Then explain the fact that one of Anti-Venom's powers is purging foreign substances from people, which in the comics includes radiation, and when he comes near Spider-man, which starts eliminating the radiation, Spider-man starts losing his powers. If the radiation isn't the source of Spider-man's powers, losing the radiation wouldn't cause Spider-man to lose his powers. The spider bite isn't what gave Peter powers, but the fact that it was an irradiated spider. You have to remember that this is a fictional universe, so the creators of Spider-man and Hulk were allowed to claim that radiation can give regular men superhuman powers.