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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
Study period:
10 May 2010 - 13 May 2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP compliant, guideline study. No analytical monitoring.
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
yes
Remarks:
No analytical monitoring
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
yes
Remarks:
No analytical monitoring
Qualifier:
according to
Guideline:
EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not applicable
Analytical monitoring:
no
Details on sampling:
Not applicable
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution of nominal 100 mg/L was prepared by dissolving 100.1 mg of test item in 1000 mL of test water using ultrasonic treatment for 25 minutes and intense stirring for 15 minutes. This was diluted with test water to produce the range of test item concentrations.
- Controls: Blank control (test water only). Potassium dichromate is tested as a positive control twice a year.
- Evidence of undissolved material (e.g. precipitate, surface film, etc): No
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Strain: Clone 5
- Source: In lab culture, original source University of Sheffield / UK in 1992
- Age at study initiation (mean and range, SD): 6-24 hours
- Feeding during test: no

ACCLIMATION
- Acclimation period: Breeding conditions same light and temperature conditions as test. Parental daphnids maintained in test water for >48 hours prior to test start
- Acclimation conditions (same as test or not): Yes
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
None
Hardness:
150 mg CaCO3/L
Test temperature:
20-21°C
pH:
7.5 - 7.8
Dissolved oxygen:
8.1 - 8.5 mg/L
Salinity:
Not applicable
Nominal and measured concentrations:
Nominal concentrations: Control, 4.6, 10, 22, 46, 100 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Beakers
- Type (delete if not applicable): closed (covered with glass plates)
- Material, size, headspace, fill volume: 250 mL glass beakers filled with 125 mL of test medium
- Aeration: Prior to test but not during.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted test water (analytical grade salts dissolved in purified water) according to ISO 6341, with hardness lowered to meet OECD and EPA guideline requirements.
- Intervals of water quality measurement: Beginning and end of test. Appearance of test media also evaluated at 24 hours.

OTHER TEST CONDITIONS
- Adjustment of pH: None reported
- Photoperiod: 16:8 light/dark cycle with 30 minute transition period.
- Light intensity: 520-680 Lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobility. Daphnids considered immobile if they do not swim after 15 seconds of gentle agitation.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.15
- Range finding study: Yes
- Results used to determine the conditions for the definitive study: Yes
Reference substance (positive control):
yes
Remarks:
Potassium dichromate, tested twice a year
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
75 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95 % confidence limits could not be determined
Duration:
24 h
Dose descriptor:
NOEC
Effect conc.:
46 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
37 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% CL: 30-45 mg/L
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
22 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
See table 1.
Results with reference substance (positive control):
Most recent test (March 2010, study C86933) reported an EC50 of 0.43 mg potassium dichromate/L. This demonstates the senstivity of the test organisms and is within the internal historical range (0.43 - 1.1 mg/L)
Reported statistics and error estimates:
24- and 48-hour EC50s calculated via linear regression and moving average models respectively
NOEC determined directly from the raw data.

Table 1. Effect on the Mobility of Daphnia magna

Nominal test item concentration
(mg/L)
No. of daphnids tested Immobilized daphnids after 24 hours Immobilized daphnids after 48 hours
No. % No. %
Control 20 0 0 0 0
4.6 20 0 0 0 0
10 20 0 0 0 0
22 20 0 0 0 0
46 20 0 0 17 85
100 20 16 80 19 95
Validity criteria fulfilled:
yes
Remarks:
Mortality in controls <10%; Dissolved oxygen levels at end of test > 3
Conclusions:
The 48-hour EC50 for Daphnia magna exposed to the test material was determined to be 37 mg/L. The 48-hour NOEC was determined to be 22 mg/L
Executive summary:

The sensitivity of Daphnia magna to the test material was determined in a GLP-compliant test performed to standard guidelines. The 48-hour EC50 was found to be 37 mg/L with 95 % confidence intervals of 30 - 45 mg/L. The 48-hour NOEC was determined to be 22 mg/L. All results are based on nominal concentrations.

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
04-06 July 2007
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: Similar to OECD guideline 202, well documented, intended as a screening study. No analytical monitoring.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
yes
Remarks:
Fixed concentrations at 1, 10 & 100mg/L; No analytical monitoring
Principles of method if other than guideline:
Simplified OECD Guideline 202 for screening purposes.
GLP compliance:
no
Remarks:
Quality assurance standard: ISO/IEC 17025
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Strain: Straus 1820
- Source: bred
- Length at study initiation (length definition, mean, range and SD): <2mm
- Method of breeding: 250L glass aquaria, aerated reconstituted water
- Feeding during test: not reported
- Food type: Sera Micropan (Sera GmbH, Heinsberg)
- Amount: 15g in 1L
- Frequency: Once per day except weekends

