Tobacco Documents Online

Mr. Repace also concludes that his illustration provides results consistent with those shown in figure 5 for the "Six City Study." Without some quantitative information the subject of consistency admits broad interpretation, with one possible interpretation being that there. is no adequate degree of consistency to justify use of the model. One can reasonably assume that the heating season includes the months from October to March. To be valid and therefore useful the model must be able to predict the large variability shown in the results for the cases of one smoker and more than one smoker. It is important to note that the categories for the field results differ from those of the model results thus constraining the ability to compare between the two. Taking March 1978 as an example, field measurements show a mean RSP level of 35 µg/m3; by contrast the model predicts 44 µg/m3, a bias of 26 %. Mr. Repace apparently attaches significance to his prediction of 84 ug/m3 for his :,cenario of three "habitual smokers." How this result is consistent with a measured result for "greater than one smoker" (whether this average smoker is "habitual" is unknown) is unclear. 6 Mr. Repace provides another example to "validate" the model. He starts by noting the "large impact" caused by smoking on the levels of RSP. This "large impact" is 10 ug/m3 for an assumed occupation of the room by one "habitual smoker." If the author is to make such a statement it would be instructive to know what represents a "low impact." Mr. Repace next proceeds to calculate the RSP level for the case of a chain smoker, one, who according to Mr. Repace, is consuming cigarettes at a rate of six cigarettes per hour. The reader can only assume the purpose of this example, since its representat'iveness is unknown and since it delves into the world of the bizarre. Is the reader to assume that this smoking rate continues (as it must if the model is to be appropriate as defined by Mr. Repace)? If this assumption is taken to its illogical end, the reader must conclude that the person is smoking almost five packs of cigarettes per day and gobbling food between puffs. In the same paragraph Mr. Repace notes that ETS can be very persistent, taking, for example, 3 hours for 95 % removal. The reader can only speculate why this factor was riot taken into account when Mr. Repace "modeled" RSP in the forgoing example dealing with homes. Instead he assumes that RSP exists only during the 16 hours he associates with the "habitual smoker" being awake. . Cb Mr. Repace then shares with the reader "several interesting factors" revealed ~ by recent research. He relies on a personal communication to provide this N Ctt 11 W

i information. Although it is certainly possible that floor-to-floor communication of RSP can occur, the significance of such communication and its representativeness are unknown. Mr. Repace is specul,iting; the paragraph should either be omitted or the above issue should be addressed with scientific data. The paragraph discussing work by Williams and coworkers should be omitted. Green and coworkers (1985) published a letter (In the same journal that contained the paper by Williams and coworkers) that discredited the method, results, and conclusions reported by Williams and coworkers. Following his citation- of the paper by Williams and coworkers, Mr. Repace presents results from surveys of air exchange rates done in offices. This information does not fit within the paragraph. P: can be assumed that the author might be attempting to make a point about values for air exchange rates in offices; however, the information he provides, specifically, only mean air exchange rates, is insufficient to be useful for one interested in assessing the assumption of his model. The information on air exchange rates might be useful if ranges and standard deviations were provided. Mr. Repace's summary to Section B is unsupported. To his credit he notes that "limited" field tests of the general equilibrium mcdel have been done. This reviewer is concerned that Mr. Repace may be statirn3 that the two examples he provides in the section represent the limited field i:ests. If these indeed are the limited field tests, then Mr. Repace is not applying the scientific paradigm, which would require that the model predictions be performed before the field measurement rather than after as he has done in all his manuscripts where the model is used. On the contrary, the model does not predict RSP levels reasonably well, rather, the model can be manipulated so that its "predictions" agree with results from field studies selected by author. Rather than being "clear that both models and observations ... yield consistent results," it is clear that whether they can or cannot is open to question. Mr. Repace's concluding statement in this paragraph is at odds with the data he uses to "validate" his model. If the statement "RSP levels wnen smoking is allowed will result in substantial increases over RSP levels ir nonsmoking occupancy" is true, how can it be that the Data of Figure 5 show essentially no differences among RSP levels in June 1977 for "outdoor," "indoor," "no smokers," and "indoor one smoker"? The reader deserves to know the meaning of "substantial" in quantitative terms. 12

