Smoking just one cigarette can make a teenager a nicotine addict, according to a New Zealand study of 100,000 14 and 15-year-olds reported Thursday.
Teenage girls are at greatest risk of addiction because oestrogen, the hormone responsible for sexual maturity, increases the blood levels of nicotine, public health researcher Murray Laugesen told the New Zealand Herald.
"It's a hormonal effect," he said, noting that symptoms of tobacco addiction occurred earlier in girls than boys.
The paper described results of the survey he conducted with Robert Scragg of Auckland University and US researchers Robert J. Wellman and Joseph Difranza as groundbreaking.
They found that after smoking one cigarette 50 percent of teens questioned went on to become regular smokers. After 10 cigarettes, more than 80 percent smoked regularly.
The survey found that each subsequent cigarette meant a further slide towards addiction and after 100 cigarettes, 95 percent were regular smokers.
"We knew cigarettes were addictive," Laugesen said. "But what is new is we have related the addiction to the number of cigarettes. And that hasn't been done before."
Although it is illegal to sell cigarettes to people under 18, Laugesen said young people would always be able to obtain them as long as they were sold.
"Parents cannot protect their children from smoking," he said. "There is a case to consider the elimination of all sales over the next 10 years."