Cotinine for assessment of passive smoking
We all know that passive exposure to smoke is equally if not worse than active smoking. Only difference is that the quantum of smoke inhaled is likely to be lesser with passive smoking. This may not be very true in the case of small children whose parents smoke. Cotinine is a metabolite of nicotine and estimation of cotinine levels can be used to assess the level of smoking better than a questionnaire, due to obvious errors in individual assessments. Cotinine can be detected even upto a week after smoking. Levels in blood, urine and saliva are proportionate to the level of exposure to tobacco.
A recent recent study published in the prestigious journal Circulation used cotinine levels to assess the passive smoking levels in children of parents who smoked. The study found that children with higher cotinine levels due to passive smoking of one or both parents had higher chance of plaque deposition in their blood vessels to the brain (carotid arteries). The study also documented that children of parents who had good ‘smoking hygiene’ (not smoking in the vicinity of the child) had lower levels of plaques and undetectable levels of cotinine in blood. The participants were from the Cardiovascular Risk in Young Finns Study involving about 2500 children. It is interesting to note that the blood samples were drawn in early 1980s when the study started and the cotinine levels were estimated in frozen samples in 2014!