Ch 6

 Toxicologists detect and identify drugs and poisons in body fluids, tissues, & organs to determine their influence on human behavior  They can work in legal institutions such as crime labs and medical examiners’ offices  In hospital labs- where identifying a drug overdose may represent the difference between life and death  In other facilities that monitor the intake of drugs and other toxic substances (blood tests on children exposed to lead paints, analyzing urine for drugs for employers

 Ethyl alcohol is the most heavily abused drug  40% of all traffic deaths in the U.S., nearly 17,500 fatalities per year, are alcohol related, along with 2 million injuries each year requiring hospitalization  All chemicals that enter the body are broken down by chemicals in the body and transformed into other chemicals that are easier to eliminate  This is called metabolism and consists of three steps: absorption, distribution, and elimination

 Alcohol appears in blood within minutes after it is consumed  It slowly increases in concentration while it is absorbed from the stomach and small intestine into the bloodstream and is carried to all parts of the body (absorption)  It takes 60 to 90 minutes from the time of the final drink until absorption is complete  When absorption is complete, alcohol is evenly distributed through the watery portions of the body (2/3 of the body’s volume)  Fat, bones, and hair are low in water content and contain little alcohol  After absorption is complete, the blood reaches a maximum alcohol level and then it slowly decreases until hitting zero again

 determine the rate at which alcohol is absorbed into the bloodstream, such as:  The total time taken to consume the drink  The alcohol content of the drink  The amount consumed  Quantity and type of food present in the stomach while drinking  Alcohol consumed on an empty stomach is absorbed faster than with food in the stomach  Beer is absorbed more slowly than an equivalent concentration of alcohol in water because of the carbs present in beer

 As alcohol is distributed by blood, the body starts to eliminate it  It is eliminated by two methods:  Oxidation: 95 to 98% of alcohol is eventually oxidized to carbon dioxide and water  Takes place in liver  Excretion: the remaining is excreted unchanged in the breath, urine, and sweat  The amount of alcohol exhaled in the breath is in direct proportion to the concentration of alcohol in the blood  The elimination (“burn-off”) rate of alcohol is about % per hr

 The most obvious measure of intoxication would be the amount of alcohol a person has consumed  Its not that easy because many factors are involved  Toxicologists concentrate on the blood which provides us with the alcohol circulating throughout the body, carrying it to all tissues, including the brain  If blood is not available, such as a victim that bleeds to death, a water-rich organ can be used such as the brain, CSF or vitreous humor to determine BAC accurately

 The most convenient method is the breath test  This collects and measures the alcohol content of our alveolar (lung) breath  Remember, alcohol is expelled unchanged in the breath of a person who has been drinking  The key to accuracy is that the unit must capture the alcohol in a deep lung breath of the person  The subject must blow for a minimum of 6 seconds  The instruments have an integrated slope detector that tells whether or not the breath given is deep

 Avoid measuring mouth alcohol resulting from recent vomiting, belching, or recent intake of alcohol  The recent gargling of an alcohol- containing mouthwash can lead to the presence of mouth alcohol  Here, the alcohol concentration detected in the exhaled breath is higher than the concentration in the alveolar breath  The operator must not allow the subject to take any foreign material into his/her mouth for minutes before the breath test  Subject must not belch or regurgitate during this time  Mouth alcohol will disappear after 15 to 20 minutes

 Usually preliminary tests are conducted before a breath or blood test is required  Horizontal-gaze nystagmus is a voluntary jerking of the eye as it moves to the side  A person is unaware that the jerking is occurring and can’t stop or control it  The subject follows a penlight with the eye as far to the side as the eye can go  The more intoxicated, the less the eye has to move to the side before it begins to jerk  Usually when the BAC is about 0.10 percent, jerking will begin before the eyeball has moved 45 degrees to the side

 These are divided attention tasks, testing the subject’s ability to comprehend and execute two or more simple tasks at once  This is affected by increasing blood alcohol levels  Walk and turn: suspect maintains balance while standing heel-to-toe and at the same time listening to and comprehending instructions  During the walk stage, the suspect must walk a straight line, heel-to-toe for nine steps, turn around on a line, and repeat  One-leg stand: suspect maintains balance while standing with heels together listening to instructions.  During the balancing, the suspect must stand on one foot while holding the other foot several inches off the ground for 30 seconds  The suspect must be counting out loud during this 30-second time period

