Auteur: Henk Tennekes

Two agrochemical companies are fighting back against an E.U.-wide ban on three common neonicotinoid pesticides. Syngenta Crop Protection, which manufactures and sells one of the compounds in Europe, announced yesterday that it has brought a legal case earlier this month before the Court of Justice of the European Union, based in Luxembourg. Bayer CropScience, another producer, has done the same, a company spokesperson tells ScienceInsider. In April, the European Commission decided to introduce a 2-year moratorium on the compounds—clothianidin, imidacloprid, and thiamethoxam—following reports by the European Food Safety Authority (EFSA) saying the substances pose an “acute risk” to honey bees essential to farming and natural ecosystems. The Dutch toxicologist Henk Tennekes infers that pesticide producers are ignoring compelling evidence implicating neonicotinoid pesticides in insect decline.

Two agrochemical companies are fighting back against an E.U.-wide ban on three common neonicotinoid pesticides. Syngenta Crop Protection, which manufactures and sells one of the compounds in Europe, announced yesterday that it has brought a legal case earlier this month before the Court of Justice of the European Union, based in Luxembourg. Bayer CropScience, another producer, has done the same, a company spokesperson tells ScienceInsider. In April, the European Commission decided to introduce a 2-year moratorium on the compounds—clothianidin, imidacloprid, and thiamethoxam—following reports by the European Food Safety Authority (EFSA) saying the substances pose an “acute risk” to honey bees essential to farming and natural ecosystems. The Dutch toxicologist Henk Tennekes infers that pesticide producers are ignoring compelling evidence implicating neonicotinoid pesticides in insect decline.

EFSA scientists based their conclusions on the data submitted for the substances’ initial market approval, as well as later laboratory and field studies. They examined modes of contamination that had been overlooked when neonicotinoids were first approved for sale. But some scientists are unconvinced that the pesticides are a leading cause of pollinator deaths, and E.U. countries are divided over the issue.

“The Commission took the decision on the basis of a flawed process, an inaccurate and incomplete assessment by [EFSA] and without the full support of EU Member States,” Syngenta wrote in a statement published yesterday. “In suspending the product, [the European Commission] breached EU pesticide legislation and incorrectly applied the precautionary principle,” added John Atkin, Syngenta’s chief operating officer.

Syngenta, based in Basel, Switzerland, insists that its products are not responsible for the decline of bee populations and that the problem lies instead in “disease, viruses and the loss of habitat and nutrition.” A Syngenta spokesperson says that the company not only wants the decision reversed, but has also submitted a claim for damages. “We are also seeking to defend our reputation which has been significantly damaged,” the spokesperson tells ScienceInsider in an e-mail.

There have been “no new scientific facts” supporting a product withdrawal after years of preliminary testing and widespread use, says the spokesperson for Bayer, which is based in Monheim, Germany. He says at stake is not just these compounds, but also the way in which the European Union makes its regulatory decisions. “It’s very important for us to have guidance and clarity” regarding the European Union’s regulatory framework, he says, because these regulations have a strong impact on the firm’s investment decisions.

But several environmental groups have praised the European Commission’s action. “The Commission was right to intervene,” Mark Breddy, a spokesman for Greenpeace EU, said in a statement. “The environmental risks and the threat to agricultural production posed by these pesticides far outweigh any benefits.” Some E.U. countries, including France and Italy, have already restricted the use of neonicotinoids, with no significant impacts on agricultural production, Greenpeace says.

It may take the court years to reach a decision. In the meantime, the legal cases have no suspensory effect, so the restrictions on the three chemicals will apply as planned from 1 December in all 28 E.U. member states.

Source: ScienceInsider, 28 August 2013
http://news.sciencemag.org/europe/2013/08/pesticidemakers-challenge-e.u.-neonicotinoid-ban-court

Regulatory decisions based on current risk approaches are flawed simply because the science underpinning the risk of chemicals is inappropriate in many cases. A fundamental problem is to use one methodology for all compounds, irrespective of their toxic mode of action in organisms. According to the theories of Druckrey and Küpfmüller, the character of a poison is primarily determined by the reversibility of critical receptor binding. Chemicals showing irreversible or slowly reversible binding to specific receptors will produce cumulative effects with time of exposure, and whenever the effects are also irreversible (e.g. death) they are reinforced over time; these chemicals have time-cumulative toxicity.This concept was validated by Druckrey and co-workers with genotoxic carcinogens, the action of which is described by what is now known as the Druckrey-Küpfmüller equation: c x t˄n = constant, where c = exposure concentration, t = median time to effect, and n is an exponent > 1, which reflects reinforcement of the effect over time. Using data generated by Sanchez-Bayo, Tennekes demonstrated that the Druckrey-Küpfmüller equation also described the toxicity of (non-genotoxic) neonicotinoid insecticides to arthropods. This discovery showed that the theories of Druckrey and Küpfmüller were generally applicable in toxicology and, perhaps even more importantly, that risk assessment procedures needed to be revised, because the risks of time-cumulative toxins had been seriously underestimated.

Regulatory decisions based on current risk approaches are flawed simply because the science underpinning the risk of chemicals is inappropriate in many cases. A fundamental problem is to use one methodology for all compounds, irrespective of their toxic mode of action in organisms. According to the theories of Druckrey and Küpfmüller, the character of a poison is primarily determined by the reversibility of critical receptor binding. Chemicals showing irreversible or slowly reversible binding to specific receptors will produce cumulative effects with time of exposure, and whenever the effects are also irreversible (e.g. death) they are reinforced over time; these chemicals have time-cumulative toxicity.This concept was validated by Druckrey and co-workers with genotoxic carcinogens, the action of which is described by what is now known as the Druckrey-Küpfmüller equation: c x t˄n = constant, where c = exposure concentration, t = median time to effect, and n is an exponent > 1, which reflects reinforcement of the effect over time. Using data generated by Sanchez-Bayo, Tennekes demonstrated that the Druckrey-Küpfmüller equation also described the toxicity of (non-genotoxic) neonicotinoid insecticides to arthropods. This discovery showed that the theories of Druckrey and Küpfmüller were generally applicable in toxicology and, perhaps even more importantly, that risk assessment procedures needed to be revised, because the risks of time-cumulative toxins had been seriously underestimated.

While most toxicants with a generic mode of action can be evaluated by the traditional concentration–effect approaches, a certain number of chemicals, including carcinogens, methylmercury, rodenticides, neonicotinoids and cartap insecticides have toxic effects that are reinforced with time of exposure (time-cumulative effects). Therefore, the traditional risk approach cannot predict the impacts of the latter chemicals in the environment. New assessment procedures are needed to evaluate the risk that the latter chemicals pose on humans and the environment.
Since imidacloprid and other neonicotinoid insecticides have time-cumulative effects on arthropods, the risk of foraging worker bees feeding on tiny levels of residues becomes an issue that cannot and should not be ignored Given that honey bee workers can live up to a few months in winter time, any residue concentration found in pollen will have a lethal effect provided there is sufficient time of exposure. The values of n are 2.2 and 5.8 for thiamethoxam and imidacloprid, respectively.