New York, Dec 24 (IANS): Even if you consider yourself a light or "casual" smoker, it does not necessarily mean that you have completely escaped nicotine addiction, warns new research.

Many light smokers -- those who smoke one to four cigarettes per day or fewer -- meet the criteria for nicotine addiction and should therefore be considered for treatment, said the study published in the American Journal of Preventive Medicine.

"In the past, some considered that only patients who smoke around 10 cigarettes per day or more were addicted, and I still hear that sometimes," said Jonathan Foulds, Professor at Pennsylvania State University in the US.

"But this study demonstrates that many lighter smokers, even those who do not smoke every day, can be addicted to cigarettes. It also suggests that we need to be more precise when we ask about cigarette smoking frequency."

The researchers examined an existing data set from the National Institutes of Health in the US, including more than 6,700 smokers who had been fully assessed to find out if they met the 11 criteria listed in the 5th edition of the Diagnostic and Statistical Manual (DSM-5) for tobacco use disorder.

They found that 85 per cent of the daily cigarette smokers were addicted to some extent -- either mild, moderate or severe addiction.

"Surprisingly, almost two thirds of those smoking only one to four cigarettes per day were addicted, and around a quarter of those smoking less than weekly were addicted," Foulds said.

The researchers found that the severity of cigarette addiction, as indicated by the number of criteria met, increased with the frequency of smoking, with 35 per cent of those smoking one-to-four cigarettes per day and 74 per cent of those smoking 21 cigarettes or more per day being moderately or severely addicted.

"Lighter smoking is correctly perceived as less harmful than heavy smoking, but it still carries significant health risks," said Jason Oliver, Assistant Professor at Duke University in the US.