Carboxylic acids, C5-9

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

Study performed in 1993.

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data from reliable source

Qualifier:

according to guideline

Guideline:

EPA OPP 72-2 (Aquatic Invertebrate Acute Toxicity Test)

Version / remarks:

Freshwater invertebrate acute using TGAI or TEP (FIFRA 158.490)

GLP compliance:

not specified

Specific details on test material used for the study:

Nonanoic acid is one of the main constituents of the target UVCB substance

Analytical monitoring:

not specified

Vehicle:

no

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Strain: no data
- Source: no data
- Age at study initiation (mean and range, SD): < 24 h


ACCLIMATION
- Acclimation period: no data

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

96 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% CL: 64-119 mg/L

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

39 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity (48-h EC50) of nonanoic acid was determined to be 96 mg/L.
Nonanoic acid is one of the main constituents of the target UVCB substance.

Executive summary:

The acute toxicity of nonanoic acid was tested on Daphnia magna according to EPA OPP guideline 72 -2. There is no detailed information on the number of test concentrations and analytical verification of test concentrations. The 48 -h EC50 is 96 mg/L (95% CL: 64 -119 mg/L); 96 -h NOEC: 39 mg/L.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

2004

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Samples were taken from the control and each test group from the bulk test preparation at 0 hours and from the pooled replicates (R1 to R4) at 48 hours for quantitative analysis. Samples were stored frozen prior to analysis.
Duplicate samples were taken and stored frozen for further analysis if necessary.

Vehicle:

no

Details on test solutions:

Following a preliminary range-finding test, 20 daphnids (4 replicates of 5 animals) were exposed to WAFs of the test item over a range of nominal loading rates of 10, 18, 32, 56 and 100 mg/L for 48 hours at a temperature of 20 °C to 21 °C under static test conditions. The number of immobilized daphnia and any adverse reactions to exposure were recorded after 24 and 48 hours.
Nominal amounts of test item (50, 90, 160, 280 and 500 mg) were each separately added to the surface of 5 liters of test water to give the 10, 18, 32, 56 and 100 mg/L loading rates respectively. After the addition of the test item, the test water was stirred by magnetic stirrer using a stirring rate such that a vortex was formed to give a dimple at the water surface. The stirring was stopped after 23 hours and the mixtures allowed to stand for 1-Hour. A wide bore glass tube, covered at one end with Nescofilm was submerged into the vessel, sealed end down, to a depth of approximately 5 cm from the bottom of the vessel. A length of Tygon tubing was inserted into the glass tube and pushed through the Nescofilm seal. The aqueous phase or WAF was removed by mid-depth siphoning (the first 75 to 100 mL discarded) to give the 10, 18, 32, 56 and 100 mg/L loading rate WAFs. Microscopic inspection of the WAFs showed no micro-dispersions or undissolved test item to be present.
The concentration and stability of the test item in the test preparations were verified by chemical analysis at 0 and 48 hours

Test organisms (species):

Daphnia magna

Details on test organisms:

The test was carried out using first instar Daphnia magna derived from in-house laboratory cultures.
Adult daphnids were maintained in 150 mL glass beakers containing 100 mL Elendt M7 medium in a temperature controlled room maintaining the water temperature at 18 to 22 °C. The lighting cycle was controlled to give a 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods. Each culture was fed daily with a mixture of algal suspension (Desmodesmus subspicatus) and GEMMA Micro 300 suspension. Culture conditions ensured that reproduction was by parthenogenesis. Gravid adults were isolated the day before initiation of the test, such that the young daphnids produced overnight were less than 24 hours old. These young were removed from the cultures and used for testing. The diet and diluent water are considered not to contain any contaminant that would affect the integrity or outcome of the study.

