Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

The chlorinated isocyanurates (trichloroisocyanuric acid and sodium dichloroisocyanurate) produce free available chlorine, in the form of hypochlorous acid (HOCl) as they dissolve in water. As the equilibria involve all of the possible chlorinated isocyanurates, the toxicity of trichloroisocyanuric acid (TCCA), sodium dichloroisocyanurate (NaDCC) and sodium dichloroisocyanurate dihydrate (NaDCC.2H2O) will be virtually equivalent at the same available chlorine concentration. The parent compound for all chlorinated isocyanurates is isocyanuric acid (cyanuric acid). All of the chlorinated isocyanurates are essentially equivalent, once they are dissolved in water at the low concentrations at which they are used.

Based upon the available chlorine content and the dissociation constants for the chlorinated isocyanurate species, TCCA is considered to be the most toxic, or reactive form. Therefore test results for this species will be considered as the "worst-case" for the chlorinated isocyanurates allowing read-across for the less reactive dichlorinated forms.

The chlorinated isocyanurates are unstable in the environment, because the free available chlorine is rapidly reduced. CYA, or its salt, is the stable degradation product. Therefore, CYA, or its sodium salt, is the substance of interest for environmental studies.