3,4-dichlorobenzonitrile

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January - March 1997

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

GLP study and according to Guideline OECD 203 ("Fish Acute Toxicity Test"). Nevertheless reliable with restrictions: undissolved test substance particles in test solution at concentrations >/= 10 mg/L, signs of toxicity at concentrations >/= 18 mg/L.

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Qualifier:

according to guideline

Guideline:

other: EEC directive 92/69, Part C.1

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

SAMPLING FOR ANALYSIS OF TEST CONCENTRATIONS:
During the final test samples for TOC-analysis were taken as follows:
- Frequency: From 0, 3.2 and 56 mg/L at the start of exposure. After 24 hours of exposure from 32 mg/L. At the end of the exposure period from 0, 3.2 and 18 mg/L.
- Volume: 10 mL from the approximate centre of the test vessels.
- Sample storage conditions before analysis: the samples were stored in a deep-freeze.

Vehicle:

not specified

Details on test solutions:

PREPARATION OF TEST SOLUTIONS:
Test concentrations of 10, 18, 32 and 56 mg/L were prepared sperately, due to the poor solubility of the test substance in the test medium. Test concentrations of 3.2 and 5.6 mg/L were prepared using a stock solution of 10 mg/L. Ultrasonic treatment and magnetic stirring were used alternately to accelerate the suspending of the test substance. In addition, the temperature was increased up to 40 °C. Before introduction of the fish test solutions were cooled to 21 °C. Test solutions up to 5.6 mg/L were clear and colorless without precipitation. From 10 mg/L upwars, test solutions were clear with increasing test substance particles present in the medium.

Test organisms (species):

Cyprinus carpio

Details on test organisms:

TEST ORGANISM
- Common name: carp
- Strain: cyprinus carpio, Teleostei, Cyprinidae
- Source: Zodiac, proefacc, "De Haar Vissen", L.U. Wageningen, The Netherlands.
- Length at study initiation (length definition, mean, range and SD): 2.97 +/- 0.38 cm (range finding test), 2.51 +/- 0.17 cm (final test).
- Weight at study initiation (mean and range, SD): 0.84 +/- 0.31 g (range finding test), 0.54 +/- 0.10 g (final test).
- Method of breeding: F1 from a single parent-pair bred in UV-treated water
- Feeding during test: bevor test daily with Trouvit. No feeding from 24 hours prior to the test and during the total test period

ACCLIMATION
- Acclimation period: at least 12 days after delivery
- Feeding frequency: daily with Trouvit
- validity of batch: In the batch of fish used for the test, mortality during the seven days prior to the start of the test was less than 5 %.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

no data

Hardness:

250 mg CaCO3/L

Test temperature:

20.0 - 21.0 °C
measured daily in one control vessel, beginning ar the satrt of the test (see table 1)

pH:

8.1 -7.2
measured daily in all vessels, beginning at the start of the test (see table 1)

Dissolved oxygen:

9.4 - 6.0
measured daily in all vessels, beginning at the start of the test (see table 1)

Salinity:

Ca2+: 80mg/L
Mg2+: 12 mg/L
Na+: 15 mg/L
K+: 3 mg/L
CL-: 145 mg/L
sulfate: 49 mg/L
HCO3+: 47 mg/L

Nominal and measured concentrations:

nominal test concentrations: 0, 3.2, 5.6, 10, 18, 32 and 56 mg/L
measured test concentrations were based on TOC-analysis relative to nominal concentrations (see Table 2).

Details on test conditions:

TEST SYSTEM
- Test vessels: 18 litre, all-glass
- Aeration: the test media were not aereted during the test
- No. of organisms per vessel: 7

TEST MEDIUM / WATER PARAMETERS
- Intervals of water quality measurement: once a week

OTHER TEST CONDITIONS
- Photoperiod: 16 hours photoperiod daily

RANGE-FINDING TEST:
Three fish per concentration were exposed to a concentration range of 1 to 100 mg/L with an increasing factor of 10.

Reference substance (positive control):

yes

Remarks:

blank-control; test medium without test substance or other additives (0 mg/L).

Duration:

2 h

Dose descriptor:

LC50

Effect conc.:

42.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

24 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

24 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Results with reference substance (positive control):

The 96h-LC50 of this test with pentachlorophenol was 0.16 mg/L with 95 % fiducial limits of 0.14 and 0.19 mg/L . The range of the 96h-LC50 for carp is generally between 0.10 and 0.46 mg/L based on historical data of reference test approxomately every 3 months since april 1988. The carp orginating from this batch can be considered as sentitive to toxic substances.

