Seems like the only reason Salt Iodization doesn't make the list of "top" charities is because it is much harder to prove benefits back to the charity level. If

Seems like the only reason Salt Iodization doesn't make the list of "top" charities is because it is much harder to prove benefits back to the charity level. If a charity lobbies the local supermarket to label iodized salt which people want which causes better health, it is nearly impossible to prove that it was the charity that caused the better health. Malaria nets are much easier: How many nets went out, did the nets make it to the people we intended, how many fewer people got malaria? Iodization is much more difficult to track because so much money needs to be spent at the lobbying level instead of the "buying iodine" level. Malaria nets also score extremely well in their ranking system because those charities can accept a TON of money before diminishing returns start to kick in. Against Malaria has said "we could easily accept >$50 million in donations" where the two Iodization organizations GiveWell tracks have said they could probably only accept $2-5 million without major changes (even though both of them lost their primary funding sources in the past few years and are thus decreasing their programming). This all doesn't mean GiveWell is wrong in their current recommendations. They are up front about disclosing the problems with their methodology, but you should keep it in mind when choosing which charities to donate to.