diuron (ISO); 3-(3,4-dichlorophenyl)-1,1-dimethylurea

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:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions. Test concentrations were not confirmed by chemical analysis.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

DRAFT

Principles of method if other than guideline:

OECD Guide-line 202 (Proposal, September 1982)

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The solution with the highest concentration was prepared by dissolving 10 mg in 1L dilution water.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Waterflea
- Strain: Daphnia magna Straus
- Source: Federalboard of health, Berlin
- Age at study initiation: 6 to 24 hours
- Food type during housing: Selenastrum subspicatum and yeast

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

not given

Test temperature:

20.7°C

pH:

7.91 – 8.10

Dissolved oxygen:

100.2 to 100.5 %

Salinity:

not applicable

Nominal and measured concentrations:

Nominal: 1.0, 1.8, 3.2, 5.6 and 10 mg Diuron/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: beakers, fill volume of 50 mL
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 9
- Aeration: aeration was stopped a few hours prior to test start

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water prepared according to DIN 38412, water by adding CaCl2 0.08 mole/L, MgSO4 0.02 mole/L, NaHCO3 0.03 mole/L and KCl2 0.003 mole/L

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: test was conducted in the dark


EFFECT PARAMETERS MEASURED: Observations on immobilization of the daphnia were made after 24 and 48 hours

Reference substance (positive control):

yes

Remarks:

K2Cr2O7

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

1.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% CL

Results with reference substance (positive control):

Tested concentrations: 0.75, 1.00, 1.33, 1.78, 2.37, 3.16 mg K2Cr2O7 / L.
EC50: 1.57 mg/L, 95 % confidence interval: 1.22 2.05 mg /L

Reported statistics and error estimates:

Probit analysis

Table 1. Immobilisation data

Test-Substance Concentration (nominal) [mg/L]
	ImmobileDaphnia
	Number      24 h         48 h		Percentage       24 h        48 h		Oxygen [%] 48 h	pH   48 h	Temperature [°C] 48 h
Pre test
Control	n.s.	n.s.	10	28	100.4	7.99	19.3
0.01	n.s.	n.s.	0	17	n.d.	n.d.	19.3
0.1	n.s.	n.s.	3	13	n.d.	n.d.	19.3
1.0	n.s.	n.s.	7	13	n.d.	n.d.	19.3
10	n.s.	n.s.	20	100	102.0	8.01	19.3
Main test
Control	1/90	8/90	1	9	100.2	7.92	20.7
1.0	1/30	5/30	3	17	n.d.	n.d.	20.7
1.8	1/30	22/30	3	73	n.d.	n.d.	20.7
3.2	8/30	30/30	27	100	n.d.	n.d.	20.7
5.6	13/30	30/30	43	100	n.d.	n.d.	20.7
10	14/30	30/30	47	100	100.5	7.91	20.7

n.s.: not stated                    n.d.: not determined

Table 2.         Effect data

	EC50^1	95 % c.l.	EC0^1	EC100^1
24 h [mg/L]	n.d.	n.d.	n.d.	> 10.0 (n)
48 h [mg/L]	1.4 (n)	1.2 – 1.6	n.d.	3.2 (n)

¹effect data are based on nominal (n) concentrations

n.d.: not determined

Table 3. Validity criteria for acute daphnia immobilisation test according to OECD Guideline 202

	Fulfilled	Not fulfilled
Immobilisation of control animals <10%	X
Control animals not staying at the surface	X
Concentration of dissolved oxygen in all test vessels >3 mg/L	X

Executive summary:

A short-term acute toxicity test was conducted in accordance with the prevailing OECD testing guidelines (OECD 202), however the test concentrations were not confirmed by chemical analysis.

Based on the nominal concentrations, the 48h EC50 was calculated to be 1.4 mg/L Diuron.

Therefore the test item (Diuron) was proved to be harmful to Daphnia magna.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP Guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
To accelerate the solution procedure, a three amount of the water solubility of the test item (35 mg/L) under exposure conditions was taken (105.2 mg/L) and added directly to 1 litre of dilution water and treated for 1 hour in an ultrasonic bath and afterwards stirred for 24 hours on a magnetic stirrer. Finally undissolved particles of the test item were removed by filtration using folded filters of pore size 7-12 µm

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Waterflea
- Strain: Daphnia magna STRAUS
- Source: Strain of Bundesgesundheitsamt Berlin;
- Age at study initiation: < 24 h

ACCLIMATION
- Acclimation period: maintained for more than 15 years in the test facility; neonates separated from parent Daphnia by filtration prior to acute test
- Acclimation conditions (same as test or not): yes
- Type and amount of food: no feeding during test period
:

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

268 mg/L CaCO3

Test temperature:

18 - 22°C

pH:

7.7-7.8 (measured at 48h)

Dissolved oxygen:

saturation: 95-96% (measured at 48h)
mg/L: 8.4-8.5 (measured at 48h)

Salinity:

not applicable

Nominal and measured concentrations:

Nominally control, 8, 16, and 32 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 50 mL glass beakers with 20 mL of test medium
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water (M4 medium) was used for the maintenance of the test animals and the preparation of stock and test solutions of the test item.
- Intervals of water quality measurement: The pH and oxygen values were measured at the end of the test.

OTHER TEST CONDITIONS
- Photoperiod: 16 : 8 hour light-dark photoperiod
- Light intensity: < 1000 lux

EFFECT PARAMETERS MEASURED: Mobility (normal mobility behaviour and the loss of locomotory actions of the neonates), observed at 24 and 48 hours.

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

22.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: none
- Mortality of control: none
- Abnormal responses: none

Analysis of the immobilisation rates gave the following results:

 

Time [h]	EC0 [mg/L]	EC100 [mg/L]	EC50 (geometric mean of EC0/EC100 [mg/L])
24	16	> 32	> 32
48	16	32	22.6

Highest test concentration resulting in 0% immobilisation (EC 0 48h): 16 mg/L

Lowest test concentration resulting in 100% immobilisation (EC 100 48h): 32 mg/L

The results are expressed in terms of nominal concentrations at 24 and 48h. Recovery rates ranged from 100.9 – 101.1% of nominal values at 0 hours, and from 99.2 – 100.2% of nominal values at 48 hours, respectively.

Executive summary:

A short-term acute toxicity study was conducted in accordance with the prevailing OECD testing guidelines (OECD 202), with GLP.

Based on the nominal concentrations, the 48h EC50 was calculated to be 22.6 mg/L Diuron.

Therefore the test item was proved to be only slightly harmful to Daphnia magna.

Description of key information

Diuron is acutely harmful to aquatic invertebrates

Additional information

Two short-term acute toxicity tests with Daphnia magna, according to OECD guideline 202, are available for Diuron.

A study conducted under GLP conditions and based on measured concentrations determined the EC₅₀ (48h) to be 22.6 mg/L (Weyers, 2008). A second study, where only nominal concentrations were used, calculated the EC₅₀ (48h) as 1.4 mg/L (Heimbach, 1983). Therefore, Diuron is found to be acutely harmful to aquatic invertebrates as evidenced by EC₅₀ values in the range of 1.4 to 22.6 mg/L. The most conservative estimate of acute toxicity coming from the key study with and EC₅₀ value of 1.4 mg/L (Heimbach, 1983).