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Short-term toxicity to fish

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short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Principles of method if other than guideline:
Acute toxicity (96 h) towards fish applying a static stystem having mortality as endpoint.
Tests were conducted according to "Standard method for examination of water and wastewater", 13th edn, Am. Publ. Hlth. Ass.,Washington DC
GLP compliance:
not specified
Analytical monitoring:
Test organisms (species):
Lebistes reticulatus
Test type:
Water media type:
Limit test:
Total exposure duration:
96 h
20 - 25 mg CaCO3/L
Test temperature:
22 - 24.5°C
6.3 - 6.9
Dissolved oxygen:
6.9 - 7.8 mg/L
Nominal and measured concentrations:
nominal concentrations tested between 0.1-3.2 mg/L
Reference substance (positive control):
not specified
96 h
Dose descriptor:
Effect conc.:
0.61 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Remarks on result:
other: 0.28 - 1.34 mg/L (95 % CL)
Sublethal observations / clinical signs:

stability of the test substance was checked experimentally:

- survival of 15 fish placed in a 3 day old 10 mg/L hydrazine solution in undiluted ground water observed after 6 h

- response (10 dead fish) similar to that of freshly prepared solutions containing 10 mg/L hydrazine

Thus, assuming similar effective concentrations in fresh and altered solutions, nominal concentrations were reported.

Executive summary:

The acute toxicity of hydrazine towards fish (Lebistes reticulatus) accounts for 0.61 mg/L (LC50, 96 h, nominal) (Slonim, 1977).

Description of key information

The acute toxicity of hydrazine towards fish (Lebistes reticulatus) accounts for 0.61 mg/L (LC50, 96 h, nominal) (Slonim, 1977).

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
0.61 mg/L

Additional information

Despite the study was neither performed according to current guidelines, nor following GLP principles, it was used to assess the short-term effects of hydrazine towards fish. Main criteria to assess the reliability of fish studies are a mortality in the control samples of less than 10 % and an oxygen concentration not falling below 60 % of saturation over the entire test duration. Both criteria are fulfilled. As the test item is know to degrade due to auto-oxidation processes, the determination of test item concentration is quite crucial to prove the constant exposure of test organisms towards the test item throughout the entire test duration. Reported results reflect nominal values as no direct hydrazine analysis was performed. Nevertheless, hydrazine concentrations were indirectly checked comparing the survival of 15 fish placed in a 3-day-old solution with a nominal hydrazine concentration of 10 mg/L to the adverse effects of a freshly prepared test solution with the same nominal concentration. Ten of the 15 fish were dead in the altered hydrazine solution within 6 h yielding a similar response to that of a freshly prepared hydrazine solution. Thus, it can be assumed, that the concentration of the active ingredient in the altered as well as in the freshly prepared solutions was in the same order of magnitude justifying the use of nominal concentrations. These findings are supported by Fisher et al. (1980a) presenting an LC0(96 h) of 0.43 mg/L hydrazine (nominal).