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Description of key information

Carbonate not photodegradable, Guanidine susceptible to photohydroxylation, but not to direct photolysis

Key value for chemical safety assessment

Half-life in air:
9 d
Degradation rate constant with OH radicals:
0 cm³ molecule-1 d-1

Additional information

The relevant part of the submission item Guanidine carbonate is the Guanidine (CAS 113-00-8) as discussed in the section on Environmental fate and pathways above. It is present as the Guanidinium kation (see section Dissociation constant). The carbonate, which is fully mineralized, is negligible for the environmental assessment and disregarded in the following discussion.

The assessment of Guanidine (CAS 113-00-8) has been adopted from HSDB (2008): The rate constant for the vapour-phase reaction of guanidine with photochemically-produced hydroxyl radicals (indirect photolysis) has been estimated as 4.2•10-11 cm³ per molecule per second at 25 °C (0.000000000042 cm³ molecule-1 s-1 = 86400•0.000000000042 cm³ molecule-1 d-1 = 0.0000036288 cm³ molecule-1 d-1) using a structure estimation method (Meylan & Howard 1993) by US EPA EPI Suite (2007) software. This corresponds to an atmospheric half-life of about 9 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm (Meylan & Howard 1993). Guanidine does not contain chromophores that absorb at wavelengths >290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight (Lyman et al 1990).

  • HSDB Hazardous Substances Databank (2008). GUANIDINE, CASRN: 113-00-8, Number: 7603. Last Revision Date: 2008-08 -26, Last Review Date: Reviewed by SRP 5/8/2008, Update History: Complete Update on 2008 -08-26, 38 fields added/edited/deleted, Created 20071213
  • Meylan WM, Howard PH (1993). Chemosphere 26:2293-9
  • Lyman WJ et al (1990). Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 7-4, 7-5, 8-12
  • US EPA United States Environmental Protection Agency (2007). Estimation Program Interface (EPI) Suite. Ver.3.20. February, 2007. Available from, as of Dec 17, 2007: