Fatty acids, tall-oil, reaction products with linseed oil, maleic anhydride and methanol

PBT assessment

PBT assessment: overall result

Reference

Name:

Addition product of maleic anhydride, tall oil fatty acids, linseed oil and methanol

Type of composition:

legal entity composition of the substance

State / form:

liquid

Reference substance:

Addition product of maleic anhydride, tall oil fatty acids, linseed oil and methanol

Reference substance:

Addition product of maleic anhydride, tall oil fatty acids, linseed oil and methanol

Reference substance:

Addition product of maleic anhydride, tall oil fatty acids, linseed oil and methanol

Reference substance:

Addition product of maleic anhydride, tall oil fatty acids, linseed oil and methanol

Reference substance:

Addition product of maleic anhydride, tall oil fatty acids, linseed oil and methanol

PBT status:

the substance is not PBT / vPvB

Justification:

Persistence: The results from the ready biodegradability CO₂ evolution test (screening criterion) indicated 41% biodegradation in 28 days; therefore, under test conditions, ready biodegradability was not observed. The degradation rate of 41% in 28 days is evidence of inherent, primary biodegradability (> 20% biodegradation) and significant mineralisation (> 40% degradation). The test substance was also reported as "very likely inherently biodegradable". Therefore, no definitive determination on persistence can be made based on available information. However, in the absence of a definitive determination, the substance may be described as potentially “persistent” (“potentially P”). The substance is described as “not very persistent” (“not vP”), based on its inherent biodegradability and significant mineralisation in the ready biodegradability test.  The substance is a UVCB which contains substantial proportions of linseed oil and tall oil triglycerides, diglycerides and fatty acids, derivatized with maleic anhydride and methyl ester. The basis of these substances in naturally-occurring lipids suggests that environmental biodegradation is expected, even if the strict criteria for ready biodegradability have not been observed.

 

Bioaccumulation: A precise value for the octanol-water partitioning coefficient of the substance could not be experimentally determined; the partition coefficient was reported as log Kow < 0.3 - > 6.2. Therefore, a representative ester of the UVCB substance was used for purposes of predictive modeling using EPI-Suite. The representative ester was identified based on a molecular weight that was within the training set range of the relevant EPI-Suite models, and a structure which was biased to maximise the potential for environmental exposure, based on the predicted values for water solubility, partition coefficient and adsorption coefficient. The predicted partition coefficient for the representative ester was log Kow = 9.9576. This value is above the threshold for the screening criterion (i.e., log Kow ≤ 4.5), at or below which a substance may be considered as both “not bioaccumulative” (“not B”) and “not very bioaccumulative” (“not vB”). Since the predicted value of partition coefficient exceeds this screening threshold, the substance may be considered to be potentially bioaccumulative (“potentially B”).

 

However, additional evidence indicates that the substance is unlikely to be very bioaccumulative. ECHA guidance states that “although log Kow values above eight can be calculated, they cannot usually be measured reliably. Such values should therefore be considered in qualitative terms only…Based on current knowledge, for PBT assessments, a calculated log Kow of 10 or above is taken as an indicator of reduced bioconcentration” (ECHA, November 2014.Guidance on Information Requirements and Chemical Safety Assessment. Chapter R.7c: Endpoint-specific guidance, Version 2.0. Section R.7.10.3.4, p. 26). Therefore, although the substance may be considered as potentially bioaccumulative, it is not considered to be very bioaccumulative; the predicted partition coefficient of the representative ester (log Kow = 9.9576, equivalent to log Kow = 10 at two significant figures) meets the indicator of reduced bioconcentration (log Kow ≥ 10). The UVCB contains substantial proportions of linseed oil and tall oil triglycerides and diglycerides derivatized with maleic anhydride and methyl esters; these constituents have higher molecular weights than the representative ester and therefore lie outside of the training set range of the KOWWIN v1.68 model. These more complex, higher-molecular weight constituents have predicted partition coefficient values that greatly exceed the indicator of reduced bioconcentration (log Kow ≥ 10). Therefore, the substance is considered as potentially bioaccumulative (potentially P), but not very bioaccumulative (not vB).

 

Toxicity: A definitive determination regarding the mammalian toxicity of the substance indicates that the substance is not toxic. With respect to mammalian toxicity, the substance has not been classified as “carcinogenic, mutagenic or toxic for reproductive toxicant” (CMR) and has not been classified as “STOT RE” with respect to chronic exposures; these are definitive determinations of “not T” with respect to mammalian toxicity.

 

The results of the short-term aquatic toxicity tests indicate that that the substance is presumably “not toxic” (“not T”) when compared to the screening criteria for short-term aquatic toxicity.  The EC₅₀ values for algal growth inhibition and short-term daphnid toxicity to the substance, and short-term fish toxicity to tetrapropenyl succinic anhydride (based on read-across) were each reported at > 100 mg/L. Since the substance was predicted to have a log Kow ≥ 10, indicating a reduced potential for bioaccumulation, and because both inherent biodegradability and significant mineralisation were observed in a ready biodegradability test, the substance may be considered as presumably "not T" for both acute and chronic exposures. The substance is "not T" with respect to mammalian toxicity, based on definitive criteria (the substance has not been classified as “carcinogenic, mutagenic or toxic for reproductive toxicant” (CMR) and has not been classified as “STOT RE” with respect to chronic exposures). The substance is "not T" with respect to aquatic toxicity, based on the screening criterion (the lowest L(E)C₅₀ for all three trophic levels is ≥ 0.01 mg/L). 

 

Conclusions: Any determination based on screening criteria requires that “each of the three properties persistency, bioaccumulation and toxicity need to be considered in conjunction” (Chapter R.11, “PBT Assessment”, Guidance on information requirements and chemical safety assessment, ECHA, May 2008, Section R.11.1.2.2, p. 13). Therefore, the substance is considered as “not PBT “(potentially P, potentially B and presumably not T) and “not vPvB” (not vP, unlikely to be vB).