Paraquat is one of the world’s most widely used herbicides. It’s also highly toxic and some research points to a link with Parkinson’s disease.

Its use is highly restricted in some countries, and banned in others.

Towards the middle of 2026, Australia’s pesticides regulator is set to release its long-awaited regulatory review into the herbicide, after public consultation and considering the latest data from the United States.

Let’s see what the evidence says about paraquat’s toxicity and any link with Parkinson’s disease.

Paraquat is a non-selective herbicide that basically kills all the vegetation it touches. It’s rapidly absorbed by the leaves. There it generates unstable, oxygen-containing molecules known as “reactive oxygen species”. These break down the leaves’ cell membranes, destroy the plant’s green parts and stop photosynthesis. Essentially, with photosynthesis gone, the whole plant dies.

In Australia, paraquat is used widely in broadacre cropping to kill weeds and is an alternative to the common herbicide glyphosate. It’s also used for spot spraying. It’s popular with farmers because it can be used on a variety of weeds. It’s also rapidly inactivated when it touches the soil. This means it doesn’t remain in the soil to affect future........

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