The minimum detectable difference (MDD) is a measure of the difference between the means of a treatment and the control that must exist to detect a statistically significant effect. It is a measure at a defined level of probability and a given variability of the data. It provides an indication for the robustness of statistically derived effect thresholds such as the lowest observed effect concentration (LOEC) and the no observed effect concentration (NOEC) when interpreting treatment-related effects on a population exposed to chemicals in semi-field studies (e.g., micro-/mesocosm studies) or field studies. MDD has been proposed in the guidance on tiered risk assessment for plant protection products in edge of field surface waters (EFSA Journal 11(7):3290, 2013 ), in order to better estimate the robustness of endpoints from such studies for taking regulatory decisions. However, the MDD calculation method as suggested in this framework does not clearly specify the power which is represented by the beta-value (i.e., the level of probability of type II error). This has implications for the interpretation of experimental results, i.e., the derivation of robust effect values and their use in risk assessment of PPPs. In this paper, different methods of MDD calculations are investigated, with an emphasis on their pre-defined levels of type II error-probability. Furthermore, a modification is suggested for an optimal use of the MDD, which ensures a high degree of certainty for decision-makers.

This position paper intends to stimulate a profound rethinking of contemporary agricultural practice. We criticise the current intensity of chemical plant protection in Germany as ecologically unsustainable and thus threatening the achievement of key targets of environmental protection and nature conservation policies. In the first part of the paper, we provide background information on the use of plant protection products (PPP) in German agriculture, the role of agricultural policy, European pesticide legislation, the principles of and framework for environmental risk assessment and risk management of PPP, as well as environmental effects of PPP. The second part is presented against the backdrop of the European "Sustainable Use Directive" (2009/128/EC). This directive requires that "Member States shall adopt National Action Plans to set up their quantitative objectives, targets, measures, and timetables to reduce risks and impacts of pesticide use on human health and the environment and to encourage the development and introduction of integrated pest management and of alternative approaches or techniques to reduce dependency on the use of pesticides." Reflecting on the corresponding debate in Germany, we suggest the following five key principles for a sustainable use of PPP and provide recommendations for their implementation: (1) minimising use; (2) identifying, quantifying, and communicating risks; (3) optimising risk management; (4) compensating for unavoidable effects; (5) internalising external costs.

Agricultural soils provide a multitude of ecosystem services enabling safe and efficient crop production. These services depend on a good ecological status comprising the typical biodiversity of communities of soil organisms. The process of pesticide registration involves an Environmental Risk Assessment to ensure that the general protection of ‘biodiversity’ is achieved. The description of the specific risks to non-target soil communities requires advanced methods in a tiered approach, proposed to be ‘multispecies higher-tier’ test systems at the semi-field level. A well-described and -understood test system could serve as a surrogate reference tier for the calibration of the risk assessment of pesticides.

We have investigated the effect of antimicrobials triclosan (TCS) and triclocarban (TCC) on biodegradation of 17beta-Estradiol (E2) and 17 alpha-Ethynylestradiol (EE2) in a sandy soil from South Australia. Two separate batch studies were conducted. In the first, the rates of loss of E2 and EE2 were determined at time intervals of 0, 3, 7, 14, 21, 28 and 56 d after initial spiking of soil with each estrogen at 1 mg kg(-1) and the antimicrobials at 10 and 100 mg kg(-1). Little loss of E2 and EE2 (<15%) under sterile conditions was noted compared to rapid loss in non-sterile soil (>60% in 24h). There were no measurable effects on estrogen degradation by the two antimicrobials at spiked concentrations up to 100 mg kg(-1). The experiments were repeated to study degradation rates of the estrogens within the first 24h (0, 3, 8, 24h), 3 d and then weekly to 56 d. Again, E2 and EE2 degradation was not significantly affected by the presence of TCS up to 100 mg kg(-1) (p>0.05). However TCS did significantly affect biodegradation of the estrogens when the soils were spiked with 1000 mg kg(-1) of TCS (p<0.0005). In contrast, presence of TCC in soil showed no significant effect on biodegradation of the two compounds up to 1000 mg kg(-1) (p>0.05). Considering environmental concentrations of the antimicrobials reported in the literature, it is highly unlikely these biocides would have any adverse impact on biodegradation of E2 or EE2 in soils.