Hexamethylene diisocyanate, trimers, reaction products with 2-hydroxyethyl acrylate

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:

19 Sep 2016 - 03 Mar 2017

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:

according to guideline

Guideline:

other: OECD Series on Testing and Assessment No. 23

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesanstalt für Umwelt, Messungen und Naturschutz Baden-Württemberg, Germany

Analytical monitoring:

yes

Remarks:

HPLC-MS/MS detection

Details on sampling:

- Concentrations: Control and 100 mg/L
- Sampling method: Samples were taken at 0 h (initial value), at 24 h (fresh and aged solutions) and at 48 h (aged test solutions). Retain samples were also taken at every sampling.
- Sample storage conditions before analysis: Samples were deep-frozen (≤ -18 °C) until analysis. The maximum storage period from sampling to analysis was 8 d.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test item is a UVCB consisting of compounds with partly low water solubility. Therefore, the test item was applied as water soluble fraction (WSF). A stock solution of 100 mg test item in 1000 mL test medium was prepared by stirring at room temperature in the dark for 48 h. Then, undissolved test item was allowed to sediment during 1 h before the water soluble fraction (WSF) was withdrawn from the middel of the vessel (according to OECD 23). Transfer of undissolved test item was avoided. The WSF was used as test solution. This preparation procedure was repeated after 24 h.
- Controls: Untreated test medium
- Evidence of undissolved material: The stock solution was slightly turbid and undissolved test item was sedimented. The test solution was clear and no precipation was observed throughout the test.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain/clone: Clone V
- Source: Federal Environment Agency, Berlin, Germany
- Age at test start: < 24 h (freshly hatched)
- Breeding conditions: Single culture (1 daphnid per 100 mL) in Elendt M4 medium. The pH of the aerated medium ranged from 6.0 - 9.0. Dissolved oxygen was > 60% saturation and total hardness was 140 - 250 mg/L CaCO3. Daphnids were reared at 20 ± 2 °C in a climatic chamber with a light regimen of 16 h light/8 h dark per day.
- Food type: Single cell green algae (Desmodesmus subspicatus)
- Frequency: At least 3 times per week
- Feeding during test: No

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

232 mg/L CaCO3 = 13 °dH

Test temperature:

20.2 ± 1.1 °C (mean)

pH:

7.89 ± 0.13 (mean)

Dissolved oxygen:

8.7 ± 0.5 mg/L (mean)

Nominal and measured concentrations:

Control and 100 mg/L (nominal)
< LOQ and 2.00 mg/L (measured, initial mean measured concentration)

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL glass beakers filled with 50 mL test solution.
- Type: The vessels were covered with a glass plate.
- Renewal rate of test solution: every 24 h
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Other: One additional replicate without organisms for physico-chemical measurements.

TEST MEDIUM / WATER PARAMETERS
- Culture medium different from test medium: Culture medium same as test medium (Elendt M4)
- Intervals of water quality measurement: Temperature, pH and oxygen concentration were measured at 0, 24 h (fresh and aged solutions), and 48 h (aged solutions) in one separate replicate of the test item loading rate without organisms.

OTHER TEST CONDITIONS
- Photoperiod: 16 h light/8 h dark

EFFECT PARAMETERS MEASURED:
- Immobilisation: after 24 and 48 h

RANGE-FINDING STUDY
- Results used to determine the conditions for the definitive study: The test item loading rate was chosen based on the first GLP test run.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

>= 2 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: No
- Mortality of control: 5% after 48 h
- Any observations that might cause a difference between measured and nominal values: The application solution was clear and no precipitations were observed during the test.

Results with reference substance (positive control):

- Results with reference substance valid? Yes, the EC50 (24 h) values were within the historical data range and fulfilled the requirements of the OECD guideline 202.
- Relevant effect levels: EC50 (24 h) was between 1.0 and 2.0 mg/L potassium dichromate.

Reported statistics and error estimates:

Since no immobilisation higher than the allowed control immobilisation occurred during the test, no statistical analysis was performed.
The NOELR was established based on the highest test item loading rate at which the immobilisation is not higher than the allowed control immobilisation (≤ 10% immobilisation).

ANALYTICAL RESULTS

The measured test item content was between 1 - 2% of nominal in fresh samples with an initial mean concentration of 2% of nominal. In the aged samples no test item could be determined (Table 1). Therefore, toxicological endpoints were evaluated based on nominal test item loading rate and on the actual initial mean concentration of test item.

Table 1. Analytical results.

Nominal test item loading rate [mg/L]	Sampling [h]	Test item found		Actual test item concentration [mg/L]^1
		[mg/L]	% of nominal
0	0 fresh	n.d.	-	-
	24 fresh	n.d.	-
	48 aged	n.d.	-
100	0 fresh	2.31	2	2.00
	24 aged	< LOQ	-
	24 fresh	1.39	1
	48 aged	< LOQ	-

- = not calculated; n.d. = not detectable; LOQ = 1.00 mg/L test item

¹⁾Based on the initial mean value

BIOLOGICAL RESULTS

After 48 h of exposure no immobilisation above the allowed control immobilisation was observed in the control and 100 mg/L test item loading rate. The reported EC50 (48 h) is > 2.00 mg test item/L (actual). The corresponding NOELR (48 h) is ≥ 100 mg test item/L (nominal) and the NOEC (48 h) is ≥ 2.00 mg test item/L (actual).

Thus, no toxic effects of the test item were recorded at the tested loading rate.

Validity criteria fulfilled:

yes

Description of key information

EL50 (48 h) > 100 mg/L (nominal, OECD 202, D. magna)

Additional information

There is one experimental study available, in which the short-term toxicity of Hexamethylene diisocyanate, trimers, reaction products with 2-hydroxyethyl acrylate (CAS 162492-01-5) to aquatic invertebrates was investigated according to OECD guideline 202 and GLP.

In a semi-static test, D. magna was exposed to a nominal test item loading rate of 100 mg/L for 48 h. Since the substance is a UVCB, the test solution was applied as water soluble fraction (WSF). The test item concentration was analytically verified by HPLC-MS after 0, 24 (fresh and aged solutions), and 48 h (aged solutions).

The measured test item content was 1 – 2% of nominal in fresh samples with an initial mean of 2% of nominal. In the aged samples the test item could not be determined. Therefore, effect concentrations were determined based both on the nominal test item loading rate and the measured mean initial concentration.

After 48 h no toxic effects occurred. The reported EL50 (48 h) is > 100 mg/L (nominal) and the EC50 (48 h) is > 2.00 mg test item/L (measured mean initial concentration). The corresponding NOELR (48 h) is ≥ 100 mg/L (nominal) and the NOEC (48 h) is ≥ 2.00 mg test item/L (measured mean initial concentration). Thus, no effects were observed up to the limit of water solubility of the substance.