MACDONALD G, DAVIDSON G
Bull World Health Organ. 1953;9(6):785-812.
The authors first review the doses and cycles of application normally recommended in different parts of the world for DDT, BHC, and dieldrin in controlling malaria, and then discuss the experimental evidence concerning their actual efficacy in the field. The irritant effect of the various insecticides is compared, DDT being found the most irritant and dieldrin the least. BHC appears to be highly irritant when solid, but not when vaporized. The problem of the application of residual insecticides to absorbent surfaces, such as mud, is considered; the wettable powders are generally accepted as the most efficient formulation for such surfaces, but even with these a marked loss in toxicity may occur, requiring higher initial doses and more frequent application than on non-absorbent surfaces. With volatile insecticides, such as BHC, some degree of absorption slows down the loss by volatilization, but at the usual field dosages of 0.1 g and 0.2 g of gamma-BHC per m(2) the decline in toxicity is still rapid. Experiments have also shown that mixtures of DDT and BHC may, in some circumstances, combine the initial high kill of the latter with the persistent moderate kill of the former.Considering the insecticidal efficiency needed for the control of malaria, the authors find that most natural circumstances would be met by attaining a mortality-rate of about 65% of mosquitos entering treated shelters; 85% mortality would be suitable for the most severe conditions and 65% mortality for controlling moderate transmission by endophilic mosquitos.
作者首先回顾了世界不同地区通常推荐用于控制疟疾的滴滴涕、六六六和狄氏剂的施用剂量和周期,然后讨论了有关它们在实地实际效果的实验证据。比较了各种杀虫剂的刺激作用,发现滴滴涕的刺激性最强,狄氏剂的刺激性最弱。六六六呈固体时似乎刺激性很强,但汽化后则不然。考虑了将残留杀虫剂施用于吸收性表面(如泥土)的问题;可湿性粉剂通常被认为是用于此类表面的最有效剂型,但即便使用这些剂型,毒性也可能会显著降低,这就需要比在非吸收性表面上施用时更高的初始剂量和更频繁的施用。对于挥发性杀虫剂,如六六六,一定程度的吸收会减缓挥发造成的损失,但在每平方米0.1克和0.2克γ-六六六的通常实地剂量下,毒性下降仍然很快。实验还表明,在某些情况下,滴滴涕和六六六的混合物可能会兼具六六六初期的高杀灭率和滴滴涕持续的中等杀灭率。考虑到控制疟疾所需的杀虫效率,作者发现,达到约65%进入经处理庇护所的蚊子死亡率,就能应对大多数自然情况;85%的死亡率适用于最严峻的条件,65%的死亡率适用于控制嗜室内性蚊子的中等传播情况。