Heptasodium bis[4-hydroxy-5-[(2-hydroxy-1-naphthyl)azo]-3-[(2-hydroxy-3-nitro-5-sulphophenyl)azo]naphthalene-2,7-disulphonato(5-)]cobaltate(7-)

Endpoint summary

Description of key information

Short-term toxicity to fish

LC₅₀ (96 h, Danio rerio) = 160 mg/l (nominal)

Short-term toxicity to aquatic invertebrates

EC₅₀ (48 h, Daphnia magna) > 66.9 mg/l (measured concentration; equivalent to 100 mg/l nominal)

EC₅₀ (48 h, Daphnia magna) > 52.9 mg/l (measured concentration; equivalent to 100 mg/l nominal)

Toxicity to aquatic plants

E_rC₅₀ (7 d, Lemna minor) > 63.9 mg/l based both on frond number and on dry weight (measured concentration; equivalent to 100 mg/l nominal)

Toxicity to microorganisms

IC₅₀(3 h, activated sludge bacteria) = 2200 mg/l (nominal)

Additional information

The following data on toxicity of the test item to fish and microorganisms was obtained. No data on the aquatic toxicity of the test item was available for short-term toxicity to aquatic invertebrates or toxicity to algae or other aquatic plants, therefore, a read-across approach was adopted. Specifically, available data on Similar Substance 01 (cobalt complex with 2 phenyl-azo-naphtyl ligands functionalised by similar groups) was used to complete the data for these endpoints. In addition, information regarding Similar Substance 02 was taken into account. It is expected that the test item will present similar effect levels to invertebrates and aquatic plants. Detailed justification of the read-across approach is given in Section 13 of IUCLID.

 

Fish acute toxicity

The acute toxicity of Acid Black 076 to fish was investigated on Danio rerio according to the OECD Guideline 203 (1982). Twelve Zebrafish per concentration were exposed to test item concentrations (100, 180, 320, 560 and 1000 mg test item/l) for 96 h in a static system and monitored daily for mortality. A control group was tested in parallel which was exposed to test water without the addition of test item. Test water was monitored daily for oxygen saturation, oxygen concentration, pH and temperature. Test water was also measured at the beginning and end of the test for actual test item concentrations. Measured concentrations were between 97 % and 106 % of the nominal concentration, therefore, the determination of the biological results was based on the nominal concentrations.

The LC₅₀ (96 h) of the test item to Zebrafish was found to be 160 mg/l.

 

Invertebrate acute toxicity

The short-term toxicity of Similar Substance 01 towards aquatic invertebrates was assessed in 2 acute toxicity studies on Daphnia magna according to the OECD Guideline 202, one conducted in 2015 and the other in 2017. In both studies, nominal test solutions of 0, 6.25, 12.5, 25, 50, and 100 mg/l were used. The colour of the test solutions increased from very light pale pink to a deep purple color. In the first study, the colour of the test solutions remained unchanged throughout the test, however at test completion, reddish grains were observed at the bottom of the test vessels in the 12.5 mg/l test solution, and dark red/purple precipitate was observed in the 50 mg/l and 100 mg/l test vessels. In the 2017 study, suspended particles of test item were visible in the 50 mg/l and 100 mg/l test concentrations from the start of the test. Throughout the test, the color of the test solutions remained consistent. The test endopoints were based on the mean measured concentration of test item in both studies since the measured concentrations were not within 80 -120 % of the nominal concentrations. The mean measured concentrations were 5, 10.1, 18.8, 35.3, and 66.9 mg/l in the first study and 5.0, 9.6, 18.3, 34.1, and 52.9 mg/l in the second study.

As undissolved material was present in both studies, it can be concluded that the daphnids in the test solutions were exposed to the highest test concentration (nominal concentration: 100 mg/l; measured concentrations: 66.9 mg/l and 52.9 mg/l, respectively). Neither study revealed effects in any of the concentration groups, not even in the highest one (nominal 100 mg/l) which displayed precipitated test material. In conclusion, no effects of the test item on Daphnia magna were noted up to the solubility limit.

Additional supporting data for Similar substance 02 is available, as follows.

A study on the toxicity of Similar Substance 02 to Daphnia magna was performed according to the OECD Guideline 202 (1993) under static exposure conditions. 20 Daphnia magna per dose (10 animals per flask) were exposed to nominal test item concentrations of 45, 100 and 220 mg/l (corresponding to measured concentrations of 27, 58 and 131 mg/l), a vehicle control and a blank control. A reference substance, potassium dicromate, was tested separately. At nominal concentrations of 100 and 220 mg/l, a sediment at the bottom of the test vessel was noted after 24 hours.

