(Beyond Pesticides, January 24, 2017) An analysis conducted by scientists at the University of St. Andrews in Scotland is calling into question the conclusions reached in a study conducted by multinational chemical company Syngenta, which indicated that honey bees were not at risk from the widely used neonicotinoid insecticide thiamethoxam. The challenge to the Pilling et al 2013 study is important because while many experiments have been performed in the lab or semi-lab environment, this study was a field experiment developed to test pollinator exposure under normal agricultural conditions. The conclusions of such real-world experiments are weighed more heavily by regulators when making safety and use determinations.
St. Andrews’ scientists focus in on the Pilling et al claim that because its study did not have high levels of replication, that it would have been misleading to perform formal statistical analysis. They respond that this would indeed be the case if Pilling et al had intended on finding statistical significance and concluded that there was no effect based on those tests. However, Syngenta’s scientists instead simply graphed average values over time based on their measurements (measurements such as number of bees in a hive, hive weight, number of brood, etc.), and compared these values between pesticide-treated and control (non-treated) colonies. It was this comparison, which Pilling et al viewed as “similar” between treated and control colonies, that was used to determine that thiamethoxam was a low risk to honey bees.
The authors of the St. Andrews’ study assert that Syngenta’s treatment of its data is “not just misleading in this case but also are unacceptable in principle, for if data are inadequate for a formal analysis (or only good enough to provide estimates with wide confidence intervals), then they are bound to be inadequate as a basis for reaching any sound conclusions.” The St. Andrews researchers make clear that Pilling et al could have performed statistical analysis to determine the power of the effects recorded by including confidence intervals in its comparative assessment. After performing this analysis themselves, researchers determined that the Pilling et al estimates were so imprecise that little could be derived from the data. The scientists stated in conclusion, “Given that the data in this case are largely uninformative with respect to the treatment effect, any conclusions reached from such informal approaches can do little more than reflect the prior beliefs of those involved.”
Other independent scientists have also criticized the Pilling et al study for its experimental design, including a 2015 piece in Environmental Sciences Europe, coauthored by a team of scientists including renowned researcher David Goulson, PhD. The authors of this piece find issue with a range of factors in Pilling et al, including the short period of exposure for pesticide-treated honey bees, the use of the pesticide at rates lower than recommended agricultural practice, the use of only one pesticide rather than a commercial product, and the failure to capture important data such as overwintering losses.
Poorly constructed studies and inaccurate or misleading conclusions put scientific integrity at risk for the broader scientific community. For this reason, it remains critical that regulators in both Europe and the U.S. consider both the data and critiques of independent scientists. The totality of the science on thiamethoxam and neonicotinoids in general paints a concerning picture for not only honey bees but a range of wild pollinators throughout the world. While Europe’s moratorium on neonicotinoid application to flowering crops remains in place, and Health Canada recently announced restrictions on the neonicotinoid imidacloprid to protect aquatic invertebrates, EPA recently announced that neonicotinoids present “no significant risks” to honey bees, despite finding a multiple instances where bees were at risk of toxic exposure.
It remains up to concerned residents to take action in response to EPA’s dismissal of the science. By getting active in your local community, fighting to enact BEE Protective policies, local residents can make changes that ripple up to the national level. For more information on taking action to protect pollinators, see Beyond Pesticides’ BEE Protective webpage.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.