Test type:

static

Water media type:

other: Elendt M7 medium

Limit test:

no

Total exposure duration:

48 h

Hardness:

Reconstituted Water – Elendt M7 Medium
Ingredient Final Concentration (mg/L)
H3BO3 0.715
MnCl2.4H2O 0.090
LiCl 0.077
RbCl 0.018
SrCl2.6H2O 0.038
NaBr 0.004
Na2MoO4.2H2O 0.016
CuCl2.2H2O 0.004
ZnCl2 0.013
CoCl2.6H2O 0.010
KI 0.0033
Na2SeO3 0.0022
NH4VO3 0.00058
Na2EDTA.2H2O 0.625
FeSO4.7H2O 0.249
CaCl2.2H2O 293.8
NaHCO3 64.8
MgSO4.7H2O 123.3
Na2SiO3.9H2O 10
KCl 5.8
NaNO3 0.274
K2HPO4 0.184
KH2PO4 0.143
Thiamine hydrochloride 0.075
Cyanocobalamine (vitamin B12) 0.0010
D(+) biotin (vitamin H) 0.00075

Test temperature:

from 20 to 21 °C

pH:

7.9 ±0.3

Dissolved oxygen:

The dissolved oxygen concentration at the end of the test is equal to or greater than 3 mg/L in the control and test vessels

Salinity:

According to the reported composition (Elendt M7 Medium)

Conductivity:

According to the reported composition (Elendt M7 Medium)

Nominal and measured concentrations:

Nominal Loading Rate: 10, 18, 32, 56 e 100 mg/l
Determined concentration of the test item in test sample:
0 hrs: 6.28, 9.73. 19.1, 35.3, 63.8 mg/l
48 hrs: 4.10, 7.39, 13.1, 24.3, 48.8 mg/l

Details on test conditions:

As in the range-finding tests 150 mL beakers jars containing approximately 100 mL of test preparation were used. At the start of the test five daphnids were placed in each test and control vessel at random, in the test preparations. Four replicate test and control vessels were prepared. The test vessels were then covered to reduce evaporation and maintained in a temperature controlled room maintaining the water temperature at 18 to 22 °C with a maximum deviation of ±1 °C with a photoperiod of 16 hours light (between 200 and 1200 lux) and 8 hours darkness with 20 minute dawn and dusk transition periods. The daphnids were not individually identified, received no food during exposure and the test vessels were not aerated.
The control group was maintained under identical conditions but not exposed to the test item.
The test preparations were not renewed during the exposure period.

Reference substance (positive control):

yes

Remarks:

A positive control (Envigo study number LK67NP) used potassium dichromate as the reference item at concentrations of 0.32, 0.56, 1.0, 1.8 and 3.2 mg/L. Exposure conditions for the positive control were similar to those in the definitive test.

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

61 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Remarks:

Loading Rate WAF

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Remarks:

Loading Rate WAF

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

LOELR

Effect conc.:

56 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Remarks:

Loading Rate WAF

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EL50

Effect conc.:

61 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Remarks:

Loading Rate WAF

Basis for effect:

mobility

Results with reference substance (positive control):

A positive control (Envigo study number LK67NP) used potassium dichromate as the reference item at concentrations of 0.32, 0.56, 1.0, 1.8 and 3.2 mg/L.
Exposure conditions for the positive control were similar to those in the definitive test.
Analysis of the immobilization data was carried out using the Trimmed Spearman-Karber method at 24 hours and the Binomial Distribution method at 48 hours. All statistical analysis was carried out using the ToxRat Professional computer software package with results based on the nominal test concentrations and gave the following results:

Time Point (Hours) EC50 (mg/L) 95% Confidence Limits (mg/L) NOEC (mg/L) LOEC (mg/L)
24 0.79 0.73-0.86 0.56 1.0
48 0.75 0.56-1.0 0.56 1.0

The NOEC is based upon equal to or less than 10% immobilization at this concentration.
The results from the positive control with potassium dichromate were within the normal range for this reference item.

Reported statistics and error estimates:

The EL50 values and associated confidence limits at 24 and 48 hours and the slope of the response curve and its standard error were calculated by Probit analysis using Linear Maximum-Likelihood regression. The Lowest Observed Effect Loading (LOEL) rate and the NOEL rate at 24 and 48 hours were calculated using the Fisher’s Exact Binomial Test with Bonferroni correction. All results were calculated using the ToxRat Professional computer software package (TOXRAT).

