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Short-term toxicity to fish

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Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2009-05-18 to 2009-05-22
Reliability:
2 (reliable with restrictions)
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 850.1075 (Freshwater and Saltwater Fish Acute Toxicity Test)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:

TEST MATERIAL
- Name of test material (as cited in study report): decanal, Ald C-10 BHA
- Substance type: Colourless to pale yellow liquid
- Physical state: Liquid
- Impurities (identity and concentrations): No data
- Composition of test material, percentage of components: No data
- Isomers composition: No data
- Purity test date: 2009-12-07
- Lot No: 0002825582
- Expiration date of the lot/batch: 2010-12
- Stability under test conditions: Stable under normal storage conditions
- Storage condition of test material: Room temperature
- Smiles notation (if other than submission substance): O=CCCCCCCCCC

STABILISER CONTROL
- Name of test material (as cited in study report): BHA, 2-t-butyl-4-methoxy phenol
- Substance type: No data
- Physical state: No data
- Analytical purity: 99.9 %
- Impurities (identity and concentrations): No data
- Composition of test material, percentage of components: No data
- Isomers composition: No data
- Purity test date: 2009-12-07
- Lot No: 0000231975
- Expiration date of the lot/batch: 2010-12
- Stability under test conditions: No data
- Storage condition of test material: No data
Analytical monitoring:
yes
Details on sampling:
- Sampling time: 0, 72 hrs (freshly prepared test solutions) 24, 96 hrs (spent test solutions)
- Sampling method: 9 mL removed using pipette
- Sample storage conditions before analysis: No data
Vehicle:
no
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
TEST ORGANISM
- Common name: Rainbow trout
- Strain: No data
- Source: Trout Lodge, Sumner, Washington, United States
- Age at study initiation (mean and range, SD): No data
- Length at study initiation (representative sample of 10): total length 46 mm, range 41 to 49 mm, SD 3.9 mm
- Weight at study initiation (representative sample of 10): mean 0.8969 g, range 0.5455 g to 1.5721 g, SD 0.2882 g
- Method of breeding: No data
- Feeding during test: No

ACCLIMATION
- Acclimation period and conditions: ≥12 d in the lab, > 7 d in dilution water within ± 2 °C of test temperature (same as test).
- Type of food: Standard commercial fish food (salmon starter diet)
- Amount of food: No data
- Feeding frequency: Daily, although fish were not offered food 24 hrs prior to their use in the definitive test
- Health during acclimation: No diseases were observed nor were the fish treated for disease, and no mortalities occurred during the 48 hr period prior to definitive test initiation
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Hardness:
150 mg CaCO₃/L
Test temperature:
15.5 to 17.0 °C (table 3)
pH:
7.8 to 8.4 (Table 5).
Dissolved oxygen:
8.6 to 12.5 mg/L (91 to 131 % saturation) in fresh solutions, and from 4.3 to 10.1 in spent solutions (45 to 106 % saturation) (Table 4)
Salinity:
Conductivity: 358 μS.
Nominal and measured concentrations:
Nominal: 0 (control), 0 (stabiliser control), 1.0, 1.5, 2.2, 3.3, and 5.0 mg/L
Measured (geometric mean): 0 (control), 0 (stabiliser control), 0.478, 0.844, 1.32, 1.76, 3.77
Details on test conditions:
RANGE-FINDING TEST
- Test vessel: 10 L glass jars
- Type: Closed (covered with parafilm)
- Material, size, headspace, fill volume: 8L test or control water per vessel
- Test treatment solutions were prepared by diluting appropriate aliquots of test substance to a volume of 8 L with dilution water.
- The stabiliser control was prepared by weighing 0.00016 g of BHA into a 10 L glass jar and bringing the jar to a volume of 8 L with dilution water
- After 48 hr, surviving fish were transferred to freshly prepared solutions.

TEST SYSTEM
- Test vessel: 21 L glass jars
- Type: Closed
- Material, size, headspace, fill volume: 21 L test or control, no headspace due to volatility
- After 48 hr, surviving fish were transferred to freshly prepared solutions.
- No. of organisms per vessel: 7
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- No. of vessels per stabiliser control (replicates): 1
- Biomass loading rate (instantaneous): 0.2990 g/L/day

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Moderately hard freshwater prepared blending naturally hard well water with well water that was demineralised by reverse osmosis (RO). The well water and RO water were blended together to yield a total hardness of 130 to 160 mg/L as CaCO₃.

