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Toxicity to soil microorganisms

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Low toxicity

Key value for chemical safety assessment

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No experimental data from a guideline study on toxicity to soil microorganisms are available. Testing, required in Annex IX, 9.4.2. has been waived in accordance with column 2 restrictions.

The publication of Praveen-Kumar & Brumme (1999) indicates the absence of effects up to a level of 1074 mg/kg dw soil. Lees & Quastel (1946) report effects on the nitrogen transformation rate of ammonium. A concentration of 750 mg Guanidine carbonate/kg soil dw. had a significant inhibitory short term effect. While for 1 day 100 % inhibition was observed the effect decreased significantly but was visible for more than 14 days. This confirms the assessment of low toxicity to soil organisms.

Further confirming experimental findings are reported in the literature on guanidine (CAS 113-00-8). Mitchell (1987, Bull Environ Contam Toxicol 39:974-81) reports rapid degradation for low initial concentrations of guanidine, but rates of degradation decreased with increasing nominal concentration. At an initial concentration of 10 mg/kg soil dw, Guanidine was 78 % biodegraded after 10 days; however, at an initial concentration of 400 mg/kg soil dw, guanidine was 62 % biodegraded after 25 days (HSDB 2008). This may indicate beginning inhibition at this level, which corresponds to (MW guanidine = 59.071 g/mol) 6.77 mol guanidine/kg soil dw or (converted on the basis of the MW = 90.0835 g/mol, equimolar Guanidinium kation concentration) to 610 mg/kg soil dw of guanidine carbonate.

  • HSDB Hazardous Substances Databank (2008). GUANIDINE, CASRN: 113-00-8, Number: 7603. Last Revision Date: 2008-08 -26, Last Review Date: Reviewed by SRP 5/8/2008, Update History: Complete Update on 2008 -08-26, 38 fields added/edited/deleted, Created 2007-12-13

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