Ferric ammonium citrate

Short-term toxicity to fish

Additional information

There are no reliable data describing the short-term toxicity of the registered substance to fish. However, testing to determine short-term toxicity of the registered substance to fish is not considered appropriate on the grounds that:
- short-term toxicity of the substance to aquatic invertebrates is low,
- uptake of the substance by fish is low (Theil, 1987),
- both citric acid and iron are physiologically important for fish,
- any effects of ammonia can be assessed on the basis of extensive existing information on its hazards to aquatic organisms.

Citric acid has been shown to be of low toxicity to fish in a study from Juhnke and Ludemann (1978) where two 48 h LC50 values corresponding to 440 mg/L and 760 mg/L have been determined in two laboratories for the effects of citric acid on mortality of the freshwater fish Leuciscus idus melanotus.

Toxicity data with iron indicate short-term effects to lie in the range 10-100 mg/l, however these are mediated via the production of insoluble iron oxides and hydroxides. The effects are due to smothering or clogging of the gills or respiratory membranes rather than intrinsic toxicity. In addition, pH effects confound iron toxicity observed in the studies.

A 96-hour LC₅₀value of 53 mg/l has been reported in the online disseminated dossier for ammonium sulfate (CAS: 7783-20-2) as the lowest short-term toxicity value for salmonoid species among the 29 fish species as given in U.S. EPA (1999). A 96 hour LC₅₀ value of 57.2 mg/l is also reported for Prosopium williamsoni as the lowest value for non-salmonid species. The LC₅₀values are adjusted to pH 8, and are equivalent to 0.76 mg NH₃/l for salmonoid species and 0.82 mg NH₃/l for P.williamsoni.

Theil, E. (1987) Ferritin: structure, gene regulation, and cellular function in animals, plants, and microorganisms.Ann. Rev. Biochem.56: 289–315.