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Ecotoxicological information

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
Study period:
1989
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Deviations:
yes
Remarks:
deviation of the nominal concentration was geater than 20 %
GLP compliance:
yes
Specific details on test material used for the study:
Trade name: PYRONIL 45
Batch number: 6159-199-3
Purity: >95%
The test material contains more impurities than the registered substance. As a conclusion sameness is unclear. Usually a new study should be investigated to test the registered substance. But due to animal wellfair reasons the present acute fish toxicity study was used as a worst case (more impurities) to describe the toxic behavior of the registered substance.
Analytical monitoring:
yes
Details on sampling:
Samples were taken at 0 hours and 96 hours.
Vehicle:
yes
Details on test solutions:
Test dilutions were prepared individually at each concentration by adding ethanol (2 mL) to the appropriate weights of the substance and then adding the mixtures directly to the dilution water (20 litres).
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
The fish used for the preliminary tests were obtained as fry from West Acre Trout Farm, Kings Lynn, Norfolk. The fry were reared from eggs imported from Denmark.
The fish used for the definitive test were obtained as fry from Padworth Fisheries, Mill House, Padworth, Berkshire. The fry were reared from eggs imported from USA. At the laboratory, these fry were held in an aerated supply of filtered dechlorinated tap water under flow-through conditions until removed for testing.
Mortality during the 14-day period prior to the definitive test was less than 2.5 %.
The fish were last fed 28 hours before the start of the definitive test.
The mean wet-weight of the fish used in the definitive test, based on a sample of ten fish was 1.45 g.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Hardness:
198 - 208 mg/L as CaCO3
Test temperature:
15 +/- 1°C
pH:
7.63 - 8.04
Dissolved oxygen:
69 - 96 %
Nominal and measured concentrations:
Nominal: 62.5, 125, 250, 500, 1000mg/L
Measured values at 0 hours (mean): 3.7, 9.9, 30.7, 28.6, 30.4 mg/L
Measured values at 96 hours (mean): 2.59, 1.57, 0.637, 2.65, 0.922 mg/L
Results indicate that the aqueous solubility of the substance had been exceeded at all exposure levels and that test preparations were not homogeneous due to the large variation of different samples of the same test concentration at the same time. The variation observed in measured concentrations is presumed to reflect the presence of undissolved substance in samples taken for analysis.
Details on test conditions:
A preliminary toxicity test was carried out under static conditions and nominal concentrations of 1, 10, 100 and 1000 mg/L.
Definitive test:
Test dilutions were prepared individually at each concentration by adding ethanol (2 mL) to the appropriate weights of the substance and then adding the mixtures directly to the dilution water (20 litres). The test was carried out under static conditions. Groups of ten fish were exposed to nominal concentrations of 62.5, 125, 250, 500 and 1000mg/L. Control groups of fish were exposed to dilution water alone or dilution water containing ethanol (0.1 mL/L). Fourteen groups of five fish were removed from the holding tank and randomly placed into the test and control vessels until each contained ten fish. The fish were not fed during the test. Observation of the fish were made within 45 minutes of their addition to the test vessels and again after 2 and 4 hours. Thereafter, observations were made at 24, 48, 72 and 96 hours. Temperature, pH and dissolved oxygen was measured at the start of the test and each day either immediately before or following the observations of fish behaviour.
Photoperiod during the test: 16 h light, 8 h dark
Apparatus: all-glas aquaria with a capacity of 25 L, aeration was achieved through a Pasteur pipette connected to an oil-free supply of compressed air.
Reference substance (positive control):
no
Remarks:
no reference substance was used
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Details on results:
Since no mortalities were observed during the test, the LC50 value could not be calculated. Further levels intentionally exceeded the aqueous solubility od the substance. Although the results of analysis showed that exposure levels were neither achieved or maintained and that test preparations were not homogeneous (homogenisation could neither be achieved with solvents nor with ultrasound), they nevertheless represent conditions of maximum attainable exposure.
Sublethal observations / clinical signs:

No mortalities were observed during the test. The substance was, therefore, not considered to be acutely toxic to rainbow trout at nominal concentrations up to 1000 mg/L. Exposure levels intentionally exceeded the aqueous solubility of the substance. Although the results of analysis showed that exposure levels were neither achieved or maintened and that test preparations were not homogeneous, they nevertheless represent conditions of maximum attainable exposure.

Validity criteria fulfilled:
no
Remarks:
Measured concentrations were far below 80 % of the nominal concentrations. Undissolved material was observed in all dosed vessels. However, as no adverse effect was observed the study was assessed as reliable.
Conclusions:
For the substance a 96h-LC50 of > 1000 mg/L (nominal) was observed on Rainbow trout. No toxic effects could be observed.
Executive summary:

In order to determine the acute toxicity to fish of the substance, Rainbow trout was exposed to the test solution of 5 nominal concentrations of the test substance ( 62.5, 125, 250, 500, 1000mg/L) and blank control solution for a period of 96 h under static conditions. The applied method was the OECD Guideline 203. No effects were observed and the 96h-EC50 is interpreted as > 1000 mg/L (nominal).

This value lies far above the water solubility and the measured concentrations. Since the test solution was not filtered and undissolved substance was observed in all test vessels the value is considered as reliable and reflects a worst case situation. Despite it can not be excluded that the intake by ingestion of the substance took place no effects were observed. Therefore, the study is regarded as valid and useful to assess the acute toxicity to fish.

As a conclusion it can be stated that the substance is not toxic to fish until the limit of its water solubility.

Description of key information

For the substance a 96h-LC50 of > 1000 mg/L (nominal) was observed on Rainbow trout.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
1 000 mg/L

Additional information

"should read > 1000 mg/L"

In order to determine the acute toxicity to fish of the substance, Rainbow trout was exposed to the test solution of 5 nominal concentrations of the test substance ( 62.5, 125, 250, 500, 1000mg/L) and blank control solution for a period of 96 h under static conditions. The applied method was the OECD Guideline 203. No effects were observed and the 96h-EC50 is interpreted as > 100 mg/L.

This value lies far above the water solubility and the measured concentrations. Since the test solution was not filtered and undissolved substance was observed in all test vessels the value is considered as reliable and reflects a worst case situation. Despite it can not be excluded that the intake by ingestion of the substance took place no effects were observed. Therefore, the study is regarded as valid and useful to assess the acute toxicity to fish.