16

attributable to smoking was about 80% in

this series. Pipe smoking was as common as

cigarette smoking and gave similar relative

risk. The pipe smoking cases, however, had

significantly higher mean age and mean smok-

ing years at the time of diagnosis than the

cigarette smoking cases. An obvious dose-

response relation was found for both

cigarette and pipe smoking. In ex-smokers,

the relative risk gradually decreased from

five years after cessation of smoking. This

decrease was, however, much less pronounced

in ex-pipe smokers than in ex-cigarette

smokers. High relative risks were obtained

for small cell and squamous cell carcinomas.

For adenocarcinomas the relative risk was

considerably lower but still significantly

increased. Two types of controls were used,

i.e. deceased and living. Comparison with

living controls gave generally higher risk

estimates than comparison with deceased con-

trois.

Nested Case-Control Study Lung Cancer among

Chemical Workers.

Bond, G.G., Flores, G.H., Shellenberger,

R.J. et al. Dow Chemical USA, Epidemiology,

H & ES, Midland, MI 48674, U.S.A. Am. J.

Epidemiol. 124: 53-66, 1986.

A recent cohort mortality study of

19,608 male employees of a major Texas

chemical production facility had suggested

that they might be at higher risk of lung cancer compared with the male population of

the United States or Texas but not with the

male population of the five-county area in

which they reside. An occupational exposure

was a possible explanation for this pattern,

and a nested case-control study was under-

taken of the 308 lung cancer deaths observed

between 1940 and 1981. Two control groups,

one a decedent and the other a 'living'

series, were individually matched to cases

one-for-one. Interviews were conducted with

subjects or their next of kin to collect in-

formation on smoking and other potential

confounders. These data were combined with

employee work history records and industrial

hygiene data to form the basis of the

analyses. Traditional stratification methods

and conditional logistic regression were

employed to examine for effect modification

and to control confounding. Statistically

significant, positive and negative associa-

tions were found for assignment to several

work areas within the facility. Suggestive

associations were observed for exposure to

sulfur dioxide and heat. These and addi-

tional associations are discussed relative

to evidence from other studies.

Morphology of Bronchogenic Carcinoma in

Workers Formerly Exposed to Crocidolite at

Wittenoom Gorge in Western Australia.

Baker, J.E., Reutens, D.C., Graham, D.F. et

al. N.H. and M.R.C. Research Unit in

Epidemiology and Preventive Medicine,

University of Western Australia, Nedlands,

WA, Australia. Int. J. Cancer 37: 547-550,

1986.

Cytology and histology material from 46

bronchogenic carcinomas occurring in ex-

workers from the Wittenoom crocidolite mine

and mill in Western Australia and a matched

random sample of 234 other bronchogenic car-

cinomas occurring in Western Australia over

the same period were reviewed by a single

histopathologist without knowledge of asbes-

tos exposure status. Squamous-cell car-

cinomas formed 45.7% of the cancers in the

asbestos-exposed group but only 32.5% of the

cancers in the comparison group. This dif-

ference could not be explained by dif-

ferences in smoking history between the two

groups of lung cancer patients or in the

type of histopathological material available

for review. The excess of squamous-cell can-

cers was observed in subjects both with and

without parenchymal asbestosis.

Investigation of Lung Cancer Among Female

Cosmetologists.

Osorio, A.M., Bernstein, L., Garabrant,

D.H., Peters, J.M. Division of Occupational

Health, Department of Preventive Medicine,

University of Southern California, School of

Medicine, Los Angeles, CA 90033, U.S.A. J.

Occup. Med. 28: 291-295, 1986.

Using a population-based cancer

registry to identify subjects, a case-

control study of female cosmetologists in

Los Angeles County was conducted to inves-

tigate possible occupation and environmental

causes for the elevated lung cancer risk

found in this group. A standardized ques-

tionnaire was administered to proxy inform-

ants for deceased lung cancer patients and

deceased nonpulmonary cancer control

patients. No association between lung cancer

and specific beauty shop tasks, beauty

product use, or environmental exposures were

observed in the crude analysis or after con-

trolling for smoking status. Case subjects

had held more jobs outside of cosmetology

than control subjects, but these jobs did

not appear to be associated with any known

hazardous exposures. Despite the elevated

risk of lung cancer among female cos-

metologists, researchers were unable to re-

late this excess to any specific occupa-

tional tasks or exposures. The excess of

lung cancer in cosmetologists is most likely

accounted for by a higher frequency of smok-

ing in this occupational group.

