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EC number: 626-470-2
CAS number: 5405-40-3
- Table 1: Incidence of immobility in the range-finding test
Response at 24 h
Response at 48 h
- Table 2: pH and oxygen concentrations during the limit test (main test)
Start (t=0 h)
End (t=48 h)
Nominal / Actual
100 / 130
- Table 3: Concentrations of DL-LACTONE in test medium (final
Relative tonominal [%]
(1) Mean of duplicate analysis. The maximum deviation between the
responses was calculated for each sample and was < 10%.
(2) Reserve sample.
n.d.: not detected.
n.a.: not applicable.
Analysis of the samples taken during the limit test showed that the
measured concentration was 144 mg/L in the freshly prepared 100 mg/L
test solution. An extra sample was analysed at t=0 to check whether the
high recovery was correct. The measured concentration in the reserve
sample was 140 mg/L.
The measured concentration after 24 hours was 123 mg/L.
Hence, the measured concentration remained within a 20% window during
the 24-hour period between refreshment.
Preparation of test solutions proved to be repeatable as the
concentration measured in the freshly prepared 100 mg/L solution after
24 hours of exposure was 138 mg/I.
In conclusion: the average exposure concentration during the study was
approximately 130 mg/L. No clear explanation can possibly be given for
the relative high recoveries measured.
- Table 4: Acute immobilisation of daphnia after 24 and 48 hours in the
limit test (main test)
Concentration (mg/L) DL-LACTONE
ACCEPTABILITY OF THE TEST
1. In the controls, no daphnia became immobilised or trapped at the
surface of the water.
2. The analytical program provided clear evidence that the actual
concentrations during the 24-hour period between refreshment had been
maintained at more than 80 % of the initial concentration.
3. Further, all test conditions remained within the ranges prescribed by
- Table 5: Acute immobilization of daphnia after 24 and 48 hours in the
reference test with potassium dichromate
Expected response (%) After 48 hours (1)
(1): Based on historical data of the previous years (n>60).
(2): A maximum response of 10% does not invalidate the results of
The actual responses in this reference test with K2Cr2O7 are within the
ranges of the expected responses at the different concentrations. Hence,
the sensitivity of this batch of D. magna was in agreement with the
historical data collected in the laboratory.
RS-Pantolactone (named DL-Lactone in the report) was tested for
its short-term toxicity to aquatic invertebrates with Dapnia magna according
to OECD TG 202. The study procedures described in the report fulfil also
the ISO International Standard 6341: "Water quality - Determination of
the inhibition of the mobility of Daphnia magna Straus - Acute toxicity
test, Third edition, 1996-04-01.
RS-Pantolactone was completely soluble in test medium at the
concentrations tested. The complete project was performed under
semi-static test conditions with renewal of test solutions after 24
hours of exposure as the test item proved to be unstable in water at pH
values of 7 and 9 in the hydrolysis test performed at NOTOX (Project
257568, IUCLID5 chapter 5.1.2).
A range-finding test was followed by a limit test exposing Daphnia
for a maximum of 48 hours to a concentration of 100 mg/I and a
blank-control. The test was performed in duplicate with 10 daphnia per
vessel. Samples for analysis of actual exposure concentrations were
taken from the freshly prepared solutions at the start and the 24-hour
old and freshly prepared solutions after 24 hours of exposure.
Analysis of the samples taken during the limit test showed that
the measured concentration remained within a 20% window during the
24-hour period between refreshment. The average measured concentration
corresponded with approximately 130 mg/I.
RS-Pantolactone induced no acute immobilisation of Daphnia magna
at or below 100 mg/L, corresponding with an average measured
concentration of 130 mg/L (NOEC).
Hence, the 48h-EC 50 was above 130 mg/L, the maximum concentration
By expert judgement it is concluded that L-Pantolactone will get
the same results:
L-Pantolactone: 48h EC 50 above 130 mg/L.
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