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Ecotoxicological information

Long-term toxicity to aquatic invertebrates

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Description of key information

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 chronic ecotoxicity studies. A Daphnia magna reproduction study (OECD 211) has been performed with the Monosodium salt of cyanuric acid (equivalent to 75.6% cyanuric acid).    

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
121 mg/L

Additional information

A Daphnia magna reproduction study (Sewell 2007) was performed with the monosodium salt of cyanuric acid (equivalent to 75.6% cyanuric acid).Daphniawere exposed to nominal concentrations of 50, 160, 500, 1600 and 5000 mg/L (equivalent to 37.8, 121, 378, 1210 and 3780 mg cyanuric acid/L) for a period of 21 days.The numbers of live and dead adul tDaphnia and young daphnids (live and dead) were determined daily. Exposure of Daphnia magna to monosodium salt of cyanuric acid resulted in signifciant mortalities at the test concentrations of 500,1600 and 5000 mg/L resulting in 30%, 50% and 70% mortalities by day 21 respectively, compared to an observed mortality of 20% in the control by day 21. The NOEC was considered to be 160 mg/L (equivalent to 121 mg/L CYA) on the basis that at this concentration there were no significant mortalities (immobilisation) observed in the parental generation (P1) and that there were no significant differences between the control and the 160 mg/L test group in terms of numbers of live young per adult by day 21.