In July and August of 1987, 187 residents who ate soup made from sea clams in Champerico on the Pacific coast of Guatemala suffered from food poisoning (Paralytic Shellfish Poisoning), resulting in 26 deaths. Children under the age of six showed a high mortality rate of 50%, while adults over 18 had a mortality rate of 7%. The cause of their deaths was a toxic substance contained in the clams, which does not decompose even when boiled. This toxic substance was produced by algae living in the sea. At the time of the incident, the sea was showing a red tide phenomenon, where algae proliferate explosively and turn the water a dark red color.