • 0.05 – increased talking, excitement, higher pitch • 0.10-0.15 – loud, boisterous • 0.15 – nausea, vomiting, lethargy, stupor Standardized Field Sobriety Tests • Three-phase process •. Initial observation of vehicle in motion and how driver stops the vehicle • Weaving, unsignaled lane changes, rapid changes in speed First direct contact with the driver • Physical appearance, eye condition, breath odor, speech • Driver exiting vehicle • Does he/she need help? • Psychomotor tests • One-leg stand (OLS) • Walk and turn (WAT) • Horizontal gaze nystagmus (HGN) • Preliminary breath test • Behavioral tolerance develops with repeated use • Those tasks learned under influence often performed better when repeated at that blood concentration • Specimen of choice for alcohol • Breath* – non-invasive • Blood – trained healthcare physician • Urine – controlled conditions • Studies have shown that a properly collected breath sample accurately reflects BAC at time of collection • *Only the terminal portion of the expired breath is in equilibrium with arterial blood and reflects BAC Drugs and Driving • Correlation between BAC and impairment has been well-established • Not the case with drugs • Drug Evaluation and Classification Program (DEC) • Recognize role of drugs of abuse and the impaired driver • Drug Recognition Experts (DRE) • Trained officers using standardized curriculum to recognize individuals under impairment Drug Evaluation and Classification Program • Validated in 1984 to provide mechanism for obtaining evidence that driver was impaired at the time of the stop • Based on cooperation of 3 disciplines • Law enforcement (DRE who documents impairment) • Toxicology (provides analytical and expert opinion) • Prosecution (carries out legal action • Drug Evaluation and Classification • Performed in a controlled environment • Not on the roadside • Occurs post-arrest • Based on impairment resulting from the use of drugs within 7 categories: • CNS depressants • CNS stimulants • Hallucinogens • Phencyclidine • Narcotic analgesics • Inhalants • Cannabis • Discipline #1 – DRE • Drug Recognition Evaluation • 12 step evaluation • May or may not be officer performing the stop n Subjective evaluation • 12 Steps: 1) Breath alcohol test – if neg, then other drugs may be present 2) Interview of arresting officer – history of arrest 3) Preliminary exam of the suspect – injury, illness 4) Examination of the eyes - HGN 5) Divided-attention psychophysical tests – OLS, WAT 6) Vital signs examination – pulse, blood pressure, temp 7) Dark Room examination – pupil dilation/constriction 8) Examination of muscle tone 9) Examination for injection sites 10) Suspect’sstatementsandotherobservations 11) Opinionoftheevaluator–influencedbydrugs? 12) Toxicologicalexamination • Discipline #2 – Toxicology • Objective evaluation • Direct drug analysis (blood and/or urine) • Presence of drug in blood – suggests cause of impairment • Presence in urine – only that person has been exposed to the drug • No well-established correlation between blood concentration and performance impairment for any drug other than alcohol • Toxicologist provides expert opinion as to whether the influence of drugs played a role in impairment • Impairment noted by DRE in combination with Toxicology confirmation provides reasonable scientific evidence that impairment was caused by use of the drug. • Cooperative effort of DRE and Toxicologist is essential for correct evaluation of impairment due to drugs • Discipline #3 – Prosecution • DRE and Toxicologist testify on on findings from evaluations-