Tumours of the respiratory tract in rats and hamsters following chronic inhalation of engine exhaust emissions

✍ Scribed by J. Brightwell; X. Fouiliet; A. -L. Cassano-Zoppi; D. Bernstein; F. Crawley; F. Duchosal; R. Gatz; S. Perczel; H. Pfeifer

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: English
• Weight: 811 KB
• Volume: 9
• Category: Article
• ISSN: 0260-437X
• DOI: 10.1002/jat.2550090106

✦ Synopsis

The potential carcinogenic effect of inhaled automobile exhaust emissions was examined in rodents. Both rats and hamsters were exposed to the emissions from (1) a gasoline engine, (2) a gasoline engine fitted with a three-way catalytic converter, (3) a diesel engine and (4) a diesel engine with particle filtration. Exposures were for 16 hours per day, 5 days per week, for 2 years. All hamsters were sacrificed at the end of the 2year exposure period, whereas the rats surviving after 2 years of exposure were maintained for a further 6month observation period without additional exposure to emissions. Some of the hamsters in each treatment group were pretreated with diethylnitrosamine to induce respiratory tract tumours.

No statistically significant changes were seen in the incidence of respiratory tract tuniours in emissionexposed hamsters compared to controls. This lack of a treatment-related effect was seen in both the nitrosamine pretreated and the non-pretreated hamsters.

There was no increase in the incidence of lung tumours in rats exposed to filtered diesel exhaust or to the exhaust from the gasoline or gasoline-catalyst engines.

There was a statistically significant increase in the incidence of lung tumours in rats exposed to diesel engine emissions compared to controls. A clear dose response was evident in both males and females, although the incidence of lung tumours was markedly higher in females (96% in rats surviving beyond 2 years) than in males (44% in rats surviving beyond 2 years). An increased incidence of lung tumours was observed only in rats exposed to mean concentrations of diesel soot particles of either 2200 or 6600 jq$n". No increase was observed at 700 kg/m3. In comparison, the projected mean concentration of diesel soot particles in major US cities with 20% of light-duty vehicles diesel-powered has been estimated to be 0.5 & n 3 .