Smokers from lower socioeconomic groups also have a higher smoke intake and may thus be more nicotine dependent [ 44], making smoking cessation more difficult.
These effects may vary due to reinforcer magnitude and amount of acute smoke intake (dose).
In the most extreme example, in a test carried out in 1987, the "real smoking" machine drew 86% more nicotine and 114% more tar from Player's Extra Light than the ISO machine detected, although smoke intake was only 27% higher.Regardless of how this came about, the irony is that low-tar brands may have ended up causing more health problems than high-tar ones.
The dose and rate of nicotine administration were individualized based on previous measures of ad lib smoke intake.
These confounding variables included body mass index (kg m−2), smoking status (never, ex-smoker and current smoke), ethanol intake (current drinker or not), daily green tea intake (yes or no) and work schedule (rotating-shift or not).
In the general population, the primary sources of cadmium exposure are cigarette smoke, food intake (shellfish, offal, certain vegetables), and ambient air particularly in urban areas and in the vicinity of industrial settings.
Exposure to styrene in the general population occurs at levels of micrograms per day due mainly to inhalation of indoor air and cigarette smoke and intake of food that has been in contact with polystyrene.
We performed additional analyses to examine associations of active smoking, grilled and smoked meat intake, and a combined measure of these factors with p53 mutation status, type, and effect using referent groups consisting of never smokers with low lifetime grilled and smoked meat intake.
For PAH DNA adducts, potential confounders were age at menarche, income, smoking status, and grilled and smoked meat intake.
For example, examining associations between current smoking and insertions/deletions and between grilled and smoked meat intake and G C→A T transitions at CpG sites yielded ORs of 3.06 (95% CI, 0.87 10.77) and 2.68 (95% CI, 0.89 8.09), respectively [see Supplemental Material, Table 2 (doi:10.1289/ehp.0901233)].
The questionnaire detailed the daily average number of cigarettes smoked, daily intake of tap water, coffee, and tea, and weekly consumption of wine, beer, cider, and liquors.
