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                 last menstrual period. J Epidemiol Community                                                                             neonatal mortality in Belgium and the United       lum Kristensen FB, Chen JH, Masuy
                 Health. 1984;38:79-80.                                                                                                   States. Paediatr Perinat Epidemiol. 1995;          Stroobant G. A comparison of prenatal care
             22. Buekens P, Wilcox AJ, Kiely J, Masuy-                                                                                    9:273-280.                                         utilization in the United States and in Europe.
                 Stroobant G. Birthweight, preterm births and                                                                         23. Buekens P, Kotelchuck M, Blondel B, Bor-           Am JPublic Health. 1993;83:31-36.

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                                                                                                                                      Effects of Radon Mitigation
                                                                                                                                      vs Smoking Cessation in Reducing
                                                                                                                                      Radon-Related Risk of Lung Cancer
                               .. , ^ .. ,s , _   ^. 4,   ....~~~~~~~~~~~~~~~~~~~~~~~..
                                                                                     ..   ...                             ..
                                                                                                                                      David Mendez, PhD, Kenneth E. Warner, PhD, and Paul N. Courant, PhD

                                                                                                                                      Introduction                                       estimate the effects on risk reduction of
                                                                                                                                                                                         radon mitigation alone, smoking cessation
                                                                                                                                           The Environmental Protection Agency           alone, or both together. We assumed that
                                                                                                                                      (EPA) considers radon a major cause of lung        mitigation means reducing all elevated
                                                                                                                                      cancer that is responsible for 7000 to 30 000      radon exposures to 2 pCi/L, the level that
                                                                                                                                      deaths in the United States annually.' The         EPA believes can be attained on average.' If
        .t'K' .......,....:-                                                                                                          agency has urged Americans to test their           individuals were to remediate one home
                                                                                                                                      homes and remediate those in which radon           and then move to another high-radon home,
                                                                                                                                      readings exceed 4 pCi/L.2                          we assumed that they would remediate that
                                                                                                                                           EPA distinguishes the risks of radon          home as well.
                                                                                                                                      exposure for smokers and never smokers in                To compute the risk reduction attribut-
                                                                                                                                      its A Citizen s Guide to Radon.3 The risks         able to quitting smoking, we assumed that
                                                                                                                                      are dramatically higher for smokers, reflect-      background lung cancer risk declines lin-
                                                                                                                                      ing an interaction effect between radon and        early from levels for current smokers to the
                                                                                                                                      cigarette smoking.3-5 Although the guide           average for former smokers in 15 years. This
                                                                                                                                      recommends quitting smoking, along with            was an extremely conservative approach
                                                                                                                                      remediating homes with high radon read-            that, for 2 reasons, considerably underesti-
                                                                                                                                      ings, no publication has compared the risk         mates risk reduction: (1) it treats the average
                                                                                                                                      reduction attainable by radon mitigation,          risk for former smokers as the risk attained
                                                                                                                                      smoking cessation, or the two combined.            15 years following cessation, although the
                                                                                                                                                                                         average former smoker has been abstinent
                                                                                                                                  :                                                      only a few years, and (2) empirical evidence
                                                                                                                                      Methods                                            on lung cancer risk reduction after cessation
                                                                                                                                                                                         of smoking indicates a rate of decline more
                                                                                                           In our analysis, we used the standard                                         rapid than linear.'0
*' ' .t.'''"' .'.'                                                                                   radon lung cancer risk model used by EPA,                                                 As with EPA's results, our findings
                    T" ,   "
                               f4 , ';
                                ' 'iKj                                                               BEIR [V,4 linked with 2 other models, one                                           represent averages for both sexes. In actual-
                                                                                                     describing the distribution of radon in homes                                       ity, risks will be higher for men, and risk
                                                                                                     in the United States6'7 and one characterizing                                      reductions greater, because men have
                                                                                                     Americans' patterns of moving to new                                                higher background lung cancer rates."
 9,...S.:....~ ~ ~
         ~~                                                ~            I'. -
                                                                                ~ ~~~~~~~~~~~~~~~~~~ (averaging 10 or:11 moves through-
                                                                                          s '' *;
                                                                                                     homes8 . ......e.
                                                                                                     ~ ~ ~ ~ ~ ~ ~*
                                                                                                                  ~M,-        >
                i.. .... Z. s
                 't                                                                by~~~~~~",Mt
                                                                                 ..os.ed-.           out their lives9). Introducing realistic pat-

