TO prove that a drug or chemical has an etiologic relation to aplastic anemia is a difficult task. This is due mainly to the low incidence with which their use is followed by the disease, making it necessary to accumulate a sizable number of suspicious cases to find a statistical argument in its favor. Thus, recognition of the aplastic-anemia-inducing effect of chloramphenicol, the most offending drug in this respect in the United States, was delayed for several years.1 Likewise, the indirect toxic effects of the insecticides are not widely recognized though a few cases of blood dyscrasias after their use . . .