The toxic impact of pesticides on bees and other pollinators has doubled in a decade, new research shows, despite a drop in the amount of pesticides used.
Modern pesticides have much lower toxicity to people, wild mammals, and birds and are applied in smaller amounts, but they are even more toxic to invertebrates. The study shows that higher toxicity outweighs lower volumes, leading to an overall deadlier impact on pollinators and waterborne insects like dragonflies and mayflies.
The scientists said their work contradicts claims that decreasing the amount of pesticides used is reducing their environmental impact. Research also shows that the toxic impact of pesticides used on genetically modified crops remains the same as on conventional crops, despite claims that GM crops would reduce the need for pesticides.
The research is based on the use and toxicity of 380 pesticides applied in the US from 1992 to 2016. Scientists said the same trend of lower volumes but greater toxic impact is likely for many regions of the world, but Open access data on pesticide use is not available in the EU, Latin America, China or Russia.
Pesticides are a factor cited by scientists for the fall of the populations of some insects. Insects play a vital role in the ecosystems that sustain humanity, particularly by pollinating three-quarters of crops.
“Compounds that are particularly toxic to vertebrates have been replaced by compounds with less toxicity to vertebrates and that is indeed a success,” said Professor Ralf Schulz, from the University of Koblenz and Landau in Germany, who led the research. “But at the same time, pesticides became more specific and therefore unfortunately also more toxic to ‘non-target organisms’ such as pollinators and aquatic invertebrates.”
Schulz said: “GM crops were introduced on the grounds that they would reduce agriculture’s dependence on chemical pesticides. Obviously, this is not true if you look at toxicity levels. “
The study, published in the journal Science, used US government data on pesticide use and the toxicity level of each chemical to give a measure of “total applied toxicity.” This made it possible to evaluate the changes over time. Looking only at the amount of pesticide applied gives a false picture, the scientists said, because some are orders of magnitude more toxic than others.
They found that the replacement of organophosphate and carbamate insecticides reduced the overall toxicity to mammals and birds by a factor of nine. “In stark contrast, the total toxicity applied to invertebrates has increased markedly since about 2005,” they said, even though the amount of insecticide applied decreased by 40%.
This was because pyrethroid and neonicotinoid replacements are more toxic to pollinators and aquatic invertebrates. The damage to bees has led the EU to ban the use of some neonicotinoids outdoors.
The scientists said the impact on insects could have knock-on effects on other animals, such as the birds that depend on them for food, as indicated in a 2014 study in the Netherlands. They also said that the lack of public data on pesticides in many places “potentially mask a crucial driver of global biodiversity decline.”
“The more we know about the issues, the better, therefore I would call our study good news,” said Schulz. “So obviously it’s a political and social debate about what kind of effects we want pesticides to have or not.”
Chris Novak, President of CropLife America, representing pesticide companies, said: “Our members continue to innovate solutions that have less impact on human health and the environment, but our innovations must meet the needs of a dynamic agricultural system. We are committed to continue working with the [US] Environmental Protection Agency to apply the best science, balancing the risks and benefits of pesticide use. “
Josie Cohen, Pesticide Action Network UK, He said: “Some neonicotinoid insecticides are 10,000 times more toxic than DDT, the most notorious insecticide in history. The UK government urgently needs to deliver on its promise to improve the current woefully inadequate monitoring system for pesticides by going beyond simply measuring the weight of chemicals. “
George is Digismak’s reported cum editor with 13 years of experience in Journalism