Shulgin is in excellent helath, but during his experimentation, he never took a compound he hadn't positively identified as being pure and being exactly the compound he was looking for. Also, whenever testing a new compound, he took no more than 0.5mg the first time, waited a few days, took 1mg, waited, took 2mg, waited etc. until he found the perfect level for the compound (or deemed it inactive). By slowly incrementing the dosage like that there is no great risk for overdose, as any toxic symptoms will be very mild at very low doses, and thus the testing can be aborted as soon as it is discovered that the compound has undesirable effects (such as amnesia, effects on heart rate and blood pressure etc).