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EC number: 232-033-3 | CAS number: 7783-90-6
Toxicity to soil macroorganisms except arthropods
Administrative data
Link to relevant study record(s)
Description of key information
The number of juveniles produced was the most sensitive endpoint producing an a EC10 value of 15 mg Ag/kg dry soil and a NOEC of 11.2 mg Ag/kg dw.
Key value for chemical safety assessment
Additional information
The earthworm growth and reproduction test (AECOM 2011a) was conducted to comply with the OECD Guidelines for the Testing of Chemicals Method 222: Earthworm Reproduction Test using Eisenia fetida as a test species. The test media used consisted of 10% sphagnum peat, 20% kaolinite clay and 70% fine silica sand, with an addition of calcium carbonate to raise the pH. Characterisation of the soil indicated that it had a pH of 7.2, organic carbon content of 4.3% and consisted of 76% sand, 9% silt and 15% clay.
The test was conducted using 8 rates of Ag addition, which were measured and ranged from 3.27 to 216 mg Ag/kg dry soil at day 0, plus a control treatment. Earthworm mortality, growth and avoidance were measured over 28 days. At 28 days the surviving worms were removed and the test soil retained for reproduction measurements after an additional 28 days. The most sensitive endpoint over the initial 28 days was earthworm growth (measured as the change in weight from day 0 to day 28), which produced a NOEC of 39.0 mg Ag/kg dry soil. Following the reproduction component of the test, the number of juvenile worms and cocoons in each treatment was counted. Number of juveniles was the most sensitive endpoint producing an a EC10 value of 15 mg Ag/kg dry soil and a NOEC of 11.2 mg Ag/kg dw.
The results are sound and robust with few issues of concern beyond those already discussed in the overall terrestrial endpoint summary (single soil and no aging after spiking). For this test, the measured concentrations of Ag in the test soils were conducted on a sub-sample collected at the commencement of the test and an additional sub-sample collected at the completion of the test. In addition, at both the commencement and completion of the test one of the test treatments was duplicated for Ag analysis. This gives an indication of the variation in distribution of Ag in the test treatments as well as analytical variation. In addition, the results from a soil reference standard were also presented, indicating that there was a suitable recovery of Ag of 94.4%. However no replication was used for the soil reference standard.
A testing proposal was submitted to ECHA for the chronic testing of earthworms in eight soils, after leaching and aging of the spiked soil.There were no objections to the testing proposal by ECHA or the Member State’s Competent Authoritiesand data will be added to this dossier once results are available.
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