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将１５０只昆明种小鼠随机分为三组（Ⅰ、Ⅱ、Ⅲ组）。Ⅰ、Ⅱ组小鼠每天同时在一染毒柜中暴露于煤焦沥青烟气３小时，柜内沥青烟气浓度平均为０．１７ｍｇ／Ｌ。Ⅱ组小鼠每周再接受维生素Ａ灌胃两次，每次给维生素Ａ醋酸酯７５０ＩＵ。烟气暴露共４个月，另再观察４个月，灌胃持续至小鼠处死。Ⅲ组为空白对照组。８个月中，Ⅰ、Ⅱ组小鼠皮肤肿瘤的总发生率分别为８３．３％和５９．２％，Ⅱ组明显低于Ⅰ组（Ｐ＜０．０５）。Ⅰ、Ⅱ组皮肤鳞癌的发生率分别为６６．７％和３０．６％；其中Ⅰ组有８例癌发生了转移，而Ⅱ组仅有１例。Ⅱ组皮肤癌的发生率和转移率均显著低于Ⅰ组（Ｐ＜０．０１）。此外，Ⅱ组发瘤小鼠的平均荷瘤数也明显少于Ⅰ组（Ｐ＜０．０５）。Ⅲ组无皮肤肿瘤发生。结果提示，维生素Ａ可有效地阻断由沥青烟气所致的皮肤肿瘤的发生、癌变和转移，或可用于高危险职业工人皮肤癌的预防。
150 Kunming mice were randomly divided into three groups (groups I, II, and III). Groups I and II were simultaneously exposed to coal tar pitch smoke for 3 hours at a time in a drug cabinet, and the average concentration of pitch smoke in the cabinet was 0.17 mg/L. Group II mice were given twice weekly vitamin A gavage, giving 750 IU vitamin A acetate each time. The smoke was exposed for a total of 4 months, another 4 months, and the mice were sacrificed by gavage until the mice were sacrificed. Group III was a blank control group. In 8 months, the total incidence of skin tumors in group I and II was 83.3% and 59.2%, respectively, and in group II was significantly lower than that in group I (P<0.05). The incidence of cutaneous squamous cell carcinoma in group I and II was 66.7% and 30.6%, respectively; in group I, 8 cases had metastasis, while in group II, there was only 1 case. The incidence and metastasis rate of skin cancer in group II were significantly lower than that in group I (P<0.01). In addition, the average tumor volume in the tumor-bearing mice of group II was also significantly less than that in group I (P<0.05). There was no skin tumor in group III. The results suggest that vitamin A can effectively block the occurrence, canceration, and metastasis of skin tumours caused by asphalt smoke, or can be used for the prevention of skin cancer in high-risk occupational workers.