1,3-bis(hydroxymethyl)urea

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:

from 2011-10-28 to 2012-07-02

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:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)

Deviations:

no

Qualifier:

according to guideline

Guideline:

ISO 6341 (Water quality - Determination of the Inhibition of the Mobility of Daphnia magna Straus (Cladocera, Crustacea))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Samples for concentration control analysis were taken from each freshly prepared solution (0 h and 24 h) from additionally prepared test vessels without daphnids and at the end of each exposure interval (after approx. 24 h and 48 h) from all test vessels with mobile daphnids and the lowest concentration with 100% immobilisation.

Vehicle:

no

Details on test solutions:

The stock test solution (120 mg/L) was prepared by directly adding 120 mg of test substance to 1L of test medium. The mixture was stirred on a magnetic stir plate for about 10 minutes at 20 ± 2 °C.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Strain/clone: STRAUS 1820
- Source: supplied by Institut National de Recherche Chimique Appliquée, France, in 1978
- Age at test initiation: < 24 hours (at least 3rd brood progeny)
- Feeding during test: no feeding during exposure period

ACCLIMATION
- Acclimation conditions: The Daphnia are cultured under the identical conditions as the test including test media (Elendt M4), water quality, and temperature (20 ± 1 °C).

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

2.20 – 3.20 mmol/L

Test temperature:

20.0 – 20.4 °C

pH:

7.5 – 8.5

Dissolved oxygen:

8.8 - 9.1 mg O2/L

Salinity:

NA

Conductivity:

550 - 650 μS/cm

Nominal and measured concentrations:

Nominal concentrations: 0 and 120 mg/L
Measured concentrations: 0 and 120.8 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: beakers
- Type: open
- Material, size, headspace, fill volume: glass (nominal volume 100 mL), test volume 50 mL
- Aeration: none
- Renewal rate of test solution (frequency/flow rate): every 24 h
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: 0.1 animals/mL

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M4, OECD 202
- Total organic carbon: < 2 mg/L
- Alkalinity: 0.80 – 1.00 mmol/L
- Ca/mg ratio: about 4 : 1
- Conductivity: 550 - 650 μS/cm
- Culture medium different from test medium: no
- Intervals of water quality measurement: monthly intervals

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hours light : 8 hours darkness
- Light intensity: 136 - 673 lux at a wave length of 400 - 750 nm

RANGE-FINDING STUDY
- Test concentrations: 100 mg/L
- Results used to determine the conditions for the definitive study: no immobilisation at 100 mg/L after 48 h

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 120 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

>= 120 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

> 120 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Results with reference substance (positive control):

The EC50(24h) of the reference substance potassium dichromate was 1.13 mg/L (experiment date: 24 Oct 2011). This result is within the range of 0.6 – 2.1 mg/L (ISO 6341) and indicates that the culture of Daphnia magna used in this study is responding normally to toxic stress.

ANALYTICAL CONCENTRATION CONTROL

Method of analysis: Total organic carbon.

Limit of quantification (LoQ): 3.2 – 7.0 mg/L mg/L

Recovery efficiency: 100 – 101 %

Table 1. Analytically measured concentrations of the test substance in the test solutions

Nominal concentration [mg/L]	Analytically measured concentrations				Mean measured concentration [mg/L]	Mean measured concentration [% of nominal]
	Renewal interval 1		Renewal interval 2
	Fresh test solution [mg/L]	24 h test solution (old) [mg/L]	Fresh test solution [mg/L]	24 h test solution (old) [mg/L]
0	<LOQ	<LOQ	<LOQ	<LOQ	-	-
120	120.7	120.6	119.6	122.2	120.8	101%

- not determined

All measured concentrations deviated less than 20% from the nominal concentration. Following recommendations in OECD 202 the results should be evaluated based on the nominal concentrations. The measured concentrations were stable over the exposure period.

Table 2. Number of mobile Daphnids

Nominal concentration [mg/L]	Number of mobileDaphniaat each observation period
	Replicate 1 [h]			Replicate 2 [h]			Replicate 3 [h]			Replicate 4 [h]			∑	∑
	0	24	48	0	24	48	0	24	48	0	24	48	24h	48h
0 (control)	5	5	5	5	5	5	5	5	5	5	5	5	20	20
120	5	5	5	5	5	5	5	5	5	5	5	5	20	20
Number of test animals per replicate: 5 Number of test animals per test group: 20

 

Validity criteria fulfilled:

yes

Remarks:

This test was fully compliant with all the following validity criteria required by the corresponding test guidelines and is considered valid. ≤ 10% immobilisation in the control O2 concentration > 3 mg/L in control and test vessels

Conclusions:

In conclusion, the 48-hour EC50 value for the test item in this acute toxicity study with Daphnia magna was >120 mg/L based on the nominal concentration of the test substance and >120.8 mg/L based on the mean measured concentration.

Executive summary:

In the acute immobilisation test with Daphnia magna (STRAUS), the effects of the test item were determined according to OECD 202 and EC 440/2008 C.2. The study was conducted in a semi-static system over a period of 48 hours with a limit concentration of 120 mg/L. The validity criteria of the test guideline were fulfilled. The estimated EC50 value (48 hours) of the test item based on the nominal concentration is > 120 mg/L.

Description of key information

The 48-hour EC50 value for the test item in an acute toxicity study with Daphnia magna was >120 mg/L based on the nominal concentration of the test substance and >120.8 mg/L based on the mean measured concentration.

Additional information

In the acute immobilisation test (reference 6.1.3-1) with Daphnia magna (STRAUS), the effects of the test item were determined according to OECD 202 and EC 440/2008 C.2.The study was conducted in a semi-static system over a period of 48 hours with a limit concentration of 120 mg/L. The validity criteria of the test guideline were fulfilled. The estimated EC50 value (48 hours) of the test item based on the nominal concentration is > 120 mg/L.