Ferric ammonium citrate

Endpoint summary

Additional information

Short-term toxicity to invertebrates data are available with the registered substance reaction mass of ammonium iron (III) citrate and ammonium sulfate (EC no. 932-833-9). The preliminary investigation indicates that no effects on mobility of Daphnia magna occurred during a 48 h exposure up to a concentration of 100 mg/l. WAITING DEFINITIVE STUDY RESULTS. No further data are available on the registered substance, however, assessments have been made on the components of the registered substance. The components are assessed separately, as iron, ammonium sulfate and citric acid, as these are expected to dissociate in solution. Additional information on the basis for read across approach is given in an expert report (Peter Fisk Associates, 2012) attached in Section 13 of the IUCLID 5 dossier.

Ferric ions are widespread in the natural environment, largely as oxides, while elemental iron is to be found in the built environment (iron is the fourth most abundant element, accounting for approximately 5% (by weight) of the Earth's crust (Wildermuth, 2004). Iron is present naturally in abundance, in all environmental compartments, apart from water, where solubility of the hydroxide and oxides is limiting, and therefore dissolved concentrations are low, although sediment concentrations can be high.Iron plays an important role in biological processes, with iron homeostasis being under strict control.Toxicity studies with iron salts show effects to aquatic organisms 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, as a result of a production of iron hydroxyl complexes, the pH of the test media is lowered, which if not neutralised, will further contribute to the apparent toxicity of iron salts (OECD 2007a, iron salts and Peter Fisk Associates, 2012).

The non-ferric chemical species that are part of the registered substance and should be taken into consideration are ammonium sulfate and citrate.

Citrate is not expected to contribute to the potential for ecotoxicity of the registered substance. Short-term aquatic toxicity data are available indicating the lack of toxicity from citric acid. Moreover, citrate is involved in the metabolism of eukaryote cells.

Ammonium sulfate is a known toxicant for aquatic organisms, in particular to fish and aquatic invertebrates and the toxicity of the substance will be greatly influenced by the presence of ammonia (NH3) ions. Therefore, the contribution of ammonia needs to be taken into account when determining the hazard and setting the PNECs for risk characterisation. Ammonia ecotoxicity data have been reviewed in the OECD/HPV programme of peer review. The best available data are summarised in the SIAR for the Ammonia category (OECD 2007b, ammonia). Further review of the data has not been considered necessary. Toxicity of ammonia is dependent on the degree of ionization and is therefore highly pH and temperature dependent. Long-term exposure of fish to ammonium compounds result in a NOEC of 11 mg/l, equivalent to 1.2 mg un-ionized NH₃/l, based on length and weight of fry. Short-term EC₅₀values for invertebrates range from 21.8 mg total NH₃/l for ammonium chloride to > 25.7 mg total NH₃/l for ammonium sulfate. Long-term studies with invertebrates showed lower NOEC values of 3.1-3.47 mg total NH₃/l. The algae, Chlorella vulgaris, EC₅₀ (biomass; 0-5 d) was 1300 mg/l using ammonium chloride. In a 21-day test with Chlorella vulgaris and ammonium sulfate, an EC₅₀ of 25,476 mg/l (2700 mg N/l) was established from exponential growth on day 11-18. Ammonia that is unionised is toxic to aquatic organisms at concentrations below 1 mg/l (OECD 2007b).

The ammonium sulfate disseminated dossier data available online (CAS 7783-20-2) broadly agrees with the data presented in the Category Ammonia SIDS (2007), with invertebrates being the most sensitive species in the long-term. However the results in the disseminated dossier are mostly expressed in terms of ammonium sulfate rather than unionized ammonia. Short-term fish LC₅₀ range from 27 to 681 mg/l of ammonium sulfate:

• A 30-day EC10 value of 5.29 mg/l has been reported for sub-lethal effects on reproduction in the freshwater fish, Lepomis macrochirus. The value is adjusted to pH 8 and 25°C.
• A 10-week EC10 value of 3.12 mg/l has been reported for effects on reproduction of the freshwater invertebrate, Hyallela azteca. The value is adjusted to pH 8 and 25°C. A
• An 18-day EC50 value of 2700 mg/l has been determined for effects on cell numbers of the freshwater algal species, Chlorella vulgaris.

References:

OECD SIAR 2007a.SIDS Initial Assessment Report for SIAM 24, Paris, France, 17 -20 April 2007. Chemical Category: Iron Salts. Sponsor Country: Finland. Industry sponsor/consortium: CEFIC Incopa Iron Salts Group. July 2007.

OECD SIDS 2007b. SIDS Initial Assessment Report for SIAM 24, Paris, France, 17-20 April 2007. Chemical Category: Ammonia. Sponsor Country: United States. Industry sponsor/consortium: European Fertilizers Manufacturing Association (EFMA-Europe) and The Fertilizer Institute (TFI-US). January 2007.

REACH disseminated dossier for ammonium sulfate (CAS: 7783 -20 -2).

http://apps.echa.europa.eu/registered/data/dossiers/DISS-9ebc8a1a-f93f-2e2d-e044-00144f67d031/DISS-9ebc8a1a-f93f-2e2d-e044-00144f67d031_DISS-9ebc8a1a-f93f-2e2d-e044-00144f67d031.html

Wildermuth, E.et al.,2004. Iron compounds. In: Bohnet, M.et al.(eds). Ullman's Encyclopedia of Industrial Chemistry. 7thEdition. Wiley,. Web-version, Release 2004.