Lately, paraquat has attracted attention with respect to its possible link to Parkinson’s disease.
On hearing this, I thought sarcastically ‘is that all’.
Paraquat is nasty, and I once used it to kill suckers coming out the rootstock of cherry trees without harming the tree itself (it doesn’t move within any plant).
The active ingredient is MPTP which stands for (take a very long breath and possibly some sandwiches for a break along the way) 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine.
MPTP is a widely-used herbicide that kills whatever it touches.
Sadly, MPTP is rumoured to be the number one choice of North Korean farmers when they finally tire of this mortal coil, and I won’t describe the gore here.
Therefore, in my orchard I wore a space suit – two actually – with Perspex face shield and three pairs of gloves and afterwards burnt everything I wore (including duds and corset underneath).
A purported link has been made between MPTP and Parkinson’s disease, based on cases in a NSW village – a kind of ‘Parky cluster’.
It is here the science splits opinions in a fog where the picture is not clear.
Gee, it’s a morbid one this week.
There is a central part of the brain (name far too long and in Latin) which, when damaged, can cause Parkinson’s.
In a mice study, application of MPTP to nasty but non-lethal levels caused damage to this area and begot the disease.
The schools of thought are thus:
“Although it is undisputed that acute exposure to certain chemicals such as MPTP is sufficient to cause human Parkinson-ism, the evidence that the risk for PD (Parkinson’s Disease) increases because of environmental exposure is generally weaker.”
That confusing statement is from Professor Colin Berry et al’s very thorough 2010 paper.
I needed to then consult Dr Lila Landowski – a personal associate, neurology lecturer, TED talker and part-time funky actress – to explain it to me (that’s her in the photo).
Simply put, bath yourself in the stuff and you will get Parkinson’s, but follow the safety instructions and there is no evidence that prolonged exposure causes the disease.
“What’s important here is where human culpability is at play,” Dr Double-L (to her friends) told me.
“In theory, if you follow the guidelines, then you lower the risk.”
A literature review from the last five years was published only five weeks ago and its 21 papers all agree: there’s no statistical causality.
In science, literature reviews are the big guns. Scientists tend to listen when a mass of research is collated, and we’d be wise to do the same.
Glyphosate (Roundup, Zero) has attracted similar attention, and although its manufacturer Monsanto has paid out US farmers who claimed it gave them cancer, a court case can rely on circumstantial evidence whereas science uses evidence-evidence.
Australia’s regulatory body (APVMA) says glyphosate products ‘are considered safe’, and the caution lessens as you cross the globe: the European Food Safety Authority says any link is ‘unlikely’, the EPA in the US says there is no evidence and Health Canada is a bit more ballsy: ‘it does not cause damage to human DNA’.
Can sufferers confidently recall their safety habits over the years? (Some Monsanto plaintiffs have admitted to shirts being soaked. What were they thinking?)
And while glyphosate can decompose relatively quickly to harmless ammonia gas, CO2 and water, MPTP can take up to six years to become just CO2, but it needs to cling to some good soil meantime.
The French were clever: a chemical first used in 1888 was copper sulphate (the blue crystals at high school which we dared each other to lick).
But back then, this ‘Bordeaux mixture’ was found, by accident, to kill powdery mildew; however its initial use was quite original.
It stopped children from stealing grapes. Even licking them.
It turned them blue (the grapes, not the kids).
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