I C. Measured concentrations of RSP From ETS t L 0 L Figure 8, which shows results from RSP measurements arid predictions and National Ambient Air Quality Standards (NAAQS) is inappropri<<te and should be omitted. Users of the Compendium can be expected to misunderstand and misinterpret this presentation. While there are several reasons why inclusion of NAAQS levels is inappropriate, the major one deals with averaging times. Assuming all other factors the same, the averaging times for the measurements and the standards must be the same for comparisons to be meaningful, as distinguished from appropriate. The U.S. EPA has algorithms which the author should use to adjust for averaging times. Even if all information was Fresented on the same time scale, discussions of exceedances would be meaningless, since from a regulatory standpoint criteria documents, standards, and reference methods do not exist. The data reported by Repace and Lowrey are on the timia scale of minutes. If the standards were adjusted to that same basis, it is reasonable to assume that all these data would be below adjusted "standards." If this presentation is to be included in the Compendium, the standards should be adjusted to time scales equivalent to those of the measured RSP values. Associating the Table with IARC is unnecessary and misleading; only the first published reference need be identified: Repace and Lowrey, 1980. The quality of the data reported by Repace and Lowrey in Figure 8 is unknown; nonetheless, it is known that these results are biased high because no apportionment was made for sources of RSP other than ETS. The degree of Has also is unknown. The representativeness of the sample population is qui!stionable. Results from surveys conducted since 1980 (Repace and Lowrey's experimental approach cannot properly be categorized as a survey) indicate that '2epace and Lowrey's sample population is probably nonrepresentative. Mr. Repace infers from his few measurements of questionable quality and representativeness that "the bulk of the RSP found in buildings where there is smoking is due to ETS." By selective referencing he is able to suggest that 85% of the indoor RSP in those buildings is due to ETS. Since 1980, surveys done in offices show mean RSP levels of approximately 125 µg/m3, a result indicating that Repace and Lowery's data base is probably biased. In addition, methods capable.of apportioning ETS have shown that less than half of the RSP found from surveys can be attributed to ETS (Ogden, TCRC 1989). Again, the data base of Repace and Lowrey is indicated to be biased. 13 L

Table 8 contains mostly old literature citations. Many more investigations have been conducted since this table was published in 1986. In addition, the reference to the U.S. Department of Transportation study done in aircraft cabins is incomplete since results were provided in that report. The mean level of RSP in cabins before smokers were segregated was only 40 ug/m3. (The reviewer recommends that Mr. Repace address this result with the equilibrium model.) Mr. Repace notes that in a setting such as a work environment, where the average exposure is several hours, ETS would be expected to disseminate throughout the airspace where smoking is occurring. Inasmuch as no data are available to support this speculation, the author should drop thi> statement from the text. Similarly, 'Mr. Repace speculates about exposures in transit and selectively references his paper (Repace, 1988) in connection with ETS in aircraft. Mr. Repace omits all otfier references surrounding his paper (Oldaker, Environ. Sci. Technol. 1987, 1988) and fails to inform the reader i:hat his position is based on an assumed relationship between RSP and nicotine. Specifically, Mr. Repace assumes that a constant ratio exists between the two indicators thereby allowing him to predict RSP from nicotine. Oldaker (Environ. Sci. Technol. 1988) has addressed some of the assumptions contained in this approach and Oldaker and coworkers (Excerpta Medica Interantional Congress Series 1989) have presented results showing that ratios have no predictive value. D. Exposure of Nonsmoking populations to ETS U The first paragraph of this section addresses risk, a subject which is inappropriate for•inclusion in view of the absence of risk assessment results. Mr. Repace identifies the Seventh Day Adventists as a subpopulation where few of its members are nonsmokers. The connection between this population and lung cancer incidence is unclear; the author should clarify the importance of this subgroup within the discussion. The author identifies cotinine as an indicator of exposure to ETS. Although cotinine is related to nicotine exposure because cotinine is a nicotine metabolite, the relation between cotinine levels in body fluids and exposure to ETS, as distinguished from nicotine, is currently unknown. Some investigators assume that the presence of cotinine in body fluids provides a lower estimate of exposure to ETS because of results from experiments in environmental chambers 14 Vv

that show nicotine to decay more rapidly than RSP. Although Eudy and coworkers (1987) have found appreciable background levels of nicotine in the absence of ETS in one setting, systematic investigations of this phenomenon have not been performed. Nonetheless, because nicotine can adsorb as well as desorb from surfaces of rooms, it is reasonable to assume that appreciable background levels of nicotine might exist in typical real-world settings, thus admitting the possibility that nicotine might overestimate exposure to ETS. In addition, it is known that this background can persist in the absence of RSP from ETS (Eudy, 1987), the implication being that cotinine might indicate only that exposure to nicotine has occurred, or, stated another way, tha1: nonsmokers have occupied spaces where smokers have been but where no ETS currently exists. The author notes: "The forgoing illustrates that exposure to ETS is very widespread in the population."•Based upon the uncertainties raised in the above paragraph, it is perhaps more accurate to state that exposure "appears" to be widespread. The author notes: "However, additional data on the Jistribution of smokers in the nonsmokers' environment as well as the distribLtion of ETS levels in the environment are needed in order to characterize the <<ctual ETS exposures of the population." This statement, which represents an a:curate description of the current understanding of ETS exposure, directly speaks to one of the assumptions of the equilibrium model: the distribution of smokers in nonsmokers' environments is unknown (this information is contained in the assumed term Mr. Repace identifies with Dhs). In addition, this statement speaks to the quality of the equilibrium model: if estimates provided by the model provided results of adequate quali'ty, then characterization of actual ETS exposures would be unnecessary. The author follows with the statement that in the absence of such data, population exposures can be estimated by models or by extrapolation from biological markers. Clearly both these approaches are valid, but only within the context of the statement; however, the quality of such estimates remains vague because the issue is not addressed within the text. The reviewer recommends that the author provide some information addressing the quality of such estimates. 15

