http://www.erowid.org/ask/ask.cgi?ID=1778 I doubt so, you would throw up from eating too much cactus before you overdosed on mescaline. San Pedro is way less potent that peyote, there is little danger. Probably the only way you could overdose is if you took pure mescaline.
some reports on erowid talk about one man collapsind dead and others who had cuts in there stomac and throat
I think its just common sense to remove the spines before eating any type of cactus, whether it be for food (la tuna, prickly pair, etc) or not.
In relation to the article on erowid about the case of the man dieing from the cuts on his stomach and throat, the cause of death was given as Mallory-Weiss esophageal lacerations, the man in the case had a history of alcohol abuse which is strongly linked to the condition, so although the cactus induced heavy vomiting and ultimately killed the guy he would most likely not have died if he wasn't already suffering from Mallory-Weiss syndrome caused by his years of alcoholism.
