WHO has endorsed the use of DDT in small amounts to be sprayed indoors. I think it's a sane decision. They have concluded that small amounts indoors do not pose a considerable hazard. For me, the case always concerns the tradeoff between costs and benefits. Bioamplification is of course an important issue, but this is not some big swathe of species that you are bathing with the compound. On the other hand, the number of lives it spares which would otherwise be snatched away by malaria, still one of the most pernicious diseases around, will be a substantial benefit.