Millettia thonningii

Safety & Hazards

The leaf juice is poisonous^[1]. Millettia species in general contain a range of toxic substances, especially isoflavones. Rotenone is probably the best known of these isoflavones and it is found especially in the seeds and roots of the plants. Rotenone is often used locally as a fish poison - the rotenone kills or stuns the fish making them easy to catch, but the fish remain perfectly safe for warm-blooded creatures to eat. Rotenone is classified by the World Health Organization as moderately hazardous. It is mildly toxic to humans and other mammals, but extremely toxic to many insects (hence its use as an insecticide) and also to aquatic life, including fish. This higher toxicity in fish and insects is because the lipophilic rotenone is easily taken up through the gills or trachea, but not as easily through the skin or the gastrointestinal tract. The lowest lethal dose for a child is 143 mg/kg, but human deaths from rotenone poisoning are rare because its irritating action causes vomiting. Deliberate ingestion of rotenone, however, can be fatal. The compound decomposes when exposed to sunlight and usually has an activity of six days in the environment. Millettia species often also contain other potentially toxic compounds, especially saponins and alkaloids^[2].