This time, the authors followed for 10 years the 79,990 women in the Women's Health Initiative Observational Study and concluded that, compared to women who had never smoked, former smokers had a 9% higher risk of breast cancer, whereas current smokers had a 16% higher risk. In fact, the highest risk for breast cancer was found in those who had smoked for 50 years or more compared to those who had never smoked.
Amongst never smokers, those with the most passive exposure had a 32% greater risk of developing breast cancer compared to those without such exposure. So just what constitutes excessive passive exposure? Ten or more years during childhood, 20 or more years as an adult at home, and/or 10 or more years as an adult at work. In particular, the last qualification has some very significant public health & legislative implications , even in our fair city, where just about anything goes.