Sublethal observations / clinical signs:

Range-finding test:

The results of the range-finding test showed thst the LC50 was between 10 and 100 mg/L (Table 3).

Table 3: Incidence and total mortality in the range-finding test:

Concentration (mg/l)	Initial number of fish	Cumulative mortality					Total Mortality (%)
		3 h	24 h	48 h	72 h	96 h
Blank-control	7	0	0	0	0	0	0
1.0	3	0	0	0	0	0	0
10	3	0	0	0	0	0	0
100	3	3	-	-	-	-	100

Final study:

The mortality data are presented in Table 4.

Table 4: Incidence and total mortality in the final study.

Concentration (mg/l)	Initial number of fish	Cumulative mortality					Total Mortality (%)
		2 h	24 h	48 h	72 h	96 h
Blank-control	7	0	0	0	0	0	0
3.2	7	0	0	0	0	0	0
5.6	7	0	0	0	0	0	0
10	7	0	0	0	0	0	0
18	7	0	0	0	0	0	0
32	7	0	7^1	-	-	-	100
56	7	7	-	-	-	-	100

¹Recorded 20 hours following the start of the test.

Clinical effects observed during the final test:

Fish exposed to the blank, 3.2, 5.6 mg/L showed no abnormalities in swimming behaviour during the exposure period. Although fish exposed to concentrations at 10 and 18 mg/L survived the 96 -hour eposur, they showed severe distress in swimming behaviour throughout the entire test period. Fish exposed to 32 mg/L also showed severe distress in swimming behaviour before they were found dead.

Based on the LC50 the 'Bewertungszahl' for toxicity in fish is 4.6.

Reference Test:

This reference test was carried out to check the sensitivity of the test system (see table 5). The reference substance was pentachlorophenol.

Table 5: Incidence of mortality observed in the reference study.

		Number of dead fish recorded at different points in time after start of exposure.
Nominal Concentration (mg/L)	Number exposed	24 h	48 h	72 h	96 h	Total %
0.00	7	0	0	0	0	0
0.10	7	0	0	0	0	0
0.15	7	2	0	0	0	29
0.22	7	7	-	-	-	100
0.32	7	7	-	-	-	100
0.46	7	7	-	-	-	100

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the present test 3,4-Dichlorobenzonitrile induced no lethal effects in carp at or below nominal 18 mg/l. The LC50 decreased from nominal 42.3 mg/l after 2 hours of exposure to nominal 24 mg/l after 24 h exposure. The LC50 remained at 24 mg/l during the remaining 72 h of exposure. Based on the LC50 the 'Bewertungszahl' for toxicity in fish is 4.6.

Executive summary:

In a 96 -hour acute toxicity study, carp (Cyprius carpio) were exposed to 3,4 -Dichlorobenzonitrile at nominal concentrations of 0 (control, solvent control), 3.2, 5.6, 10, 18, 32, 56 mgmg under static conditions. 3,4 -Dichlorobenzonitrile incduced no lethal effects in carp at or below nominal 18 mg/L. The LC50 decreased from nominal 42.3 mg/L after 2 hours of exposure to nominal 24 mg/L after 24 h exposure. The LC50 remained at 24 mg/L during the remaining 72 h of exposure.

Result Synopsis:

Seven carp (Cyprius carpio) with mean lenght 2.51 +/- 0.17 cm were exposed to concentrations ranging from 3.2 to 56 mg/L (7 per concentration and control) in a static test type.

The test substance could not easily be dissolved, despite recoveries of carbon contents still ranged from 60 - 83 %. Based on the LC50 the 'Bewertungszahl' for toxicity to fish is 4.6.

However, undissolved test substance particles occured in the test solution at concentration >/= 10 mg/L. Therefore, signs of toxicity could also have been related to physical effects.

Description of key information

The 96-h LC50 of 3,4-Dichlorobenzonitrile in carp (Cyprinus carpio) determined in a static acute test

according to OECD 203 is 24 mg/L.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

24 mg/L

Additional information

In a 96-h acute toxicity study, carp (Cyprinus carpio) were exposed to 3,4-Dichlorobenzonitrile at nominal concentrations of 0 (control, solvent control), 3.2, 5.6, 10, 18, 32 and 56 mg under static conditions. 3,4-Dichlorobenzonitrile induced no lethal effects in carp at or below nominal 18 mg/l. The LC50 decreased from nominal 42.3 mg/l after 2 hours of exposure to nominal 24 mg/l after 24 h exposure. The LC50 remained at 24 mg/l during the remaining 72 h of exposure.

However, undissolved test substance particles occurred in the test solutions at concentrations >/= 10 mg/L. Signs of toxicity could therefore also have been related to physical effects.