Chemical analysis of the fresh test preparations at 0 hours showed measured test concentrations to range from 6.3 to 64 mg/L. Chemical analysis of the aged test preparations at 48 hours showed measured test concentrations to range from 4.1 to 49 mg/L.

The dissolved test item may have been one or several components of the test item. Given that the toxicity cannot be attributed to a single component or a mixture of components, but to the test item as a whole, the results were based on nominal loading rates only.

Cumulative Immobilization Data and Observations in the Definitive Test

Nominal Loading Rate (mg/L)	24 hours
	Cumulative Immobilized Daphnia (Initial Population: 5 Per Replicate)						Observations
	Rep1	Rep2	Rep3	Rep4	Total	%	Rep1	Rep1	Rep1	Rep1
Control	0	0	0	0	0	0	5N	5N	5N	5N
10	0	0	0	0	0	0	1C 4N	5N	5N	5N
18	0	0	0	0	0	0	5N	5N	5N	5N
32	1	0	0	0	1	5	4N	5N	5N	5N
56	0	0	0	5	5	25	5N	5N	5N	AI
100	5	5	5	5	20	100	AI	AI	AI	AI

Nominal Loading Rate (mg/L)	48 hours
	Cumulative Immobilized Daphnia (Initial Population: 5 Per Replicate)						Observations
	Rep1	Rep2	Rep3	Rep4	Total	%	Rep1	Rep1	Rep1	Rep1
Control	0	0	0	0	0	0	5N	5N	5N	5N
10	0	0	0	0	0	0	3C 2R	5N	5C 5T	5N
18	0	0	0	0	0	0	5C 5T	5N	5N	5N
32	1	0	0	0	1	5	4C	5N	5N	5N
56	0	0	0	5	5	25	3C 2N	5N	5N	AI
100	5	5	5	5	20	100	AI	AI	AI	AI

Rep = Replicate; N = Normal; C = Covered in debris; R = Reduced mobility; T = Trapping at surface; AI = All daphnia immobilized

The relationship between percentage immobilization and concentration at 48 hours is given in the attached Figure.

Analysis of the immobilization data by Probit analysis using Linear Maximum-Likelihood regression at 24 and 48 hours based on the nominal loading rates gave the following results:

Time (Hour) EL50 (mg/L Loading Rate WAF) 95% Confidence limits (mg/L Loading Rate WAF)

24 61 53 - 71

48 61 53 - 71

The NOEL after 24 and 48 hours exposure was 32 mg/L loading rate WAF. Correspondingly the LOEL was considered to be 56 mg/L loading rate WAF.

The slope and their standard error of the response curves at 24 and 48 hours was 8.0 (standard error = 0.029).

Sub-Lethal Effects

Sub-lethal effects of exposure were observed in the 10, 18, 32 and 56 mg/L loading rate WAF test concentrations. These responses were reduced mobility, covered in debris (mainly around antennas) and trapping at surface

Validity criteria fulfilled:

yes

Remarks:

The test was considered to be valid given that none of the control daphnids showed immobilization or other signs of disease and that the oxygen concentration at the end of the test was equal to or greater than 3 mg/L in the control and test vessels.

Conclusions:

Exposure of the freshwater invertebrate Daphnia magna to the test item has been investigated and gave the following results:
Time Point (Hours) EL50 (mg/L Loading Rate WAF) 95% Confidence Limits (mg/L Loading Rate WAF) NOEL (mg/L) LOEL (mg/L)
48 61 53 - 71 32 56

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1970

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Qualifier:

no guideline followed

Principles of method if other than guideline:

The substance octanoic acid was tested on Artemia Salina using the LC50 assay method.

GLP compliance:

not specified

Specific details on test material used for the study:

Not specified

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

Artemia salina

Test type:

not specified

Water media type:

saltwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

None

Hardness:

Not specified

Test temperature:

Not specified

pH:

Not specified

Dissolved oxygen:

Not specified

Salinity:

Not specified

Conductivity:

Not specified

Nominal and measured concentrations:

Not specified

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

240 mg/L

Nominal / measured:

not specified

Conc. based on:

not specified

Basis for effect:

not specified

Remarks on result:

other:

Remarks:

No test duration of this short-term test is given in the publication but is assumed that the test duration might be similar to the duration of the freshwater tests.

