WHEN you drive a motor vehicle after drinking alcohol — be it wine, beer, rum, Baileys, vodka, or other spirits — how many drinks do you think you would need in your system to fail a breathalyser test?

Is it two, three, four, five, or six drinks? You really don’t know, do you? You simply assume that since you do not feel impaired or drunk, then you are okay to drive!

Well, the issue is not as clear and straightforward as you would presume, and such an approach has caused many to be charged with driving drunk or driving under the influence of alcohol.

Passing a breathalyser test after you have been drinking depends on several factors, including the quantity of alcohol consumed per unit time, your body weight, and the metabolic efficiency of your liver. Many countries have set a limit of 0.08 per cent blood alcohol concentration (0.04 per cent for commercial drivers), above which individuals may be charged for driving while impaired.

Blood alcohol concentration

We should note that our blood alcohol concentration begins rising within 15 minutes of completing our first drink. Research done at the University of New Mexico in the USA and the National Highway Traffic Safety Administration revealed data which showed progressive impairment with alcohol consumption.

Using beer as an example, after two beers there was some loss of judgement and individuals had trouble doing and completing two tasks at the same time. After three beers the person had reduced coordination, some difficulty steering, and reduced ability to track moving objects.

After four beers the person had difficulty processing information and difficulty reasoning, and if driving, difficulty controlling speed. After five beers there was a marked slowing down of reaction time, with difficulty staying within the driving lane and braking when needed. After seven beers the person had serious difficulty focusing on driving and controlling the motor vehicle.

Researchers were therefore able to plot a graph based on a person’s body weight, the number of drinks they consume, and the consequent blood alcohol level each hour. Based on the blood alcohol level, individuals were classified as possibly impaired, distinctly impaired, and legally intoxicated.

Safe drinking

Based on the results, individuals were advised not to take more than one standard drink (that is one five-ounce glass of wine, one 12oz bottle of beer, one 1.5oz shot of distilled spirits, etc) per hour, as that would keep their blood alcohol level under the legal limit of 0.08 per cent. Anything above that rule of thumb may cause impairment.

The graph showed that for men with a weight of 140-200 lb, they were possibly impaired if they drank two drinks within the space of one hour. They were distinctly impaired if they drank three, and were legally intoxicated if they drank four or more drinks within the hour.

In comparison, women in the weight range of 140-200 lb were distinctly impaired if they drank two drinks within the hour. Three drinks or more rendered them legally intoxicated. Further, once individuals reach the blood alcohol concentration of 0.08 per cent, it takes 5.3 hours for the alcohol to be metabolised by the liver and be eliminated from your body.

Hence the advice, stick to no more than one drink each hour!

Additional harm

We should note that like many other countries in the Caribbean, Jamaica reportedly has more bars than churches. Our 300-year history of sugar cane fermentation and rum distillation has rendered alcohol consumption commonplace in every community and virtually within every family. Consequently, when individuals consume alcohol we customarily do not become very concerned unless its consumption is likely to cause harm to others.

However, habitual alcohol consumption can have harmful effects on the person (for example liver damage, alcohol dependency, diabetes, cancer, etc), as well as on the family, directly depriving them of finances. The intoxicated person may also subject members of the family to emotional or physical abuse. Additionally, third parties may also be harmed in the process, particularly when impaired individuals get behind the wheel of a motor vehicle.

Affecting the high and low

People from all social classes in our society have problems with alcohol, and alcohol addiction is sometimes the bane of some families. So, in light of the social harm that alcohol can cause across all societies, many cultures, religious groups, and countries have banned its use, while others have come full circle in permitting access to alcohol but limiting its sale to adults only. While it is unfortunate that the latter is not strongly enforced, it is incumbent on us to positively influence all who indulge, and guide them using the outcome of research which indicates they should have no more than one drink per hour. We owe our society that much!

Dr Derrick Aarons MD, PhD, is a Jamaican family physician and consultant bioethicist; a specialist in ethical issues in health care, research, and the life sciences; and is the health registrar and head of the health secretariat for the Turks & Caicos Islands.