New method quantifies very low levels of neonicotinoid pesticides in honey

Researchers at the University of Neuchâtel, Switzerland, have developed an ultra-sensitive method to quantify the extremely low levels of neonicotinoid pesticides in honey. This follows their study of the global contamination of honey by these pesticides published in the Journal. Science in October 2017. The authors, who also include colleagues from the Botanical Garden of Neuchâtel, found that these pesticides do not break down in honey over a period of 40 months. These results were published in the journal Environmental pollution.

The long-term stability of these molecules is worrying: "If these pesticides are brought back to the hive with nectar, it means that the entire colony, including the queen, is exposed throughout its life to these neurotoxins," says Blaise Mulhauser . , director of the Neuchâtel Botanical Garden.

"Similarly, the concentration of these pesticides will be stable for several years also in honey intended for human consumption," adds Edward Mitchell, co-author of the study. "Until now, only a few samples had total neonicotinoid concentrations above the current accepted limits for human consumption, but we do not really know what impact these substances have on human health in the long term, and this concern is growing. "

This new method represents a significant step forward and a major feat in terms of badytical capacity for the badytical chemistry platform in Neuchâtel led by the lead author of the study, Gaétan Glauser: this method now makes it possible to detect concentrations as well. only 2 picograms per gram of honey. . This corresponds to the mbad of a quarter-dollar American coin in the mbad of 5.6 Eiffel towers or 278 statues of liberty!

Increasing sensitivity up to 1000 times compared to previous methods now provides a clearer picture of environmental contamination by neonicotinoid pesticides. "The maximum allowable levels for human consumption are in the range of 50,000 pg / g, while concentrations as low as 100 pg / g affect bees and other pollinators and beneficial insects." This concentration may seem extremely low, but it represents molecules in the brain of a single bee, "notes Edward Mitchell.

Four additional molecules not tested in the 2007 study (dinotefuran, nitenpyram, sulfoxaflor and flupyradifurone) were found in 28% of the 36 samples badyzed. "Dinotefuran and nitenpyram are not new substances," says Gaétan Glauser, "they are less used and less often measured, but to get an overall picture, we wanted to include them in our list." Dinotefuran is not allowed in Switzerland but is used in the US, USA and Japan Nitenpyram is mainly used to treat animals. "

The inclusion of sulfoxaflor and flupyradifurone among neonicotinoids is currently the subject of debate. "Early scientific studies have shown that these molecules have the same effects as other neonicotinoids and share the same mode of action targeting nicotinic acetylcholine receptors in the nervous system," says Gaétan Glauser. . "Rather than wait 10 or 20 years to test their effects exhaustively, it seems more reasonable to apply the precautionary principle and consider these new molecules as neonicotinoids."