2,6,10-trimethylundec-9-enal

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 Sept. 2000 - 10 Nov. 2000

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

slightly modified/adapted to the kind of test substance (poorly water soluble and volatile).

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch N°20070036
Expiry date 31-Mar-2001

Analytical monitoring:

yes

Details on sampling:

Performed at t=0 and t=48 hours

Vehicle:

no

Details on test solutions:

As the test substance is poorly water soluble, the test substance was tested using the aqueous extracts from the test substance. For this purpose, suspensions of the test substance were prepared in dilution water. For this purpose, the test substance was weighed into the glass vessels with the respective amount of water used for the preparation of the aqueous extracts. The test substance was introduced into the dilution water whilst shaking an a shaking machine (approx 130 rpm) for 24h at room temperature. It is assumed that during that time equilibration between the test substance and the water was achieved. Thereafter, the suspensions were filtered through filter paper which was previously rinsed thoroughly with ultrapure water (Seral, „Purelab Plus") in order to eliminate possible soluble impurities from the filter material. The filtered extracts were used directly for the test without any further dilution steps.

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnia magna STRAUS of laboratory bred (originally derived from Dr. Knie, LWA Düsseldorf) were used for the test. The animals used for the test were not older than 24h.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Remarks on exposure duration:

The incubation period was 48h.

pH:

As a control the pH was measured at the beginning of the test and after 48h.

Nominal and measured concentrations:

1st main Test (Nominal; (aqueous extracts)) : 1 mg/L, 2 mg/L, 4 mg/L, 8 mg/L, and 10 mg/L loading rates
2nd main Test (Nominal; (aqueous extracts)) : 0.25 mg/L, 0.5 mg/L, 1 mg/L, 2 mg/L, 4 mg/L, and 8 mg/L loading rates

Details on test conditions:

- As the test substance exhibits partial adsorptive properties the aqueous extracts of the test substance were transferred into the respective test vessels, and after approx. 1 hour, the aqueous extracts were replaced by a second part of the aqueous extract. By that measure the surfaces of the glass walls were saturated with the test substance, and losses due to adsorption avoided.
As the test substance contains volatile components the test was performed in closed bottles. For this purpose, the aqueous extracts of test substance were filled into the test vessels (100 mL-carboys ) up to the neck, and after introducing of the animal the vessels were closed with the glass-stoppers. By this measure any gas-phase was avoided.
- Four parallel test solutions with 5 animals were prepared for each concentration, respectively.
- As a control the pH was measured at the beginning of the test and after 48h. The daphnia were not fed during the test.

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

0.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: Loading Rate

Details on results:

SCREENING TEST:
A screening test was performed in order to find out the concentration range of the test substance for the main test. Three concentrations of the test substance were used: 1.0 mg/L, 10 mg/L and 100 mg/L (Loading Rated). After 48 hours the immobilisation observed was 0, 10 and 100% respectively.

1st MAIN TEST:
Based on the results of the screening test, the following concentrations were tested: 1mg/L, 2mg/L, 4 mg/L, 8 mg/L and 10 mg/L (Loading Rates). After 48 hours the immobilisation observed was 85, 100, 100, 100 and 100% respectively. In contrary to the screening test there was a higher inhibitory effect at the lowest concentration of 1 mg/L. Therefore a second main test was performed using two lower concentrations.

2nd MAIN TEST:
The following nominal concentrations were tested: 0.25 mg/L, 0.5 mg/l, 1 mg/L, 2 mg/L, 4 mg/L and 8 mg/L (Loading rate). After 48 hours the immobilisation observed was 0, 5, 75, 100, 100, and 100% respectively.

TOC analyses performed with the test solutions of the 1st main test at 0 hour and 48 hours showed that the organic matter of the test substance remained constant (See "Any other information on results incl. tables" for details). For this reason, the results of the test were based on the nominal concentrations (i.e. loading rates).

TOC values determined within 1st Main Test

Nominal Concentrations / Loading Rates (mg/L)	Mean Values of measured values t0h, (mg/L TOC)	Mean Values t0h, measured Values, net - Blank (mg/L TOC)	Mean Values of measured values t48h, (mg/L TOC)	Mean Values t48h, measured Values, net - Blank (mg/L TOC)	% Recovery (Mean Value)
Blank	0	0	0.11	0	-
1	(4.42)*	(4.42)*	0.68	0.57	(12.9) - ignored due to error of 0h determination
2	0.66	0.66	0.79	0.68	102.6
4	1.68	1.68	2.10	1.98	118.0
8	2.61	2.61	3.10	2.99	114.3
10	3.53	3.53	4.31	4.19	118.7

* Value too high, attributed to either an impurity in the test flask or in the flask for preparation of the eluate.