ACCLIMATION
- Acclimation period: 4h
- Acclimation conditions (same as test or not): reconstituted water
- Type and amount of food: none
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
None
Hardness:
Reconstituted water according to ISO 6341
Test temperature:
20±0.5°C
pH:
Average 7.3 at test start
Dissolved oxygen:
Average 5.9mg/L at test start
Salinity:
Not applicable
Nominal and measured concentrations:
Nominal concentration used: 1, 10, 100mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: flasks
- Material, size, fill volume: glass, 100mL, 50mL test medium
- Aeration: none
- No. of organisms per vessel: 20
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 3

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water
- Intervals of water quality measurement: start and end of the test

OTHER TEST CONDITIONS
- Adjustment of pH: none
- Photoperiod: 16h
- Light intensity: no data; white fluorescent tubes

EFFECT PARAMETERS MEASURED: Numbers of immobile daphnia at 24 and 48h.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Justification for using less concentrations than requested by guideline: screening test
Reference substance (positive control):
yes
Remarks:
Periodically conducted with potassium dichromate
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
> 10 - < 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
The NOEC was 10mg/L after an exposure of 24 and 48h, respectively.
Results with reference substance (positive control):
Conducted periodically. No explicit results reported.

Immobilisation of Daphnia magna at 24 and 48h.

Conc.

Replicate

No. animals

No. Immobile 24h

No. Immobile 48h

Control

1

20

0

1

 

2

20

0

1

 

3

20

0

0

1mg/L

1

20

0

0

 

2

20

0

0

10mg/L

1

20

0

0

 

2

20

0

2

100mg/L

1

20

18

20

 

2

20

17

19

pH range in starting flasks: 7.1 to 7.3; Oxygen concentration range in starting flasks: 5.8 to 6.0.

pH range in flasks at end: 7.7 to 7.8; Oxygen concentration range in flasks at end: 6.1 to 6.4.

Replicates were combined to give average pH and oxygen concentrations at the end of the test.

Validity criteria fulfilled:
yes
Remarks:
Oxygen and pH values acceptable, control immobilisation acceptable.
Conclusions:
Well documented and conducted under a recognised quality control standard. No analytical monitoring. Screening level study (limited number of predefined concentrations) not designed to yield a valid EC50.
Executive summary:

The acute toxicity of salicylamide to daphnia magna was investigated under static exposure conditions over a period of 48h. A screening test with nominal concentrations of 100, 10, and 1mg/L was performed. 40 individual daphnia divided in 2 test vessels were exposed to each conetration of the test substance. No analytical verification of the test material was conducted; evaluation of the test was based on nominal concentrations assuming the substance to be stable in water over a 48h period. Based on the immobilisation data, the nominal EC50(48h) of salicylamide to daphnia magna was estimated to be 10 -100mg/L. The NOEC was 10mg/L after 48h exposure. Almost 100% immobilisation was observed at the nominal concentration of 100mg/L after 48h.

Description of key information

EC50 = 37 mg/L, 48h, Daphnia magna, OECD 202, Höger 2010
EC50 = 10 - 100 mg/L, 48h, Daphnia magna, screening test, Häner 2007

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
37 mg/L

Additional information

The acute toxicity of the substance to Daphnia magna was determined in a 48-hour static screening test, by Häner (2007). The study was conducted under a recognised quality control standard. No analytical measurements were performed. The 48h EC50 was found to be in the range 10-100 mg/L, with a NOEC of 10 mg/L over the same period. Almost 100% immobilisation was seen at the nominal 100 mg/L concentration.

 

The acute toxicity of the substance to Daphnia magna was determined in a 48-hour static test under GLP and according to OECD Guideline 202 (2004), by Höger (2010). The nominal concentrations tested were control group, 4.6, 10, 22, 46 and 100 mg/L. No analytical measurements were performed in the test. The 48h EC50 was found to be 37 mg/L (30-45 mg/L, CI=95%) based on nominal concentrations.The pH was reported in the range 7.5-7.8.

 

The EC50 result of the guideline study falls within the range determined by the screening level study. The two available studies both have shortcomings in the experimental design, but the independent determinations lend credibility to the results. However, this consistency does not remove any inherent uncertainty due to potential hydrolysis.

 

In literature studies investigating hydrolysis, the substance has been shown to be hydrolytically unstable, but under strongly acid and alkaline conditions at elevated temperatures (~100 °C). No experimental information is available at relevant temperatures - see section 5.1.2. However, the algae growth inhibition study by Liedtke (2010) demonstrated a decrease in salicylamide concentration during the 96 h study period, which may be attributable to hydrolysis (the pH observed at the end of the study was 8.2-9.4).

 

As a result, the aquatic invertebrate study by Höger is not considered in itself to be fully reliable, as toxicity may be underestimated due to the lack of analytical measurements of test item concentrations during the study. However, the neutral pH of the test media, and half the duration (48h) of the algae study, are likely to mitigate the degree of test concentration reduction which was observed by Liedtke. Finally, the Daphnia magna EC50 (37 mg/L) is significantly higher than regulatory cut-offs for classification (at 10 mg/L), and is not used for risk assessment (PNEC derivation), both of which are driven by the toxicity to algae.

 

The available data is thus considered to be adequate for the purposes of classification and labelling and risk assessment based on the weight-of-evidence, in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.2.