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Toxicity to soil microorganisms

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Description of key information

The effects of the test item on the metabolic activity of soil micro-organisms were determined according to OECD Guideline 216 (2000) at Dr. U.Noack-Laboratorien,D-31157 Sarstedt, Germany. The test item was applied via demineralised water at concentrations of 10, 31.6, 100, 316 and 1000 mg/kg soil dry weight. Untreated field soil, adjusted to a moisture content corresponding to nominally 45% of its maximum water holding capacity and mixed with a source of organic nitrogen (lucerne meal), was tested as the control under the same test conditions as the test item replicates. The effects of the test item on nitrogen transformation by soil microflora were determined by comparing rates of formation of the terminal transformation product, nitrate-nitrogen (NO3--N), in soil treated with the test substance against the rate observed in the untreated control. After 28 days of exposure a statistical significant stimulation of the nitrate transformation was determined for the test item concentrations 10 and 1000 mg/kg soil dry weight (Figure1). These stimulation were below 25 % and showed no dose-response relationship. The corresponding no-observed effect concentration (NOEC) was 1000 mg/kg soil dry weight.

Key value for chemical safety assessment

Long-term EC10 or NOEC for soil microorganisms:
1 000 mg/kg soil dw

Additional information