Chromium tris((2-ethylhexanoate)

PBT assessment

PBT assessment: overall result

Reference

Name:

legal entity composition

Type of composition:

legal entity composition of the substance

State / form:

liquid

>= 99 - <= 100 % (w/w)

Reference substance:

legal entity composition

Reference substance:

legal entity composition

This impurity is considered relevant for the classification and labelling of the substance

PBT status:

the substance is not PBT / vPvB

Justification:

Persistence:

The persistence of the test substance, Chromium tris(2-ethylhexanoate), was evaluated in two biodegradation studies conducted according to test guidelines OECD 301B and OECD 301F.  The test substance was not readily biodegradability (32.6% and 19.6% biodegradability respectively for OECD 301B and OECD 301F tests).  Therefore, the substance potentially meets the Persistent (P).

The test substance is unlikely to be very Persistent (Vp) since there was some biodegradation in both assays and there was no indication the test substance was toxic to the microorganisms in the activated sludge.  

Bioaccumulation:

There are no experimental data to address the bioaccumulation potential of the test substance. Instead, the bioaccumulation potential of the test substance was estimated from the structural and physical chemical properties using EpiSuite v 4.1.  Using this approach, we conclude the test substance is neither Bioaccumulative (B) nor very Bioaccumulative (vB).

The octanol/water partition coefficient of the test substance is an indicator of the potential for bioaccumulation since it is a predictor of the mobility of a substance through biological membranes by passive diffusion (ECHA 2017).  The estimated partition coefficient (log Kow) of the test substance is 7.6 (see appendix 1 for output of the EpiSuites estimations).  Substances with Log Kow values greater than 4.5 are assumed to have the potential for bioaccumulation (ECHA 2017).

However, partition coefficient estimates alone are generally not good predictors of bioaccumulation potential of organometallic substances (ECHA 2017).  Because of this, other physical and chemical properties should also be included to estimate bioaccumulation potential.  

One approach is to include molecular weight in addition to partition coefficient information to estimate bioaccumulation potential as a bioconcentration factor (BCF).  According to the ECHA guidelines, substances with measured or modelled BCFs of > 2000 are considered bioaccumulative while BCFs of greater than 5000 are viewed as evidence that a substance is very bioaccumulative (vB).  The estimated BCF of the test substance is 1639 L/Kg which is below the threshold for classification as B or vB.

Toxicity:

The test substance is considered as toxic according to the ECHA criteria (2017) since the substance is legally classiifed as Reprotoxic 1B, H360D (metal salt of 2-ethylhexanoic acid).