UCSF

Background

Volatile organic compounds (VOC) from tobacco smoke are associated with cancer, cardiovascular, and respiratory diseases. The objective of this study was to characterize the exposure of nonsmokers to VOCs from secondhand smoke (SHS) in vehicles using mercapturic acid metabolites.

Methods

Fourteen nonsmokers were individually exposed in the backseat to one hour of SHS from a smoker seated in the driver's seat who smoked three cigarettes at 20-minute intervals in a stationary car with windows opened by 10 cm. Baseline and 0- to 8-hour postexposure mercapturic acid metabolites of nine VOCs were measured in urine. Air-to-urine VOC ratios were estimated on the basis of respirable particulate matter (PM2.5) or air nicotine concentration, and lifetime excess risk (LER) of cancer death from exposure to acrylonitrile, benzene, and 1,3-butadiene was estimated for adults.

Results

The greatest increase in 0- to 8-hour postexposure concentrations of mercapturic acids from baseline was MHBMA-3 (parent, 1,3-butadiene; 2.1-fold), then CNEMA (acrylonitrile; 1.7-fold), PMA (benzene; 1.6-fold), MMA (methylating agents; 1.6-fold), and HEMA (ethylene oxide; 1.3-fold). The LER of cancer death from exposure to acrylonitrile, benzene, and 1,3-butadiene in SHS for 5 hours a week ranged from 15.5 × 10(-6) to 28.1 × 10(-6) for adults, using air nicotine and PM2.5 to predict air VOC exposure, respectively.

Conclusion

Nonsmokers have significant intake of multiple VOCs from breathing SHS in cars, corresponding to health risks that exceed the acceptable level.

Impact

Smoking in cars may be associated with increased risks of cancer, respiratory, and cardiovascular diseases among nonsmokers.