Alcohol in blood damning piece of proof

MUMBAI: Janhavi Gadkar’s blood alcohol content, which sources alleged was four times the permissible limit, seems to be the most damning piece of evidence against the lawyer who had to be extricated from the car crash site early on Tuesday, say criminal and forensic legal experts.
The permissible level of alcohol is 30mg per 100ml of blood. The blood alcohol content (BAC) depends on several factors, including the amount consumed, the time lag between the end of drinking and collection of a blood sample, and the person’s weight.
Experts say RCF police’s evidence against Gadkar would be “staggering and tight” if her blood report is correct.
Rukmani Krishnamurthy, former director of Directorate of Forensic Science Labs and now chief of Helik Advisory, said alcohol tests range from basic breath to blood tests.
Breath tests are the most common as the analysis devices—breathalyzers—are lightweight, portable and provide immediate results. Breathalyzers measure the alcohol that passes through alveoli air sacs as blood flows through vessels in the lungs, and is expelled on a subject’s breath. Breathalyzer results, particularly those derived from fuel cell sensor breath tests, are considered sufficiently accurate.
But what holds good as evidence during trial is the chemical analysis done at forensic science labs. Such tests determine the blood-alcohol concentration by gas chromatography of a suspect, and yield more concrete evidence of intoxication. Krishnamurthy said gas chromatography gives an accurate percentage of alcohol in blood.
BAC is usually expressed as a percentage of ethanol in blood in units of mass of alcohol per volume of blood.
Alcohol is quickly absorbed into the blood stream and can be measured within minutes of a drink. Its absorption is faster on an empty stomach, says the expert. “The amount of alcohol in the blood reaches its highest level about an hour after drinking. But food pushes up the time.’’
Around 90% of alcohol is broken down in the liver. The rest of it passes out in urine and exhaled breath. Alcohol has a noticeable effect on the body, even when consumed in small amounts. In large quantities, it acts as a sedative and depresses the central nervous system, say doctors. As a forensic test tool in criminal cases, especially in drunk driving crashes where lives are taken, these lab tests form a crucial basis in the evidence link during court trials.
Alcohol tests “should be done as soon as possible as with time, the content may drop,’’ said Krishnamurthy.