7-acetamido-4-hydroxy-3-[[4-[[2-(sulphooxy)ethyl]sulphonyl]phenyl]azo]naphthalene-2-sulphonic acid, sodium salt

PBT assessment

PBT assessment: overall result

Reference

Name:

Reactive Orange 72

Type of composition:

legal entity composition of the substance

State / form:

solid: particulate/powder

Reference substance:

Reactive Orange 72

PBT status:

the substance is not PBT / vPvB

Justification:

Persistence Assessment

The test substancedisplayed very low biodegradability in an inherent biodegradability modified Zahn-Wellens test. This indicates that it is unlikely to achieve a half-life of less than 40 or 60 days within fresh water or marine water, respectively, attributed to ready biodegradation alone. However, the substance does undergo rapid hydrolysis at environmentally relevant pH’s, (t_½= 6 days at pH7 and < 1 day at pH9), indicating the potential for significant removal by hydrolysis. At use conditions during dyeing (pH > 10 at ≥ 60°C) the substance is hydrolytically unstable. At 50°C and pH9, more than 99% of the substance was degraded at the firstmeasure point of 1.5 hours. As such, degradation is anticipated via this route. Studies on direct phototransformation in water are not available but itwas found that the sulfonated azo dyes can be destroyed by UV photooxidation process (Saliha 2004). The kinetics of the degradation depends on the azo, benzene and naphthalene groups of the dyes. The first step of the degradation is related to cleavage of the azo bond of the molecule and naphthalene ring which leads to further degradation until complete mineralization.It is concluded, therefore, that abiotic processes would contribute significantly to the depletion of the substance within the environment.

Based on its high water solubility, low partition coefficient and fairly rapid hydrolysis rate at environmentally relevant pH’s, it can be concluded that it is unlikely thatReactive Orange 72/78could potentially be persistent within the environment. Abiotic effects will result in eventual removal from the environment and hence significant contact with the organisms in the food chain can be considered to be minimised. As such, the substance does not fulfil the requirements of Annex XIII, Para 1.1 based on evaluation of available data, and cannot be considered a “P” and “vP” based in this data.

 

Bioaccumulation Assessment

Reactive Orange 72/78 has an estimated log Kow of ≤ -2.61,which is in line with the partition coefficient of structural analogues. This value indicates that possible bioaccumulation in the food chain is not anticipated. Given the fact that the substance is subject to hydrolysis at biologically relevant pH’s, it is anticipated that bioaccumulation of the substance itself would not occur, as hydrolytic effects in association with metabolic effects would result in removal of the substance.

Based on the physico-chemical and environmental data for the substance, it is proposed that the substance does not fulfil the requirement of Annex XIII, Para 1.2 based on evaluation of available data, and cannot be considered a “B” or “vB” based on the available data.

 

Toxicity Assessment

The substance or its structural analogues did not cause any hazardous effects to any of the trophic levels in the aquatic organisms examined in the acute toxicity studies. The substance is not considered as harmful to aquatic organisms, nor did it demonstrate significant toxicity in any of the mammalian studies conducted on the substance. 

As such, the substance does not fulfil the requirements of Annex XIII, Para 1.3 based on evaluation of available data, and cannot be considered as “T” for the purposes of the assessment.

 

Summary and overall Conclusions on PBT or vPvB Properties

The substance cannot be considered to fulfil all the criteria for Persistence, Toxicity or Bioaccumulation, as specified in REACH Annex XIII. As such, the substance cannot be considered a PBT or vPvB substance, based on the available data.

Likely routes of exposure:

Not applicable