Results with reference substance (positive control):

No

Validity criteria fulfilled:

not specified

Conclusions:

The LC50 of octanoic acid after 48 h was 240 mg/l

Reference 4

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1989

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Qualifier:

no guideline followed

Principles of method if other than guideline:

To investigate the quantitative structure-activity relationship (QSARs) for the acute toxicity of fatty acids and their sodium salts to aquatic organisms, red killifish (Oryzias latipes) and gammarus (Hyale plumulosa) were studied upon their sensitivity to a series of the acids and the sodium salts.Studies on red killifish was conducted both under saline and fresh water conditions. Good QSARs of fatty acids were obtained using an zoctanol/water partition coefficient as the single parameter. The log LC50 of fatty acid salts with C8 to C12 carbon chain length was linearly related to a logarithm of the critical micelle concentrations (CMCs).
Then Hyale plumulosa was studied under static marine water conditions for 48 h.

GLP compliance:

not specified

Specific details on test material used for the study:

Caprylic acid as reported in this publication without any other detail

Analytical monitoring:

yes

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: octanoic acid was dissolved in artifical sea water by adding 10 g/L and mixing in an Erlenmeyer flask for 24 h with a magnetic bar at room temperature (25 ± 2 °C). Mixture was left still for a few hours and the upper layer was removed with a capillary pipette. The lower layer was used for testing.

Test organisms (species):

Gammarus sp.

Details on test organisms:

TEST ORGANISM
- Common name: Gammarus (Hyale plumulosa)
- Length at study initiation: 5 mm
- Food type: commercial fish food until test started

ACCLIMATION
- Acclimation period: 2 weeks

Test type:

semi-static

Water media type:

saltwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

51 mg CaCO3/L

Test temperature:

25 +/- 2°C

pH:

8.2

Dissolved oxygen:

If dissolved oxygen was < 60 % of air saturation, aeration was provided once for 5 min at 24 h intervals.

Salinity:

25 per mille

Nominal and measured concentrations:

Animals were exposed to a geometric series of concentrations of the test chemical (max. 1000 mg/L), but when LC50 values of the test chemicals were close to or higher than the saturated concentrations, animals were exposed only to the saturated solutions and the half-dilution of the saturated solutions.

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume: 200 mL
- Renewal rate of test solution: after 24 h
- No. of organisms per vessel: 10 per test vessel
- Aeration: if oxygen saturation was < 60% of air saturation aeration for 5 min, 24 h interval

OTHER TEST CONDITIONS
- Photoperiod: 12 h light/12 h dark

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

128 mg/L

Nominal / measured:

not specified

Conc. based on:

not specified

Basis for effect:

not specified

Validity criteria fulfilled:

not specified

Conclusions:

The LC50 of caprylic acid after 48 h was 128 mg/l

Reference 5

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1998

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

hardness of test water was lower than that recommended by the Guideline

GLP compliance:

yes

Remarks:

according to the Japanese GLP Standard

Specific details on test material used for the study:

Not specified

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0 and 20 mg/L
- Sampling method: 10 mL test solution was sampled directly from each test vessel at test initiation and after 48 hours.
- Sample storage conditions before analysis: Analysis was conducted immediately after sampling, no storage.

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test substance was dissolved in vehicle, and this stock solution was diluted in dilution water and stirred for 1 hour.
- Controls: dilution water with/without vehicle
- Chemical name of vehicle: dimethylformamide
- Concentration of vehicle in test medium: 0.1 mL/L
- Evidence of undissolved material: not observed

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Source: Bred in-house (origin: Incorporated Administrative Agency, National Institute for Environmental Studies, Tsukuba, Japan)
- Age at study initiation: max 24 hours
- Feeding during test: no

ACCLIMATION
- Acclimation period: 2 - 4 weeks
- Acclimation conditions: same as test
- Type and amount of food: Chlorella vulgaris, 0.1 - 0.2 mg C/day
- Health during acclimation: 1% mortality was observed

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Post exposure observation period:

None

Hardness:

