I would like to pickle vegetables in oil or vinegar. Is there a hazard caused by botulism?

Germany

Human botulism is a serious but relatively rare disease. The disease is an intoxication caused by extremely potent toxins preformed in foods. The toxins are produced by the bacterium Clostridium botulinum.

The sporulated form of the bacterium is commonly found in soils, aquatic sediments and fish. The spores are heat-resistant. Under anaerobic conditions (without oxygen), botulinum spores can germinate, and the bacterium grow and produce the toxin. Ingestion of the toxin present in improperly prepared food is dangerous and may be fatal. Botulism is mainly a foodborne intoxication but it can also be transmitted through wound infections or intestinal infection in infants.

The botulinal toxin has been found in a variety of foods, including low-acid preserved vegetables, such as green beans, spinach, mushrooms, and beets; fish, including canned tuna, fermented, smoked and salted fish; and meat products, such as ham, chicken and sausage. The toxin is destroyed by normal cooking processes (heating at 85 degrees for five minutes or boiling for a few minutes). Clostridium botulinum will not grow, and therefore the toxin will not be formed in acidic foods (pH less than 4.6). However, the low pH will not inactivate any preformed toxin.

Prevention of botulism is based on good food preparation (particularly preservation) practices and hygiene. Botulism may be prevented by inactivation of the bacterial spores in heat-sterilized, canned products or by inhibiting growth in all other products. Commercial heat pasteurization (vacuum packed pasteurized products, hot smoked products) may not be sufficient to kill all spores and therefore safety of these products must be based on preventing growth and toxin production. Refrigeration temperatures combined with salt content and/or acidic conditions will prevent the growth or formation of toxin.

WHO Botulism

http://www.who.int/mediacentre/factsheets/who270/en/print.html