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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

In a read-across approach with Guanidine nitrate,  in a 72 hour acute toxicity study, the cultures of Pseudokirchneriella subcapita were exposed to Guanidine Nitrate. The 72h-EC50values based on yield ( and growth rate) were 6.3mg a.i./L (6.3 mg a.i./L) and the 72h-NOEC values based on yield (and growth rate) were 11.8 mg a.i./L (33.5 mg a.i./L), respectively. 

Key value for chemical safety assessment

EC50 for freshwater algae:
33.5 mg/L
EC10 or NOEC for freshwater algae:
6.3 mg/L

Additional information

In a 72 hour acute toxicity study (Seibersdorf, 2010), the cultures of Pseudokirchneriella subcapita were exposed to read-across substance Guanidine Nitrate. The 72h-EC50 values based on growth rate (yield) were 33.5mg a.i./L (11.8 mg a.i./L) and the 72h-NOEC values based on yield (and growth rate) were 6.3 mg a.i./L, respectively.

The study was performed under static conditions in accordance with the EC regulation 761/2009 Part C.3.

Justification for read-across:

Guanidine hydrochloride and guanidine nitrate dissociate in aqueous media to yield the guanidine ion and the respective anion. Therefore it is reasonable to discuss the effects of the ions separately. The chloride ion is a naturally occurring essential ion in human beings with well-known metabolism and mechanisms of action as described in standard textbooks on pharmacology and physiology. As well it is found as salt in the Earth´s crust and is dissolved in seawater. Effects of guanidine hydrochloride are expected to be based primarily on the guanidine ion. The physiological processing of the guanidine ion is expected to be independent of the individual source. Therefore read-across from guanidine hydrochloride for effects of guanidine dissociated from guanidine nitrate is considered valid. This strategy is supported by a quite similar toxicological profile of both substances, as shown in acute toxicity, irritation, sensitization and genotoxic studies.

A more detailed justification is attached and outlined in CSR chapter 1.1.2 as well.

Justification for non-classification:

GuCl is fast degradable (and inherently biodegradable) following criteria of GHS regulation (legal stand October 2012). Therefore there is no need for environmental classification (GHS legal stand October 2012).