If ricin is swallowed, its symptoms are nasty but not fatal. But if it is injected or inhaled or absorbed through the mucus membranes, a dose the size of a few grains of salt will kill an adult man. Ricin inhibits the protein synthesis of cells, causing cell death, and damage to the major organs. There is a delay of a few hours before the appearance of symptoms, which include high fever, seizures, severe diarrhoea, chest pains, breathing difficulties and oedema