Dichlobenil

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 August 2004 to 06 January 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 207 (Earthworm, Acute Toxicity Tests)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EEC Commission Directive 87/302/EEC

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on preparation and application of test substrate:

- Method of mixing into soil (if used): incorporated into dry soil using reverse osmosis water and a Hobart A200N mixer

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

TEST ORGANISM
- Common name: earthworm
- Source: Blades Biological, Cowden, Edenbridge, Kent, UK

ACCLIMATION
- Acclimation period: 24 hours

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

14 d

Test temperature:

20-21.1 °C

pH:

6.0-6.4

Moisture:

28-29 % (initiation); 23-26 % (termination)

Details on test conditions:

TEST SYSTEM
- Test container (material, size): 1 L glass beakers
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 4
- No. of replicates per control: 4

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Composition (if artificial substrate): industrial quartz sand (70 % w/w), kaolinite clay (20 % w/w), sphagnum moss peat (10 % w/w)
- Maximum water holding capacity (in % dry weight): 30 % is considered the appropriate maximum moisture content

OTHER TEST CONDITIONS
- Photoperiod: continuous illumination
- Light intensity: 681-702 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): weights recorded at day 0 before addition of test material or control and day 14 (surviving animals); mortalities and sublethal effects were recorded at day 14

VEHICLE CONTROL PERFORMED: no

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0.1, 1.0, 10, 100 and 1000 mg/kg
- Results used to determine the conditions for the definitive study: yes

Nominal and measured concentrations:

0, 100, 180, 320, 560 and 1000 mg/kg

Reference substance (positive control):

yes

Remarks:

chloroacetamide

Key result

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

270 other: mg/kg

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: 95 % C.I. 250-290 mg/kg

Key result

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

180 other: mg/kg

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

Cumulative mortality data in the definitive test are presented in Table 1 whereas the mean earthworm weights are presented in Table 2.

Results with reference substance (positive control):

The results of the positive control study gave a 14-Day LC50 for chloroacetamide of 28 mg/kg with 95 % confidence limits of 26-30 mg/kg confirming the sensitivity of the test.

Table 1: Cumulative mortality data

	Cumulative mortality (initial population: 40)		% mortality
Concentration (mg/kg)	Day 7	Day 14	Day 7	Day 14
Control	0	0	0	0
100	0	0	0	0
180	0	0	0	0
320	26	32	65	80
560	40	40	100	100
1000	40	40	100	100

Table 2: Mean earthworm weights

	Mean earthworm weights (g)
Concentration (mg/kg)	Day 0	Day 14
Control	0.45 ± 0.090	0.38 ± 0.082
100	0.46 ± 0.084	0.41 ± 0.073
180	0.44 ± 0.096	0.38 ± 0.089
320	0.42 ± 0.090	0.29 ± 0.074
560	0.42 ± 0.079	100% mortaity
1000	0.40 ± 0.078	100% mortality

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the test, the 14 day LC50 of the test material to earthworms was 270 mg/kg (95 % C.I. 250-290 mg/kg). The NOEC was determined to be 180 mg/kg.

Executive summary:

In a GLP compliant acute earthworm toxicity study conducted in line with standardised guideline OECD 207, the acute toxicity to earthworm of the test material over 14 days was determined. Earthworms were exposed to the test material at nominal test concentrations of 0, 100, 180, 320, 560 and 1000 mg/kg. Under the conditions of the test, the 14 day EC₅₀ based on mortality was determined to be 28 mg/kg (95 % C.I. 250-290 mg/kg). The NOEC was determined to be 180 mg/kg.

Description of key information

The 14 day EC50 of the test material was determined to be 270 mg/kg and the NOEC determined to be 180 mg/kg according to a study performed in line with OECD Guideline 207.

Key value for chemical safety assessment

Short-term EC50 or LC50 for soil macroorganisms:

270 mg/kg soil dw

Additional information

In a GLP compliant acute earthworm toxicity study conducted in line with standardised guideline OECD 207, the acute toxicity to earthworm of the test material over 14 days was determined. Earthworms were exposed to the test material at nominal test concentrations of 0, 100, 180, 320, 560 and 1000 mg/kg. Under the conditions of the test, the 14 day EC₅₀ based on mortality was determined to be 28 mg/kg (95% C.I. 250-290 mg/kg). The NOEC was determined to be 180 mg/kg.