Making the right conclusions based on wrong results and small sample sizes: interpretation of statistical tests in ecotoxicology.

In environmental risk assessments statistical tests are a standard tool to evaluate the significance of effects by pesticides. While it has rarely been assessed how likely it is to detect effects given a specific sample size, it was never analysed how reliable results are if the test preconditions, particularly of parametric tests, are not fulfilled or how likely it is to detect deviations from these preconditions. Therefore, we analyse the performance of a parametric and a non-parametric test using Monte Carlo simulation, focussing on typical data used in ecotoxicological risk assessments.

Telemetry-based field studies for assessment of acute and short-term risk to birds from spray applications of chlorpyrifos.

In a program of avian field studies, radiotelemetry was combined with observations, carcass searches, residue analysis, and determination of brain acetylcholinesterase (AChE) activity to assess the acute and short-term risk posed by chlorpyrifos to birds. Studies were conducted in field crops (brassicas, Poland) and orchards (pome, Italy; citrus, Spain). In total, 25 individual applications of chlorpyrifos were studied on 13 sites.