Non-smokers at risk if living with smokers

Non-smokers or those who have quit smoking but who live with someone who smokes continue to be at risk from second-hand smoke, British researchers said.

Researchers at University College London and St. George’s, University of London measured recent exposure to tobacco smoke in non-smoking middle-aged men by measuring levels of cotinine — a compound carried in the blood — at points 20 years apart.

A blood cotinine level more than 0.7 nanograms per milliliter is associated with a 40 percent increase in the risk of a heart attack and other studies have suggested that even a level of 0.2ng/mL may increase the risk, the researchers said.

The researchers found that while in 1978-80, 73 percent of men had a cotinine level more than 0.7ng/mL, by 1998-2000 that proportion had fallen to 17 percent.

However, despite the number of non-smoking men at risk having fallen, half of those who still had a high cotinine level — more than 0.7 ng/ml — in 1998-2000 lived with a partner who smoked. Non-smoking men who had a partner who smoked had average cotinine levels of 1.39ng/mL, almost twice the level associated with an increased risk of a heart attack.

Their cotinine levels were nearly eight times higher than the cotinine levels of men whose partner didn’t smoke, the researchers said.