55.2 mg/L (as CaCO3)

Test temperature:

19.8 °C (20 ± 1 °C )

pH:

7.7 - 8.1

Dissolved oxygen:

7.5 - 8.5 mg/L (> 60% of saturated oxygen)

Salinity:

None

Conductivity:

Not measured

Nominal and measured concentrations:

nominal concentration: 20 mg/L
measured concentration: 21 mg/L (geometric mean)
Since measured concentrations did not deviate by more than 20% from the nominal concentrations, nominal concentrations were considered for statistical analysis

Details on test conditions:

TEST SYSTEM - Test vessel: 100 mL beaker - Material, fill volume: glass, 100 mL - No. of organisms per vessel: 5 - No. of vessels per concentration: 4 - No. of vessels per control: 4 - No. of vessels per vehicle control: 4
TEST MEDIUM / WATER PARAMETERS - Source/preparation of dilution water: charcoal-treated, dechlorinated and aerated tap water in Takarazuka, Japan - Alkalinity: 55 mg/L - Ca/Mg ratio: 16/3.3 - Culture medium different from test medium: same as test medium - Intervals of water quality measurement: pH, oxygen content and temperature of test solutions were determined at test initiation and at the end of the study.
OTHER TEST CONDITIONS - Photoperiod: 16 : 8 hours day-night regime
EFFECT PARAMETERS MEASURED: Mobility observed daily

Reference substance (positive control):

yes

Remarks:

potassium dichromate (reagent grade)

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

> 20 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

> 20 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Dose descriptor:

NOEC

Effect conc.:

20 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: no abnormality was observed
- Mortality of control: 0%
- Other adverse effects control: not observed

Results with reference substance (positive control):

- Results with reference substance were as expected.
- EC50: 0.54 mg/L for 48 hours

Validity criteria fulfilled:

yes

Conclusions:

Daphnia magna was exposed to 0 and 20 mg/l of n-octanoic acid for 48 hours under static conditions. None of the daphnia died in the 20 mg/L group. EC50 was then estimate at > 20 mg/l. (based on nominal concentrations).

Reference 6

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

GLP compliance:

yes

Specific details on test material used for the study:

- Name of test material (as cited in study report): n-Heptanoic acid
- Substance type: acid
- Physical state: Liquid
- Analytical purity: >97.7%
- Lot/batch No.: FHH02

Analytical monitoring:

yes

Details on sampling:

- Concentrations: control (0 mg/L) ; 10 ; 18 ; 32.1 ; 56 and 100 mg/L
- Sampling method: tank water from each tank was analysed at 0 h (fresh media) and 24 h(expired media)
- Sample storage conditions before analysis: not indicated, but probably assayed right after sampling

Vehicle:

no

Details on test solutions:

Elendt M4 medium as described in the OECD 202 guideline.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Strain:
- Source: Ministry of the Environment, National Institute of Environmental Studies (presently the National Institute for Environmental Studies)
- Feeding during test: no feeding

ACCLIMATION
- Acclimation period: 1 month
- Type and amount of food: 0.2 mg carbon/day/daphnia
- Feeding frequency: daily
- Health during acclimation (any mortality observed): 0% mortality during the acclimation period

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

None

Hardness:

Not specified

Test temperature:

20.2 -20.4°C (min-max)

pH:

5.7 - 8.1 (min-max)

Dissolved oxygen:

8.2-8.8 (min-max)

Salinity:

None

Conductivity:

Not measured

Nominal and measured concentrations:

Nominal: control ; 10 ; 18 ; 32 ; 56 and 100 mg/L
Measured concentrations at 0h: 0 ; 9.3 ; 21.3 ; 35 ; 64.6 and 117 mg/L
Measured concentrations at 24h: 0 ; 9.1 ; 17.3 ; 28.6 ; 53.3 and 106 mg/L

Since measured concentrations did not deviate by more than 20% from the nominal concentrations, nominal concentrations were considered for statistical analysis

Details on test conditions:

TEST SYSTEM
- Test vessel:glass beaker
- Type (delete if not applicable): closed with Teflon sheet
- Material, size, headspace, fill volume: 100 mL test solution
- Aeration: None
- Renewal rate of test solution (frequency/flow rate): semi static: daily renewal
- No. of organisms per vessel: five
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Elendt M4 medium, as mentioned in the OECD 202 guidelines.

