Throw out the DE... it is very ineffective in many environments (especially humid) on an many things. To me it is an over rated, over used, false sense of security that can be harmful not JUST to the user but also the birds, the environment, and so on... I realize most my link are mostly from the same site... but I still consider them valid...
https://the-chicken-chick.com/the-cut-dry-truth-about-diatomaceous/
https://the-chicken-chick.com/diatomaceous-earth-de-benefitrisk/
https://the-chicken-chick.com/raising-chickens-naturally-diatomaceous/
Lisa from Fresh Eggs Daily lost my readership when she stated that she WORMS with DE... What a load of crap with tons of viewers blindly following her ignorance... why not spend the money for before and after fecal floats... to PROVE if it works or not. According to the following link... it does NOT work as a worming agent in cattle studies... duh, it doesn't work when wet like all the inside of the body is...
https://en.wikipedia.org/wiki/Diatomaceous_earth
The IDEA of prevention is nice... but you can't prevent what you don't have... so not having to deal with something doesn't ACTUALLY mean you are preventing anything. You may or may not be. Some locations simply don't have the same conditions or loads... when I lived in the city, NO issues. Now in the Pacific Northwest where wildlife abounds... I deal with their issues on my land. Dealing with something isn't what makes a bad keeper... NOT dealing with it if you know about it, would.
Best prevention... don't invite wild birds or animals to your yard, good flock nutrition, rodent control, and don't bring in unknown fowl from another pasture or location... standard dirt baths rock... turns out, molting is ONE way birds help rid themselves of parasites.
Oh and for me... it isn't just about when you are applying this dangerous stuff to you birds that counts... EVERY time I see them shake out a big cloud fills the air... for yourself, my dogs, bees, other flock members and CHICKS to try and recover from!
NO thank you.
Guess it's clear I am in the anti DE camp. My reasons are clear, but to each their own.
And I really don't care whether food or industrial grade... food grade has what maybe extra clay (or something) removed from it... I still consider it ALL to have possible toxic effects.
ETA: what is removed is Silica... that doesn't change the (alleged) micro cuts being made to every surface it touches.