                                                                                                     tems of residential mobility greatly reduces                                        David Mendez and Kenneth E. Warner are with
                                                                                                     estimates of the individual risk confronted                                         the Department of Health Management and Policy,
         .    wwr
                                                                                                     by people currently residing in high-radon
                                                                                                                         r, ..
                                                                                                                                                                                         School of Public Health, University of Michigan,
                                                                                                     homes, simply because they will spend most                                          Ann Arbor. Paul N. Courant is with the Depart-
                                                                                                     of their lives in lower-radon homes.5'8 The                                         ment of Economics and School of Public Policy,
                                                                                                     models and the analytical process have been                                         University of Michigan.
                                                                                                     described elsewhere '8 (a technical appendix                                              Requests for reprints should be sent to David
                                                                                                                                                                                         Mendez, PhD, Department of Health Management
                                                                                                     is available from the authors).                                                     and Policy, School of Public Health, University of
                                                                                                           In using the BEIR IV model, we                                                Michigan, 109 S Observatory St, Ann Arbor, MI
                                                                                                     assumed a multiplicative relationship                                               48 109-2029.
                                                                                                     between smoking and radon exposure to                                                     This paper was accepted October 17, 1997.

                                                                                                                                                                                                American Journal of Public Health 811
Public Health Briefs

                                                                                                    lung cancer. However, they will not change
   TABLE 1-Lifetime Risk of Radon-Related Lung Cancer: 40-Year-Old Living in                        our qualitative finding that smoking cessa-
            Current Home for 10 Years More                                                          tion is more effective than mitigation in
                                                        Radon Exposure: Current Home                reducing radon-related lung cancer risk.
                                                        4 pCVL                 10 pCVL                    The radon-related health benefits of
                                                Does Not Mitigates Does Not Mitigates
                                                                                                    quitting smoking pale in comparison with its
                                                 Mitigate      Now       Mitigate     Now           other contributions to health." The principal
                                                                                                    health motivation for quitting smoking,
   Smoker who does not quit smoking, %            1.69        1.35        3.00        1.83          therefore, is not to solve a radon problem.
   Smoker who quits smoking now, %                0.81        0.65        1.45        0.90          Still, we find it intriguing that mastering
   Never smoker, %                                0.09        0.07        0.16        0.10          America's premier cause of preventable pre-
                                                                                                    mature mortality, cigarette smoking, domi-
                                                                                                    nates strategies to deal with the problem
     To illustrate model results, we consider      risk reduction than does quitting smoking        posed by indoor radon as well. O
here two representative 40-year-olds who           after having mitigated the radon problem.
have smoked since 20 years of age, one in a        (The never smoker confronts a lifetime risk
home with a radon reading of4 pCi/L and the        of 0.16%, which mitigation would lower by        Acknowledgment
other in a home with a reading of 10 pCi/L, a      nearly 40%.)                                     This paper was supported by grant ROI CA57691
very high level reached or exceeded in only             Not shown are results associated with       from the National Cancer Institute.
0.7% of residences. We assumed that these          varying the age of the individual or the
individuals would live in their current homes      minimum length of continued residence in
for 10 more years and thereafter move              the same home. These results would not           References
according to the residential mobility model.       qualitatively alter the findings. Varying the     1. Technical Support Document for the 1992
                                                   age at which one quits smoking would                 Citizen's Guide to Radon. Washington, DC:
