Insecticides

Das wiesen französische Forscher an einem See in einem Weinanbaugebiet in Südostfrankreich nach. In den Sedimenten des Seebodens fanden die Wissenschaftler Mittel für Pflanzenschutz und Schädlingsbekämpfung aus dem gesamten 20. Jahrhundert. Das Insektengift DDT und seine Abbauprodukte wurden noch lange nach dem Verbot im Jahr 1972 in das Gewässer eingeschwemmt, berichtet das Team um Pierre Sabatier von der Université de Savoie in Le Bourget du Lac (Region Rhône-Alpes) in den “Proceedings” der US-Nationalen Akademie der Wissenschaften (“PNAS”).

Das europäische Pesticide Action Network (PAN Europe) hat in einer Studie das Zulassungsverfahren für Pestizide scharf kritisiert. EU-Kommission und Mitgliedstaaten ließen unabhängige wissenschaftliche Risikoanalysen oft unter den Tisch fallen.
PAN Europe untersuchte die Zulassung von sieben Pestiziden und stellte fest, dass die Mitgliedstaaten zahlreiche Studien über die Giftigkeit der Pestizide aus administrativen Gründen nicht berücksichtigt hatten. Statt unabhängiger Studien würden stattdessen überwiegend Analysen zu Rate gezogen, die die Industrie in Auftrag gegeben hatte, so die NGO. „Diese Praxis verstößt nicht gegen das EU-Recht, aber es entspricht mit Sicherheit nicht der Grundidee der Pestizidverordnung“, kommentierte PAN Europe. Die Pestizidverordnung sieht vor, dass alle wissenschaftlichen Publikationenin die Entscheidungsfindung einfließen sollen, die in Kreuzgutachten überprüft wurden.

The closer women live to areas of heavy agricultural pesticide use during pregnancy, the more likely that their children will have autism spectrum disorders, according to a study in Environmental Health Perspectives. The University of California researchers stated that this is the third study to find strong links between autism and proximity exposures to agricultural pesticides, particularly organophosphates, during pregnancy. The research was part of the population-based, case control Childhood Autism Risks from Genetics and Environment (CHARGE) study and involved 970 children. Commercial pesticide application data was mapped in relation to the mothers’ residential addresses during pregnancy, and the children were tested for Autism Spectrum Disorders (ASD) and developmental disabilities. “Approximately one-third of CHARGE study mothers lived, during pregnancy, within 1.5 km (just under 1 mile) of an agricultural pesticide application,” wrote the researchers. “Proximity to organophosphates at some point during gestation was associated with a 60% increased risk for ASD.” The figures were even higher for third-trimester exposures and second-trimester chlorpyrifos applications.

Imidacloprid is a relatively new insecticide in the chloronicotinyl nitroguanidine class. Imidacloprid has a wide variety of uses; it is used on cotton and vegetable crops, turf grass and ornamental plant products, in indoor and outdoor cockroach control products and in termite control products. Imidacloprid acts as a competitive inhibitor at nicotinic acetylcholine receptors in the nervous system resulting in impairment of normal nerve function. Scientific literature on human imidacloprid poisoning has been relatively sparse. We report three subjects who presented with imidacloprid poisoning.

The metabolic degradation and persistence of imidacloprid in paddy field soil were investigated following two applications of imidacloprid at 20 and 80 g a.i. ha−1 at an interval of 10 days. The soil samples were collected at various time intervals. The limit of quantification for the analysis of imidacloprid and its metabolites was obtained at the concentration of 0.01 mg kg−1. The initial deposits of total imidacloprid were found to be 0.44 and 1.61 mg kg−1 following second applications. These residues could not be detected after 60 and 90 days following second applications of imidacloprid at lower and higher dosages, respectively. In soil, urea metabolite was found to be the maximum, followed by olefine, nitrosimine, 6-chloronicotinic acid, 5-hydroxy and nitroguanidine. The half-life values (t 1/2) of imidacloprid were worked out to be 12.04 and 11.14 days, respectively, when applied at lower and higher doses, respectively.

Pour François Ramade, professeur émérite d'écologie à l'université de Paris-Sud, les insecticides modernes, notamment les néonicotinoïdes, sont responsables d'une véritable "catastrophe écologique". Et, selon lui, "la réponse des pouvoirs publics des pays développés et des institutions multilatérales est absente ou dérisoire". Les personnes de plus de 40 ans se souviennent des pare-brise, phares et calandres de voiture constellés de cadavres d'insectes. La propreté des voitures actuelles est le signe d'une disparition massive d'insectes qui doit nous alarmer. L'agriculture moderne a permis, par l'usage massif d'« intrants », une augmentation considérable de la productivité des cultures. Elle atteint depuis quelques décennies des limites dues à l'impact environnemental de ses pratiques. En effet, l'accroissement de productivité qu'elle a permis n'est pas dû à une révolution biologique dans le contrôle de la photosynthèse, mais à un recours sans cesse accru aux engrais chimiques et aux pesticides, dont les conséquences écologiques néfastes sont connues.

The neonicotinoid insecticide imidacloprid is among the pesticides that most frequently exceed current water quality standards in Dutch surface waters. Recent research shows that effects of imidacloprid on water organisms occur at concentrations below these standards. Mayflies appear to be particularly sensitive with chronic No Observed Effect Concentrations in the nanogram per liter range. The aim of this study was to derive updated water quality standards in accordance with the methodology of the European Water Framework Directive by evaluating the available recent literature on acute and chronic ecotoxicity of imidacloprid to aquatic organisms in laboratory and semi-field experiments. It is concluded that the standard for longterm exposure should be lowered to 8.3 nanogram per liter, the standard for short-term concentration peaks can be maintained at the current value of 0.2 microgram per liter. The European Commission set restrictions to the use of imidacloprid-based products to reduce the risks for bees and the Dutch national authorities issued emission reduction measures to protect aquatic life. Future monitoring data will ultimately reveal if these measures are sufficient to meet the newly proposed standards.