Chromium trichloride

Short-term toxicity to aquatic invertebrates

Description of key information

For freshwater invertebrates an EC50 (daphnia magna, 48h) of 63.3 mg/L and for saltwater invertebrates an EC50 of 34.7 mg/L is used for hazard and risk assessment.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

63.3 mg/L

Marine water invertebrates

Marine water invertebrates

Effect concentration:

34.7 mg/L

Additional information

Freshwater

In the key-study by Kühn et al. (1989) Chromium trichloride has been found having an EC50 (daphnia magna, 24 h) of 22 mg Cr/L and 111 mg CrCl3.6H2O/L respectively. In this study performed by the German BGA in total 73 investigations were carried out in order to determine the "no observed effect concentration" (NOEC) of 73 environmentally relevant substances in the 21 d Daphnia reproduction test. As range finding test, acute tests were performed with 24 hours duration. The test was conducted in line with the provisional procedure proposed by the Federal Environmental Agency (Umweltbundesamt) (as of 1 January 1984). Daphnia magna Straus was used as the test organism. The concentrations of substances in the test preparations were chemically quantified.

For chromium(III), tested as chromium trichloride hexahydrate, the EC 0 were 11 mg Cr/L (equivalent to 55 mg CrCl3.6H2O mg/L) and the EC 50 found was 22 mg Cr/L and 111 mg CrCl3.6H2O/L respectively.

In a supportive study reported by Melnikow et al. (2011) EC50 (daphnia similis, 48h) of 3.24 mg Cr/L and 9.88 mg chromium trichloride, anhydrous/L were reported, equivalent to 16.6 mg/L as CrCl3.6H2O, the water soluble form of chromium trichloride.

In this study according to a Brasilian standard for acute toxicity to aquatic invertebrates Daphnia similis were exposed to different concentrations of chromium trichloride for 48 hours to determine the EC50. As water hardness in Brasil is much lower than in Europe or North America, the study was performed with a water hardness of only 40 - 48 mg calcium carbonate per liter. The study result was, that the EC50 towards Daphnia Similis is 3.24 mg/L (as chromium) which equates to 9.88 mg/L as chromium trichloride or 16.6 mg CrCl3.6H20/L respectively.

In another supportive study presented by Anderson (1948) various metal chlorides were investigated for their acute toxicity to daphnia magna. Whereas sodium chloride had very low toxicity with hardly any dependency on exposure duration, toxicity to heavy metal salts appeared to be higher the longer exposure was. For many salts toxicity increased when exposure exceeded 16 hours at which the daphnia reached the molten stage. This was also observed for chromic chloride, which showed increasing toxicity following 16 hours of exposure up to 64 hours, the maximum exposure time in this study. Apparently, the daphnids were more susceptible to these substances at the time of melting than they were before the molten stage. The EC50 in this publication for chromic chloride thus was found being 3.6 mg CrCl3/L or 6.1 mg CrCl3.6H2O/L. However, as this finding is even lower than the chronic toxicity data found in long-term studies with daphnia magna, the results should be taken with caution and thus are not used for hazard and risk assessment here.

Given the reduced exposure time in the study by Kühn et al. and the low water hardness used in the study by Melnikov et al. the results for daphnia magna when exposed for 48 hours is expected in the range of 10 – 100 mg/L as chromium trichloride nonahydrate and for hazard and risk assessment the arithmetic average of 111 mg/L and 16.6 mg/L (i.e. EC50 of 63.3 mg/L) is taken forward for hazard and risk assessment.

Saltwater

In the key study published by Calabrese et al. (1973) the acute toxicity of 11 heavy metals on embryonic development of the American oyster Crassostrea virginica was studied and the concentrations at which 50 % of the embryos survived were determined. The most toxic metals and their LC50 values were mercury (0.0056 ppm), silver (0.0058 ppm), copper (0.103 ppm) and zinc (0.31 ppm) in this study. Those metals that were considered relatively toxic and their LC50 values were nickel (1.18 ppm), lead (2.45 ppm) and cadmium (3.80 ppm). The metals that were relatively non-toxic were arsenic (LC50 7.50 ppm), chromium (LC50 10.3 ppm) and manganese (LC50 16.0 ppm), whereas aluminum was non-toxic at LC50 of 7.5 ppm, the highest concentration tested.

Thus, the 48h-LC50 of chromium chloride to American oyster ( Crassostrea virginica ) was 10.3 mg Cr/L and the 48h-LC50 based on chromium trichloride is 31.4 mg/L and based on chromium trichloride hexahydrate is 52.8 mg/L accordingly.

In a supporting publication by Boutet et al. (1973) two crayfish species (Austropotamobius pallipes and Orconectes limosus) were tested for acute and chronic toxicity towards various metal ions. The EC50 (based on mobility) found for chromium(III) was 3.4 and 6.6 mg Cr/L respectively.

In this study in total 14 different metal ions were tested for acute and chronic toxicity on freshwater crayfish (2 species: Austropotamobius p.p. and Orconestus limosus) at 16 °C. The acute study was performed with 96 hours exposure period with both species. The EC50 values found were 3.4 mg Cr/L and 6.6 mg Cr/L for Austropotamobius p.p. and Orconestus limosus respectively, equivalent to 17.4 and 33.8 mg CrCl3.6H2O/L.

Thus, the EC50 to saltwater invertebrates also is in the range of 10 – 100 mg/L as chromium trichloride nonahydrate and the arithmetic mean of (52.8, 17.4, and 33.8) 34.7 mg/L is taken forward for hazard and risk assessment.