Reaction mass of chromium (+ 3) hydroxide sulfate and sodium sulfate

Endpoint summary

Description of key information

Short-term toxicity to fish

Key_Short-term toxicity to fish: LC₅₀(96h) > 10000 mg/L (nominal) and > 3.21 mg Cr/L (arithmetic mean measured) for Danio rerio (semi-static daily renewal, freshwater, Method of the German Umweltbundesamt (UBA), Berlin of May 1984, quivalent to ISO 7346-1, GLP)

Long-term toxicity to fish

Key_Long-term toxicity to fish: NOEC (26d) ≥ 1000 mg/L (nominal) and ≥ 0.018 mg Cr/L (arithmetic mean measured) for Danio rerio (semi-static with media renewals at intervals of 2-3 days, freshwater, Method of the German Umweltbundesamt (UBA), Berlin of May 1984, equivalent to the draft version of OECD TG 210 of 1988, GLP)

Long-term toxicity to aquatic invertebrates

Key_Long-term toxicity to aquatic invertebrates: Daphnia magna EC50 (21d) > 0.02 mg/L (nominal, based on total Chromium) and > 0.015 mg Cr/L (time weighted average, based on background corrected dissolved Chromium) for effect parameters mortality, living offspring produced per surviving parental animal and the total number of living offspring produced at the end of the test per parent daphnia at the start of the test excluding from the analysis parental accidental and/or inadvertent mortality (semi-static with media renewals at intervals of 2-3 days, freshwater, OECD 202 - Part II (1984), GLP)

Toxicity to aquatic algae

Key_Toxicity to aquatic algae and cyanobacteria: Desmodesmus subspicatus ErC50 (72h) ≥ 849 µg/L (nominal) and > 148 µg Cr/L (initial mean measured), ErC10 (72h) = 12 µg/L (nominal) and 2 µg Cr/L (initial mean measured)(static, freshwater, OECD 201 and EU Method C.3, GLP)

Toxicty to microorganisms

Key_ISO Standard 8192 (OECD 209), GLP, potassium chromium hydroxide sulpfate (as a realtive insoluble Cr(III) salt), nominal concentrations of 0 (control), 1000, 1800, 3200, 5600 and 10000 mg/L, 3 -h EC50 was therefore >10000 mg 'Chromosal B'/L (> 110 mg Cr/L), the highest concentration tested.

Additional information

General

Based on the chemical structure of the test material, Chromium is considered to be the most relevant active ingredient. Therefore the chemical analysis as well as the result evaluation was based on concentrations of dissolved Chromium in all ecotoxicological studies. Many chromium compounds are only slightly soluble or not soluble at all in water. Chromium(III) oxide and chromium(III) hydroxide are insoluble in water. Therefore, only low concentrations of dissolved Chromium were determined in the test media of all aquatic studies even though nominal concentration up to 1000 mg test material/L were applied with a the test substance purity of 80% Cr2(OH)2(SO4)2*Na2SO4.

Despite its name, basic chromium sulfate is acidic. When added to water, a pH in the range of < 2 is established at which the substance is readily soluble in water.

At a neutral or slightly acidic range as provided for water hazard testing (and buffered), the substance hydrolyses faster than it can cause harm. The result is chromium(III) oxide that is virtual insoluble as stated in the disseminated REACH registration dossier at ECHA's website. The poorly soluble substance chromium(III) oxide is thus evaluated by comparing the dissolved chromium(III) ion level resulting from the T/Dp at a loading rate of 1 mg/L after 7 and 28 d with the lowest acute or chronic effect concentration, respectively, as determined for the (soluble) chromium(III) ion.The lowest reliable acute and chronic effect concentrations determined for the (soluble) chromium(III) ion are a 72 h ErC50 > 148.1 µg Cr(III)/L and a 72 h ErC10 of 2.0 µg Cr(III)/L observed in a growth inhibition test for the effects of chromium (III) hydroxide sulphate on freshwater algae Desmodesmus subspicatus (Neuhahn, 2010). Dissolved chromium concentrations of <0.01 µg/L in the T/Dp after 7 and 28 days at pH 6 (i.e. the pH that maximizes the dissolution) are significantly lower than the lowest reliable acute effect concentration derived for algae (i.e. EC50 > 0.148.1 mg Cr(III)/L) and the lowest reliable chronic effect concentration derived for algae (i.e. ErC10 of 2.0 µg Cr(III)/L). Hence, chromium(III) oxide is not sufficiently soluble in environmental media to cause acute or chronic toxicity to algae at the level of the lowest acute and chronic effect concentration (expressed as the EC50/EC10, respectively). In addition chromium(III) compounds are largely bound to suspended matter and thus minimise the bioavailability.

