Despite the rigorous regulatory frameworks designed to prevent or mitigate environmental damage, pesticide use is still linked to declines in insects, birds and aquatic species, an outcome that raises questions about the efficacy of current regulatory procedures.
In a Policy Forum article published in the Jan. 24 issue of Science, experts say aging environmental risk assessment regulations for pesticides are out of line with current environmental science and toxicology, and are based on false assumptions that misrepresent the dynamic ecological systems in modern agricultural landscapes.
As a result, many pesticide policies that aim to protect against environment damage fail to deliver on their promises, creating unexpected harmful effects of pesticide use, they conclude.
To implement a regulatory framework that provides adequate environmental protection, a radical overhaul of the current approach to environmental risk assessment for pesticides is necessary, said Christopher Topping, a researcher at Denmark's Aarhus University and lead author of the paper.
Topping and his colleagues argue that a more holistic, integrated systems-based approach to pesticide regulation would represent a much more realistic picture of the agricultural environment and have the flexibility to account for currently overlooked factors, including climate change, habitat loss and landscape homogenization, which can exacerbate the adverse impacts of pesticide use.
"Critically, [our approach] takes the scale of use of pesticides compared to the resilience of the ecosystem into account," while balancing agronomic and economic costs and benefits with regionally tailored risk mitigation options, said Topping.
In the European Union and United States, as well as other nations worldwide, most of the current assessment guidelines were developed in the mid-1990s and are based on the 'one pesticide, one use' approach. Under this approach, the safety of an individual pesticide is largely evaluated on its single use in a specific crop. While the concept's aim to balance the potential risks per pesticide is well-intentioned, the assessments do not account for how pesticides are used in the real world, including the impacts of exposure on biodiversity throughout wider ecological communities.
According to Topping, a decade's worth of scientific insight into agroecology and toxicology has brought the faults and failings of the current pesticide risk assessments into focus - many of which were overlooked or simply unknown when the regulations were first implemented nearly 30 years ago.
However, changing 30 years of risk assessments is a huge undertaking, said Topping; "The first challenges will be developing the legal and economic basis necessary, and then there are the scientific challenges of ensuring that we assess the correct aspects of the ecosystems and that we have the necessary data to do this effectively."
Changes to the administrative structures involved present a particular challenge. Agreement between many governmental interests has been difficult to achieve and those who work within the current system fear overcomplication or prefer to wait for a sure-fire scientific solution.
By contrast, "I believe that the pesticide industry would by and large be positive because this would provide a way forward that does not involve blanket bans," said Topping.
While in need of a new approach, the current risk assessments have been successful, said Topping, who noted that the use of some highly persistent or toxic pesticides with acute risks to human health has been banned in some countries. For instance, the European Union has banned chlorpyrifos, which has been linked to neurological effects and persistent developmental disorders, especially in children. Petitions to implement a ban on chlorpyrifos in the United States were denied by the U.S. Environmental Protection Agency in 2019.