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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:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
This study is used for read-across and therefore has been assigned a reliability of 2 (reliable with restrictions). The study, if used in support of isophthalic acid, has a reliability of 1 (reliable without restriction).
Justification for type of information:
The test substance rapidly hydrolyses to isophthalic acid (IPA). Therefore, the study with IPA is being used to fulfil this data requirement. Additional documentation, provided within the IUCLID Assessment Reports section, supports the read-across approach.
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: Samples were collected from the test solutions containing 0, 80, 350 and 1000 mg/L of the test substance at 0 hours and 48 hours.
- Sampling method: High Performance Thin-Layer Chromatography
- Sample storage conditions before analysis: less than 20ºC
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION: The stock solution was prepared once before starting the test. The amount of test material used was 4999.8 mg. The test material was added to 5 L reconstituted water, it was allowed to dissolve after addition of NaOH for pH adjustment. The formation of a clear solution was enhanced by using a stirrer and lasted approximately 24 h. The concentration of the stock solution was 1000 mg/L. The stock solution was diluted with water to prepare the individual test concentrations.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM:
- Strain: Daphnia magna (Straus)
- Age at study initiation: 6-20 hours
- Feeding during test: None

ACCLIMATION
- Acclimation period: 6-20 hours
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
213 - 249.0 mg/L CaCO3
Test temperature:
22.1 - 22.3 °C

pH:
7.7 - 7.9
Dissolved oxygen:
8.1 - 9.0 mg/L
Salinity:
freshwater
Nominal and measured concentrations:
Nominal Concentrations used in test: 0, 80, 130, 220, 350, 600 and 1000 mg/L
Measured Concentrations at 0 hours: 0, 74, 317, 1050 mg/L and 0, 74.3, 364, 1005 mg/L
Measured Concentrations at 48 hours: 0, 64, 303, 832 mg/L and 0, 70, 269, 920 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 300 mL; height: 5 cm; diameter: 9 cm; glass
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4


TEST MEDIUM / WATER PARAMETERS
- Conductivity: at time 0 hours
0 mg/L - 580 µS/cm
80 mg/L - 600 µS/cm
130 mg/L - 760 µS/cm
220 mg/L - 850 µS/cm
350 mg/L - 970 µS/cm
600 mg/L - 1100 µS/cm
1000 mg/L - 1300 µS/cm

OTHER TEST CONDITIONS
- Adjustment of pH: initially adjusted to 7.8
- Photoperiod: light/dark (16/8 h).
- Light intensity: 940 ±. 270 Lux, which corresponds to 15.6 ± 3.4 µE x sec e-1 x m e-2

TEST CONCENTRATIONS
- Range finding study: 1, 3, 10, 30 and 100 mg/L
Reference substance (positive control):
no
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 952 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
952 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Behavioural abnormalities: none
- Other biological observations: none
- Mortality of control: none
Reported statistics and error estimates:
Probit analysis was used to determine the EC values. When less than 3 test substance concentrations caused immobilisation between 0 % and 100 % the geometrical: mean was used to determine the EC50.

It is thought that Isopthalic Acid was hydrolysed under test conditions. As a result it is believed that under test conditions and after pH adjustment to the required physiological value Isophthalic Acid and Isophthalic Sodium Salt, respectively, were the test materials investigated in this study.

Immobilisation (%)

Nominal Concentration (mg/L)

Time (h)

Control

Salinity Control*

80

130

220

350

600

1000

0

0

0

0

0

0

0

0

0

24

0

0

0

0

0

0

0

0

48

0

0

0

0

0

0

0

0

* The salinity control consisted of test medium amended with NaOH solution only.

 

Measured Concentrations

Nominal IPA Conc. (mg/L)

Measured mg IPA/L, Time 0

% of nominal

Measured mg IPA/L, Time 48 h

% of nominal

80

74.4

93

64

80

 

74.3

93

70

88

350

317

91

303

87

 

364

104

269

77

1000

1050

105

832

83

 

1005

101

920

92

 

 

In the report, the endpoint is given as >876 mg/L, apparently the mean measured value at the highest concentration, but based on the 48-h data only, i.e. (832 + 920)/2. This is incorrect; the mean should include the 0-h data as well, i.e. (1050 + 1005 + 832 + 920)/4 = 952 mg/L.

 

Validity criteria fulfilled:
yes
Conclusions:
48-hour EC50 could not be determined as it was greater than the highest measured concentration tested (>952 mg/L).
Executive summary:

In accordance with GLP regulations the acute toxicity to Daphnia magna (Straus), water-flea, was investigated in a static test system during a test period of 48 hours. The study was performed according to the OECD Guideline 202, Part I, 1984. The nominal concentrations to which the test organisms were exposed were 80, 130, 220, 350, 600 and 1000 mg/L.

 

The analytically determined actual concentrations of the test material at the beginning of the study were found to be within the range of 91% and 105% with an average of 97.8%. After 48 hours of exposure, analysed concentrations of the test material were relatively unchanged from measurements at 0 hours. They were found to be within the range of 77% and 92% of the nominal values with an average of 84.5%.

 

The EC50(48 h) was >952 mg/L test substance (as sodium terephthalate), based on the mean measured exposure concentration at the highest treatment. Based on the absence of treatment-related immobilisation exceeding that observed in the salinity control, the NOEC was 952 mg TS/L.

 

It is thought that Isopthalic Acid was hydrolysed under test conditions. As a result it is believed that under test conditions and after pH adjustment to the required physiological value Isophthalic Acid and Isophthalic Sodium Salt were the test materials investigated in this study.

Description of key information

The study was conducted using isophthalic acid, the primary degradate of isophthaloyl dichloride, according to OECD 202 under GLP. Daphnia magna were exposed in a static test system over a period of 48 hours to the test substance after conversion to its sodium salt. The nominal concentrations to which the test organisms were exposed were 80, 130, 220, 350, 600 and 1000 mg/L. Exposure concentrations were verified analytically at the start and end of the test and were between 77% and 105% of the nominal values. The static 48-h EC50of the test substance (converted to its sodium salt prior to exposure) to Daphnia magna was >952 mg/L, based on the mean measured concentration at the maximum treatment applied. Based on the absence of treatment-related immobilisation exceeding that observed in the control, the NOEC was 952 mg/L.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
952 mg/L

Additional information