Calcium 4-chloro-2-(5-hydroxy-3-methyl-1-(3-sulfonatophenyl)pyrazol-4-ylazo)-5-methylbenzenesulfonate

Endpoint summary

Additional information

Pigment yellow 191 (calcium 4-chloro-2-(5-hydroxy-3-methyl-1-(3-sulfonatophenyl)pyrazol-4-ylazo)-5-methylbenzenesulfonate) is a non-volatile fine powder with high melting point value (320˚C). It is only slightly soluble in water. Based on the aerobic aquatic biodegradation screening test (OECD 301D) it is not readily biodegradable in water (deg-% 35 after 28 d). However, at test concentration of 24.5 mg/l it is not toxic to STP microorganisms (3-hour I-% 7.63 to 9.17 %) based on the activated sludge respiration study (OECD 209).Pigment yellow 191 is hydrolytically stable with a half-life of over one year at test temperature of 50˚C.

As a conclusion of the biotic and abiotic degradation, substance is considered as persistent material. However, the octanol-water partition coefficient (log Kow 1.8442) is not indicating Pigment yellow 191 to have adsorption potential as the log Kow is less than 4. Based on the adsorption coefficient of 26.3 L/kg (log Koc 1.42; OECD 121), it is not considered as having a strong potential for adsorption to soil and organic matter. According to all available data on the substance it is not considered as persistent or very persistent or bioaccumulative.

 

Pigment yellow 191 is not hazardous to aquatic organisms based on the following key study results. The low short-term toxicity test results do not indicate to further investigate the long-term toxicity of the substance.

• The 96 h LC50 (Danio rerio; mortality); > 500 mg/l and the 96 h NOEC; 500 mg/l (method 84/449/EWG, C.1; OECD 203; 1984)
• The 48 h EC50 (immobilisation) to invertebrates; 750 mg/l and the 48 h NOEC; 100 mg/l (method 84/449/EWG, C.2)
• The 72 h EC50 (Desmodesmus subspicatus;growth rate) at its maximum solubility (90 mg/l) did not cause inhibition - toxic effects, but there was observed the opposite effect – a stimulation of growth. No effective – inhibition concentrations could be calculated (OECD 201). EC50 value > 90 mg/l.

It is non-volatile solid and only slightly water soluble. The evaporation to atmosphere or from water compartment is expected to be low based upon on the high melting point value (320 deg. Celsius).There is no data available on the phototransformation of substance in air, water or soil. However, as a non-volatile solid it is not expected to distribute to the atmosphere. There is no data available to estimate the ozone layer hazard of this substance. Substance contains chlorine but is not expected to degrade chemically. The most important fate process is the slow biodegradation in water (deg-% 35 after 28 d).

In general, degradation rates in sediment and soil are assumed to be reduced by default if a substance is highly sorptive. Strong binding behavior to soil particles (log Kow or log Koc > 3; Koc > 500 to 1000) might also justify long-term soil organism toxicity testing if particular sensitivity and/or persistence are anticipated. As Pigment yellow 191 is not rapidly biodegradable but has no strong adsorption potential to solid particles (Koc 26.3, log Koc 1.42 and log Kow 1.8442), the chemical safety assessment does not indicate to further evaluate the soil/sediment biodegradation or terrestrial toxicity of the substance.