E. Integrated Exposure Analysis 1J, L L I The author states: "Estimating the magnitude of the passive smoke dose is difficult, and it is of doubtful validity to extrapolate from the uptake of one marker to another." This statement, which correctly describes current understanding, contradicts many of the statements made earlier by the author. In sections above, the author states that estimates of the exposure of the population to ETS can be estimated by extrapolation from biological markers. Both these statements cannot be true. The author states: "under extreme conditions of incloor air pollution, it has been calculated that a nonsmoker would inhale volatile nitrosamines equivalent to 10 nonfilter cigarettes or 35 filter cigarettes." The significance of this statement is unclear and consequently it should either be revised or omitted. The extreme conditions are not described, thus admitting the possibility that they are unrealistic as is the case for most experiments addressing the uptake of ETS components. (ETS levels are typically made unrealistically high to enable'detection of ETS components in body fluids.) In addition, the author's choice of words implies fact, "would," rather than extrapolation and assumption, which would require use of "possibly might." The author's assumption that formation of cotinine from nicotine and clearance from the body does not differ substantially from non:,mokers to smokers need not be an assumption, because research indicates that this is false. The remainder of the paragraph is not supported and therefore should be omitted. Mr. Repace uses an RSP to nicotine ratio of 13:1 to calculate RSP levels which might have accompanied a mean nicotine concentration of 15 gg/m3. Use of ratios for predictive purposes is invalid (Oldaker and coworkers, Excerpta Medica Interantional Congress Series 1989). In addition, a 13:1 ratio is unjustified because the value was computed from results of an experiment done in an environmental chamber where the ETS levels were unrealistically high. Mr. Repace continues to address the ratio approach through mainstream and sidestream smoke. These are not ETS. The quality of sidestream data varies from unknown to poor. The use of ratios derived from these data is unsupported. The paragraph containing these speculations should tie omitted. 16 L

Because the paragraph going from page 89 to paqe 90 relies on so many assumptions, its message is speculation; the paragraph should be omitted. The author notes that these estimates must be interpreted with caution because they may substantially underestimate exposure to other components of ETS. In view of the assumptions made, the estimates should not be -interpreted at all. As for the cautionary note, this is pure speculation and therefore should be omitted-. L :. I The author correctly states that RSP lacks specificity for ETS; however, the extent of this lack of specificity is not given. The author also states that "the prevalence of smokers correlates well with RSP levels in homes and other enclosed areas." Descriptive statistics relating to this correlation should be included. Without such statistics, the reader may misunderstand the author by thinking that correlation implies prediction, which for the data provided by the "Six City Study" is not the case. The author also states that the "Six City Study" demonstrated that ETS exposures in the home ard at work were significant contributors to personal exposure to RSP. This statement should include statistics that quantify the significance of such exposures. Finally, the author states: "In general,'measurements in a large number of locations using measures of smoke generation such as the number of people smoking or the number of cigarettes being smoked have shown a definitive relationship of smoke generation to particulate levels." This statement is vague and therefore misleading. First, the conclusion is not-a generalization, because, as the author as stated several times before, the relationships have been assessed from a limited number of studies, where the author's analysis employed only the summary results from those studies. Thus, while the limited studies to which the author refers included a large number of locations, analysis was performed only on the summary results of the studies. The author chose not to include results of the majority of studies in his analysis. Finally, the author's use of the "phrase definitive relationship" is unclear since it is accompanied by no quantitative information. Although correlation can be interpreted as a "definitive relationship," correlation does not mean that the relationship can be used for prediction. The author also makes the blanket statement that "in U.S. homes, there are few other sources of RSP, and therefore, the relationships of RSP measurements to ETS are quite accurate." This statement is untrue and insupportable. Spengler and coworkers concluded that 50 % of the RSP in the studies of homes could be attributable to ETS. The accuracy of these relationships is, ,from the standpoint of prediction, not supported, again, 17 'L

because while correlation may be "accurate," the strength of correlation is too poor to allow predictions to be made. On page 90, Mr. Repace summarizes efforts in conne,:tion with the model. He states that the model was validated. The paper by Repace and Lowrey shows only that the model could be fit to data from experiments (lone in artificial settings as distinguished from real-world settings. Equilibrium conditions were imposed on these spaces and levels of RSP were excessive. Finally, these "demonstrations" did not address all the input parameters of the model, such as the number of habitual smokers, the smoking rate, the smoke generation rate, etc. To support the validity of the model, the authur cites work by Kuller and coworkers, which is not included with the references. Mr. Repace's discussions relating to probability-weighted exposures to ETS that appear in Table 13 cannot be followed. The reviewer recommends that the two paragraphs be revised to include literature citations supporting the values assumed as well as a development of the arithmetic used to obtain the estimates. In addition, the paragraphs should present the issumptions precisely and describe the extent to which the assumptions would be expected to affect the final results. In summarizing this section, Mr. Repace notes the disadvantages of the model and states that the NRC, Surgeon General, and IARC have utilized this data base ["the RSP-based estimates "] for exposure assessment purposes. Although this reviewer recognizes that the equilibrium model has been described in these documents, he is unaware that any of these organizations has used the model. The author should'cite publications describing use of the model. 18