Following a request from the European Commission, the European Food Safety Authority (EFSA) assessed the scientific publication by Bøhn et al. (2016), including its relevance for the environmental risk assessment of Bt-maize events MON810 and Bt11 for cultivation. In their publication, Bøhn et al. (2016) reported that the purified Cry1Ab protein is toxic to the non-target aquatic crustacean Daphnia magna (Cladocera: Daphniidae) at concentrations exceeding expected environmental concentrations under field conditions, and thus suggesting cross-order activity of the Cry1Ab protein against D. magna. EFSA acknowledges that the study reported in the publication by Bøhn et al. (2016) addresses an objective relevant for the environmental risk assessment of Bt-plants expressing the Cry1Ab protein for cultivation, as the data can inform environmental risk assessments by determining the activity spectrum of the Cry1Ab protein, and corroborating or rejecting the risk hypothesis of no harm to D. magna. However, owing to limitations associated with the design and reporting of the study, EFSA considers that several uncertainties remain, which do not allow a proper interpretation of the effects observed by Bøhn et al. (2016). In addition, EFSA notes that the observed differences were seen at Cry1Ab protein concentrations above expected environmental concentrations under field conditions, and that the authors did not bring their study results in the context of expected exposure levels in the field. As the evidence reported in Bøhn et al. (2016) is insufficient to indicate the necessity to revise the environmental risk assessment conclusions for maize MON810 and Bt11, EFSA considers that the risk assessment conclusions on maize MON810 and Bt11 for cultivation made by the Panel on Genetically Modified Organisms remain valid and applicable.