#1 2006

@

alcoholican

contents

Alcohol effects at specific Blood Alcohol Content (BAC in g/dl)

0.03-0.12

• They become more self-confident or daring.
• Their attention span shortens.
• They may look flushed.
• Their judgement is not as good -- they may say the first thought that comes to mind, rather than an appropriate comment for the given situation.
• They have trouble with fine movements, such as writing or signing their name.

0.09-0.20

• They become sleepy.
• They have trouble understanding or remembering things (even recent events).
• They do not react to situations as quickly (if they spill a drink they may just stare at it).
• Their body movements are uncoordinated.
• They begin to lose their balance easily.
• Their vision becomes blurry.
• They may have trouble sensing things (hearing, tasting, feeling, etc.).

0.18-0.30

• They are confused -- might not know where they are or what they are doing.
• They are dizzy and may stagger.
• They may be highly emotional -- aggressive, withdrawn or overly affectionate.
• They cannot see clearly.
• They are sleepy.
• They have slurred speech.
• They have uncoordinated movements (trouble catching an object thrown to them).
• They may not feel pain as readily as a sober person.

0.25-0.4

• They can barely move at all.
• They cannot respond to stimuli.
• They cannot stand or walk.
• They may vomit.
• They may lapse in and out of consciousness.

0.35-0.50

• They are unconscious.
• Their reflexes are depressed (i.e. their pupils do not respond appropriately to changes in light).
• They feel cool (lower-than-normal body temperature).
• Their breathing is slower and more shallow.
• Their heart rate may slow.
• They may die.

Over 0.50

The person usually stops breathing or suffers cardiac arrest and dies.

(source)

Calculating your BAC

There are many BAC calculators on the Internet, however unless you take your laptop to a bar with an access point, these aren't much use when you're out on a Saturday night.

What we need, as atomicans, is a formula by which to calculate our BAC.

It is really a simple calculation:

BAC = volume of alcohol in the blood (g) / total blood volume (dl)

It would be difficult to work out the total weight of alcohol that is disbruted to your blood stream. But, it is, ultimately unecessary. If we know the amount of alcohol the person has consumed, we can simply work out the alcohol concentration in the total water in the body and multiply this by the concentration of water in the blood, 80.6%.

BAC = 0.8 (total alcohol ingested (g) / total water volume (dl)

Ofcourse, the body metablisises the alcohol over time

BAC = (weight of alcohol in the blood / total blood volume

But that won't work as the body doesn't strictly metabilise alcohol, but rather water, and with it the alcohol

BAC = 0.8 (total alcohol ingested (g) / total water volume (dl) - alcohol metabilised

To find the weight of alcohol ingested we could multiply the concentration of alcohol in the drink by the total size of the drink by 0.79 (the specific weight of alcohol). But, for simplicity sake we will use the standard drinks method. We need to know the number of standard drinks consumed (this is usually printed on the alcohol packaging). One standard drink is equal to 10 grams of alcohol. So to obtain the total alcohol ingested just multiply the no. standard drinks (d) by 10.

BAC = 0.8(10d/ total water volume) - alcohol metabilised

Total water mass (wm) can be found by multiplying body weight by the average amount of water in the human body. This is 49% for women and 58% for men.

wm(male)=0.58(body wieght)
wm(female)=0.49(body weight)

This gives us the water content in kg. Converting the weight of water into volume is simple since water has a specific gravity of 1. So to convert the kg to dl we multiply by 100

BAC = 0.8(10d / 100wm) - alcohol metabilised
    = 0.8(d/10wm) - alcohol metabilised

Metabolisism is hard to calculate with any degree of accuracy since so many factors can create variation. Alcohol itself varies the metabolic rate.

We can get a good estimate of the amount of alcohol metabilised, however by simply multiplying the time in hours since the first drink (t) was consumed by the average rate a person's BAC reduces by which is 0.017 per hour. We should also add 0.01 (20% of legal limit) on at the end to allow for tolerance. Better to be safe than sorry.

So that gives us our formula

BAC = (0.8(d/10wm) - 0.017t) + 0.01

• d = no of standard drinks consumed
• wm = water mass in kg
  • wm(male)=0.58(body wieght)
  • wm(female)=0.49(body weight)
• t = time since first drink in hours

It can also be said then that your blood alcohol concentration is equal to 80% of the number of standard drinks consumed over 10 times your water mass (which is approximately half a woman's body mass or 60% of a mans) minus 0.01 per 40 minutes since the first drink was consumed, add 0.01 for tolerance.

Simple right :P

(res)