OTHER TEST CONDITIONS
- Adjustment of pH: None
- Photoperiod: 16L:8D
- Light intensity: 800 lux max

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Immobilization, once a day

TEST CONCENTRATIONS
- Spacing factor: 1.8
- Test concentrations: 0 ; 10 ; 18 ; 32 ; 56 and 100 mg/L

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

72 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other:

Remarks:

CI (95%) = [56;100]

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

All daphnia died in the 100 mg/L group while no other daphnia died in the other groups, except one in the 56 mg/L group. EC50=72 mg/L based on nominal concentrations.

Results with reference substance (positive control):

- Results with reference substance valid
- EC50/LC50: 0.89 mg/L

Reported statistics and error estimates:

EC50 was determined by the probit regression method.

Heptanoic acid concentrations throughout the experiment

	Measured concentrations
Nominal concentrations (mg/l)	0 h	% nominal	24 h	% nominal
Control	< 0.07	-	<0.07	-
10	9.3	93	9.1	91
18	21.3	118	17.3	96
32	35.0	109	28.6	89
56	64.6	115	53.3	95
100	117	117	106	106

Validity criteria fulfilled:

yes

Conclusions:

Daphnia magna were exposed to graded concentrations of n-heptanoic acid. EC50 was estimated at 72 mg/L.

Executive summary:

Daphnia magna were exposed to graded concentrations of n-heptanoic acid (0 ; 10 ; 18 ; 32 ; 56 ; 100 mg/L) for 48 hours under semi-static conditions (test solution renewal once a day). All daphnia died in the 100 mg/L group. One daphnia died in the 56 mg/L group. No other daphnia died. EC50 was then estimated at 72 mg/L.

Description of key information

48-h EL50 = 61 mg/L.

The available result on the target substance (daphnia magna) was used for the assessment.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

61 mg/L

Additional information

A study was performed to assess the acute toxicity of the test item to Daphnia magna. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (April 2004) No 202, "Daphnia sp., Acute Immobilisation Test" referenced as Method C.2 of Commission Regulation (EC) No. 440/2008.

Due to the low aqueous solubility and complex nature of the test item, for the purposes of the test, the test medium was prepared as a Water Accommodated Fraction (WAF).

Following a preliminary range-finding test, 20 daphnids (4 replicates of 5 animals) were exposed to WAFs of the test item over a range of nominal loading rates of 10, 18, 32, 56 and 100 mg/L for 48 hours at a temperature of 20 °C to 21 °C under static test conditions. The number of immobilized daphnia and any adverse reactions to exposure were recorded after 24 and 48 hours.

Chemical analysis of the fresh test preparations at 0 hours showed measured test concentrations to range from 6.3 to 64 mg/L. Chemical analysis of the aged test preparations at 48 hours showed measured test concentrations to range from 4.1 to 49 mg/L.

The dissolved test item may have been one or several components of the test item. Given that the toxicity cannot be attributed to a single component or a mixture of components, but to the test item as a whole, the results were based on nominal loading rates only.

Several other studies are available for the main substance constituents and in particular, the ones with RL 1 or 2:

1) the acute toxicity of nonanoic acid was tested on Daphnia magna according to EPA OPP guideline 72 -2. There is no detailed information on the number of test concentrations and analytical verification of test concentrations. The 48 -h EC50 was 96 mg/L (95% CL: 64 -119 mg/L); 96 -h NOEC: 39 mg/L.

2) the acute toxicity of octanoic acid was tested on Daphnia magna according to OECD 202. The 48 -h EC50 was > 20 mg/L ; 48 -h NOEC: 20 mg/L.

3) the acute toxicity of heptanoic acid was tested on Daphnia magna according to OECD 202. The 48 -h EC50 was 72 mg/L ; 48 -h NOEC: 32 mg/L

It can be underlined the results on the constituents are in agreement with the available experimental result on the target substance (Carboxylic acids, C5 -9).