The ingredients in Goofer Dust, War Water, and condition formulas such as the oils, powders, incense, and bath crystals for Break Up, Damnation, Destruction, DUME, Revenge, and so forth are not highly toxic in and of themselves, although some do contain hot Red Pepper and/or Black Pepper oils and powders, Sulphur powder, and certain herbs and zoological essences that are not pleasant to smell or touch. Unless one is allergic to the ingredients, one need not wear gloves or masks -- but it is the custom to not burn the incenses of these formulas inside one's own house, for spiritual as well as olfactory reasons.
If you intend to continue or renew an enemy work from time to time, or wish to save money by keeping such supplies around for possible future use, i recommend that you store them in a container that will close tightly, and put them away in a low, dark area of the house, or in a garage or an outdoor shed. This is done not because the items are harmful physically, but because it is spiritually distracting to keep such energies "loose" in the home.
If you have completely finished working with a given assortment of harming supplies and do not want them on your property at all, you may remove any left-over materials through disposal in a crossroads or at a cemetery. For instructions in this sort of disposal, please read the "Hoodoo in Theory and Practice" web page on "Laying Tricks and Disposing of Ritual Remains in the Hoodoo Tradition" at http://luckymojo.com/layingtricks.html
After casting a spell or laying a jinx with negative energies that have been directed against an enemy, it is the custom, as Abraxas wrote above, to cleanse oneself. A Hyssop bath and recital of the 51st Psalm ("Purge me with Hyssop") is recommended. The Hyssop is brewed into a bath-tea. Many people will then light two small white candles dressed with Blessing Oil in the bathroom (birthday candles or a pair of 4" altar lights in star candle holders would be the most economical way to go). They then perform the bath, recite Psalm 51, and step out between the two white candles, cleansed.
Good luck to you.