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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

Key value for chemical safety assessment

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No key study has been selected regarding the endpoint of toxicity to microorganisms. However, a weight of evidence approach can be applied to assess the toxicity to STP microorganisms. Considering first the studies conducted on a mixed inoculum, the following results have been found :

- on Shk1 (genetically modified Pseudomonas extracted from activated sludge of an industrial WWTP) EC50 (bioluminescence inhibition) - 5 min=583 mg/l (Ren & Frymier, 2002)

- on anaerobic activated sludge (methanogenic activity inhibition): EC50 - 48H = 1166 mg/l (Sierra-Alvarez & Lettinga, 1989) and EC20 -48H = 806.9 mg/l (Shcherbakova et al., 1999).

Guaiacol has also been tested on individual bacterial species, likeTetrahymena thermophila (endpoint: motility): LOEC-20 min = 380 mg/l (Gilron et al., 1999).

Three other studies have been considered of low relevance regarding the assessment of STP microorganisms, they nevertheless led to similar results:

On Saccharomyces cerevisiae (growth rate): EC50 -210 min = 227 mg/l (Koch, 1992).

On Vibrio fischerii (bioluminescence inhibition) EC50-30 min = 92.03 mg/l (Nalecz-Jawecki et al., 2000)

On Escherischia coli (cell growth): EC50 -24H = 600 mg/l (Zaldivar et al., 2000)

All these results led to the conclusion that guaiacol is not harmful for microorganisms and that conclusion can be extrapolated to the STP microorganisms as well.