ets exposure, lung cancer - Legacy Tobacco Documents Library

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Iru . J Cancer: 39, 1ti2-169 (1987) ~. . P
0 1987 Alan R . L.iss, Inc .
MEASUREMENTS OF PASSIVE SMOKING AND ESTIMATES OF LUNG CANCER
RISK AMONG NON-SMOKING CHINESE FEMALES
Litsda C . Koot, John H-C . Ho~, Daisy SA'w3 and Ching-yet Hot
il3ept of Communitv Medicirte, Univrrsirl of Ho+tg Kn+t ; . Hong Kong : 2Radiwhtrapy Drpr ., 6aprisr Hospiral, Kowloon,
fa'ong Kong : and 3/ruriswe of Parholog) . Qurrn Efi ;ehrrh Hosptrcl, 14jlir Road, Kowloon . Hong Kong .
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t.Hetime e :powrss to enviro~nm.ntat tobacco smoke from 28 .t}00 inhabitir,ts/km2, with tmly
the home ac workptaci for tY "rsever-smoked" ferrule lung a{uce per person .
eancer patienu and 137 "t+ev.rsrnoked " district contr-alt were
S m2 of available living
•stimated in Hong Kong to a .ueu the possibie causal rotationship
of passive ,mokint to lung tincer risk . llelat}.e risks
MATERlAL AlJll MET1fUDS
based on the husband's unokint habits, or lifetime estimatas
of total yean, total hours, maan hoursiday, or totsl ciraraest
day unok .d by aach houuhold smoker did not show dosa
rsponse rawta . Similarly, when such catetories as mean
hours.~day, or earlier age of inicial eapowra, were combined
with Ygan of expoture, there were no apparent Increases in
From 1981-3, E8 never-smoked female lung cancer patients
and 137 never-smoked female district controls were interviewed
as pan of a larger retrospective study of femalc lung
cancer in Hong Kong covering 200 cases :nd 200 controls In
the orig nal study . pauents were matched with an equal numbtr
relative risk . However, when the data were sepe=ated by of healthy controls by age (f S years), district of residence
histological type and location of the primary tumor, it was (N-34), and housing type (pubGc or private housing), the
asen t.hat peripheral tumon in the middle or bwer bbes, or, laner being in indication of soc)o-economic status Det3ils of
fess strongly, squamous or smalt-cell tumors In the middle or
}ower tob*s, had incrsuint ratauve ritkt that might lndicate
some assotiatlon with pauive srt .ohin= eaposure .
subject selection, lung cancer histological typing, and method
of conducting the interviews have been discussed elsewhere
(Koo et al ., 1983, 198A) . Never-srrwked subjects wrre defintxl
as those who had smokeA less than 20 cigarenes ip the pasi .
Epidemiologieal dsu linking passive smoking %kith lung All dau on ~assive smoking exposures were double-checked
cancer among non-smokers have been controversial Six studies
(Htnyama, 1981 ; Trichopouios ei al„ 1981 ; Correa ci al .,
1983 ; Knoth et al ., 1983 ; Miller, 1984 ; Garfinkel ri at ., 1985)
found significantty elevated relative risks (RR) in the range of
2 .0 to 3 .5 based on the smoking tubits of the spouse . Five
other studies (Garfsnkel, 1981 ; Kabat and Wynder, 1984, Chan
and Fung, 1982 ; Koo ei af ., 1984 ; Wu cr al . 1985) two of
which were conducted in Hong Kong, did not find significantly
elevated RR from inhalation of sidestream tobacco smoke
Four of these epidemiological studies (Hinyama, 1981 . Trichopoulos
er al ., 1981 ; Garfinkel, 1981 ; Chan and Fung,
1982) defsned exposure solely by two questions : whether the
spouse smoked (yestno), and the number of cigarenes smnked
per day by the spouse . Five other studies (Correa er a1 ., 1983,
irSiller, 1984 ; Garfinkel ei ol., 1985, Ksbat and Wynder, 1984 ;
Wu er a1 ., 1985) aJso included questions about whether involuntary
smoke exposure hnd occurred at work (yes/no), and/or
whether the parents has smoked (yes/no) . Such data seem
rather crude indices of exposure, providing only very indirect
iaforrnafion on tbe 6KTrer add amount of exposurc . Funher•
morc, altrtough spcntse(s), parents, or co-workers might have
smoked, the actual degrte of contact of the non-smoker with
tttese smokers could have been very low, or even nil (Friedsrun
ei a1 ., 1983) . In our detailed sasdies (Koo ei at., 1983,
1984) of passive smoking exposures, smoking parents or
spauses were sometimes rocalled as inflicting litnle or no exposure
on the sub}'ut . In those cases where, for example, tfu
husbard smoked but lived aepuated from the wife, then our
study counted such wives as unexposed subjeru . Among our
never-smoked subjects, this was found to be true for 3 cases
a.ad 3 controls .
In order to asseu the possible qusal relationship of passive
smoking to lung eancer risk, dau from detailed life-hisrory
exposures ttut were elicited in intensive 1 .5- to 2-hr taperncordad
interviews of never-smoked female lung cancer cases
and district controls havc been ana)yxed . Emphasis is placed
on the eonsistetscy of the data, the strengths of tltc RR, and
whether dose-tccponse relationships were present .
with other data elicited in the ltfe-history interviews, espeeially
residential pancrns since birth (i,ewhere she) liver :,
type of housing . number of rooms, number of eo-habitants,
etc ), occupatloru, and rnanul life to reduce errors in estitnating,
exposure levels
Among the txver-smoked subjects, the mean age of the
patients was 57 .8 (so 10 .81) and that for the controls was 59 .3
(sD 9 .94) This umple included 60 who were widows usd 3
who had never mi .rried ; eone had rrtarried more ihan txsct .
In the design of the interviews, separate data were eallectad
to take into account that within the life-histories of the subjecu,
sidestream tobarcro smoke could originate from : (a)
different people who stnoked in the presence of the subjest ;
(b) different places frequenud by the subject ; and (c) different
types of tobacco . Persons who smoked included related and
unrelated members of the household, and even co-habituns
who shared an apartrrtent unit (if their tobacco smoke was
tooticxd b) the subjea) . It was difficult to quantify expoi ;ilre
levels from places that could have varying daily amounts of
environmental tobacco smoke and were occasiorully visistti
by the subject such as cinemu, while playing majong, or in
t7anspon vthicles . This analysis will ottly take into account
exposures that remained relatively regular during the lifetttnes
of the subjects i .e . from exposures r.l borne and the workplace(s)
. Among our subjects, tobacco srrsoke mosdv otiS'saued
from cigarettes smoked by household members, ared
from pipes (water and regular) smoked by parents or in-laws
In addition to data based on the husband's smoking habits,
4 other measurements of passive smoking were evaluated : (a)
Ioul ycars ot exposure, (b) total hours of exposure, (c) mun
hours/day of exposure, and (d) total cigarettes per day snwked
by each htwsehold member weighed by their years of exposure
. These rrxasures should be a more accurate ref)ecuott t~
past lifetime expasures than simple ques :ions based on whtthc,r~
the spouse or pesenu sawked (yes/no), or whether envitvrt~
menul tobacco Ismoke was encatntered in the workplace (yen
no)
'ihis srudy of thc effects of passive smoking is panicularly
pettinent to Hong Kong because n is one of the most crowded . ~
urban ettvironrnents in the world . Its urban dertsity avetases Recoivad Jux. 24, t4a6 tad in ycvised fotm Sryternbar 19, t9iG la-A
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