Intoxication, in its usual context, relates to a high blood alcohol content (BAC), expressed as a percentage of ethanol in the blood. However it can also be related to illegal and prescription drugs such as amphetamines, cannabis, cocaine and opiates.

The BAC is used as a metric of alcohol intoxication for medical and legal purposes. As Australia occupies a top 10 place in international rankings of highest alcohol consumption per capita, blood alcohol toxicology is a particularly relevant field.

Consuming alcohol faster than the body can metabolise it results in alcohol intoxication, which causes progressive impairments to coordination and decision making. Symptoms can include confusion, blurred vision, slower reaction times, loss of balance, nausea and memory loss. An extremely high BAC, for example from binge drinking, can even result in coma or death. Chronically high BAC can lead to many health problems including cirrhosis of the liver, dementia, high blood pressure and jaundice.

Being under the influence of alcohol places individuals at a greater risk of being either a perpetrator or victim of crime. Intoxication increases the likelihood of engaging in risky and reckless behaviours as drinkers lose the ability to make rational decisions. A high number of violent and sexual assaults involve at least one party under the influence, and roughly half of traffic injuries involve alcohol.

Many industries have restrictions on the BAC of their workers. For workers operating machinery or driving heavy vehicles, they must have a BAC of near zero. Pilots and others operating in the aviation industry such as air traffic controllers must not have consumed alcohol for eight hours before the commencement of work, as well as refrain from consuming amphetamines, cannabis, cocaine and opiates. Some workplaces implement alcohol and drug testing as a protocol, engaging in pre-employment screening or random tests.


Expertise in Action

The consumption of alcohol, while a legal substance for adults, always carries some degree of risk. These risks increase as more alcohol is consumed and motor skills become increasingly uncoordinated. As well as risks at the time of drinking, consumers of alcohol also expose themselves to more long-term risks and medical researchers are constantly discovering new links between casual, binge or chronic alcohol consumption and adverse health effects. For newer drugs such as ecstasy and its variants, the long term effects are yet to be fully understood by medical researchers, especially when mixed with other illegal and prescription drugs.

While most people are able to process one standard drink of alcohol per hour, experts are needed to properly consider the numerous variables that render this inexact. Factors dictating the alcohol absorption rate for different consumers include their size, genes and health, whether they are a regular drinker, and whether they have consumed other drugs.

Claims related to blood alcohol toxicology usually result from alleged driving under the influence, or in alleged unfair dismissals from workplaces with a zero BAC limit. The influence of alcohol also plays a unique and critical role in many sexual assault cases. In many Australian states individuals are considered incapable of consenting if they are extremely intoxicated.

Toxicologists serving as expert witnesses in cases with blood alcohol as a factor are frequently faced with questions involving estimation of BAC from given consumption or estimating the consumption required to reach a measured BAC. Consulting toxicologists can use retrograde extrapolation techniques to obtain a BAC some time after the event, and can also conduct post-mortem forensic evaluations with regards to BAC. The opinions they provide can be useful to plaintiffs and defendants alike.

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