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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Qualifier:
according to guideline
Guideline:
other: DIN 38412, part 11
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
The stock solution was prepared by dissolving 2000 mg test substance in dilution water. The test concentrations were then prepared by dilution with test water.
Test organisms (species):
Daphnia magna
Details on test organisms:
Strain: STRAUS
Breeder: Dr. U. Noack-Laboratorium
Hildesheim Source: Bundesgesundheitsamt, Berlin, Germany
Method of breeding: single breeding
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Test temperature:
21 °C
Dissolved oxygen:
8.0 - 8.2 mg/L
Nominal and measured concentrations:
Test concentrations (nominal): 58, 100, 180, 320 and 580 mg/L
Details on test conditions:
TEST SYSTEM
Type: open beaker (50 mL)
Aeration: none
No. of organisms per vessel: 5
No. of replicates: 4
Controls: negative control
Highest concentration after pH adjustment

TEST MEDIUM / WATER PARAMETERS
Dilution water: according to DIN 38412 L11, 8.2
Conductivity: 658 µS/cm
Ca/Mg ratio: 5:1
Na/K ratio: 20:1

TEST CONDITIONS
Adjustment of pH: none
Illumination: 10 µE/qm×s pH
During test: 3.85 - 7.90

The number of immobilized animals were recorded after 3, 6, 24, and 48 hours after test start.
The parameters pH, temperature and oxygen concentration were determined at the end of the test.
Reference substance (positive control):
yes
Remarks:
Potassium chromate
Duration:
48 h
Dose descriptor:
EC0
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
140 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 100-180 mg/L
Duration:
48 h
Dose descriptor:
EC100
Effect conc.:
180 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
No pH effect observed.
Results with reference substance (positive control):
Reference substance: Potassium chromate
EC50 (24 h): 0.9 mg/L
Date: 12 Sep - 13 Sep 1989
Reported statistics and error estimates:
STATISTICS
Spearman-Kaerber (1984)

Table 1: pH Values at the end of the test

Concentration [mg/L]

pH

580

3.85

320

4.02

180

4.40

100

7.30

58

7.73

Control

7.90

pH-Control

7.49

 

Table 2: Mean number of mobile daphnids after 24 h and 48 h

Nominal concentration [mg/L]

Mean number 24 h

Mean number 48 h

580

0/20

0/20

320

0/20

0/20

180

0/20

0/20

100

20/20

19/20

58

20/20

19/20

Control

20/20

19/20

pH-Control

0/20

0/20

 

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to national standards (DIN)
Qualifier:
equivalent or similar to guideline
Guideline:
other: DIN 38412, part 11
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
Daphnia magna
Details on test organisms:
Species: Daphnia magna
Origin: wild population
Breeding: The clone with the highest number of offspring was used to establish a continuous daphnia breed under standardized laboratory conditions.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
24 h
Duration:
24 h
Dose descriptor:
EC0
Effect conc.:
310 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
625 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
EC100
Effect conc.:
1 250 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility

In this short-term test, Ca was present in overstoichiometric amounts. Thus, in the test system the Ca-complex was formed.

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Test procedure according to international standard.
Qualifier:
according to guideline
Guideline:
ISO 6341 (Water quality - Determination of the Inhibition of the Mobility of Daphnia magna Straus (Cladocera, Crustacea))
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
Daphnia magna
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
24 h
Key result
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
610 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility

EC50 (24 h) calculated (confidence interval 95 %):

EDTA                  610 mg/L (570-640 mg/L)

Mn(II)+EDTA     940 mg/L (800-1000 mg/L)

Fe(III)+EDTA     17 mg/L (13-21 mg/L)

Cu(II)+EDTA      38 mg/L (31-45 mg/L)

Zn(II)+EDTA       910 mg/L (840-980 mg/L)

Hg(II)+EDTA      0.00032 mg/L (0.00022-0.00052 mg/L)

Cd(II)+EDTA      310 mg/L (290-330 mg/L)

All the EC50-values, except those obtained for the free EDTA, are expressed as mg/L of total amount of the studied metal. To compare the toxicities of the metal chelates with those of the free EDTA, all the EC50 values were converted to mg/L EDTA.

EC 50 values with 95% confidence limits were calculated by a probit analysis computer program, version 2.3 (National Swedish Environmental Protection Agency).

The EC50 values of Fe3+, Cu2+, Mn2+, Zn2+, Cd2+ and Hg2+ complexed by EDTA were compared with those of the respective uncomplexed metals and free EDTA. The experiments gave the following toxicity order: Hg2+, Cu2+, Cd2+, Zn2+, Fe3+, Mn2+ (higher to lower toxicity).

After complexation, the toxicities were 1.1-1700 (EDTA) times lower. With Hg2+ complexation did not decrease the toxicity. Compared with the toxicity of free EDTA, metal complexation increased the toxicity of EDTA.

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Remarks:
Summary of available data used for the endpoint assessment of the target substance.
Adequacy of study:
weight of evidence
Justification for type of information:
Refer to the Analogue Approach Justification document provided in Section 13.
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
625 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: RA-A, CAS 64-02-8, Bringmann & Kuehn, 1977, D. magna, 24 h, RL2
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
610 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: RA-A, CAS 64-02-8, Sorvari & Sillanpaa, 1996, D. magna, 24 h, RL2
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
140 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: RA-A, CAS 139-33-3, BASF SE, 1989, D. magna, 48 h, RL2

Description of key information

EC50 (48 h) > 100 mg/L; read-across (Daphnia magna)

Key value for chemical safety assessment

Additional information

Since no studies investigating the short-term toxicity trisodium hydrogen EDTA (CAS 150-38-9) to aquatic invertebrates are available, in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5 a read-across to structurally related EDTA species was conducted. This read-across is justified in detail in the overall summary (IUCLID Section 6.1) and within the analogue justification in IUCLID Section 13.

Tests on the acute toxicity oftetrasodium EDTA(CAS 64-02-8) and disodium dihydrogen EDTA (CAS 139-33-3) to Daphnia magna are available.
The first study with tetrasodium EDTA was performed equivalent or similar to DIN 38412, part 11. Daphnia magna was exposed to several concentrations of tetrasodium EDTA. In this study calcium was present in over-stoichiometric amounts. Thus, in the test system the Ca-complex was formed. After 24 h an EC50 of 625 mg/L based on mobility resulted.
The second study with tetrasodium EDTA was performed according to ISO 6341 15. The study resulted in an EC50 (24 h) of 610 mg/L based on mobility.
These two studies are not in line with today’s standard methods since the exposure duration is too short (24 h compared to 48 h). However, the results clearly indicate low toxicity of the substances.
One additional study is available which was performed for 48 h with Disodium dihydrogen EDTA (CAS 139-33-3). In this study an EC50 (48 h) of 140 mg/L was recorded. It has to be noted that the pH significantly decreased from 7.30 at 100 mg/L to 4.40 at 180 mg/L, 4.02 at 320 mg/L and 3.85 mg/L at 580 mg/L. Thus it is highly likely that the observed effect is related to the low pH rather than to intrinsic toxicity of the substance itself.
In conclusion trisodium hydrogen EDTA (CAS 150-38-9) is considered to be of low short-term toxicity to aquatic invertebrates.