The study has been done on the mortality of malignant tu-mor in the 1990 workers exposed to pitch and the mortality ofthe 1590 workers w(?)o did not exposed to pitch.

对吉林碳素厂1990名从事沥青作业人员中恶性肿瘤死亡情况及该厂1590名不接触沥青工人死亡情况进行调查。

youdao

The study has been done on the mortality of malignant tu-mor in the 1990 workers exposed to pitch and the mortality ofthe 1590 workers w(?)o did not exposed to pitch.

对吉林碳素厂1990名从事沥青作业人员中恶性肿瘤死亡情况及该厂1590名不接触沥青工人死亡情况进行调查。

youdao