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Short-term toxicity to fish

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Reference
Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Well documented, standard guideline studywith acceptable restrictions (pH not constant and undissolved material at highest dose).
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
The dilution water used was DSWL, prepared from ground water.
2000 mg of the test substance was accurately weighed out in duplicate and each portion was dissolved in 2000 ml of dilution water, giving solutions containing 1000 mg/L. From these solutions 150, 270, 480 and 840 ml were taken and diluted to 1.5 litre with dilution water, resulting in test solutions of 100,180, 320 and 560 mg/L. New concentrated solutions were prepared daily throughout the test period.
Test organisms (species):
Danio rerio (previous name: Brachydanio rerio)
Details on test organisms:
TEST ORGANISM
- Source: commercial hatchery MB Ruysbroek BV, Noordvliet 159, Maassluis
- Length at study initiation (length definition, mean, range and SD): 2.3 +/- 0.2 cm
- Weight at study initiation (mean and range, SD): 0.10 +/- 0.02 g
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Hardness:
204mg CaCO3/L
Test temperature:
25 +/- 1 °C
pH:
pH of dilution water: 7.9 - 8.2
pH of test solutions: 4.3 - 8.2
Dissolved oxygen:
6.8 - 8.3 mg/L
Nominal and measured concentrations:
Nominal: control (DSWL medium), 100, 180, 320, 560 and 1000 mg/L
Concentrations were not determined by chemical analysis
(appropriate concentrations were determined in a preliminary range finding test)
Details on test conditions:
TEST SYSTEM
- Test vessel: 2000 ml all glass beakers
- Fill volume: 1500 ml test solution per test beaker
- No. of organisms per test concentration: 10 fish per beaker
- Feeding during test: fish were not fed
- Aeration: slightly aerated
- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate): new concentrated solutions were prepared daily --> renewed daily

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: DSWL, prepared from ground water.
- Synthetic DWSL medium
* pH: 8.0 - 8.2
* hardness (CaCO3): 204 mg/L
* Chemical analysis:
Na+ 1.17 mmol/L;
K+ 0.20 mmol/L;
Ca2+ 1.32 mmol/L,
Mg2+ 0.72 mmol/L;
Cl- 2.67 mmol/L;
SO4 2- 0.69 mmol/L
* TOC: 1.7 mg/L

OTHER TEST CONDITIONS
- Photoperiod: 16h light - 8h dark with 30 min transition

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Health: dead animals were counted and removed at least after 2h, 24h, 48h, 72h and 96h.
At the same time the condition (swimming behavior, color, respiratory function or any other observable morphological or visually behavioral criterion) of the survivors was visually compared with that of the control animals

Reference substance (positive control):
no
Key result
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
750 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% CL: 560-1000 mg/L
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
560 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
- Mortality only observed in highest dose
- Turbidity was observed in solutions >= 320 mg/L (although the solubility of the test substance in water at 20 °C was 5 g/L)
- After 2h of exposure, undissolved material was observed on the bottom of the test vessel containing 1000 mg/L
- Just before each replacement time, undissolved material was observed on the bottom of the test vessels containing 180 mg/L and higher. Some turbidity was also observed in the test solution containing 560 mg/L.
- pH decreases with increasing test concentrations: pH of 1000 mg/L solution = 4.3. Studies recently carried out in the test laboratory have shown that B. reri o survives in DSWL at a pH value of 4.3; it is therefore not likely that the low pH influenced the mortality of the fishes at 1000 mg/L.
Reported statistics and error estimates:
The maximum likelihood estimated of the L50 values were calcualted assuming a log-logistic dose-effect relation.
Validity criteria fulfilled:
yes
Conclusions:
The acute toxicity of the test substance to the freshwater fish species Brachydanio rerio was carried out as a semi-static test with daily replacement of the test solutions. The 96h LC50 (mortality) is 750 mg/L.

Description of key information

Key value for chemical safety assessment

Additional information

A GLP-conform study (Klimisch 2) according to the OECD 203 guideline for the effect of a brazing flux paste on mortality of Brachydanio rerio resulted in a 96 -h LC50 of 750 mg/L.

Short term effects of borates on fish ranged from 74 to 725 mg B/L. These data support a conclusion that borates should not be classified as dangerous for the environment.