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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
March 21 to April 16, 1997
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
HLPC at the start of exposure, 3 hours and 24 hours afterwards. Sample was taken from the middle section of each test solution.
Vehicle:
no
Details on test solutions:
Based on preliminary work that preceded this study, the maximum testing concentration was set at 1.00 mg/L (considered 100% immobilisation concentration). 5 concentrations were established with a common ratio of 1.8 ( 1.00, 0.556, 0.309, 0.171 and 0.0953 mg/L).
Test organisms (species):
Daphnia magna
Details on test organisms:
juvenile daphnia born no later than 24 hours beforehand were used. Species bred and rasied from supply from EPA Laboratory USA.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Remarks on exposure duration:
test solution changed after 24 hours
Hardness:
55.6 mg/l as CaCO3
Test temperature:
20.0-20.2 C
pH:
7.6-7.7
Dissolved oxygen:
8.6 to 8.8 mg/l
Salinity:
37.5 mg/l
Nominal and measured concentrations:
measured concentrations of the test article were 103-106% of the labeled concentrations at the start of exposure, 51.4 % -65.3% after 3 hours ad 0.0to14.0% at the time the solution was changed (24 hours).
Details on test conditions:
see below
Reference substance (positive control):
no
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
0.089 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Remarks:
arithmatic mean of the first 24 h and measures at t=0. 3 and 24h; RR 6% after 24 hours
Basis for effect:
mobility
Remarks on result:
other: 95% CL; Values based on mean measured concentrations calculated directly from data in the study report.
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
0.064 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
Values based on mean measured concentrations calculated directly from data in the study report.
Reported statistics and error estimates:
see below

- Measured Concentrations: The test concentrations were measured three times (0, 3, 24th hour) during the test period using HPLC.

Nominal Conc. (mg/L) Measured Concentration (mg/L) Geometric mean*
0 hour 3 hour 24 hours
Control n.d. n.d. n.d. ---
0.0953 0.0979 0.0622 n.d. 0.024
0.171 0.177 0.111 0.0240 0.065
0.309 0.329 0.174 0.0243 0.089
0.556 0.588 0.286 0.0376 0.15
1.00 1.04 0.522 n.d. 0.077

n.d.: <0.00567 mg/L

*: Geometric mean of measured concentration at the initial and 24th-hour (before water replacement).

Nominal Conc. (mg/L) % of Nominal concentration (%)
0 hour 3 hour 24 hours Geometric mean
Control --- --- --- ---
0.0953 103 65.3 --- 25.2
0.171 104 65.0 14.0 38.0
0.309 106 56.4 7.9 28.8
0.556 106 51.4 6.8 27.0
1.00 104 52.2 --- 7.7


- Water chemistry (pH, DO, and temperature in test): Water chemistry and temperature were measured for control and each concentration at the start and before water replacement (24th-hour) of the test.
pH: 7.6 - 7.7
DO: 8.6 - 8.8 mg/L
Water Temperature: 20.0 - 20.2 C

-Effect Data:
EC50 (48hr) 0.182mg/L (mc)
95% Confidence Interval: 0.085 – 0.11 mg/L
mc: based on measured concentrations
 
-Mortality or Immobility: None of test organisms were immobilized the behaviours at control.

Nominal Conc. (mg/L) Measured Conc. (mg/L) Cumulative Number of Immobilized Daphnia (Percent Immobility, %)
24 hour (%) 48 hours (%)
Control --- 0 0 0 0
0.0953 0.024 0 0 1 5
0.171 0.065 0 0 1 5
0.309 0.089 4 20 10 50
0.556 0.15 14 70 17 85
1.00 0.077 17 85 20 100



Validity criteria fulfilled:
yes
Conclusions:
EC50 at 48 hours was 0.182 mg/l for nominal measured concentration. Nominal NOEC at 48 hours was 0.177 mg/L and LOEC 0.313 mg/L for nominal measured concentrations. Values based on mean measured concentrations calculated directly from data in the study report.
The substance degrades very fast in the test with a (>65% loss after 24hr) therefore results are expressed as the mean goemetric mean values which would result in a LD50 of 0.089 mg/L. Based on the tables it would seem that the gemoetric mean NOEC value in this instance would be 0.064 mg/L

Description of key information

The short-term toxicity in daphnia magna is from one key study with results calculated as mean measured concentrations of EC50 (48 hours) 0.089 mg/l and NOEC of 0.064 mg/L.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
0.089 mg/L

Additional information

The key study is an Acute Toxicity in Daphnia magna completed in 1997 based on OECD method 202 with a reported EC50 (48 hours) mean measured values as 0.0.089mg/l, NOEC as 0.064 mg/L. Values were based on mean measured concentrations calculated directly from data in the study report. The measured concentrations of the test article were 103 -106% of the labeled concentrations at the start of exposure, 51.4 % -65.3% after 3 hours and 0.0 to14.0% at the time the solution was changed (24 hours). One supporting study was included with klimisch of 4: daphnia magna - EC50 (48 h): 0.24 mg/L. As the substance degrades rapidly an additional study was conducted to determine the toxicity of the degradation products versus the parent molecule. The results of this study show that the parent molecue is significanty more toxic that the degradation products.