Use of the HET-CAM test for the determination of the irritant potential ofcigarette sidestream smoke

We investigated the suitability of the HET-CAM test for the determination o f the irritant potential of cigarette sidestream smoke (SS). Coded test sol ution (0.2 ml) was applied to the chorioallantoic membrane (CAM) of 10 day- old White Leghorn chick embryos. The time from the start of exposure to the occurrence of blood vessel injection (I). haemorrhage (H) and coagulation (C) in the first 5 minutes was recorded, and irritancy scores (IS) from 0 t o 21 were calculated (Luepke, 1985). For the microbicide Kathon CG" as posi tive control, a dose-dependent increase in irritancy between 0.3 and lj g/l itre was seen (IS up to IT). Mainstream smoke (MS) or fresh SS from the Ref erence Cigarette 2R1 was passed through phosphate buffered saline (PBS) in a glass impinger. MS-PBS concentrations between 1.7 and 10 puffs/ml elicite d IS from 4.5 to 9. SS-PBS concentrations between 4.5 and 15 puffs, mi elic ited IS from 3 to 7.5, an underestimation due to mortality associated with an immediate breakdown of blood circulation through the CAM vessels, thereb y interfering with the irritation parameters I and H. We propose to test bl ood circulation-independent irritation endpoints. for example trypan blue u ptake in the CAM (INVITTOX/ERGATT/FRAME, 1996), for determination of the ir ritancy of SS. (C) 1999 Elsevier Science Ltd. All rights reserved.