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Terrestrial Plants:

The effect of Guanidine nitrate on germination and growth of wheat seedlings was tested for 14 days. At a Guanidine nitrate concentration: 200 µg N/g soil, GuNi 45.9%N; 435mgGuNi/Kg soil) there was no adverse affect in wheat growth and germination. The response of wheat dry matter production was the same as with urea. This test was used for NOEC derivation according to Guidance R7c, p. 112 (2008).

Terrestrial Microorganism:

In a non guideline test with natural soil microorganism, degradation rates for mineralisation of 14C radiolabeled guanidine carbon were determined. Quantification was made by determination of trapped 14C labelled carbon dioxide. For loading rates of 10 - 400 mg Guanidine /kg soil ww (15.9 - 636 mg Guanidine chloride /kg soil ww) mineralisation rates of Guanidine carbon to Carbon dioxide showed not tendency to decrease at any concentration.

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.

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