Organisms exposed to man-made pollution by chemical substances may, in whole or in part, lose their ability to tolerate natural stress such as e.g. cold and drought. The main hypothesis in our work is that interactions between the effects of various stressors are mainly caused by manifestations of stressors influencing the same thing, namely cell membranes. We therefore try to on one hand link molecular knowledge on the properties and impairment of membranes, and the physiological consequence on relevant organisms on the other.