Which herbicide is known for causing lethal systemic effects in humans?

• A. Glyphosate
• B. Paraquat
• C. 2,4-D
• D. Dicamba

Answer: (B)

Paraquat is notorious for causing lethal systemic effects in humans because of its way of causing widespread oxidative damage once absorbed. It rapidly enters the body and tends to concentrate in the lungs, where it undergoes redox cycling to produce reactive oxygen species. This relentless oxidative stress injures cells and tissues, leading to pulmonary edema, irreversible pulmonary fibrosis, and progressive organ failure. Ingested or inhaled paraquat can overwhelm the body's defenses, and there is no widely effective antidote, so outcomes are often fatal despite medical care.

Other herbicides listed do not share this combination of rapid absorption, selective high lung accumulation, and near‑certain progression to fatal systemic injury, so while they can cause irritation or nonfatal symptoms under some exposures, they are not known for lethal systemic effects in the same way.