Pure caffeine powder can be almost instantly fatal if handled without gloves and respiratory protection. There are no safe drugs, only safe quantities.
I believe you mean nicotine...I have observed friends taking 10 kilograms of food grade caffeine microballs and weighing and bagging in 500 mg doses to distribute at a hacker convention, with no adverse effects.
Food grade caffeine granules are both diluted and granulated to prevent machine material handling errors from becoming deadly at food packaging plants. The powdered stuff is quite dangerous.
The info I have is that the granules are mainly to ease mechanical processing. Given that ld50 of anhydrous caffeine USP is above 100mg per kilo of body weight, I do not think a few grams, especially through skin, would be much risk. The msds advises gloves, due to it being a skin irritant, but that is for constant exposure.
Fine powders are a fire safety and explosion risk, of course, especially in automated storage and processing environments....flour, non dairy creamer, aluminum powder, etc are great fun.
If there is any info to the contrary I would be very interested.
"Given that ld50 of anhydrous caffeine USP is above 100mg per kilo of body weight, I do not think a few grams, especially through skin, would be much risk."
Fine water-soluble powders are absorbed quickly when inhaled, producing a very high peak concentration in the blood that supplies the heart. If it is enough to stop the heart from beating, you die, even if dose averaged over the whole body is reasonable.
