Malathion (also known as marathon) is a parasympathetic insecticide made of organic phosphorus. It will irreversibly combine with cholinesterase and has low toxicity to humans. In the former Soviet Union, this chemical is called "carbophos", in New Zealand and Australia as "maldison", and in South Africa as "mercaptothion". It is an over-the-counter pharmaceutical product in Hong Kong. Malathion is highly volatile and has low toxicity to humans and animals. As long as it is placed in a ventilated place, its toxicity will be reduced immediately. Marathon pesticides will be dispersed into the environment when they are manufactured and used in large quantities. If the spraying process falls into the soil, the marathon will combine with the soil and will be hydrolyzed quickly without polluting the groundwater source.