Interaction Between Tobacco Smoking and Oc-

cupational Exposures in the Causation of

Lung Cancer. Steenland, K., Thun, M. National Institute

for Occupational Safety and Health (NIOSH),

Cincinnati, OH 45226, U.S.A.J. Occup. Med.

28: 110-118.

The nature of the interaction between

smoking and occupational exposure is con-

troversial, in part because of lack of

agreement on the definition of interaction

and in part because of the scarcity of

adequate epidemiologic data. Occupational

investigators have assessed interaction

primarily as a departure from an additive

rather than from a multiplicative model of

relative risks (or rate ratios). To deter-

mine whether smoking modifies the effect of

occupational lung carcinogens, the litera-

ture was reviewed for only four established

occupational lung carcinogens for which

there are data on smoking: radon daughters,

asbestos, arsenic, and chloromethyl ethers.

Where possible, departure was assessed from

both an additive (synergism) and a multi-

plicative model (effect modification). Only

nine studies were considered to have suffi-

cient sample size and to provide sufficient

information on tobacco use and occupational

exposure to evaluate interactions. The ex-

isting data were contradictory for three of

the agents studied: asbestos, radon daugh-

ters, and arsenic. Inconclusive or con-

tradictory findings may result from small

sample size or lack of comparability of the

level of occupational or tobacco exposure.

It is noteworthy that, for these four

agents, whenever smoking did modify the ef-

fect of occupational exposure, the lung can-

cer rate ratio was greater for nonsmokers

(compared to nonexposed nonsmokers) than

smokers (compared to nonexposed smokers).

However, with the exception of chloromethyl

ethers, absolute lung cancer rates were

higher for smokers than nonsmokers, regard-

less of occupational exposure.

17

Induction of Lung Tumors by Radioactive

Isotopes Implanted in the Rat Lung.

Kal, H.B., Zurcher, C., Van Bekkum, D.W.

Radiobiological Institute TNO, 2288 GJ

Rijswijk, Netherlands. J. Natl. Cancer Inst.

76: 943-946, 1986.

Squamous cell carcinomas were induced

in the lungs of male WAG/Rij inbred rats by

radiation emitted from the isotopes iridium-

192 or iodine-125. These isotopes were im-

planted by a survival procedure in the lungs

of young rats. Forty rats received implants

of 1251-seeds. In a 14-month observation

period, 30 of the 40 animals with implants

of 1921r-wires developed tumors. Malignant

hemangioendotheliomas occurred with the

highest frequency (50%). From the lungs of

12 rats, squamous cell carcinomas were

found. In the observation period of 17

months, 3 rats with implants of 1251-seeds

developed tumors, among which i squamous

cell carcinoma could be identified. Tumor

fragments were transplanted in syngeneic

hosts for propagation of the tumors. His-

tologic appearances of tumors remained con-

stant in subsequent passages. Responses of

transplanted tumors growing in the flanks of

syngeneic hosts of doses of radiation,

methotrexate, or vinblastine were deter-

mined. Although the histologic appearance of

the 5 squamous cell carcinomas were similar,

tumor-doubling times and responses to ir-

radiation and chemotherapeutic drugs were

different. Small cell or large cell car-

cinomas were not observed.

Lung Cancer Mortality (1950-80) in Relation

to Radon Daughter Exposure in a Cohort of

Workers at the Eldorado Beaverlodge Uranium

Mine.

Howe, G.R., Nair, R.C., Newcombe, H.B. et

al. Epidemiology Unit, National Cancer In-

stitute of Canada, University of Toronto,

Ont. M5S IA8, Canada. J. Natl. Cancer Inst.

77: 357-362, 1986.

A cohort study of 8,487 workers

employed between 1948 and 1980 at a uranium

mine in Saskatchewan, Canada, has been con-

ducted. A total of 65 lung cancer deaths was

observed (34.24 expected, P < 10-5). There

was a highly significant linear relationship

between dose and increased risk of lung can-

cer giving estimates for the relative and

attributable risk coefficient of 3.28% per

working level month (WLM) and 20.8 per WLM

per 106 person-years. Age at first exposure

had a significant modifying effect on risk.