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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

Toxixity of Green liquor sludge to waste water treatment plant microbes  was low in a 3 hr standard respiration inhibition test (EC50 33300 mg/l).

Key value for chemical safety assessment

EC50 for microorganisms:
33 300 mg/L

Additional information

Microbial toxicity data, respiration inhibition (OECD 209/C.11) test results (EC50/NOEC) are available for GLS reference sample. This information is sufficient to derive a PNECSTP(PNECmicroorganisms) for GLS.


For the PNECSTPderivation CSA guidance R10 (Table R.10-6) provides listing of the relevant tests systems, effect concentrations that are determined using them as well as the corresponding assessment factors.

An assessment factor (AF) of 10 is to be applied to the NOEC of a sludge respiration test 209/C.11. The corresponding AF is 100 when PNEC is based on the EC50.

No NOEC has been reported for GLS. Normally EC10 values may be regarded as NOEC in microbial tests, but just EC20 =27 000 mg/l has been calculated for GLS and EC10 has not been reported. Applying the EC50 = 33 300 mg/l (71 000 mg/l wet wt.) and applying an AF 100 results PNECSTP 333 mg/l (dwt.).