The Canning Connection
Plant foods associated with botulism are canned vegetables. In a typical scenario, vegetables contaminated with C. botulinum from the soil are not washed adequately and subjected to temperatures inadequate for killing the bacteria. As the vegetable sits on the shelf, botulinum toxin is released into the can. Because the toxin is odorless and colorless, the unsuspecting person eats the contaminated vegetable. Vegetables having neutral pH are most likely to harbor botulinum bacteria. Examples are beans, peas, and corn. Canned vegetables with low pH, such as canned tomatoes, are resistant to the growth of C. botulinum because of the acidic environment.
Fortunately, this scenario is rare as modern commercial canning techniques have virtually eliminated the risk of botulism. However, many home canners do not know the proper prevention techniques. About 10 outbreaks of botulism still occur each year in the United States. Most of these outbreaks are traced to food poisoning. Less frequently, botulism in humans stems from wound infections, or even more rarely a gastrointestinal infection of newborns. In animals, botulism can be traced to the eating of contaminated animal carcasses, or hay or grass that has been contaminated by a dead, toxic animal. Animals that characteristically feed on dead animals, such as vultures, are apparently resistant to the effects of botulinum toxin.