Glyphosate
Why in News?
Glyphosate is in news because India is moving to restrict (not fully ban) its use after the paraquat ban, following health and environmental concerns, and because of fresh reports of its misuse in Himachal forests for off‑season pea cultivation.
About
- Chemical Profile: It is a broad-spectrum, systemic herbicide and crop desiccant first brought to the market by Monsanto in 1974 under the trade name Roundup.
- Non-Selective Nature: It is a non-selective weedkiller, meaning it indiscriminately kills almost all green vegetation and plants it comes into contact with, rather than targeting specific weeds.
Mechanism of Action
- Enzyme Blocking: It blocks the shikimic acid pathway in plants by inhibiting a specific enzyme called EPSP synthase.
- Protein Deprivation: By stopping this enzyme, the plant can no longer synthesize essential aromatic amino acids (like phenylalanine, tyrosine, and tryptophan) needed for growth, causing it to die within 1 to 3 weeks.
- Systemic Absorption: It is absorbed directly through the leaves and stems and translocates rapidly to the roots and active growth regions.
- Genetically Modified Crops: It is primarily paired with "Roundup Ready" GMO crops (like soy, corn, and cotton) modified to survive the chemical while surrounding weeds die.
- Pre-Harvest Desiccation: Farmers frequently spray it on non-GMO crops like wheat just before harvest to kill the plant uniformly, allowing for quicker and easier machine harvesting.
The Global Health & Safety Divide
- The WHO Stance: The World Health Organization's International Agency for Research on Cancer (IARC) categorises glyphosate as "probably carcinogenic to humans" (Group 2A), specifically linking it to Non-Hodgkin Lymphoma.
- The US EPA Stance: Conversely, the US Environmental Protection Agency (EPA) maintains that glyphosate is "not likely to be carcinogenic" when used strictly according to label instructions.
- Other Health Concerns: Beyond cancer, independent studies link prolonged exposure to liver inflammation, kidney damage, gut microbiome disruption, and reproductive/endocrine issues.
Environmental Impacts
- Soil and Water Persistence: While it binds to soil particles, its breakdown product—AMPA (aminomethylphosphonic acid)—is highly persistent and frequently washes into groundwater, streams, and rainwater.
- Biodiversity Loss: Heavy usage has severely depleted wild plants like milkweed, devastating vital pollinator populations such as monarch butterflies and honeybees.
- Superweed Resistance: Over-reliance has caused many toxic weed varieties to develop immunity, trapping farmers in a vicious cycle of spraying ever-increasing volumes of the chemical.
