Diatomaceous Earth like many 'natural products' come in a variety of guises, some of them good and some not so you have to do your research to ensure what you're buying is not harmful. If the item is sold as food/feed grade then it is safe for human and animal/livestock consumption and use. There is a type of DE on the market which is used in pool cleaning, it is heated to very high temperatures to create a crystalline structure and various chemicals are added, this type is not suitable for human/animal use and labelling is marked to say so, but if buying over the internet then you have to be sure of what you're buying. The Pool type DE is harmful and if breathed in is carcinogenic - it is both the chemicals it contains and the crystalline structure which make it toxic. Food Grade DE (also known as Fossil Shell Flour) is the pure fossilised rock very finely ground into a flour like consistency, it contains microscopic sharp 'shards' of millions of dead hard celled algae called Diatoms. These shards attach to anything with an exoskeleton, as they continue to move about the shards cut into the exoskeleton damaging the insect and making it dehydrate and then die. Food grade DE has a variety of uses, you can sprinkle it on your bed to rid yourself of bed bugs, on your pets to prevent ticks and fleas and in bedding to help prevent red mite etc. There are no chemicals in it, it is purely made effective by the mechanical action of the shards attaching to the exoskeleton and damaging it.
People also take it internally and there are proven benefits to taking it. Studies have shown Diatomaceous Earth to significantly lower cholesterol by removing plaque and keeping arteries and veins supple. It also helps to regulate blood pressure. DE contains Silica which has been proven to be vital to our survival. It can make hair thicker and nails stronger, but it also helps our bodies absorb calcium and phosphorus. New studies are finding that silica may be more important for our bones than calcium and that it plays a major role in the healing of osteoporosis. Here is an excerpt from a proven medical study which says taking it internally by humans actually lowers cholesterol... http://www.ncbi.nlm.nih.gov/pubmed/9533930
It is recommended that you do not inhale too much of the dust that is produced from food grade DE, this isn't because it is carcinogenic like the crystalline substances of Pool Grade DE or Asbestos, these are totally different substances. It is not good for anyone to breathe in any amount of dust for prolonged periods - be it chalk dust, house dust, sawdust, dust from wheat/grain etc etc and a mask should be used in very dusty situations otherwise if you breathe in too much dust whatever type over a period of time may cause lung problems.
My initial question was linked to the fact that the chicks using the dust bath with newly added DE both had leg problems immediately after using it and I wondered if anyone had seen this and made me wonder if it was some reaction to the DE as it was certainly a worrying coincidence. Now I'm guessing it was just them getting carried away and overdoing it, almost like a cramp and had nothing to do with the DE in it.
I don't usually start using new things until I've thoroughly read up on it and now that I have done much more research today I'm quite happy to carry on using it as I'd intended. I have been using Colloidal Silver on myself and my animals for the last ten years with amazing results and my chicks have been having it since they were hatched. Most people who haven't researched it would probably say that this is something I shouldn't be using either. Maybe this post will encourage others to try DE, or I've just wasted 20 mins writing a reply to tell people more about it and how it is a good and not a bad thing! I'm satisfied though and that's the main thing.