23

ing number of experimental results demonstra-

te, but they should not be considered a mere- ly natural detoxification mechanism since many degradation products appear to be more reactive and mutagenic than parent PAH.

Our results demonstrated that sun light intensity, 0 concentration and nature of adsorbing su~strate may induce significant modifications in the kinetic of these pheno- mena.

Implications in analytical methods and in risk assessment are discussed.

Lung Cancer and the Air Pollution. One Thou-

sand Dog S in Kawasaki C~ty, Japan I 2 Takemoto , ~., Katayama , H., Abe , Y., Kawai H., Imagawa , U. i. Department of Public Health, Saitama Medical School. 2. Department of Public Health. 3. Internal Medicine, Tokyo Medical Dental University.

Lungs of the dog are good models for study- ing the relation between air pollution and lung cancer. One thousand dogs with recorded life histories in Kawasaki city were autop- sied. As results of histopathological studies, their degrees of lung contamination increas- ed with age. 43.0% of the old dogs from the industrial area had highly contamination lungs, as opposed 20.6% of the dogs to the same age group from the residential area.

The concentration of metals in the lung was usually greater in older dogs. The lungs of dog living in industrial areas exhibited significantly greater concentration of Cr, Ni, Cd, Pb, and Co, than those living in commertial and residential areas.

There were seven malignant cases included 4 from the industrial area, 1 from commertial area, 2 from the r-sidential area (lung cancer).

Therefore, air pollution is recognized to give a strong influence on the incidence on lung contamination and lung cancer of dogs.

Rat Lung Carcinoma Produced by 2 Year Inhala- tion of Diesel Exhaust Particulates. lwai, K., Yamagishi, M., Udagawa, T. Research Institute of Tuberculosis, Japan Anti-Tuber- culosis Association, Kiyose-shi, Tokyo 204, Japan.

Various kinds of arylhydrocarbon including dinitropyren have been detected in diesel ex- haust particulates. In vitro studies using Ames test, chromosomal aberration, sister chromatid exchange or cell transformation have revealed mutagenicity of the particulates, while evidence has been lacking under in vivo carcinogenicity until now.

Chronic inhalation studies were carried out using SPF rats of Fisher 344 strain feed- ed in aseptic chambers (Particulate 4.9 1.6 mg/m ). Diesel exhaust diluted i0 times by clean air was introduced into the animal chambers, 8 hrs/day, 7 days/week, for up to 2 years. Similarly diluted but particulate-

excluded gas or clean air was conducted to

the control chambers. Hyperplastic and metaplastic changes of

bronchiolar and type II alveolar epitheliums

were noted with increasing extent according to exposure duration, accompanying marked parti- culate deposition in alveoli. Some of them transformed into neoplastic change and to ma- lignant ones in 2 years exposed rats. Two ty- pes of malignant tumor, adenocarcinoma and adenosquamous carcinoma were seen, showing different cell character under electron-micro- scopy. Incidence of tumor (both benign and malignant) in particulated gas exposed rats (8/19 42.1%) was significantly higher than that in de-particulated (0/16 0%) or clean air (1/22 4.5%) group.

Diesel exhaust particulates have carcino- genicity in rat lung, at least in this expe- rimental model.

Lung Cancer Screening in Mining & Related In- dustries in B.C. Embree, V., Enarson, D.A., LeRiche, J., Nelems, B. Department of Medicine, Vancouver General Hospital, U.B.C., Vancouver, B.C.

3 yrs. of a 5 yr. program of lung cancer screening are completed. Sixteen sites are en- rolled: 2999 people determined eligible (40+ yrs) and available (still actively employed at time of visit). 82% (2467) are enrolled. Participants 50+ yrs. plus smoking 20+ ciga- rettes/day are followed 6-monthly with sputum sample, respiratory questionnaire and annual chest x-ray. Participation at follow-up visits is over 70% overall. Community and postal fol- low-up supplement mine site visits. Sputum samples adequate for analysis have been ob- tained on 59% of participants. Overall rates of metaplasia and dysplasia are higher at sites with exposures to known carcinogens. Prevalence of metaplasia in exposed populati- on (n=599) is 3.9% vs. 1.7% in unexposed; pre- valence of dysplasia is 6.2% in exposed vs. 2% in unexposed. The occupational exposure effect masks the expected dose-response relationship of smoking on sputum results. For all sites combined, prevalence of metaplasia is 5.8%, 5.4% and 8.9% for non-smokers, <20 cig./day and 20+ cig./day respectively; prevalence of dysplasia is 3.4%, 3.2% and 5.6% respective- ly. When sites with a known occupational hazard for lung cancer are excluded, the expected dose-response relationship is apparent: pre- valence of metaplasia is 2.9%, 5.8% and 8.4% for the respective groups; prevalence of dys- plasia is 1.9%, 3.2% and 4.5% respectively.

Bronchogenic Carcinoma in Libyan Patients. A Fifteen Year Study. Wassef, S.A. The Pathology Department, Tripoli Central Hospital, Tripoli, The Socialist Peop- le's Libyan Arab Jamahiryah.

There is no reliable population-based data with regards bronchogenic carcinoma in the

Eastern Mediterranean countries and the mor-