Theo C. M. Brock

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Single-species acute toxicity data and (micro)mesocosm data were collated for 16 insecticides. These data were used to investigate the importance of test-species selection in constructing species sensitivity distributions (SSDs) and the ability of estimated hazardous concentrations (HCs) to protect freshwater aquatic ecosystems. A log-normal model was(More)
The risk assessment of fungicides in Europe uses information from ecotoxicity studies performed on vertebrates, invertebrates, and primary producers, but not nontarget fungi. But which toxicity data should be used to assess risk and how important are modes of action and exposure regimes? A data set was compiled comprising acute single-species toxicity data(More)
A literature review of freshwater (model) ecosystem studies with neurotoxic insecticides was performed to assess ecological threshold levels, to compare these levels with the first tier approach within European Union (EU) administration procedures, and to evaluate the ecological consequences of exceeding these thresholds. Studies published between 1980 and(More)
Toxicity data for tropical species are often lacking for ecological risk assessment. Consequently, tropical and subtropical countries use water quality criteria (WQC) derived from temperate species (e.g., United States, Canada, or Europe) to assess ecological risks in their aquatic systems, leaving an unknown margin of uncertainty. To address this issue, we(More)
The toxicity of the pyrethroid insecticide lambda-cyhalothrin to freshwater invertebrates has been investigated using data from short-term laboratory toxicity tests and in situ bioassays and population-level effects in field microcosms. In laboratory tests, patterns of toxicity were consistent with previous data on pyrethroids. The midge Chaoborus(More)
In the European registration procedure for pesticides, microcosm and mesocosm studies are the highest aquatic experimental tier to assess their environmental effects. Evaluations of microcosm/mesocosm studies rely heavily on no observed effect concentrations (NOECs) calculated for different population-level endpoints. Ideally, a power analysis should be(More)
The fate of the insecticide Dursban 4E (active ingredient chlorpyrifos) and its effect on crustaceans and insects was studied in indoor experimental freshwater ecosystems that intended to mimick drainage ditches. A single dose (simulating aerial drift) was applied to achieve nominal chlorpyrifos concentrations of 5 or 35 micrograms/L. Two experiments were(More)
Secondary effects of a single dose of the insecticide Dursban 4E (active ingredient chlorpyrifos) were studied in indoor experimental freshwater ecosystems intended to mimic drainage ditches. Two experiments were performed, one in which all model ecosystems were dominated by the macrophyte Elodea muttallii, and one using systems devoid of macrophytes. In(More)
Experimental results are reported on four types of freshwater model ecosystem after administration of a single dose of chlorpyrifos. The fate, and primary and secondary effects of chlorpyrifos were compared between the model ecosystems, and were evaluated in the light of the predictive value of the current ecotoxicological hazard assessment procedure for(More)
The aim of the study was to compare the effects of the pyrethroid insecticide lambda-cyhalothrin (treated at 10, 25, 50, 100, 250 ng active ingredient a.i./L) on a drainage ditch ecosystem in spring and late summer. Microcosms (water volume approximately 430 L) were established using enclosures in a 50-cm-deep experimental ditch system containing(More)