First a disclaimer: Benz knows much more of chemistry than I do..
But I disagree with him. It has been documented several times about residual solvent trapped inside different kinds of crystals in literature:
gc-ms analysis of solvent trapped inside cocaine Crystallization of organic compoundseffect of solvent on crystal structureNow, of course there are all sorts of factors to this. Big crystal formations left undisturbed may trap more solvent, while breaking the crystals up into powder and letting it dry will certainly reduce the amount of solvent traces. In Trout's Notes, he also mentiones the very common residual taste of hydrocarbons in DMT. Anybody that extracted DMT with something like BLAB, salted with fumarate and converted fumarates to freebase with water crystallization, will know first-hand how incredibly different and much softer the smell of DMT crystallized from water actually is, in comparison to hydrocarbon-crystallized DMT.
So what can you do to eliminate solvent traces? One thing, as said, is to break up crystals. Another thing would be to redissolve in a fast evaporating and/or less toxic solvent (such as clean acetone or ethanol), and re-evaporating. Another possibility is salting out your solvent with fumaric acid, washing your fumarates with acetone to remove your other solvent traces, letting it dry, then redissolving in water and doing the water crystallization as described in BLAB, and knowing the last thing to touch your crystals was water is much nicer.
Regarding health, as benz said, health issues arise from long term exposure, and I would also guess that in general there is nothing to worry about if you broke it up into powder and let it dry for a while, that we are probably being over-careful, and that most people specially living in big cities are probably subjected to more toxic substances than anybody smoking dmt with a bit of solvents.
Nevertheless, considering its not hard to work to eliminate those traces, and that some people may smoke DMT regularly and/or over the years, I dont think its bad to question oneself how to eliminate solvent traces. Also, often one is not simply inhaling a bit of solvent with the DMT but might be also inhaling different combustion byproducts (if dmt is smoked instead of vaporized), which would add to the unknown health risk factors.