Iron dichloride

Toxicity to other aquatic organisms

Description of key information

No relevant effects

Additional information

This endpoint is covered by the category approach for soluble iron salts (please see the section on physical and chemical properties for the category justification/report format). Testing for this endpoint has been waived in accordance with column 2 and Annex XI, part 1 and 2, restrictions.

Information from Literature Searches and earlier Assessment Approaches

The literature reviews of Vangheluwe & Versonnen (2004), Johnson et al. (2007) and OECD (2007) revealed some data. The results of the studies, selected as “reliable” by the respective authors are listed in the following tables. Nonetheless the experiments must be rated “not reliable” (Klimisch 3) according to the Klimisch et al. (1997) scale due to methodological objections against testing of aquatic organisms as concluded in the beginning of this chapter (section „Ecotoxicological information“). True, intrinsic toxicity of iron kations in aerobic aquatic test organisms cannot be determined in studies when the solubility of the dissolved ferric kation (as the ferrous form will readily be oxidized to ferric species) is exceeded. None of the experiments found effects at such low levels (depend on pH, section “water solubility”). Notwithstanding the methodological objections formally expressed in the waiving argument for the standard aquatic test organisms, the following data are mentioned for completeness.

Vangheluwe & Versonnen (2004) report effects to an aquatic air-breathing snail (Physella gyrina) from the experiments of Birge et al. (1985, 5. data reliability sheet, p 35). The study is rated “reliable” by the authors although total (not dissolved) iron concentrations were measured and only determined 1 hour after administering the iron solutions and some information about the test is lacking, because it is well described and generally clear dose-response curves were found. Test organisms of 0.24 g wet weight from field collection were after 48 h acclimation for 96 h exposed to ferric sulphate in ASTM water. During acclimatisation the test organisms were fed algae during acclimation, but the feeding was discontinued during exposure to eight concentrations (nominal concentrations of 3.98 - 100 mg/L) and a control in a semi-static test design (renewal every 12 h). The observed endpoint was mortality and a 96 h LC50 of 12.1 (10.4-13.9) mg Fe/L was determined.

The study should be rated “not reliable” (Klimisch 3 according to Klimisch et al. 1979) as the general objections to testing of aquatic organisms as concluded in the beginning of the ecotoxicological information chapter apply.

Table: Data from the OECD (2007) assessment (table 24, p 67)

Test substance	Test organism	Test duration	Effect	LC50 [mg Fe/L]	Reference	Author’s Reliability
FeCl3.6H2O	Tubifex tubifex, (Sludge worm)	96 h	Immobility at pH 6.6	18 (n.t)	Rathore & Khangarot 2002	R2
			Immobility at pH 7.6	86 at 15 °C, 130 at 20 °C (n.t)
			Immobility at pH 8.2	110 (n.t)
FeCl3.6H2O	Physa gyrina, Pouch snail	96 h	Survival at pH 7.2	12 (m.t)	Birge et al. 1985	R2
FeSO4.7H2O	Rana hexadactyla, Indian Green Frog	96 h	Tadpole survival at pH 6.1	18 (n.ts), 3.6 (n.t)	Khangarot et al. 1985	R2

n.t. = nominal total Fe

n.ts = nominal total test substance

m.t = measured total Fe

Johnson et al. (2007, table 2.9, p 29) lists some more data on marine orgamisms, i.e an echinoderm (Arbacia punctulata), a snail (Cardium edule) and an annelid (Ophryotrocha diadema), but the the authors considered them unreliable.

• Birge WJ, Black JA, Westerman AG, Short TM, Taylor SB, Bruser DM, Wallingford ED (1985). Recommendations on numerical values for regulating iron and chloride concentrations for the purpose of protecting warmwater species of aquatic life in the Commonwealth of Kentucky. Memorandum of Agreement No. 5429, Kentucky Natural Resources and Environmental Protection Cabinet.
• Johnson I, Sorokin N, Atkinson C, Rule K, Hope S-J (2007). Proposed EQS for Water Framework Directive Annex VIII substances: iron (total dissolved). ISBN: 978-1-84432-660-0. Science Report: SC040038/SR9. SNIFFER Report: WFD52(ix). Product Code SCHO0407BLWB-E-E. Self-published by Environment Agency, Almondsbury, Bristol BS32 4UD, U.K. 65 p.
• Khangarot BS, Seghal A, Bhasin MK (1985). "Man and biosphere" - Studies on the Sikkim Himalayas. Part 5: Acute toxicity of selected heavy metals on the tadpoles of Rana hexadactyla. Acta Hydrochim Hydrobiol 2:259-63.
• Klimisch H-J, Andreae M, Tillmann U (1997). A systematic approach for evaluating the quality of experimental toxicological and ecotoxicological data. Regul Toxicol Pharm 25:1-7.
• OECD Organisation for Economic Co-operation and Development (2007). SIDS Initial Assessment Report for SIAM 24. Chemical Category: Iron Salts. Self-published, Paris, France, 17-20 April. 138 p.
• Rathore RS, Khangarot BS (2002). Effects of temperature on the sensitivity of sludge worm Tubifex tubifex Müller of selected heavy metals. Ecotoxicology and Environmental Safety 53:27-36.
• Vangheluwe M, Versonnen B (2004). Critical review on acute and chronic aquatic ecotoxicity data to be used for classification purposes of iron sulfate. Commissioned by ARCELOR SA, CEFIC, EUROFER, Rio Tinto plc. Final report - 25 August 2004. Prepared by EURAS, Rijvisschestraat 118, box 3. B-9052 Gent, Belgium. 76 p.