To be clear, do I understand you to be saying that
all the powder is mixed in, but you are just short of the suggested volume of the water used to mix it into the stock solution?
Your use of "solvent" is what made me wonder - I would have probably used just "water"
.
Assuming my understanding is correct, as posted above you have nothing to worry about.
And you really don't need to use extreme methods to use and make up commercially available powdered photo chemicals. A reasonably well ventilated room and normal care are fine.