Guanidinium chloride

Endpoint summary

Description of key information

There are 3 acute tests (fish, daphnia, algae) and 2 chronic tests (fish, daphnia) with freshwater organisms available, the lowest obtained chronic value is the NOEC of 2.9 mg/L for Daphnia magna. Terrestrial toxicity data are available for plants and soil microorganisms (both acute and chronic), the lowest available value is the NOEC = 435 mg/Kg soil ww for terrestrial plants.

Additional information

Short-term toxicity to fish:

The acute toxicity of Guanidine Chloride was teste with Leuciscus idus according to DIN 28412 L15 for 48h. The 48h-LC50 was determined to be 1,758 mg/l a.i. As the test duration was less than 96h, instead the result from the 96h -test with the read-across substance Guanidine nitrate was used.

The acute toxicity of Guanidine Nitrate to fish was tested in toxicity tests against Ictalurus punctatus (Channel catfish), Pimephales promelas (Fathead minnow) peer-reviewed by van der Schalie (1985) and Leuciscus idus (Goldorfe) reported by Adema (1988). The lowest 96-h-LC50 was reported as 690 mg a.i./L in the toxicity test against Pimerphales promelas.

Long-term toxicity to fish:

The NOEC to LOEC of the read-across substance Guanidine Nitrate to Fathead minnow in the 35-day long-term toxicity tested in a fish early life stage test ranged from 181 to 424 mg/L. Mortality was the parameter where significant statistical effect were found. In contrast no statistical relavant effects could be observed for hatching success, fry defromities,or fry growth (length and weight).

Short-term toxicity to aquatic invertebrates:

The study of the acute toxicity of the read-across substance Guanidine Nitrate against Daphnia magna in the report of van der Schalie (1985) shows that the 48 -h-EC50, the concentration, in which 50 per cent reduction in immobilization occurs, is at 70.2mg/L.

Long-term toxicity to aquatic invertebrates:

The toxic effect of the read-across substance Guanidine Nitrate was monitored in a 21-day toxicity test. 2.9 mg/L of the test substance was the highest concentration where no toxic effect was monitored. Because in a first chronic toxicity test of van der Schalie, 1985 an toxic effect was monitored at the lowest concentration tested (4.2 mg/L), a second test was performed with lower concentrations tested. In this second test the lowest effect concentration was reported at 6.09 mg/L. In another study of Cooney et al. (1985) the LOEC was higher. Therefore the van der Schalie study can serve as the key study. It is interesting to mention that Guaninine Nitrate is 10 to 20 times more toxic in a chronic 21-day toxicity test compared to an acute 48 h toxicity test which is reported in the same study of van der Schalie, 1985.

Toxicity to aquatic algae and cyanobacteria:

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.

Toxicity to microorganisms:

The toxicity of Guanidine hydrochloride to microorganisms was studied in an 18-h-cell multiplication inhibition test using Pseudomonas putida as test organism. Bacterial growth inhibtion was determined by measurement of the turbidity of the bacterial culture. The 18-h-EC10 was 7125 mg/L.

The 18-h-EC10 for the read-across substance Guanidine nitrate was 831.8 mg/L.

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 nitrate for effects of guanidine dissociated from guanidine hydrochloride 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 for read-across is attached in IUCLID chapter 13.