So assessments of safety of a chemical aren't hard science. They are statistical judgment calls (often based on things like giving a much, much higher dose to a rodent and looking for short-term effects).

And the reason that is is because there's no affordable, moral way to give 100,000 farmers [nor consumers] a small dose of a product for 20 years before declaring it safe. So the system guesses, and it guesses wrong, often erring against the side of caution in the US (it's actually quite shocking how many pesticides later get revoked after approval).

Europe takes a more "precautionary principle" approach. In those cases of ambiguity (which is most things approved and not), they err to the side of caution.

Notice how this claim here is again shifting the burden to the victims (their research doesn't meet standard X, allegedly). Absence of evidence isn't evidence of absence.

Chevron clasically has ignored health and safety requirements to the point where there was once the “Chevron Doctrine” which deferred legal interpretations to specialized regulatory agencies which established clearer guidance against murky legislative directives. The Doctrine was recently overturned by the ostensibly rogue SCOTUS as highlighted by the harvard business review: https://hbr.org/2024/09/the-end-of-the-chevron-doctrine-is-b...

[Edit] The below comment is inaccurate. The pesticide sprayed for gypsy moths was DDT. I am leaving this comment because it should be known that this was a thing even though it is now off topic.

P̵a̵r̵a̵q̵u̵a̵t̵ DDT is also linked to the polio pandemic. It was sprayed everywhere gypsy moths were found. Great success at killing moths. Also weakened human children to to where a common disease could get into spines and cause paralysis.

Researching this kind of stuff is not for the faint of heart. Its horrible all the way down. Not recommended for the faint of heart.

> What lead it to being "banned in dozens of countries all over the world, including the United Kingdom and China"?

Almost everyone who banned it did so because of acute toxicity - it requires careful handling to use safely.

Unfortunately, it was commonly used to commit suicide in many countries. In other countries, it was deaths from accidental ingestion, lung damage from unsafe handling, etc.

I don't know of any country that banned it because of a purported link to Parkinson's.

There's a synthetic opioid called MPPP, which, if inappropriately synthesized (IIRC, using too much heat in one step), yields MPTP, which is non-toxic in and of itself, but has the ability to penetrate the blood-brain barrier, where it is then metabolized into MPP+, which is potently neurotoxic to the dopaminergic neurons of the Substantia Nigra, reliably producing a Parkinsonism in those exposed to it (from wikipedia):

>The chloride salt of MPP+ found use in the 1970s as an herbicide under the common name cyperquat.[4][3] Though no longer in use as an herbicide, cyperquat's closely related structural analog paraquat still finds widespread usage, raising some safety concerns.

EDIT: the neurotoxicity of MPTP was discovered after a number of heroin addicts developed a sudden, irreversible Parkinsonism after injecting bad batches: https://archive.org/details/TheCaseoftheFrozenAddict

The doctor featured in that NOVA episdoe summarizes the history of MPTP and its relevance to Parkinson's research and epidemiology here: https://pmc.ncbi.nlm.nih.gov/articles/PMC5345642/

> Over the last two centuries the pendulum of opinion has swung widely as to whether the cause of PD was due to genetics or environment causes [69]. While MPTP has not yet been found in the native environment, beginning in the 1980s the pendulum swung dramatically in the direction of the environmental hypothesis, spurred not only by the observation that a simple pyridine (MPTP) could induce so many of the features of PD, but also the striking similarity between its toxic metabolite, MPP+ and paraquat (differing only by one methyl group) [70], an herbicide that is used worldwide. Since that time, a large number of studies have shown pesticide exposure is a risk factor for PD [71]. Interesting, this risk is enhanced by the presence of certain genetic variants [72], consistent to the adage that “genetics load the gun, but environment pulls the trigger”.

The other thing you should know is that they use it to help the plants grow, but they use larger amounts to kill the plants at the same time so they can uniformly harvest. So we eat more of this crap than you'd expect, because they are using it beyond expected ways

in most civilised countries: chemicals added to food are banned until proven safe

... then you have the USA

>What lead it to being "banned in dozens of countries all over the world, including the United Kingdom and China"?

political pressure. Same reason lots of stuff is banned in the EU even when it's safer than other things that aren't banned.