TOC values determined within 2nd Main Test

Nominal Concentrations / Loading Rates (mg/L)	Mean Values of measured values t0h, (mg/L TOC)	Mean Values t0h, measured Values, net - Blank (mg/L TOC)	Mean Values of measured values t48h, (mg/L TOC)	Mean Values t48h, measured Values, net - Blank (mg/L TOC)	% Recovery (Mean Value)
Blank	0.8	0	0.61	0	-
0.5	0.06	-0.73	0.08	-0.53	-
1	0.53	-0.26	0.56	-0.05	-
2	0.27	-0.52	1.20	0.59	-
4	2.36	1.57	1.67	1.06	67.3
8	2.63	1.83	2.04	1.43	78.1

According to the study report, regarding the very low measured TOC values, recovery rates should not be given for this test. From the measured TOC-value at the nominal concentration of 8mg/L and the known carbon content (73.13%) including the % purity of the test substance (91.5%) and the chemical formula of the test substance (C14H26O), a maximum water solubility of the test substance of 2.50 mg/L was calculated.

The water solubility value of 2.5 mg/L, estimated in the study report, is higher than the subsequently determined water solubility of 0.67 mg/L (Foster and Thomas, 2015). Some aldehydes are susceptible to autoxidation to the corresponding carboxylic acid. Therefore, the higher measured concentrations observed in the daphnia study test solutions may reflect some degradation of the parent aldehyde during the 24 hour equilibration period. Given, that this would reflect the stability of the test substance in real-world conditions, the test is considered reliable with restrictions and suitable for assessing the hazard of the registered substance. Given that the TOC method of analysis has a low sensitivity (approximately 1 mg/l), accurate measured concentrations of the test item were not possible, particularly for the test solutions prepared at the lower nominal concentration loading rates. Furthermore, in main test 2, the blank solutions had measured TOC values that were higher than those obtained for the lower nominal concentrations (see results for 0.5, 1 and 2 mg/L above) confounding the issue. Therefore it was considered appropriate to based the effect results on the nominal concentrations (loading rates). This was supported by the fact that in main test 2, the TOC analysis demonstrated that the organic matter of the test substance remained constant.

Validity criteria fulfilled:

yes

Conclusions:

The LC50 (48h) value has been determined to be equal to 0.9 mg/L under these test conditions.

Executive summary:

„FARENAL" was tested for acute toxicity towards Daphnia according to OECD 202, Part I. In order to investigate the influence of the test substance towards the daphnia the swinuning behaviour of the animals was recorded. As the test substance is poorly water soluble, the test substance was tested using the aqueous extracts from the test substance (termed eluates hereafter). Under the conditions used for the test, immobilisation of the daphnia was observed at nominal concentrations >0.5 mg/L. The following effective loadings (EL-values) were calculated on basis of the nominal concentrations being tested:

Inhibition Values	t24h	Standard Deviation (%)	95% Confidence-Level (%)
EL0	0.4 mg/L	14	45
EL50	1.2 mg/L	10	32
EL100	3.8 mg/L	17	53
Inhibition Values	t48h	Standard Deviation (%)	95% Confidence-Level (%)
EL0	0.3 mg/L	15	49
EL50	0.9 mg/L	9	30
EL100	2.8 mg/L	13	43

Within TOC-analyses performed with the test solutions (definitive test) only very small arnounts of the test substance were dissolved in the aqueous phase (in maximum only 2.5 mg/L representing 31% of the nominal concentration at the highest concentration [8 mg/L, definitive test] being tested). Recoveries at the three lowest concentrations could not be determined at all, and, regarding the very low measured TOC-values, „recovery rates" at the two highest concentrations being tested should not be given. Within TOC-analyses performed with the test solutions (ls t main test) at to and teil, it could be shown, that the organic matter of the test substance remained constant in the aqueous phase. For this reason, the results of this test are based on the nominal concentrations tested.

Description of key information

Effective Loading EL50 value of 0.9 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.9 mg/L

Additional information

The acute toxicity towards daphnia was studied under static conditions for 48 hours (Lebertz, 2001). The test was conducted using completely filled and stoppered vessels and the test vessels preconditioned using solutions of the test substance to minimise, respectively, losses due to volatility and adsorption. Total Organic Carbon (TOC) analysis performed at 0 and 48 hours in one of the main tests showed that the organic matter of the test substance remained constant in the aqueous phase.

As the test substance is poorly soluble, the test substance was tested using aqueous extracts of suspensions of the test substance prepared in dilution water from loading rates of 0.25, 0.5, 1, 2, 4 and 8 mg/L loading rates (final test). The suspensions were shaken for 24 hours at room temperature and then filtered through filtered paper which was previously rinsed through with ultrapure water in order to eliminate possible soluble impurities from the filter material. The filtered extracts were used directly for the test without any further dilution steps.

TOC analysis showed that the maximum concentration achieved was approximately 2.5 mg/L. This is higher than the subsequently determined water solubility of 0.67 mg/L (Foster and Thomas, 2015). Some aldehydes are susceptible to autoxidation to the corresponding carboxylic acid. Therefore, the higher measured concentration observed may reflect some degradation of the parent aldehyde during the 24 hour equilibration period. Given, that this would reflect the stability of the test substance in real-world conditions, the test is considered reliable with restrictions and suitable for assessing the hazard of the registered substance.

Given that the TOC method of analysis has a low sensitivity (approximately 1 mg/l), accurate measured concentrations of the test item were not possible particularly for the solutions prepared at the lower nominal concentration loading rates. Given also that TOC analysis for the higher test concentrations demonstrated that the organic matter of the test substance remained constant, it was considered justifiable to base the effects on the loading rates.