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Ecotoxicological information

Long-term toxicity to fish

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Reference
Endpoint:
adult fish: sub(lethal) effects
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to OECD Guideline 204 (14-day study). Limited information on substance identity
Qualifier:
according to guideline
Guideline:
OECD Guideline 204 (Fish, Prolonged Toxicity Test: 14-day Study)
GLP compliance:
no
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 0, 2.2, 6.6, 20, 60, 180 mg/L nominal
- Sampling method: drawing of water samples with dead-volume-free syringes, direct application into head-space sample flasks, that are immediately closed and analysed
- Sample storage conditions before analysis: no storage, direct measurement of samples
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Dissolving of CTC in acetone in stock solutions so that the final concentration of acetone in the test media was 158 mg/L
- Controls: acetone in water
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): the final concentration of acetone in the test media was 158 mg/L
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no
Test organisms (species):
Danio rerio (previous name: Brachydanio rerio)
Details on test organisms:
TEST ORGANISM
- Common name: zebrafish
- Strain: (Brachydanio rerio Hamilton-Buchanan), Teleostei, Cyprinidae.
- Source: Doller Zierfischzüchterei, 5950 Finnentrop-Serkenrode, Germany
- Age at study initiation (mean and range, SD): not reported
- Length at study initiation (length definition, mean, range and SD): 2.0 ± 1.0 cm
- Weight at study initiation (mean and range, SD): 244 ± 23 mg
- Method of breeding: not reported
- Feeding during test: twice daily, Tetramin

ACCLIMATION
- Acclimation period: 12 d
- Acclimation conditions (same as test or not): same as test
- Type and amount of food: Tetramin, amount not reported
- Feeding frequency: once daily
- Health during acclimation (any mortality observed): not reported
- Mortality of controls was within the ranges of the guideline
Test type:
flow-through
Water media type:
freshwater
Limit test:
no
Total exposure duration:
14 d
Post exposure observation period:
no
Hardness:
- see table 1
Test temperature:
23 ± 1 °C
pH:
8.15 ± 0.2
Dissolved oxygen:
concentration: saturation, controled, but not reported
Salinity:
see table 1
Nominal and measured concentrations:
see table 2
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
2.5 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
behaviour
Details on results:
- Observed effects at each concentration for each observation time: differences in behaviour (food intake, position, breathing, motion, weight) at 8.7 mg/L and higher concentrations
- Concentrations that produce lethal or other effects: lethal effects at 18.9 mg/L
- Cumulative mortality at each concentration and for each recommended observation time if possible: see table 2
- Mortality in the controls: no mortalities in controls
- Behavioural observation of the fish: observed, but not reported in detail
- Effect concentrations exceeding solubility of substance in test medium: no
- Incidents in the course of the test which might have influenced the results: nothing reported
Results with reference substance (positive control):
no reference tested

- table 2: weight development of zebrafish during 14 d exposure to CTC

Tank no.

0

(pure water control)

1

2

3

4

5

6

(vehicle control)

Concentration nominal in mg/L

0

180

60

20

6.6

2.2

0

Concentration analytical in mg/L

0

121

18.9 ± 2.2

8.7 ± 2.4

2.5 ± 0.3

2.08 ± 0.4

0

Average start weigth per fish in mg

257

0

0

282

244

245

219

Average end weigth per fish in mg

366

0

0

389

332

n.d.

292

Average weight change in mg

109

0

0

107

88

n.d.

73

% of weight change

42.4

0

0

37.9

36.1

n.d.

33.3

n.d.: not determined

comments: tank no. 1: all fishes dead within 2 h

tank no. 2: all fishes dead within 12 d

Validity criteria fulfilled:
yes
Executive summary:

The study (Röderer, 1990) presents a NOEC of 2.5 mg/L for CTC for prolonged toxicity (14-day). Based on this value no classification of CTC for chronic aquatic toxicity is necessary in the EU. The potential of the test substance CTC (carbon tetrachloride) to induce toxicity in Zebrafish (Brachydanio rerio Hamilton-Buchanan, Teleostei, Cyprinidae) was evaluated in a survey study on different chlorinated organic solvents following OECD TG 204. 10 fishes per CTC concentration (5 concentrations tested) were exposed for 14 d in 10 L closed tanks using a flow-through system. A fresh water control and a vehicle (acetone) control were tested in addition. Fishes were observed daily for behaviour and fatalities. Observed non lethal effects were differences in behaviour (food intake, position, breathing, motion, weight) at 8.7 mg/L and higher concentrations, lethal effects were recorded at 18.9 mg/L and higher concentrations. CTC concentrations and water quality was tested daily according to OECD TG 204.

Description of key information

OECD 204 (Röderer, 1990):

NOEC (14-days)=2.5 mg/L

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
2.5 mg/L

Additional information

No experimental studies were conducted on the multiconstituent substance (Flux1). Instead, a constituent-based, Weight-of-Evidence approach, was performed.

The three major constituents were targeted, representing ca 95% of a typical composition (carbon tetrachloride (CAS n° 56-23-5),1,2-Dichloroethane (CAS n°107 -06 -2) and chloroform (CAS n° 67-66 -3)). Numerous published data were available, and a single consensus value was selected for each, from a reliable source.

No average key values were derived for the multiconstituent substance: as the Risk Assessment is conducted per constituent, individual values are used as the key data.

The potential of carbon tetrachloride (CTC) to induce toxicity in Zebrafish (Brachydanio rerio Hamilton-Buchanan, Teleostei, Cyprinidae) was evaluated in a survey study on different chlorinated organic solvents following OECD TG 204 (Röderer, 1990).

Even though the OECD 204 is no longer generally considered acceptable by regulatory authorities as a chronic study, this is the only long term toxicity to fish study available on the main constituent of Flux1. This study is of good quality and presents a NOEC of 2.5 mg/L for CTC for prolonged toxicity (14-day) and it was thus considered acceptable based on the non-polar narcosis properties of the test substance and the following acute/chronic toxicity comparison for each organism supporting the conclusion that further studies on fish would not allow us to refine the result:

Algae (Gancet 2011): EC50(72h)=2.2 mg/L vs NOEC(72h)=20 mg/L (IUCLID section 6.1.5)

Daphnia: EC50(48h)=35 mg/L (Leblanc,1980; IUCLID section 6.1.3) vs NOEC(21d)=3.1 mg/L (Thompson,1997; IUCLID section 6.1.4)

Fish: LC50(96h)=24.3 mg/L (Roderer, 1990; IUCLID section 6.1.1) vs NOEC(14d)=2.5 mg/L (Röderer, 1990; IUCLID section 6.1.2).

Based on these ecotoxicity data on CTC, a factor of 10 (ACR) is observed to sufficiently cover the acute to chronic ratio for each organism tested.The long term value for fish of 2.4 mg/L from OECD 204 is considered as reliable as there is a factor 10 between acute and chronic value.

Moreover, a new long term fish toxicity would not be needed due to the properties of the substance: a non-polar narcotic mode of action, a low partition coefficient (logKow<3) and a low potential of bioaccumulation of CTC (BCF=11).

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