The quantitative estimation of toxicant dose to cigarette smokers
For the risk assessment of cigarette smoke, a reliable estimate of the mass of chemical compounds retained in the body would be beneficial. Filter studies provide estimates of mouth exposure to compounds in cigarette smoke, but do not account for mouth spill and respiratory retention. Except for nicotine, biomarkers provide the relative uptake of certain compounds when comparing products, but generally do not provide quantitative uptake values. In addition, many compounds of interest do not have reliable biomarkers. Estimates of the respiratory retention and mouth spill allow mouth exposure to be converted to a quantitative estimate of dose. A method to estimate respiratory retention of compounds from cigarettes smoke was presented at the 64th TSRC. A method of estimating mouth spill is shown using data from two clinical studies. Mean values of mouth spill from both studies were slightly greater than 30% with a mid-quartile range of 20 to 45%. Mouth exposure, respiratory retention and mouth spill combine to allow a quantitative estimation of smoker uptake for almost any chemical compound that can be measured analytically. The samples needed from subjects are spent filters and a 24-h urine sample. These could be obtained from ambulatory studies which would have a minimal influence on smoker behavior.