Hello, I have made this movie.
The choice of using oxalic acid sublimed resulted after losing for years many families of bees with "oxalic acid drip"
I live in Italy, Rome. The climate in my country does not allow a block of brood to colonies of bees. Thus the treatment "drip" is not very effective against Varroa.
With appropriate protections, as I mentioned briefly in the movie, the risk to the beekeeper are minimized. Many professional beekeepers in Italy to use this method with satisfaction.
I am always at your disposal
Sincerely Bernardino Ferrisublimation oxalic acid