Table 3.

Parameters used to estimate air-to-urine ratio of VOC and computations of LER of cancer from exposure to acrylonitrile, benzene, and 1,3-butadiene

ParametersAcrylonitrileBenzene1,3-Butadiene
Background-corrected PM2.5 measured in car (μg/m3)a1,1551,1551,155
Background-corrected nicotine measured in car (μg/m3)a65.565.565.5
Baseline-corrected 0–8-h urine VOC (ng/mg creat)0.9150.1090.275
Baseline-corrected max urine VOC (ng/mg creat)1.1500.1440.429
PM2.5 EF (μg/cig)b1,24711,24711,2471
Nicotine EF (μg/cig)b1,2741,2741,274
VOC EF (μg/cig)b170431279
Adult respiration rate—sedentary (≥19 y), (m3/h)0.50.50.5
Average hours per day exposed in car (h/d)111
Days per week exposed to SHS in car (d/wk)555
Number of years exposed to SHS515151
A. Estimation of air to urine VOC ratio using PM2.5
 Estimated air VOC levels based on air PM2.5 (μg/m3)15.739.925.8
 Air VOC to 0–8 h urine VOC ratio (μg/m3)•(ng/mg creat)−117.2366.294.0
 Air VOC to max urine VOC ratio (μg/m3)•(ng/mg creat)−113.7277.460.3
B. Estimation of air to urine VOC ratio using air nicotine
 Estimated air VOC levels based on air nicotine (μg/m3)8.7422.214.3
 Air VOC to 0–8 h urine VOC ratio (μg/m3)•(ng/mg creat)−19.55203.352.2
 Air VOC to max urine VOC ratio (μg/m3)•(ng/mg creat)−17.60154.033.4
C. Lifetime excess risk (LER) for cancer deaths
 EPA AUR (×10−6)687.830
 LER for VOC predicted from PM2.5 (×10−6)13.94.110.1
 LER for VOC predicted from air nicotine (×10−6)7.72.25.6

NOTE: U.S. EPA AUR are obtained on EPA's Integrated Risk Information System at http://www.epa.gov/iris/.

  • aCorrected PM2.5 and nicotine = inside concentration minus outside concentration.

  • bEFs are average values of published SHS EFs and summarized by Liu and colleagues in a Supplementary Material (25).