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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

The 24-h EC50 value is 112 mg/l for inhibition of ammonia consumption in Nitrosomonas sp .

Key value for chemical safety assessment

EC50 for microorganisms:
112 mg/L

Additional information

For tetrachloroethylene toxic effects upon micro-organisms are observed at around 100 mg/l. All of the studies reported appear to be valid, but the test with Photobacterium phosphoreum (Bazin et al., 1987) is not relevant for micro-organisms in sewage treatment plants. The other tests are suitable for use in the risk assessment, but the test with Nitrosomonas sp. (Blum and Speece, 1991), which are nitrifying bacteria, is thought to be more relevant for STP organisms than the test with Tetrahymena pyriformis (Yoshioka et al., 1986). Therefore, the 24-h EC50 of 112 mg/l with Nitrosomonas sp. based on ammonium consumption is used in the assessment.