                                                   influence the findings in obvious ways. For          US Environmental Protection Agency; 1992.
                                                                                                        EPA publication 400-R-92-01 1.
Results                                            example, mitigation undertaken at 40 years        2. Cole LA. Element of Risk: The Politics of
                                                   of age reduces risk to a greater extent than         Radon. Washington, DC: AAAS Press; 1993.
     Table 1 presents the 2 hypothetical           does smoking cessation at 70 years of age.        3. A Citizen's Guide to Radon. The Guide to
40-year-olds' lifetime percentage risks of         (However, quitting smoking at age 60                 Protecting Yourself and Your Family from
contracting radon-related lung cancer, with        affords risk reduction comparable to that            Radon. 2nd ed. Washington, DC: US Envi-
the risks of a never smoker of the same age        achieved with mitigation at age 40.)                 ronmental Protection Agency; 1992. EPA
presented for comparison.                                                                               publication ANR-464.
                                                                                                     4. Committee on the Biological Effects of Ioniz-
     For the smoker living in a home with a                                                             ing Radiation, National Research Council.
radon reading of 4 pCi/L (columns 1 and            Discussion                                           Health Risks of Radon and Other Internally
2), doing nothing produces a 1.69% lifetime                                                             Deposited Alpha-Emitters. BEIR IV. Wash-
chance of radon-related lung cancer. Miti-              The striking finding of this analysis is        ington, DC: National Academy Press; 1988.
gating the radon problem but not quitting          that quitting smoking will reduce the risk of     5. Warner KE, Mendez D, Courant PN. Toward a
smoking would decrease risk by a fifti, to         radon-related lung cancer more than will             more realistic appraisal of the lung cancer risk
                                                                                                        from radon: the effects of residential mobility.
1.35%. Quitting smoking but not mitigating         directly addressing the home's radon prob-           Am JPublic Health. 1996;86:1222-1227.
radon would decrease risk by more than             lem itself. This is true even at unusually        6. The National Residential Radon Survey.
half, to 0.81%. Both mitigating radon and          high levels of radon and despite modeling            Washington, DC: US Environmental Protec-
quitting smoking reduces risk by just over         assumptions that clearly underestimate the           tion Agency; 1993.
60%, to 0.65%. The incremental gain of             risk reduction benefits of quitting smoking.      7. The EPA/State Residential Radon Surveys.
mitigation, once one has quit smoking, is          Of course, to maximize risk reduction,               Washington, DC: US Environmental Protec-
                                                                                                        tion Agency; 1993.
small relative to the incremental gain of          smokers in high-radon homes should both           8. Warner KE, Courant PN, Mendez D. Effects
quitting smoking, given that one has miti-         quit smoking and remediate the home. In              of residential mobility on individual vs popu-
gated. (The never smoker who does not              most situations, however, the latter will pro-       lation risk of radon-related lung cancer. Envi-
mitigate has less than 0.1% chance of con-         duce only a relatively small marginal gain           ron Health Perspect. 1995;103:1144-1149.
tracting radon-related lung cancer.)               once the former has been achieved.                9. Long LE. Changing residence: comparative
     For the smoker living in a home with a              Our specific findings depend critically        perspectives on its relationship to age, sex, and
                                                   on the nature of the interaction between             marital status. Popul Stud. 1992;46:141-158.
radon reading of 10 pCi/L (columns 3 and                                                            10. Halpem MT, Gillespie BW, Warner KE. Pat-
4), doing nothing translates into a 3% life-       smoking and radon in producing radon-                terns of absolute risk of lung cancer mortality
time chance of radon-related lung cancer.          related lung cancer. We used the same risk           in former smokers. J Natl Cancer Inst.
Mitigating the radon problem while contin-         model used by EPA (and widely accepted                1993;85:457-464.
uing to smoke reduces risk by nearly 40%,          elsewhere as well). This model posits a          11. Reducing the Health Consequences ofSmoking:
to 1.83%. Quitting smoking but not mitigat-        multiplicative relationship between smok-            25 Years of Progress. A Report of the Surgeon
                                                   ing and radon exposure.' Alternative mod-             General. Washington, DC: US Dept of Health
ing decreases risk by more than half, to                                                                and Human Services, Centers for Disease Con-
 1.45%. Combining mitigation and quitting          els, consistent with the existing data, that         trol; 1989. DHHS publication CDC 89-8411.
smoking reduces risk by fully 70%, to              specify a submultiplicative relationship'2       12. Lubin JH, Steindorf K. Cigarette use and the
0.9%. As before, mitigating after having           might imply that quitting smoking has a               estimation of lung cancer attributable to radon in
quit smoking creates a smaller incremental         lesser impact in reducing radon-induced               the United States. RadiatRes. 1995;141:79-85.

 812 American Journal of Public Health                                                                                       May 1998, Vol. 88, No. 5

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