Environmental Tobacco Smoke Measuring Exposures and Assessing Health Effects (1986) / Chapter Skim
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7 Exposure-Dose Relationship for Environmental Tobacco Smoke
7 Exposure-Dose Relationship for Environmental Tobacco Smoke
Pages 120-132
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From page 120... ...
For nonsmokers, the exposure is usually characterized in terms of particle or gas concentration in micrograms per cubic meter. But what is known about the total integrated close to the respiratory tract resulting from exposure to ETS by nonsmokers?
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From page 121... ...
If the geometric size, shape, and density of the individual particles or droplets are known, then the distribution of particle diameters can be described. Because it is a better predictor of the behavior of the particle in the respiratory tract, aerodynamic diameter rather than optical measurement is used to express the range of particle sizes.
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From page 122... ...
. BREATHING PATTERN Particle size is a critical factor in determining the collection efficiency, but breathing pattern is also important For example, large slow tidal volumes will favor alveolar deposition, while high inspiratory flows will promote deposition at bifurcations in the airways.
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From page 123... ...
DEPOSITION OF CIGARETTE SMOKE PARTICLES The factors discussed in the previous sections indicate that experunental measurements of the concentration of smoke aerosols in Floor environments, i.e., exposure concentrations, are insufficient for predictions of smoke deposition. ETS smoke is constantly changing, thereby complicating the collection of accurate and reproducible data regarding its particulate size.
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From page 124... ...
(1983) added an oropharyngeal compartment and a replica cast of the larynx to tile tracheobronchial casts in order to better simulate airflow patterns in the upper respiratory tract.
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From page 125... ...
This would be approximately 0.005~o to 0.26~o of that amount of tar deposited In the active smoker's lungs after smoking 20 cigarettes. The active smoker, of course, also breathes the ETS, so that the total dose received by the active smoker is the mainstream smoke plus a passive smoking dose equivalent to that received by the
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From page 126... ...
More data on the fate of BaP in ETS and on ambient concentrations are needed before estimates of the relative doses can be made meaningfully. Although the amount of smoke deposited in the lungs of nonsmokers during exposure to ETS is small compared with that encountered by the active smoker regarding mainstream smoke, it may differ in composition and toxicity.
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From page 127... ...
Clearance mechanisms in smokers may be further compromised by Jung diseases, such an emphysema and fibrosis, and by exposure to other air pollutants. Measurements of the long-term retention of compounds associated with cigarette particulates in the lungs are difficult to estimate from ciata obtained with airway casts or from differences between inhaled and exhaled aerosol concentration, since these methods do not take into account clearance mechanisms.
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From page 128... ...
Moreover, this would occur rapidly, so that acrolein is classified as an upper respiratory tract irritant. According to Table 2-10, there are between 60 and 100 fig of acrolein generated per cigarette.
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From page 129... ...
The extent to which these are indicative of the relative exposures to specific constituents that are important for particular health effects in active smokers or in nonsmokers exposed to ETS cannot be determined for any of the health ejects reviewed later in this report. Nevertheless, the estimated relative exposures give
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From page 130... ...
that are most relevant to the health effect being assessed. However, many of these specific constituents, for instance the carcinogenic constituents such as benzotaipyrene, Nnitrosodimethylam~ne, and N-nitrosodiethylam~ne, are difficult to measure; therefore, there are not enough data available to make meaningful estimates of the relative doses of these constituents.
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From page 131... ...
Bone. Human respiratory tract deposition using multimodal aerosols.
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From page 132... ...
SchlesingerR.B.~andh4.Llpp=~nn. Pa~lc~ deposhlonluc~stsoftbobum~n uppertrscheobronchl~ltree.
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