Paraquat, sometimes called Gramoxone, is one of the most commonly used herbicides in the world but also one of the most toxic - it has been banned in Finland, Sweden and Austria.
First synthesised in 1882, its herbicidal properties were recognised in 1961. The substance has been associated with health problems among workers and farmers exposed to paraquat on a regular basis.
Deaths are not infrequent, according to Stop Paraquat, an online campaign launched by NGOs, trade unions and scientists around the world aimed at ending its production.
The US Centres for Disease Control and Prevention says the herbicide is even toxic to touch, , especially if contact with the skin lasts for a long time or a person has cuts, sores or rashes through which the herbicide can enter the bloodstream more quickly. If inhaled, it can cause lung damage.
But mostly, people are affected by swallowing small to medium amounts of the poison, which leads to liver, kidney or heart failure and scarring of the lungs. Ingesting large amounts can lead to coma and seizures. The damage caused depends on the amount, duration and route of exposure of the herbicide.
If someone swallows paraquat they should be given activated charcoal or food, and emergency services should be contacted. If paraquat comes into contact with clothing or skin, the area should be washed with soap and water and medical attention sought.