Dichlobenil

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:

20 July 1987 to 1 August 1988

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 72-2 (Aquatic Invertebrate Acute Toxicity Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

50 mL aliquots of test aquaria water were transferred to 70 mL culture tubes. 10 mL of toluene was added to each sample and samples were shaken for three minutes. The toluene phase was then transferred to clean culture tubes and further diluted with toluene when necessary prior to analysis.

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Source: in house culture
- Age at study initiation (mean and range, SD): < 24 hours old

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

238-278 mg/L as CaCO3

Test temperature:

20 ºC

pH:

8.2-8.3

Dissolved oxygen:

7.7-8.3 mg/L

Nominal and measured concentrations:

0.74, 1.2, 2.7, 4.8 and 10 mg/L (nominal)
0.62, 1.0, 2.0, 3.8 and 8.9 mg/L (measured)

Details on test conditions:

TEST SYSTEM
- Test vessel: glass beakers
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: volume - one litre; covering - 50 mesh stainless steel screen
- Type of flow-through: proportional diluter
- Renewal rate of test solution (frequency/flow rate): 6.2 times per 24 hours
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- No. of vessels per vehicle control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: well water
- Total organic carbon: 0.6-3.8 mg/L
- Particulate matter: 0-1.3 mg/L
- Metals: <0.1 mg/L
- Chlorine: <0.05 mg/L
- Alkalinity: 300-320 mg/L (as CaCO3)
- Conductivity: 480-540 µmhos/cm

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): one every 24 hours for mortality and abnormal effects

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0.74, 1.2, 2.7, 4.8 and 10 mg/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

6.2 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Remarks on result:

other: 95 % C.I. 3.8-8.9 mg/L

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Details on results:

Mortality rates and observed abnormal behaviour are presented in Table 1.

Table 1: Percentage mortality and percentage abnormal effects

		% mortality		% abnormal effects
Nominal concentration (mg/L)	Mean measured concentration (mg/L)	24 h	48 h	24 h	48 h
Control	-	0	0	100 N	100 N
Solvent control	-	0	0	100 N	100 N
0.74	0.62	0	0	100 N	100 N
1.2	1.0	0	0	100 N	100 N
2.7	2.0	0	0	100 N	88 OB, 8 ERR, 5 N
4.8	3.8	0	0	90 N, 10 OB	92 OB, 8 ERR
10	8.9	15	95	65 OB/Q, 18 N. 2SUR	5 OB

N = normal

S = surfacing

ERR = erratic movement

OB = on bottom

Q = quiescent

Validity criteria fulfilled:

not specified

Conclusions:

Under the conditions of the test, the 48 hour LC50 was 6.2 mg/L (95 % C.I. 3.8-8.9 mg/L). The NOEC was determined to be 1.0 mg/L.

Executive summary:

In a GLP compliant acute Daphnia toxicity study conducted in line with standardised guideline EPA OPP 72-2, the acute toxicity to Daphnia of the test material was determined. Daphnia were exposed to the test material at nominal test concentrations of 0, 0.74, 1.2, 2.7, 4.8 and 10 mg/L (equivalent to mean measured concentrations of 0.62, 1.0, 2.0, 3.8 and 8.9 mg/L). Under the conditions of the test, the 48 hour LC₅₀of the test material was determined to be 6.2 mg/L. The 48 hour NOEC was determined to be 1.0 mg/L.

Description of key information

The 48 hour LC50 of the test material was determined to be 6.2 mg/L and the NOEC was determined to be 1.0 mg/L according to a study performed in line with EPA Guideline OPP 72-2.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

6.2 mg/L

Additional information

In the key GLP compliant acute Daphnia toxicity study conducted in line with standardised guideline EPA OPP 72-2, the acute toxicity to Daphnia of the test material was determined. Daphnia were exposed to the test material at nominal test concentrations of 0, 0.74, 1.2, 2.7, 4.8 and 10 mg/L (equivalent to mean measured concentrations of 0.62, 1.0, 2.0, 3.8 and 8.9 mg/L). Under the conditions of the test, the 48 hour LC₅₀ of the test material was determined to be 6.2 mg/L. The 48 hour NOEC was determined to be 1.0 mg/L.

In a supporting GLP compliant acute Daphnia toxicity study conducted in line with standardised guideline EPA OPP 72-2, the acute toxicity to Daphnia of the test material was determined. Under the conditions of the test, the 48 hour EC₅₀ was determined to be 16 mg/L; the 48 hour NOEC was determined to be 2.4 mg/L.

In a supporting GLP compliant acute toxicity study to the mysid conducted in line with standardised guideline EPA OPP 72-3, the acute toxicity to the mysid of the test material was determined. Under the conditions of the test, the 96 hour LC₅₀ was determined to be 2.37 mg/L; the 96 hour NOEC was determined to be 1.32 mg/L.

In a supporting GLP compliant acute toxicity study to the Eastern Oyster conducted in line with standardised guideline EPA OPP 72-3, the acute toxicity to the Eastern oyster of the test material was determined. Under the conditions of the test, the 96 hour EC₅₀ for shell growth was determined to be 1.92 mg/L; the NOEC could not be determined as all tested concentrations resulted in a significant reduction in shell growth.