Sources of Neotraxin
Neotraxin was developed by the Colonists, a.k.a. the Bigfoot Aliens. After Steve Austin was released following his first encounter with the Colonists, his memory of their existence was erased but he was given a sample of neotraxin. Col. Austin gave the neotraxin to Oscar Goldman in hopes that Dr. Rudy Wells could study its properties. After the colonist Gillian restored Steve's memories, he attempted to prove to Oscar and Rudy that the Colonists did exist. Steve mentioned the sample of neotraxin, but Oscar admitted that his primary concern was for Steve and that he had no knowledge of the whereabouts of the neotraxin sample. This sample of neotraxin is either lost to humankind or now a highly classified secret.
When Steve Austin's nuclear power pack was damaged and leaking after a shark attack, his body showed no signs radiation poisoning. It is likely that the long-term effects or continuing presence of neotraxin in his system have made his organic tissues immune to the toxic effects of radioactivity. (SMDM: Season Six, Issue #1)