As measured concentrations did not fall within 80 -120 % of nominal concentrations, mean measured concentrations were used to derive results. No immobilisation or abnormal behaviour of daphnids were noted in control or test animals at any concentration. Based on this finding, the EC₀ value after 48 hours was determined to be 131 mg/l, and therefore the EC₅₀ and EC₁₀₀ values are higher than 131 mg/l (measured concentration; equivalent to 100 mg/l nominal).

Aquatic Plants toxicity

The toxicity of Similar Substance 01 to the aquatic plant Lemna minor was assessed in a study conducted according to OECD guideline 221. Lemna minor was exposed to the test item under static conditions for 7 days at nominal test item concentrations of 1.56, 3.12, 6.25, 12.5, 25, 50, and 100 mg/l. A negative control (dilution water only) was tested in parallel. The 7-day EC₅₀ for mean yield and SGR (based both on number of fronds and on dry weight) were calculated using nonlinear regression, with 3P Log-Gompertz EV. Mean measured concentrations of the test item were between 63.9 % and 88.8 % of the nominal concentrations; as not all values fell within 80 -120 % of the nominal concentrations, the test endpoints were calculated based on geometric mean measured concentrations.

The E_rC₅₀ based on frond number was found to be higher than 63.9 mg/l (measured concentration; equivalent to 100 mg/l nominal).

The E_rC₅₀ based on dry weight was found to be higher than 63.9 mg/l (measured concentration; equivalent to 100 mg/l nominal).

For completeness of information, the following data is referred to Similar Substance 02.

The toxicity of the test item to aquatic plants was evaluated in an experimental study according to the OECD Guideline 221 (2006). Lemna gibba was exposed to the test item for 7 days and monitored for change in frond number and dry weight. Test item concentrations tested were 0.3, 0.87, 2.52, 7.32, 21.22 and 61.53 mg/l test item in test medium and a negative control of test medium only, based on a preliminary range-finding study. Three of the six concentrations (0.3, 7.32 and 61.53 mg/l) were monitored for test item concentration at the start end end of the study period. Toxicity of a reference substance, 3,5-Dichlorophenol, toLemna gibbawas evaluated in a separate study.

As values of measured concentrations fell within 80 % to 120 % of the nominal test item concentrations, results are reported using the nominal values. From the average specific growth rate calculation, the E_rC₅₀was calculated to be 28.31 mg/l based on frond number (confidence limits: 27.16 and 29.51 mg/l) and 24.22 mg/l based on frond dry weight (confidence limits: 23.24 and 25.24 mg/l).

Toxicity to micoorganisms

The inhibitory effect of Acid Black 076 on aerobic waste-water bacteria was investigated in a respiration inhibition test, according to ETAD 103 (1979), a method comparable to the OECD Guideline 209 (1984). Activated domestic sludge bacteria, fed with a standard amount of synthetic feed, was exposed to five test item concentrations (560, 1000, 1800, 3200 and 5600 mg/l and two negative controls) for a total of 3 hours. The oxygen concentration was measured at the end of the study period and the amount of inhibition was calculated from this result. No reference substance was tested.

The IC₅₀ (3 h) of the test item to activated sludge bacteria was found to be 2200 mg/l (nominal).

 

JUSTIFICATION FOR CLASSIFICATION OR NON-CLASSIFICATION

According to the CLP Regulation (EC) No 1272/2008, Part 4: Environmental Hazards, the substances can be classified for hazardous to the aquatic environment when the following criteria are met:

A) Acute (short-term) aquatic hazard Category Acute 1: 96 h LC₅₀ (fish) and/or 48 h EC₅₀ (crustacea) and/or 72 or 96 h E_rC₅₀ (algae or other aquatic plants) ≤ 1 mg/l.

B) Long-term aquatic hazard:

(iii) Substances for which adequate chronic toxicity data are not available and the substance is not rapidly degradable and/or the experimentally determined BCF ≥ 500 (or, if absent, a log K_ow ≥ 4).

Category Chronic 1: 96 h LC₅₀ (fish) and/or 48 h EC₅₀ (for crustacea) and/or 72 or 96 h E_rC₅₀ (algae or other aquatic plants) ≤ 1 mg/l;

Category Chronic 2: 96 h LC₅₀ (fish) and/or 48 h EC₅₀ (for crustacea) and/or 72 or 96 h E_rC₅₀ (algae or other aquatic plants)> 1 to ≤ 10 mg/l;

Category Chronic 3: 96 h LC₅₀ (fish) and/or 48 h EC₅₀ (for crustacea) and/or 72 or 96 h E_rC₅₀ (algae or other aquatic plants) > 10 to ≤ 100 mg/l.

The substance is not rapidly degradable, and the available data on fish, invertebrates and to aquatic plant fixed key effect levels that do not meet the criteria related to the hazard categories for acute and chronic aquatic toxicity. Therefore, the test item is not classified for aquatic toxicity according to the CLP Regulation (EC) No. 1272/2008.