Topic:
DRUNK DRIVING; ALCOHOL/DRUG ABUSE;
Location:
DRUNK DRIVING;

OLR Research Report


April 15, 1999

 

99-R-0514

RELATIONSHIP BETWEEN DRINKS CONSUMED AND BAC

 
 

By: James J. Fazzalaro, Principal Analyst

Kevin E. McCarthy, Principal Analyst

You asked for a description of the relationship between the number of drinks a person consumes and his blood alcohol concentration (BAC).

BAC is a measure of the amount of alcohol in the body. Blood alcohol is measured directly through testing blood, or indirectly through tests that use breath, urine, or saliva.

A person's BAC is affected by the amount of alcohol he consumes and the rate his body absorbs it. It is important to note that the amount of alcohol contained in a drink varies significantly. While a 12 ounce can of beer or a five ounce glass of wine contains about one half ounce of pure alcohol, a martini or manhattan contains about twice as much.

The absorption rate is affected by several variables, including the person's weight and gender and the period of time over which the alcohol was consumed. For consumption of a specified amount of alcohol, BAC decreases with the weight of the person. The BAC of a woman who consumes a specified amount of alcohol is generally .01% to .02% higher than that of a man of the same weight who consumes the same amount of alcohol. (This is because water, which dilutes the alcohol, constitutes a larger proportion of a man's weight.) BAC also declines with the amount of time over which a person consumes the alcohol. Finally, the absorption rate is affected by the person's experience in drinking, with the BAC of an inexperienced drinker being higher than that of an experienced drinker with the same characteristics. The National Highway Traffic Safety Administration has developed a computer program to calculate BAC based on these factors, available from its Website (http://www.nhtsa.dot.gov/people/injury/alcohol/bacreport.html).

Tables 1 and 2 lists the BAC level for women and men, respectively, of average weight (138 pounds for women and 170 pounds for men) for various combinations of drinks consumed, the number of hours over which the alcohol was consumed, and the drinker's experience level. The table assumes that each drink contains one-half ounce of pure alcohol.

Table 1: BAC for Average Weight Women (138 pounds)

Drinks

Hours

Low

Experience

Medium

Experience

High

Experience

1

1

.02

.02

.01

2

1

.05

.05

.03

2

2

.04

.03

.03

2

3

.03

.02

.02

3

2

.08

.07

.06

3

3

.06

.05

.04

4

3

.10

.08

.07

4

4

.08

.06

.05

5

3

.13

.11

.11

5

4

.12

.11

.11

Table 2: BAC for Average Weight Men (170 pounds)

Drinks

Hours

Low

Experience

Medium

Experience

High

Experience

1

1

.01

.01

.00

2

1

.03

.03

.03

2

2

.04

.03

.03

2

3

.01

.00

.00

3

2

.04

.03

.03

3

3

.03

.02

.01

4

3

.06

.04

.03

4

4

.04

.02

.01

5

3

.08

.06

.05

5

4

.07

.05

.03

Table 3 presents BAC data for various levels of consumption for women and men of average drinking experience. The numbers in bold are for women.

Table 3: BAC for Various Levels of Consumption

Weight

1drink/

1 hour

2 drinks

1 hour

2 drinks

2 hours

3 drinks

2 hours

3 drinks

3 hours

4 drinks

3 hours

4 drinks

4 hours

100

.03

.07

.06

.10

.09

.13

.11

110

.02

.07

.05

.09

.07

.12

.10

120

.02

.06

.04

.08

.06

.10

.10

130

.02

.01

.05

.04

.04

.03

.07

.06

.05

.04

.09

.07

.07

.05

140

.02

.01

.05

.04

.03

.02

.06

.05

.05

.03

.08

.06

.06

.04

150

.01

.01

.04

.03

.03

.02

.06

.04

.04

.03

.07

.05

.05

.03

160

.01

.01

.04

.03

.02

.01

.05

.04

.03

.02

.06

.05

.05

.03

170

.01

.03

.01

.03

.02

.04

.02

180

.00

.03

.01

.03

.02

.03

.02

190

.00

.02

.01

.03

.01

.03

.01

200

.00

.02

.00

.02

.01

.03

.01

JJF:KEM:pa