Chapter 8

Toxicology: Poisons and Alcohol

1

Alcohol may be the world's oldest known drug. Fermented grain, fruit juice and honey have been used to make alcohol (ethyl alcohol or ethanol) for thousands of years.

A major branch of forensic toxicology deals with the measurement of alcohol in the body for matters that pertain to violations of criminal law.

Chapter 8

Toxicology: Poisons and Alcohol

2

Kendall/Hunt Publishing Company2

Alcohol—Ethyl Alcohol (C2H5OH)

Most abused drug in America

About 40 percent of all traffic deaths are alcohol-related

Toxic—affecting the central nervous system, especially the brain

Colorless liquid, generally diluted in water

Acts as a depressant

Alcohol appears in blood within minutes of consumption; 30–90 minutes

for full absorption

Detoxification—about 90 percent in the liver

About 5 percent is excreted unchanged in breath, perspiration, and

urine

Chapter 8

Toxicology: Poisons and Alcohol

3

Alcohol appears in the blood within minutes after it has been taken by mouth and slowly increases in concentration while it is being absorbed from the stomach and the small intestine into the bloodstream.

When all the alcohol has been absorbed, a maximum alcohol level is reached in the blood; and the post-absorption period begins.

Then the alcohol concentration slowly decreases until a zero

level is again reached.

Factors such as time taken to consume the drink, the alcohol

content, the amount consumed, and food present in the

stomach determine the rate at which alcohol is absorbed.

Chapter 8

Toxicology: Poisons and Alcohol

4

Kendall/Hunt Publishing Company4

Rate of Absorption

Depends on:

Amount of alcohol consumed

The alcohol content ofthe beverage

Time taken to consume it

Quantity and type of food present in the stomach

Physiology of the consumer

1) Alcohol enters the mouth

2) Alcohol travels down the throat to the

stomach

3) About 20% of the alcohol is absorbed

into the blood by the stomach and

80% by the small intestine. Too

much alcohol will cause vomiting

4) Alcohol travels through the blood to

the organs of the body, including the

brain

5) Some alcohol in the blood is exhaled

through the lungs

6) Alcohol is broken down by the liver,

between ½-1 ounce per hour

7) The kidneys produce more urine to

help flush alcohol from the body

Chapter 8

Toxicology: Poisons and Alcohol

7

It takes about 30 minutes for alcohol to be

absorbed into your bloodstream.

Once the alcohol is absorbed, your body can

eliminate about 0.015% per hour.

If your stomach is full of food, the absorption

time will be longer, and so will the elimination

time.

Chapter 8

Toxicology: Poisons and Alcohol

8

Kendall/Hunt Publishing Company8

Generalizations

During absorption, the concentration of alcohol in arterial blood is higher

than in venous blood.

Breath tests reflect alcohol concentration in the pulmonary artery.

The breathalyzer also can react with acetone (as found in diabetics),

acetaldehyde, methanol, isopropyl alcohol, and paraldehyde, but these

are toxic and their presence means the person is in serious medical

condition.

Breathalyzers now use an infrared light-absorption device with a digital

readout. Prints out a card for a permanent record.

Chapter 8

Toxicology: Poisons and Alcohol

9

Alcohol Levels

Elimination of alcohol throughout the body is accomplished through oxidation and excretion.

Oxidation takes place almost entirely in the liver, while alcohol is excreted unchanged in the breath, urine, and perspiration.

The extent to which an individual may be under the influence of alcohol is usually determined by either measuring the quantity of alcohol present in the blood system or by measuring the alcohol content in the breath.

Chapter 8

Toxicology: Poisons and Alcohol

10

BAC: Blood Alcohol Concentration

Expressed as percent weight per

volume of blood

Legal limit in all states is 0.08 percent

0.04 % for Commercial Drivers

Parameters influencing BAC:

• Body weight

• Alcohol content

• Number of beverages consumed

• Time since consumption

Forensics and BAC

Since DUI is a crime, Forensic Toxicologists are used to determine BAC

• For Living suspects• Breathalyzer• Headspace Chromatography - ethanol is volatile and

readily escapes the blood and can be collected.• For dead suspects, blood, urine, and stomach contents

are frequently compromised.• Fluid from the vitreous humor is the best source for

testing

Chapter 8

Toxicology: Poisons and Alcohol

12

Kendall/Hunt Publishing Company12

Henry’s Law

When a volatile chemical is dissolved in a liquid and is brought to

equilibrium with air, there is a fixed ratio between the concentration of

the volatile compound in the air and its concentration in the liquid; this

ratio is constant for a given temperature. THEREFORE, the

concentration of alcohol in breath is proportional to that in the blood.

This ratio of alcohol in the blood to alcohol in the alveolar air is

approximately 2,100 to 1. In other words, 1 ml of blood will contain

nearly the same amount of alcohol as 2,100 ml of breath.

