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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Link to relevant study record(s)

Description of key information

OECD 201 compliant study, taking care of not losing substance through volatility, highly reliable: ErC50-72 = 20 mg/L, ErC10-72 = 6.3 mg/L and NOECr = 2.2 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:
20 mg/L
EC10 or NOEC for freshwater algae:
2 mg/L

Additional information

When this dossier was initially prepared, only one reported data was avalaible taking account of the volatility of the substance: Brack & Rottler 1994. The test was conducted according to OECD 201 with a modification of the test vessels (bipartite design) allowing sufficient CO2 supply while having a gas tight system to minimize loss of CTC during the test.The selected species is the green alga Chlamydomonas reinhardtii.

The article reports the toxicity of several substances among which CTC. An EbC10 -72 h of 0.0717 mg/L and a EbC50-72 h value 0.246 mg/L (0.217-0.278 mg/L) are obtained.

These results are to be used with great care as few track record is available on this species sensitivity and EC are not growth rate based. In addition, in this article, reported results on other substances are conflicting with good quality data on these substances.

Consequently it has been decided by the companies in the Chlorinated Solvents Consortium to sponsor a new study. In this one (Gancet, 2011), growth inhibition of freshwater algae Pseudokirchneriella subcapitata by carbon tetrachloride was measured according to OECD Guideline 201. In order to take account of the volatility of the substance, the experiment was carried out in stoppered flasks with no headspace, and using a medium buffered with HEPES in order to avoid pH drift. Good recovery of the test substance was demonstrated through analytical measurement (GC/MS) and other validity criteria were met.

Consequently the values obtained in this study can be retained as key information about algae toxicity: ErC50-72 = 20 mg/L, ErC10-72 = 6.3 mg/L and NOECr = 2.2 mg/L.