In conversations w/county health for an olive oil tasting bar and dispensing station, a question has arisen about potential for developing bacteria or botulism in oil that is exposed to the environment, for ex: drips or spillage on a counter or floor.
There is one county in California where this concern seems to come up because of ignorance about the bacteria. Botulism is a paralytic illness caused by a toxin produced by growing Clostridium botulinum bacteria. These bacteria can grow in low oxygen environments such as sealed cans and bottles or in water covered with a layer of oil. According to the Center for Disease Control (CDC), the bacteria cannot grow in the oil itself, it must have a watery media. The concern is due to infused oils or dressings where there is a mixture of oil and water. For example, un-refrigerated garlic-infused olive oil can support the bacteria because it grows in the garlic, not the oil. Olive oil by itself is routinely sealed into unsterilized bottles without any ill effect. Oil has been used for thousands of years as a preservative, keeping foods from oxidizing and desiccating and discouraging pests.