An Adverse effect is some abnormal change in an organism, which might be brought about by exposure to a chemical or to radiation for example. This effect may be as significant as a change in mortality, or may be less dramatic, such as a change in food consumption, a variation in enzyme levels, or an increase in susceptibility of the organism to other chemical or biological stress. A non-adverse effect will usually be reversed when exposure to the trigger ceases, whereas an adverse effect may be long-lasting or permanent.