Reliability of assessment tools in measuring the impact of pesticides

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Temps de lecture : 3 minutes  

It’s time for us, and for you, to make a decisive break. Because the figures -all these figures, suggestions, verbal diatribes, even the nicest ones – rely on inconclusive scenarios that are, uncertain, arguable or give rise to argument. At the start, experts agreed on a “harmless dosage” (HD) for each pesticide. This represents the limit under which tests have shown they have no effect. Another figure is added – that which is meant to guarantee total safety – the “Daily Admissible Dosage” (DAD), a hundred times lower than the HD. And that’s the end of the debate. Powerful international institutions, like the World health Organization (WHO) and the Food and Agriculture Organization (FAO), have lent and still lend their prestigious support to this form of danger assessment.

Is this right? […] Let’s take one example, gripping as it is peculiar, the dioxin. In the United-States, the Environmental Protection Agency (EPA) has been taking this seriously for about twenty years. Maybe it was the memory of the Vietnam War and the disastrous effects of the “orange agent” which actually contained dioxin? In any case, the EPA created a standard which seems unbelievable for a French person, that of the daily admissible dosage of dioxin tolerated by humans. This was a 0.0064 picogram, or a trillionth of a gram, per kilo and per day. This is nothing or so little, that the EPA means that every dioxin molecule is a threat to life.

As for the WHO, […], it fixed a totally different threshold. Until 1997, it was 10 picograms per kilo and per day, that is to say…one thousand five hundred times more. Who outbids that? Ever since, the standard ranges from 1 – 4 picograms, that is to say fifty to six hundred times more than for the Americans, protected as they are by both Coca Cola and McDonalds.

This little aside over, let’s ask the question again: are HD and DAD correct indicators of the potential effects of pesticide residues in our everyday diet? Unfortunately, the answer is no.

There is a still a minority of scientists whose opinions nevertheless carry increasing weight, who are challenging the notion of DAD. At a time when nuclear authorities, who at last agree that low radiation doses have harmful effects, and formerly denied, this issue deserves attention.

As a precaution, let us underline that anything we write further to this, comes from our own great ignorance, and an equally great desire to launch a genuine public discussion on the subject. Everyone agreed? Then let’s go. The mechanics of carcinogenesis, that is to say, whatever leads to the development of the first cancerous cell, and its proliferation, have been researched since the turn of the last century, especially by the Japanese researchers Yamigawa and Ichikawa. No need to say that this work has been the subject of great turbulence, especially since the very recent developments in molecular biology.

So much so, that several discoveries and works accredited to the cancerologist Eric Pluygers and many others, reveal that some toxins, including pesticides, have effects at levels below the detection thresholds. Is this truly revolutionary? As Pluygers mentions in a note requested by a Belgium deputy, “These notions are of major importance since the lack of threshold means that a substance is biologically active at its lowest concentration level, that of a single molecule. Under those conditions, no exposure level is admissible.”

Dear readers, when you read over these words, you will agree that it changes everything. Everything! For in a billionth of a gram of any kind of dangerous substance, there will always be at least a few dozen potentially active and devastating molecules for our genes and DNA. Besides, Pluygers sees to it that at numerous symposiums and speeches, the foundation of the pesticides “monitoring” system, the infamous daily admissible dosage, is smashed to pieces. During a conference on 5th December, 1998, he himself asserts: “We have to admit that the DAD is not applicable to a wide range of carcinogenic substances, because it does not account for the mechanisms of carcinogenesis.” And quoting Professor De Jonckheere from the University of Gand, author of a study, he adds: “DAD values are not exact data, but rather calculations based on experimental toxicological data of a pesticide. This approach does not take into account the possible synergistic effects through exposure to two or more pesticides at the same time.”

Cocktails are no longer controllable

Is there any need to insist on it? This issue is crucial. The DAD is actually fixed for each pesticide but we are currently exposed to cocktails of many substances, which mix and interact of course, without anyone being able to explain how. This knowledge is simply out of reach. No scientist, however brilliant, is able to tell us what such or such molecule produce together in a living tissue. The issue is as clear as mud, a dead silence, an ultimate taboo: so above all, let’s not talk about this DAD which protects nothing and no-one.

François VEILLERETTE and Fabrice NICOLINO.

“Pesticides: revelations of a French scandal” (p.39 to 42) – – 2007

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