Artificial sweeteners, safe or unsafe?

    In the 1970s saccharin was found to be unsafe for human consumption as research studies indicated that it caused cancer in lab rats. I remember that the initial response was the FDA banning the product product from store shelves, but that idea was rescinded with the argument that there was no alternative for diabetics to use at the time. So it was kept on the shelves but every product containing saccharin was required to have a warning label letting people know that it may cause cancer. In 2000 warning labels were removed because supposedly cancer was only found in laboratory mice or rats because their biology was slightly different.

Questions

If there is a difference between the biology of the rats and humans, shouldn't there be questions about all other products that were tested using this method? Why are food products tested by the manufacturer and not an independent laboratory? Mice and rats are used for testing food and drugs because their biology is similar to ours, but if this is not the case then how can we trust anything that the FDA has to say? If this same method is used to test other artificial sweeteners, are exemptions being made for these products as well? If a product is found to be carcinogenic but can still be sold so long as it has a warning label on it, does that mean mass murder is okay so long as you have a warning label? Euthanasia is considered to be illegal in this country, but it's okay to buy a product that will kill you?