 Used to be 0.15 %, lowered to 0.08 %  1992, DOT recommended that states adopt 0.08 % as the legal measure of intoxication  This became federal law in 2000  All states have established per se laws, meaning anyone meeting or exceeding 0.08 is deemed intoxicated for noncommercial drivers  Max allowable for commercial truck or bus drivers is 0.04 %  Canada, Switzerland, Italy, and United Kingdom have also set it at 0.08 %  Finland, France, Germany, Ireland, Japan, Netherlands, & Norway: 0.05 %  Sweden has lowered it to 0.02%

 The 5 th amendment guarantees all citizens protection against self incrimination  Against being forced to make an admission that would prove one’s own guilt in a legal matter  Consenting to a breath test might be considered a form of self incrimination  The National Highway Traffic Safety Administration recommended an implied-consent law to prevent a person from refusing to take a test on those grounds  This law states that the person must either consent to a test for alcohol intoxication, if requested, or lose their license for 6 months to a yr

 If fortunate, some clue as to the type of toxic substance present may develop due to symptoms, drug bottle present, etc.  Without this a toxicologist uses general screening procedures with the hope of narrowing thousands of possibilities to one  By this time, drugs have distributed throughout the body so they have minimal samples to go by  Few substances enter and leave the body in the same form  A good understanding of how the body metabolizes a drug is essential in detecting it  Once a toxicologist has detected, identified, and quantitated a drug or poison, he or she must assess the toxicity level

 When possible, blood and urine are taken  The entire urine sample is collected for analysis  Preferably, two consecutive voids should be collected in separate containers  For drug and poison exams, about 10 mL of blood needs to be collected  For the presence of alcohol, only 5 mL of blood is needed

 Apply nonalcoholic disinfectant before drawing blood with a needle (Zepiran, mercuric chloride, Betadine)  Once removed from person, it is preserved in a vacutainer containing anticoagulant (prevents clotting) and a preservative (inhibits growth of bacteria that can destroy alcohol)  This must then be refrigerated  In postmortem: added precaution because alcohol may be generated as a result of bacterial action  Blood may be removed from heart, femoral (leg) and cubital (arm) veins  Collection of vitreous humor & urine must be collected in these individuals (no bacterial production from bacteria)

 pH: acids are less than 7, bases are greater than 7  Acid drugs: barbiturates, aspirin  Basic drugs: phencyclidine, methadone, amphetamines, cocaine  Once a specimen has been classified as acid or base, drugs present may be identified  A screening test is performed to give the likelihood that a specimen contains a drug substance  This allows a toxicologist to examine a large number of specimens in a short amount of time for a wide range of drugs  Any positive results must be verified with an extremely specific test called a confirmatory test

 Most drugs remain in blood for 24 hrs  In urine, up to 72 hrs  May be necessary to go further back to determine if a drug has been abused  Hair is nourished by blood flowing thru capillaries located close to hair root  Drugs in blood diffuse into the base of the hair and become permanently trapped in the protein within the hair  As the hair grows, the drug’s location becomes a marker for drug intake and amount of time abused  Head hair grows 1 cm per month  Analyzing hair for drugs can date drug use back over a period of weeks, months, and even a yr depending on the length of hair.

 Inhaling CO from car fumes is common when committing suicide  A level of CO sufficient to cause death accumulates in five to ten minutes in a closed single-car garage  CO is absorbed by RBC’s and combines with hemoglobin  Oxygen normally combines with hemoglobin to transport the oxygen thru the body  If a high % of hemoglobin combines with CO, not enough is left to carry oxygen to tissue and death by asphyxiation follows  CO level greater than % is fatal  Arson: CO in a victim found dead at this scene can tell whether foul play has occurred  High levels of CO in blood proves the victim breathed in the smoke and was alive when the fire began  Low levels indicate the victim was dead before the fire started, and may have been placed at the scene to destroy the body