Response to the publication: Tennekes, H.A. (2010): The significance of the Druckrey–KÃ1⁄4pfmÃ1⁄4ller equation for risk assessment—The toxicity of neonicotinoid insecticides to arthropods is reinforced by exposure time

In his paper “The significance of the Druckrey–Küpfmüller quation for risk assessment—The toxicity of neonicotinoid insecicides to arthropods is reinforced by exposure time” (Tennekes, 010), the author refers to the Druckrey–Küpfmüller equation nd postulates its relevance for honeybee risk assessments. The ruckrey–Küpfmüller equation was established to explain the hronic effect of low concentrations of chemical carcinogens to ammals. Its essence is that for these substances the total dose equired to produce the same effect decreases with decreasing xposure levels, even though the exposure times required to prouce the same effect increase as the exposure decreases. Therefore, hen both the receptor binding and the effect are irreversible, ncreasing the exposure timewould enhance the effect. The author laims likewise, that recently similar dose–response characteristics ave been established for the toxicity of neonicotinoid insecticides o arthropods. His conclusion is that the equation would explain atterns of chronic effects of imidacloprid to honeybees and other rthropods and that this phenomenon, so far, has not been suffiiently considered in the risk assessment. The approach to extrapolate the pattern of long-term effects of arcinogenic substances to the effects of pesticides to arthropods as a certain degree of novelty. However, the concerns of the author bout potentially underestimated long-term toxicity of imidaclorid to honeybees are unfounded as the approach chosen cannot e applied to evaluate neonicotinoid chronic toxicity to insects which is based on reversible receptor binding), and moreover, as he risk assessment of imidacloprid to honey bees is based on data n which a chronic exposure of bees to imidacloprid is already fully onsidered. This is outlined in detail below: