Suspected drink drivers could soon be told to put on a pair of earmuffs by police, if a new device comes to fruition.
Japanese scientists have developed a pair of earmuffs that can estimate blood alcohol levels based on ‘transcutaneous gas’ – gas released through the skin.
The earmuffs, presented as a proof-of-concept in a new study, detect ethanol compounds in transcutaneous gas released by the ears.
In trials, the device measured alcohol intake as well as a traditional breathalyser, although the process took a lot longer – more than two hours, compared with what can be just a few minutes for breathalysers when stopped on the roadside.
A schematic image of the monitoring system for external ear-derived ethanol that consists of earmuffs and an ethanol vapor sensor (bio-sniffer)
But a breathalyser test tends to be much more invasive, often requiring a tube to be inserted into the mouth.
Also, products such as mouthwash or breath spray can ‘fool’ some breathalysers by significantly raising test results. Listerine mouthwash, for example, contains 27 per cent alcohol.
It also measures other chemical compounds – acetone (a marker of lipid metabolism) and acetaldehyde (a known carcinogen detection in the body after drinking).
The device has been developed by a Japanese team led by Kohji Mitsubayashi at Tokyo Medical and Dental University.
‘We have investigated the possibility of external ears for stable and real-time measurement of ethanol vapour,’ they say in their study.
‘For stable monitoring of transcutaneous gas, finding a body part with little interference on the measurement is essential.
‘Transcutaneous gas is more suitable to real-time and continuous assessment than breath.’
Chemical compounds that are released through the skin reflect the chemical compounds present in blood circulating in the body – including those from alcohol (ethanol).
Admittedly, measurements of breath and ‘transcutaneous gas’ are not as accurate a measure of blood alcohol levels as blood and urine samples (although these are far more invasive).
ALCOHOL AND BREATHALYSERS
Alcohol, also known as ethanol, is the main ingredient of alcoholic drinks such as beer, wine, and liquor.
When you have an alcoholic drink, it is absorbed into your bloodstream and processed by the liver.
As the alcohol in the blood travels to the lungs, some of it will evaporate into the air in the tiny lung sacs known as alveoli, and be exhaled from the body (‘alcohol breath’).
It is this alcohol that a breathalyser is designed to measure. This is why it is necessary to measure deep lung air when using a breathalyser.
While a breathalyser gives fast results, it is not as accurate as measuring alcohol in the blood.
So no breath test is as accurate as a blood or urine test.
The team’s device consists of a modified pair of commercial earmuffs that collect gas released through the skin of a person’s ears, and an ethanol vapour sensor.
If the sensor detects ethanol vapour in the gas, it releases light of different intensities, depending on the ethanol concentrations detected.
In experiments, the authors used their device to continuously monitor ethanol vapour released through the ears of three male volunteers.
Firstly, base ethanol concentrations from the transcutaneous ear gas was measured for 10 minutes without drinking alcohol.
Then the volunteers drank alcohol at the concentration of 0.4 g per kg body weight within five minutes, and the measurement continued for another 140 minutes.
The ethanol concentrations of the volunteers’ breath were also measured at regular intervals using an additional ethanol vapour sensor and a device containing reagents that change colour when exposed to ethanol.
The authors observed that changes in the concentration of ethanol released through the ears and breath were similar over time for all volunteers.
As previous research found that ethanol concentrations in the breath and blood are correlated, this indicates that the device could be used instead of a breathalyser to estimate blood alcohol levels.
Results from the earmuffs were comparable to a breathalyser – but a breathalyser test is much more invasive, requiring a tube to be inserted into the mouth. Pictured, an Australian officer using breathalyser on driver Products such as mouthwash or breath spray can ‘fool’ some breathalysers by significantly raising test results. Listerine mouthwash, for example, contains 27 per cent alcohol.
The average highest concentration of ethanol released through the ears was found to be 148 parts per billion.
Previous devices have used the hand to measure blood alcohol levels as a less invasive alternative to putting a tube into someone’s mouth.
But 148 parts per billion is double the concentration previously reported to be released through the skin of the hand, the researchers say, suggesting the ears may be more suitable.
Also, sweat coming from sweat glands in the hand can interfere with readings, the researchers point out. In comparison, an external ear canal has no eccrine sweat gland.
‘Each body part has different density of sweat glands and epidermis layers of the skin,’ they say. ‘Therefore, it is important to choose a proper body region.’
The authors also propose that the device could be used to measure other gases released through the skin, for example in disease screening.
The study has been published in Scientific Reports.
DO YOU DRINK TOO MUCH ALCOHOL? THE 10 QUESTIONS THAT REVEAL YOUR RISK
One screening tool used widely by medical professionals is the AUDIT (Alcohol Use Disorders Identification Tests). Developed in collaboration with the World Health Organisation, the 10-question test is considered to be the gold standard in helping to determine if someone has alcohol abuse problems.
The test has been reproduced here with permission from the WHO.
To complete it, answer each question and note down the corresponding score.
0-7: You are within the sensible drinking range and have a low risk of alcohol-related problems.
Over 8: Indicate harmful or hazardous drinking.
8-15: Medium level of risk. Drinking at your current level puts you at risk of developing problems with your health and life in general, such as work and relationships. Consider cutting down (see below for tips).
16-19: Higher risk of complications from alcohol. Cutting back on your own may be difficult at this level, as you may be dependent, so you may need professional help from your GP and/or a counsellor.
20 and over: Possible dependence. Your drinking is already causing you problems, and you could very well be dependent. You should definitely consider stopping gradually or at least reduce your drinking. You should seek professional help to ascertain the level of your dependence and the safest way to withdraw from alcohol.
Severe dependence may need medically assisted withdrawal, or detox, in a hospital or a specialist clinic. This is due to the likelihood of severe alcohol withdrawal symptoms in the first 48 hours needing specialist treatment.