Chapter 8

Toxicology: Poisons and Alcohol

13

Kendall/Hunt Publishing Company13

The Breathalyzer

More practical in the field

Collects and measures alcohol content

of alveolar breath

Breath sample mixes with 3 ml of 0.025 percent K2Cr2O7 in sulfuric acid

and water:

2K2Cr2O7 +3C2H5OH + 8H2SO4 2Cr2(SO4)3 + 2K2SO4 + 3CH3COOH + 11H2O

Potassium dichromate is yellow; as concentration decreases, its light

absorption diminishes, so the breathalyzer indirectly measures alcohol

concentration by measuring light absorption of potassium dichromate

before and after the reaction with alcohol.

Chapter 8

Toxicology: Poisons and Alcohol

14

Facts about BAC, or Blood Alcohol Concentration:

BAC is the amount of alcohol per volume of blood

A BAC of .10 means that the blood contains one part alcohol to one-thousand parts of blood; that may not seem like a lot, but it's a lot for a body to absorb!

Legal level for driving drunk in all states is .08.

Bodies burn or metabolize alcohol at a steady rate.

The only thing that can lower a BAC is time. There is no way to dilute the amount of alcohol in the body by drinking or eating other things.

The faster someone drinks, the higher their BAC is.

Other things that affect BAC: Gender — a woman’s BAC increases more per drink than a man’s.

Weight – Heavier people will have lower BACs

Metabolism – Faster metabolisms with have higher BACs

Use of medication – many medications interact with alcohol and change dramatically change the BAC

Chapter 8

Toxicology: Poisons and Alcohol

15

Kendall/Hunt Publishing Company15

BAC Calculation

Male

BAC =

Female

BAC =

Burn-off rate of 0.015 percent per hour, but can vary:

0.071 (oz) (% alcohol)

body weight

0.085 (oz) (% alcohol)

body weight

Women have more body

fat than men. Therefore,

they have less blood

volume than men of the

same weight.

This results in a higher

BAC for a woman than for

a man, if all other factors

are equal.

Chapter 8

Toxicology: Poisons and Alcohol

16

Number of Drinks

Body

Weight 1 2 3 4 5 6 7 8 9 10

100 .043 .087 .130 .174 .217 .261 .304 .348 .391 .435

125 .034 .069 .103 .139 .173 .209 .242 .278 .312 .346

150 .029 .058 .087 .116 .145 .174 .203 .232 .261 .290

175 .025 .050 .075 .100 .125 .150 .175 .200 .225 .250

200 .022 .043 .065 .087 .108 .130 .152 .174 .195 .217

225 .019 .039 .058 .078 .097 .117 .136 .156 .175 .195

250 .017 .035 .052 .070 .087 .105 .122 .139 .156 .173

BAC Chart for Males

BAC is weight-

dependent because

larger people have

more body water for

alcohol to be

distributed in,

resulting in a lower

BAC

Chapter 8

Toxicology: Poisons and Alcohol

17

Number of Drinks

Body

Weight 1 2 3 4 5 6 7 8 9 10

100 .050 .101 .152 .203 .253 .304 .355 .406 .456 .507

125 .040 .080 .120 .162 .202 .244 .282 .324 .364 .404

150 .034 .068 .101 .135 .169 .203 .237 .271 .304 .338

175 .029 .058 .087 .117 .146 .175 .204 .233 .262 .292

200 .026 .050 .076 .101 .126 .152 .177 .203 .227 .253

225 .022 .045 .068 .091 .113 .136 .159 .182 .204 .227

BAC Chart for Females

Chapter 8

Toxicology: Poisons and Alcohol

18

One Drink is:

Chapter 8

Toxicology: Poisons and Alcohol

19

Kendall/Hunt Publishing Company19

Chapter 8

Toxicology: Poisons and Alcohol

20

Kendall/Hunt Publishing Company20

BAC Effects

.30 to .50Death may occur at .37 or higher. BACs of .45 and higher are fatal to nearly all individuals.

.25 to .30 Very drunk. May lose consciousness.

.15Obviously drunk. Staggering, weaving, irrational behavior. The equivalent of 1/2 pint of whiskey is circulating in the blood stream.

.12 to .15Vomiting may occur. May be drowsy. Loss of critical judgment, impairment of memory and comprehension. Vision impaired.

.10Loss of inhibition. Judgment and driving impaired. Clear deterioration of reaction time and control.

.08 Judgment and driving impaired. Defines intoxication in most states.

.06 Judgment and driving somewhat impaired.

.05Definite relaxation. Most people are very mellow at this point. There can be some impairment, and ability to drive safely begins to be limited.

.04 Most people begin to feel relaxed, sociable, and talkative.

.02 Moderate drinkers may feel some relaxation and warmth.

Chapter 8

Toxicology: Poisons and Alcohol

21

Simulation A (intoxicated) Simulation B (sober)

Staggers while walking to car Walks in a straight line to car

Has blurred vision Has clear vision

Does not look both ways before crossing the

street

Looks both ways before crossing the street

Does not fasten seat belt Does fasten seat belt

Has trouble putting key in ignition Puts key in ignition easily

Exceeds speed limit Does not exceed speed limit

Does not always stay in correct lane Stays in correct lane

Drives using one hand Drives using both hands

Runs through stop signs Stops smoothly at stop signs

Does not stop for pedestrian Stops to allow pedestrian to cross street

Does not use turn signals Does use turn signals

Hits the trash can in driveway Parks car without hitting trash can