Triisodecyl phosphite

PBT assessment

PBT assessment: overall result

Reference

Name:

Triisodecyl phosphite

Type of composition:

legal entity composition of the substance

State / form:

liquid

Reference substance:

Triisodecyl phosphite

Reference substance:

Triisodecyl phosphite

PBT status:

the substance is not PBT / vPvB

Justification:

Assessment of PBT/vPvB Properties

Persistence(P, vP)

While TDP has not found to be readily biodegradable in the a screening biodegradation study, the results of this study may have been impacted by the low water solubility of TDP. TDP has been shown to hydrolyses rapidly, as such, abiotic degradation is expected to be the dominant pathway for TDP in the environment. Additionally, a recent OECD 301D study of tris isotridecyl phosphite (TiTDP) showed greater than 60% biodegradation in 35 days indicating that it is inherently biodegradable. This substance is very similar to TDP, but has a longer alkyl chain indicating that it is a reasonable (and likely conservative) analogue for evaluating this endpoint.

Based on the very short half-life in water, TDP is not expected to meet the criteria for P or vP. The hydrolysis products of TDP (isodecanol and phosphorous acid) are readily biodegradable are also do not meet the criteria for P or vP.

Bioaccumulation (B, vB)

Bioaccumulation concentration factor (BCF) cannot not be measured for TDP due to its rapid hydrolysis. The BCF model estimates for TDP are generally low, though they may be of limited utility given their wide range and the fact that hydrolysis is not considered in the model. Given the rapid hydrolysis, the bioaccumulation potential of the hydrolysis products, isodecanol and phosphorous acid, were considered. All are low and well below the criterion for B (bioaccumulative) or vB (very bioaccumulative). As such, it is concluded that TDP does not meet the criteria for B or vB.

Toxicity (T)

TDP has a low order of toxicity to mammalian species. The primary effect is skin sensitisation; for which TDP is classified.

Based on TDP’s low water solubility and rapid hydrolysis, it is not anticipated to cause aquatic toxicity based on the amount and relatively aquatic toxicity of its hydrolysis products. None of its hydrolysis products (isodecanol and phosphorous acid) are classified as dangerous to the environment.

PBT/vPvB criteria and justification

TDP is not classifiable as a PBT or a vPvB substance as it does not meet criteria for either persistence or bioaccumulation and toxicity effects are primarily related to its potential for irritation and sensitisation.

It should be noted that a similar substance, diisodecyl phenyl phosphite (DDPP), was reviewed by the ECB PBT Working Group and the conclusion from their assessment was that it is not a PBT or vPvB substance. The basis that the PBT Working Group used to determine that DDPP is not a PBT would also apply to TDP, which has a similar chemical structure.