"To investigate the association between environmental tobacco smoke, plasma cotinine concentration, and respiratory cancer or death, researchers carried out a nested case-control study within the European prospective investigation into cancer and nutrition (EPIC) involving 303 020 people from the EPIC cohort (total 500 000) who had never smoked or who had stopped smoking for at least 10 years, 123 479 of whom provided information on exposure to environmental tobacco smoke. Cases were people who developed respiratory cancers or died from respiratory conditions. ... The main outcome measures were newly diagnosed cancer of lung, pharynx, and larynx; deaths from chronic obstructive pulmonary disease or emphysema."
"The researchers concluded: “This large prospective study, in which the smoking status was supported by cotinine measurements, confirms that environmental tobacco smoke is a risk factor for lung cancer and other respiratory diseases, particularly in ex-smokers."
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