OTHER TEST CONDITIONS
- Adjustment of pH:
- Photoperiod: 16 hrs light / 8 hrs dark
- Light intensity: 581 lux

EFFECT PARAMETERS MEASURED: Mortality at 24, 48, 72, 96 hrs.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.5 ×
- Range finding study
- Test concentrations: 0 (control), 1.3, 2.5, 5.0, 10, and 20 mg/L
- Results used to determine the conditions for the definitive study:
-- The control and all test substance solutions < 10 mg/L were clear and colourless with no visible signs of undissolved test substance, precipitate, or surface film throughout the study.
-- The 10 and 20 mg/L test solutions had a slight surface film at initiation and 24 hrs.
-- Fish were observed after 24, 48, 72, and 96 hrs. After 96 hrs of exposure, there was no mortality or sublethal effects observed in the controls or any of the remaining test substance treatments.
Reference substance (positive control):
no
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
2.1 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95 % CL 1.88 and 2.35 mg/L; Mean of measured fresh solution concentrations
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
1.45 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95 % CL 1.33 and 1.59 mg
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
1.75 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: Mean of measured fresh solution concentrations
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
1.32 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
- After 96 hrs of exposure, mortality was 0 %, 0 %, 0 %, 0 %, 14 %, 100 %, and 100 % in the 0 (control), 0 (stabiliser control), 0.478, 0.844, 1.32, 1.76, and 3.77 mg/L treatments respectively.
- There were no sublethal effects noted in the control or treatments during the definitive test.

Validity criteria fulfilled:
yes
Conclusions:
The acute toxicity to rainbow trout was determined. The 96 hr LC50 was determined to be 1.45 mg/L (based on Geometric Mean Measured Concentrations).

Endpoint:
short-term toxicity to fish
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
ANALOGUE APPROACH JUSTIFICATION:
-See attached "Acute Fish Read-Across Justification for Nonanal" document for full details.
- In summary, important considerations for the use of read-across for acute aquatic toxicity are:
i) The read-across hypothesis is based on different compounds which have similar properties. It is covered by scenario 2 in the ECHA Read-Across Assessment Framework [RAAF, ECHA 2017]. The source and target substance have similar ecotoxicological properties as a result of structural similarity, the same mode of action for aquatic toxicity and similar bioavailabilities (e.g. lipophilicity as modelled by log Kow).
ii) Nonanal (the target chemical) is structurally similar to decanal (the source substance). Both are linear aliphatic mono-aldehydes. The only structural difference is the chain length ,C9 and C10 respectively.
iii) The OECD QSAR toolbox assigns the same acute aquatic toxicity classification and mode of action to both chemicals.
iv) Hydrophobicity (as modelled by log Kow) can be an important aspect in aquatic toxicity. Nonanal and decanal, which vary only by one carbon atom in chain length, have similar measured log Kow values of 3.4 and 3.8 respectively.
v) both chemicals have been tested for ready biodegradability, acute toxicity to daphnia, and toxicity to microorganisms. Both chemicals gave similar results.
Reason / purpose:
read-across source
Key result
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
1.45 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95 % CL 1.33 and 1.59 mg
Remarks:
Read-across
Conclusions:
A valid study for acute toxicity to rainbow trout is available for the analogue substance, Decanal. It is a GLP compliant study conducted in compliance with agreed protocols, with no or minor deviations for the standard test. The 96 hr LC50 was determined to be 1.45 mg/L (based on Geometric Mean Measured Concentrations).

The detailed information provided in the read-across justification document indicates that the aquatic ecotoxicity of nonanal (target substance) and decanal (source substance) are expected to be similar as a result of structural similarity, the same mode of action and similar physicochemical properties. Therefore, direct read-across from the source substance is considered to give a reliable estimate of the acute fish 96-hr LC50 for nonanal, which is 1.45 mg/L.

Description of key information

A valid study for acute toxicity to rainbow trout is available for the analogue substance, Decanal. The 96 hr LC50 was determined to be 1.45 mg/L (based on Geometric Mean Measured Concentrations)and is considered a reliable estimate for the target substance, nonanal.. 

Key value for chemical safety assessment

LC50 for freshwater fish:
1.45 mg/L

Additional information

A valid study is available for the analogue substance, decanal. It is a GLP compliant study conducted in compliance with agreed protocols, with no or minor deviations from the standard test. Important considerations for the use of read-across are:

i) Nonanal (the target chemical) is structurally similar to decanal (the source substance). Both are linear aliphatic mono-aldehydes. The only structural difference is the chain length ,C9 and C10 respectively.

ii) Both substances are expected to act via the same mode of action for aquatic toxicity. Characterization using the OECD QSAR Toolbox shows that the 5 primary profilers relevant to acute aquatic toxicity are identical

iii) There are no impurities that are expected to affect the ecotoxicological properties of the source and target substance

iv) Uptake / lipophilicity (as modelled by log Kow) is a known determinant of the toxicity in aquatic organisms. Nonanal and decanal, which vary only by one carbon atom in chain length, have similar measured log Kow values of 3.4 and 3.8 respectively, and therefore the strength of aquatic toxicity for the two substances is expected to be similar.

v) Both chemicals have been tested for ready biodegradability, acute toxicity to daphnia, and toxicity to microorganisms. Both chemicals gave similar results.

Based on the above, read-across is justified. Furthermore, the 48-h EC50 daphnia results for both substances, the algae 72h ErC50 for the target and the fish 96h LC50 for the source substance are in the same classification band (1-10mg/L) and as such the read-across is considered adequate for the purpose of classification and labelling and/or risk assessment.