In July 2010 I published a ground-breaking discovery in the journal Toxicology. My paper convincingly demonstrated that the risk of chronic exposure of arthropods (including bees) to a relatively new class of pesticides, called neonicotinoids, which are mainly produced by Bayer CropScience, had been severely underestimated. There is general consensus now about this conclusion. The discovery explained bee decline. The neonicotinoids are an important product of Bayer CropScience, generating hundreds of millions each year.

In my time as head of toxicology at a Swiss CRO (1985-1992) I developed friendly contacts with Bayer CropScience employees. My expertise as a toxicologist has never been in doubt in the chemical industry. I was generally regarded as one of the best in my field. That is why I was convinced my colleagues at Bayer CropScience would contact me to initiate a constructive dialogue on the subject, aiming to develop new risk analysis guidelines for approval by the regulators. The likelihood was that a number of products would have to be withdrawn from the market. But that is not uncommon in the agrochemical industry. Companies are constantly developing new products, building on existing know-how and experience with the first product of a new substance class.

Unfortunately, that did not happen. Instead, in October 2010, I received a note from the Editor-in-Chief of the journal Toxicology, informing me about a Letter to the Editor by two employees of Bayer CropScience, with a request to respond. It was a very opportunistic attempt to disprove my discovery. The Bayer employees denied that there was an underestimation of the risk of chronic exposure of arthropods. It was a blatant attempt to discredit my reputation as a toxicologist. My answer destroyed the Bayer CropScience epistle, at least that is how I see it. That was the start of a nasty confrontation that is going to harm both parties.

I was extremely concerned about the negative impact of these substances on biodiversity. Bayer CropScience appeared to prefer confrontation, and I remained convinced that my concerns were well founded. A major disaster loomed. I found myself compelled to publish a book to warn the general public about an impending environmental catastrophe. I succeeded. My book "Disaster in the Making" was a great succes and is read all over the world. I am now walking in the footsteps of the famous biologist and writer Rachel Carson, author of Silent Spring (1962). However, as the result of this succes, the confrontation with Bayer CropScience intensified.

Bayer CropScience has never attempted to initiate a constructive dialogue on the subject. I have never been asked to participate in further research. After a while, everyone in the agrochemical industry knew that renowned toxicologist Henk Tennekes was at odds with one of the largest producers of pesticides. Several colleagues assured me that a potential client in the agrochemical industry is unlikely to outsource work to me under such circumstances. So, the absence of a constructive dialogue during the last three years is now affecting my livelihood.

My discovery was recognized and endorsed at the European level (Annex), and the use of neonicotinoids in agriculture and elsewhere has become highly controversial. The manufacturers are doing everything they can to prevent prohibition. Whether they will succeed is highly uncertain. The reputation of Bayer CropScience (and in fact the entire agro-chemical sector) was severely damaged by the issue and that many consumers are changing to organic food.

I am not going to change my position regarding the neonicotinoids, come what may. These substances destroy biodiversity. Their continued use will lead to an environmental disaster of unprecedented proportions. Further research is urgently needed to identify substances with similar properties. These projects are ready to go and would be performed by a number of highly experienced European scientists over a period of 2 years. However, we are in need of funds. If you are willing to provide financial support for this objective, may I kindly ask you to contact me at info (at) or info (at) Be assured that all correspondence will be regarded as strictly confidential.

Yours sincerely

Dr. H. A. (Henk) Tennekes
Consultant in Toxicology
Experimental Toxicology Services (ETS) Nederland BV
Frankensteeg 4
7201KN Zutphen, The Netherlands

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