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EC number: 203-618-0
CAS number: 108-80-5
The series of tests conducted with crude cyanuric acid (CCA) and
purified cyanuric acid (PCA) in a semistatic medium at concentrations of
500, 1000 and 2000 mg/L allowed the calculation of the LT50and
the confidence interval. Inspection of the LT50values
distinguished two types of toxicity: a long term toxicity for the three
concentrations of CCA and for the concentration of 500 mg/L for PCA,
whose LT50values were higher at 1 month, as well as a medium
term toxicity for the concentrations of 1000 and 2000 mg/L of PCA, whose
LT50values were 16 and 17 days respectively.
The LT10 values obtained reflect the 5 times more rapid appearance
of the lethal effect with PCA at 1000 and 2000 mg/L (LT10= 1
week) compared to PCA at 500 mg/L and CCA at the three concentrations
tested (LT10> 5 weeks). The LT90values for the
PCA at the concentration of 1000 and 2000 mg/L. (LT90~ 1
month) reflect an effectiveness that is two times better than with PCA
at 500 mg/L and CCA at the three concentrations tested (LT90>
The study of the physicochemical properties conducted during the
course of the tests reflected an increase over time in the values of pH
as well as concentrations of Ca++and (NH3 + NH4+).
The pH values which are acidic at the beginning (6.2 ≤ pH ≤ 6.8),
increase and stabilize after 48 h (7.5 ≤ pH ≤ 7.9.). The lower the
starting pH values, the greater the increase in the Ca++concentrations.
The increase n the level of ammonical nitrogen is more pronounced with
CCA than with PCA. At the end of the experiment, the valves of the
molluscs had been attacked or perforated in the vicinity of the apex,
whereas no sign of alteration was observed in the controls. This
alteration of the shells appeared earlier with PCA than with CCA; it was
related to the concentrations of the two products.
Table 1: Water hardness measurements
Water hardness (mg/l as CaCO3)
Highest surviving concentration
0 (fresh media)
2 (old media)
7 (fresh media)
9 (old media)
14 (fresh media)
16 (old media)
Table 2: Measured concentrations of test substance:
Nominal concentration (mg/L)
less than LOQ1
less than LOQ
= Limit of quantitation
* Duplicate sample, stored frozen prior to analysis -
considered as erroneious result due to analytical error
Table 3: Daphnia lengths of the parental generation
Nominal concentration (mg/l)
Daphnia length at day 21 (mm)
* Significant differences (p <0.05)
Table 4: Summary of findings following the exposure of
Daphnia magna for 21 days
Nominal concnetration (mg/l)
% survival of P1
Number of live young
Number of dead young
Number of unhatched eggs
Per female (cumulative)
Per female (cumulative
A Daphnia magna reproduction study (OECD 211) performed with the
Monosodium salt of cyanuric acid (equivalent to 75.6% cyanuric acid).
A Daphnia magna reproduction study (Sewell 2007) was performed with the
monosodium salt of cyanuric acid (equivalent to 75.6% cyanuric acid).
Daphnia were 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 adult
Daphnia and young daphnids (live and dead) were determined daily.
Exposure of Daphnia magna to monosodium salt of cyanuric acid resulted
in significant 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
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