One consequence of this attack was the realization that you could use mustard analogs for chemotherapy. The medical officers treating those exposed did serial blood counts (not done in WWI) and noticed that white cells, in particular, were depressed by exposure. After the war this led to further research and led to the introduction of nitrogen mustard derivatives to treat leukemia (a cancer of the hematopoietic system where abnormal white cells multiply without restraint) in the late 1940s. If this does not occur, it could have a major impact retarding the development of chemotherapy for cancer.