Short-term toxicity to fish

A study of the acute toxicity of 'Chromosal B' (chromium hydroxide sulphate) to fish was conducted with zebra fish (B. danio) exposed to nominal concentrations of 'Chromosal B' ranging from 4526 to 10000 mg/L for 96 hours under semi-static conditions, with renewal of pH-adjusted media at 24 -h intervals (Caspers, 1988). The 96 hour LC50 of 'Chromosal B' was >10000 mg/L, based on the highest nominal concentration applied in the test. Based on the absence of abnormal swimming behaviour, the 96 h NOEC was 10000 mg/L (nominal). The solubility of 'Chromosal B' was low under the conditions of the test. Based on the mean measured concentration of dissolved chromium at the maximum concentration of 'Chromosal B', the 96 hour LC50 was >3.21 mg Cr/L.

Long-term toxicity to fish

A study of the long-term toxicity of 'basisches Chromsulfat' (chromium hydroxide sulphate) to fish was conducted in a 30-day early life-stage test with embryonic and hatched juvenile zebra fish (B. danio) exposed to nominal concentrations of 'basisches Chromsulfat' ranging from 3.2 to 1000 mg/L under semi-static conditions, with renewal of pH-adjusted media at 48 -72-h intervals (Adema & de Ruiter, 1990). The 30 -day NOEC of 'basisches Chromsulfat' was 1000 mg/L, based on the highest nominal concentration applied in the test and the absence of adverse effects on hatch, survival, growth and behaviour of the test organisms. The solubility of 'basisches Chromsulfat' was low under the conditions of the test. Based on the maximum mean measured concentration of dissolved chromium recorded in any of the 'basisches Chromsulfat' treatments, the 30 day NOEC was 0.018 mg Cr/L.

Short-term toxicity to aquatic invertebrates

A waiver is proposed for short-term toxicity to aquatic invertebrates, as a long-term toxicity study is available.

Long-term toxicity to aquatic invertebrates

A study of the chronic toxicity of 'Chromosal B' (chromium hydroxide sulphate) to Daphnia magna was conducted with adult female test organisms exposed for 21 days to nominal concentrations of dissolved chromium ranging from 0.0020 to 0.0200 mg/L under semi-static conditions (Caspers, 1989). Based on the absence of treatment-related adult mortality or adverse impact on numbers of juveniles per adult daphnid, the mortality and reproductive EC50 values were both greater than 0.0200 mg Cr/L, the highest nominal concentration tested. Samples of fresh and expired media were taken at intervals during the study and analysed by atomic absorbtion spectrometry. After subtraction of the mean background concentration of chromium in the untreated control, the mean measured concentrations of dissolved Cr were 0.0010, 0.0041 and 0.0144 mg Cr/L at nominal concentrations of 0.020, 0.0063 and 0.0200 mg/L, respectively. Based on mean, background-corrected concentrations, the mortality and reproductive EC50 values were both >0.0144 mg Cr/L (measured).

Toxicity to aquatic algae

A study was performed to assess the effects of Chromium (III) hydroxide sulphate on the Desmodesmus subspicatus. The study was conducted in accordance with Commission Regulation (EC) No 761/2009 amending Regulation No 440/2008, Method C.3 ‘Freshwater Algae and Cyanobacteria, Growth inhibition test’ (2009) which is equivalent to OECD Guideline for Testing of Chemicals No. 201 (2006). Exponentially growing algal cells were exposed for a period of 72 hours to a range of concentrations, nominally 0.0032, 0.01, 0.032, 0.1, 0.32, 1.0, 3.2, 32 and 100 mg/L. Initial measured concentrations were 1.28, 4.01, 8.89, 15.47, 52.49, 173.33, 327.53, 313.72, 637.73 and 848.61 µg/L. Measured values in the test media declined at subsequent analytical sampling intervals.  The results of the study are based on the initial measured concentrations; this is recommended in the guideline in those cases, where there is a decrease in concentration of test item over time, which is not accompanied by a decrease in toxicity over time. The 72 hour E_rC₅₀ of chromium (III) hydroxide sulphate was > 848.6 µg/L, the corresponding no-observed effect concentration (NOEC) was 4.01 µg/L and the E_rC10 was 11.7 µg/L. The 72 hour E_yC50 of chromium (III) hydroxide sulphate was 76.1 µg/L, the corresponding NOEC was 4.01 µg/L.

Toxicity to microorganisms

The effect of 'Chromosal B' (chromium hydroxide sulphate) on aerobic biological sewage treatment processes was assessed according to ISO Standard 8192 (equivalent to OECD Guideline 209 and ETAD method 103), by determining inhibition of respiration of the mixed community of microorganisms present in a sample of activated sludge (Caspers, 1988). Activated sludge obtained from a laboratory unit was exposed over a period of three hours to 'Chromosal B' weighed directly into the appropriate test vessels at nominal concentrations of 0 (control), 1000, 1800, 3200, 5600 and 10000 mg/L. A pair of test vessels was allocated to the control and the test substance treatments were run singly. There was also an uninoculated abiotic control containing 10000 mg 'Chromosal B'/L and the reference inhibitor 3,5 -dichlorophenol was run at concentrations of 1.0 and 20.0 mg/L. No respiration inhibition, relative to the mean control rate, occurred in any of the 'Chromosal B' treatments and the 3 -h EC50 was therefore >10000 mg 'Chromosal B'/L, the highest concentration tested.