Since earliest times, humans have used plants for food. Through trial and error, people have learned which plants are poisonous and should never be eaten, which ones have edible parts, and eventually, which plants could be made safe by proper preparation and cooking.

Many fruits and vegetables contain small amounts of natural toxicants that are of no concern when the food is consumed as part of a varied diet and eaten in moderation. Moldy or damaged plants may contain a higher level of toxins than normal ones. A chart identifying some natural toxicants in foods is in further readings in this Module.

Those who like to eat unfamiliar plants collected from the wild should first learn how to prepare and cook such food safely. Be cautious in the use of herbal medicines, herbal teas, and other plant mixtures that may have limited testing for safety.

Fish and shellfish may accumulate enough toxins from algae to make them unsafe to eat. The two types of shellfish poisoning which occur in Washington shellfish are paralytic shellfish poisoning and amnesic shellfish poisoning (also called domoic acid poisoning). The Washington Department of Health monitors shellfish for accumulation of algae toxins. If the toxins are found, the waterways are closed to shellfish gathering. For additional information read Gathering Safe Shellfish in Washington on the WSU food safety web site http://foodsafety.wsu.edu/consumers/factsheet10.htm.