Untitled Flashcards Set

Forensics II: Toxicology Unit Study Guide

Vocabulary:

Toxicology

Screening tests

Confirmatory tests

Chromatography

Spectrophotometry

Toxin

Toxicity

LD50

Chronic exposure

Acute exposure

Synergism

Antagonism




Concepts:

  • What are instances in which toxicology testing is needed in forensics?

Postmortem - suspicious/untimely deaths performed by M.E.

Criminal – after motor vehicle accidents

Workplace- drug testing employees

Sports – to test for doping of humans and animals

Environment – to test for release of toxic substances by industry, terrorism, catastrophic events.

  • Name four exposure methods of poisons into the body and the body systems affected.* = fastest

Ingestion - digestive system

*Inhalation- respiratory system – lungs

*Injection – circulatory system- bloodstream

Absorption – integumentary system – skin


  • Name three pieces of information about the victim, a crime scene detective should gather at a suspected poisoning scene.

____MEES_________________ lines = single transverse white bands on nails (results from heavy metal poisoning)

Irritated tissues - mouth, nasal

Bright red lividity - carbon monoxide

Odors- bitter almonds, garlic/onions, alcohol 

Medications the victim usually took.

What meals were eaten during three days (esp. the last meal)

Prior medical history from the medical doctor. (esp. history of cardiac arrest or liver/kidney failure)


  • What is the difference between drug identification field tests (screening tests) and laboratory tests (confirmatory tests)?

Field tests (screening tests) rule out certain chemicals but do not specifically ID the drug. Normally change colors and are fast acting.

Laboratory tests (confirmatory tests) are conclusive tests done in the lab that specifically ID the drug in question.


  • What tissues/fluids can be collected from a person to try and identify a particular toxic chemical?

Blood, urine, vitreous humor of eye, bile, gastric contents, hair/nails, liver/brain/kidney tissue

  • What is the difference between schedule I and schedule II drugs

Schedule II high potential for abuse; BUT a currently accepted medical use with severe restrictions




  • Name 4 US Federal Regulatory Agencies

Food and Drug Administration

  Environmental Protection Agency 

Consumer Product Safety Commission

Department of Transportation (DOT)

  Occupational Safety and Health Administration (OSHA) 


  • What 6 factors determine how toxic a substance will be to a person?

  1. The mode of entry into the body.Circulation/inhalation are fastest

  2. Body weight and physiological conditions of the victim, including age and sex. Children, elderly more at risk.Women store toxins in fat at higher levels.

  3. Presence of other chemicals in the body. Synergism or antagonism occur.

  4. Time exposure: Acute or chronic exposure

  5. Dosage given- more = more dangerous

  6. The chemical or physical form of the substance. Gas, liquid , solid. Gas fastest


  • How does spectrophotometry work to identify a particular chemical?

Shoots wavelengths of IR, UV or visible light at the substance which will absorb or transmit specific wavelengths of light.  Different substances produce unique patterns.




  • Distinguish between chronic and acute toxic exposure.

Acute= high dose over a short period of time- usually hours Ex. cyanide


Chronic = lower dosage over a longer period of time- usually months or years. Ex lead poisoning






  • What effects can combining 2 or more chemicals have on their level of toxicity?

Synergism = combination of the effects of 2 or more substances together that is greater than the sum of their individual effects. Example: alcohol and valium can cause respiratory depression.


Antagonism = combination of the effects of 2 or more substances together that is less than the sum of their individual effects.  Example: histamine lowers blood pressure and adrenaline raises blood pressure.


  • What are the symptoms of the following poisons?

 Carbon Monoxide-bright pink patches on the chest and thighs (bright red lividity)Usually from incomplete combustion.

 Cyanide burnt almond odor

 Lead pronounced diarrhea, vomiting and abdominal pains, brain damage. Often from older paint, water supply, soil


  • Name 4 types of field tests for alcohol consumption:

  • Horizontal gaze nystagmus (HGN)

  • Nine Step walk and turn (WAT)

  • One-leg stand (OLS)

  • Breathalyzer


  • A breathalyzer works because ___5_________% of alcohol is excreted unchanged in breath, perspiration and urine



Know how to calculate LD50 and which substances are more dangerous.

Toxin A is more dangerous because it’s    LD50  is 25 mg/kg while Toxin B’s = 31 kg/mg.  Toxin A is more dangerous because it takes less of the substance to kill.