How Long Does Paraquat Take to Become Ineffective in the Air
Paraquat is a fast-acting herbicide that is quickly absorbed by plants and causes them to wither and die, so how long does paraquat take to become ineffective in the air?
1. What Is Paraquat
Paraquat's chemical name is 1-1-dimethyl-4-4-bipyridyl cation salt. It is a fast-acting non-selective herbicide with contact action and a certain systemic action.
Paraquat is easily soluble in water and appears as a white powder. Its main component is 1,1’dimethyl4,4’dichlorobipyridyl. Paraquat is extremely toxic to humans, with a poisoning mortality rate greater than 99%, so it has now been banned or strictly restricted in more than 20 countries. In China, since July 1, 2014, the registration and production license for paraquat aqueous solution have been revoked and production has stopped; however, registration for export abroad of the aqueous solution by technical material manufacturing enterprises has been retained, and production exclusively for export is allowed. On July 1, 2016, the sale and use of the aqueous solution in China were stopped.
The scope of application of paraquat is: various annual weeds; it has a strong killing effect on perennial weeds, but their underground stems and roots can sprout new shoots; it has no effect on already lignified brown stems and tree trunks.
2. How Long Does Paraquat Take to Become Ineffective in the Air?
Paraquat generally does not become ineffective in the air, but when paraquat encounters soil it binds with the soil and becomes deactivated. Paraquat is extremely toxic to humans, and there is no specific antidote. It was banned for use by the state in 2016.
Paraquat is a non-selective herbicide. If it is not sprayed on the green stems and leaves of crops, and the liquid only touches brown lignified bark and branches, it causes no harm to crops or trees. Paraquat loses its activity upon contact with soil. When used for chemical weeding 1-2 days before sowing, it is safe for crops.
3. Toxicology of Paraquat
Paraquat has irritating and corrosive effects on the skin and mucous membranes. Systemic poisoning can cause multi-system damage, especially more severe lung damage, and can cause pulmonary congestion, hemorrhage, edema, hyaline membrane formation, and changes such as degeneration, hyperplasia, and fibrosis. In addition, it can also cause liver and kidney damage and involve systems and organs such as the circulatory, nervous, blood, gastrointestinal, and bladder systems.
The toxic mechanism has not yet been clarified. Most scholars believe that paraquat is an electron acceptor that can be actively transported by type I and type II lung cells and taken up into cells, where it acts on the cells' redox reactions. Its activation into oxygen free radicals within cells is the basis of its toxic effect. The excessive superoxide anion free radicals (O=) and hydrogen peroxide (H?O?) formed can cause lipid peroxidation of cell membranes in the lungs, liver, and many other tissues and organs, thereby causing damage to multiple systems, tissues, and organs.