Reaction mass of disodium 2-[[2-hydroxy-3-[[methyl-(2-oxido-2-oxoethyl)amino]methyl]-5-nonylphenyl]methyl-methylamino and sodium 2-[(2-hydroxy-5-nonylphenyl)methyl-methylamino]acetate

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Persistence

A ready biodegradability study according to the OECD Guideline 301B (“Ready biodegradability; CO₂ evolution test”) is available for the substance, which resulted in 0% biodegradation after 28 days, thus concluding that the substance is not readily biodegradable (Best, 2018). Further biodegradability studies (e.g. simulation tests) are not available.  

 

Although it could be argued that a negative result in a ready biodegradability test does not necessarily mean that the substance will not degrade under relevant environmental conditions, the fact that no biodegradation was apparent throughout the entire 28 day period of the ready biodegradability study, it is expected that biodegradation would also be low in further degradation studies and that the persistence (P) criteria would likely be met as a result. As such, based on the ready biodegradability study results and as a worst-case assumption, it is concluded that the substance is classified as P and vP and no further testing is considered necessary.

 

 

Bioaccumulation

Experimental bioaccumulation studies are not available for the substance and experimental studies to determine the partition coefficient (Kow) were not possible due the high surface activity of the substance. Therefore, Log Kow values of the individual components were determined via various (Q)SAR models and an overall weighted mean Log Kow value of 2.0129 was calculated for the substance, indicating that the bioaccumulation (B/vB) criteria are not met.

 

The PBT/vPvB Guidance states that constituents present in concentrations ≥0.1% (w/w) should be considered relevant for PBT/vPvB assessment. The worst-case (highest) mean Log Kow value (based on all (Q)SAR calculations) calculated from the individual components was 5.85 from the unreacted nonylphenol component, present at a concentration of 3.3% (w/w) in the substance. Mean calculated Log Kow values for all other components were <3. The BCF of the unreacted nonylphenol component was calculated in the BCFBAF (v3.01) (Q)SAR to be 123.9 L/kg wet weight (based on an experimental Log Kow of 5.76) and is therefore not considered to meet the B/vB criteria.

 

Toxicity

Chronic aquatic toxicity data are not available for the substance, however experimental study data are available for acute fish, acute Daphnia and algae toxicity. The worst-case toxicity was shown in the algae toxicity study (Vryenhoef, 2019a), resulting in an ErC50 of 2.0 mg/L and a NOEC (growth rate) of 0.15 mg/L. As such, the substance is not considered to meet the toxicity (T) criteria from an environmental perspective.