Unknown exposure to second­hand smoke may

• US researchers have identified a new biomarker which revealed that known and unknown
• exposure to second­hand smoke may lead to an increased risk of mortality in non­smokers.
   
• Serum cotinine — a metabolite of nicotine — when used as a biological marker of exposure to secondhand
• smoke was found to have associations to overall and cause­specific mortality in non­smokers.
• Increased levels of serum cotinine in blood were significantly also associated with all types of cancers, and heart disease, the researchers said.
• “The study found that non­smokers are exposed to second­hand smoke without even realising it,” said Raja Flores, Professor at the Icahn School of Medicine at Mount Sinai in New York, US.“9/28/2016 Unknown exposure to second­hand smoke may cause early death | 
• Non­smoking individuals’ cotinine blood levels accurately determined their exposure and subsequent risk of lung cancer and other smoking­related disease, Flores said.
• “Using cotinine level to measure exposure to second­hand smoke has important public health implications, because increasing the scope of smoke­free environments would likely decrease cotinine levels in the general population and ultimately death,” added Emanuela Taioli, Director at Mount Sinai.
• Further, exposure to second­hand smoke is unequally distributed in the population, the researchers said, adding that children, people living in poverty, and those who rent their housing are disproportionately affected and most vulnerable.
• The study, published in the journal Carcinogenesis, provides a more accurate way to gauge second­hand
• smoke exposure. It also presents a strong case for more stringent limits on smoking and increased preventive screenings for those more likely to have been exposed to second­hand smoke.
• For the study, the team examined 20,175 non­smokers. After adjustment for sex, education, race/ethnicity, body mass index, and smoking habits, their analysis showed a significant increase in years of life lost across cotinine concentrations.
• In the adjusted analysis, the lowest quartile of cotinine concentration — below the detectable level —
• was associated with 5.6 years of life lost while the highest quartile was linked to 7.5 years of life lost.
• A stricter legislation establishing smoke­free areas, together with education efforts in low­income and
• minority communities, is imperative, the researchers concluded.

Unknown exposure, second­hand, smoke may