Most I have taken is 1mg. I also question the validity of thumbprints. I know people who have moved crystal for GDF. They didn't have to take thumbprints. I know people who move crystal for european families, they didn't have to take thumbprints. LD-50 for LSD is listed on erowid as 12 mg and even less conservative estimates don't put it very high, relative to how much powder could fit on your thumb. I seriously think if you take a thumbprint you are risking death, and I think it is largely just folk tales. Maybe some crazy fucks have taken thumb prints but then again people do all kinds of dangerous pointless things with drugs. The most LSD anyone I know has personally taken at a single time is 15mg, and imo even that is pushing your luck as it is 3mg higher than the LD-50 listed by Erowid (although significantly below LD-50s I have seen from other places, although to be fair even the higher estimated LD-50's I have seen tend to be fairly low, relatively). I would love to see where the people on SR I see quoting LD-50's of 30 something MG per KG are getting their information from.....straight out of their assholes imo