Forensic Toxicology

Toxicology

• Definition: Analysis of body fluids or tissues for the presence of 1) controlled substances, 2) common pharmaceuticals and 3) poisons.

• What do Toxicologists know?– All about:

• drug interactions, metabolism, therapeutic vs. toxic doses, and impairment

Challenges…

• Identify 1 in 1000 drugs/poisons needle in a haystack

• Find tiny (nanogram to microgram) quantities, through the entire body

• Not always looking for exact chemicals

…metabolites are breakdown products Examples: heroin morphine in seconds

THC THC-9 in urine

Forensic Toxicology

Father of Modern Toxicology…

Orfila

Paracelsus "All things are poison and nothing is without poison, only the dose permits something not to be poisonous.”

(1530 AD)

Toxicology…when do we do it ??Antemortem = before death• DUIs BREATH

• Drug Facilitated Sex.Asslt.

BREATH, URINE

• Workplace Drug Testing

BREATH, URINE

• Parole violations BREATH

Post mortem = after death

• Homicides • Suicides• Overdose • MVA • Unexplained

death• Natural

(sometimes)

Toxicology of Alcohol

• Alcohol is absorbed into the blood, via stomach and small intestine

• Once absorbed, alcohol is:– Oxidized (oxidation = burned, with O2) in

liver– Excreted in breath and urine…

AS UNCHANGED PURE ALCOHOL !!

Alcohol in the Circulatory System

• Quantity of alcohol in the blood is…

…how drunk you are.

• Two methods of making this measurement– Measure alcohol in blood – Measure alcohol in breath

Circulation Con’t

Ratio of blood alcohol to alveoli air is approximately 2100 to 1– Means 2100 mL of Breath has the

same alcohol as 1mL of Blood

The Breathalyzer

Breathalyzer Con’t• 3 types of breathalyzers

• Measure alcohol in different ways

– Chemical… alcohol some other chemical

– Fuel Cell… alcohol electricity

– Infrared (IR) alcohol reflects IR back

Infrared and Fuel Cell Breath Tests• Infrared Breath Test

uses infrared wavelengths to test for alcohol

• Fuel Cell Test converts fuel (alcohol) and oxygen into a measurable electric current

Field Sobriety Testing

• Two reasons for the field sobriety test:

1. Assess suspects’ physical impairment

2. Determine need of evidential (urine) test.

Field Sobriety Tests• Horizontal Gaze Nystagmus

– Involuntary eye jerk as eye moves horizontally

• Walk and Turn (divided attention tasks)• One-Leg Stand

Horizontal Gase Nystagmus - CLIPhttp://www.bing.com/videos/search?

q=horizontal+gaze+nystagmus+video&view=detail&mid=95C10FAF1ABA03518D1A95C10FAF1ABA03518D1A&first=0&qpvt=horizontal+gaze+nystagmus+video&adlt=strict

Alcohol and the Law• 1939-1964:

intoxicated = 0.15% BAC

• 1965: intoxicated = 0.10% BAC

• 2003: intoxicated = 0.08% BAC

At least we don’t live in France, Germany, Ireland, or Japan (0.05%) or especially Sweden (0.02%)!

Drug Testing in the Body• Urine is most common• Immunoassay

– Based on antigen-antibody binding specificity

– Antibody produced by injecting antigen (drug) into rabbit

– Antibodies will bind to drug in urine

• Confirmation done w/TLC

False positives in Immunoassays

• Poppy seeds and Vicks 44 for opiates

• Decongestants for amphetamines

• Benadryl and numerous cough syrups for PCP