Hi WM - you'll find that this question comes up often here and is discussed in great detail in many of the discussions on tomato canning.

The simple answer is that you can't compare the requirements for one vegetable with another in any valid way without altering the risk factor at the same time. There are too many other factors such as processing times, processing pressures, natural pH of the particular food/variety, size of containers, botulism counts of that particular food, testing done or not done, long term stability of the pH, etc., etc.

Pressure canning tomatoes is optional. It is not required as it is for the low acid veggies you list. And if pressure canned the time required differs greatly as does the pressure requirements. Further, simply processing them longer would only result in mush.

More importantly, it isn't the tomato you are trying to kill of course - it is the botulism spores OR if not killed, then contained in an high acid environment where they are harmless.

Extensive lab testing has been done on canned tomatoes and has well established that unless additional acid is added to them the pH of them and the spore count tends to rise over time creating a potentially unsafe product.

As always we each have the option of accepting that info or rejecting it as long as we understand that our choice carries with it a change in the risk.

Dave

it is a good thing i like lime juice in my tomatoes.

WM