Use of environmental tobacco smoke constituents as markers for exposure

The 16-City Study analyzed for gas-phase environmental tobacco smoke (ETS) constituents (nicotine, 3-ethenyl pyridine [3-EP], and myosmine) and for pa rticulate-phase constituents (respirable particulate matter [RSP], ultravio let-absorbing particulate matter [UVPM], fluorescing particulate matter [FP M], scopoletin, and solanesol). In this second of three articles, we discus s the merits of each constituent as a marker for ETS and report pair-wise c omparisons of the markers. Neither nicotine nor UVPM were good predictors f or RSP. However, nicotine and UVPM were good qualitative predictors of each other. Nicotine was correlated with other gas-phase constituents. Comparis ons between UVPM and other particulate-phase constituents were performed. I ts relation with FPM was excellent, with UVPM approximately 11/2 times FPM. The correlation between UVPM and solanesol was good, but the relationship between the two was not linear. The relation between UVPM and scopoletin wa s not good, largely because of noise in the scopoletin measures around its limit of detection. We considered the relation between nicotine and saliva cotinine, a metabolite of nicotine. The two were highly correlated on the g roup level. That is, for each cell (smoking home and work, smoking home but nonsmoking work, and so forth), there was high correlation between average cotinine and 24-hour time-weighted average (TWA) nicotine concentrations. However, on the individual level, the correlations, although significant, w ere not biologically meaningful. A consideration of cotinine and nicotine o r 3-EP on a subset of the study whose only exposure to ETS was exclusively at work or exclusively at home showed that home exposure was a more importa nt source of ETS than work exposure.