Methyl 12-hydroxyoctadecanoate

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

The substance exhibited ready degradability in a ready biodegradability CO₂ evolution test (i.e., 80% degradation in 28 days, meeting the 10-d window).  Therefore, although a definitive determination has not been made, the substance is considered “not P” and “not vP” based upon the screening criteria.

Aquatic bioaccumulation testing was not conducted on the substance, and therefore the bioaccumulative properties of the substance cannot be definitively determined. One screening-level datum indicates that the substance may be potentially bioaccumulative (potentially B) and potentially very bioaccumulative (potentially vB); this datum is the predicted octanol-water partition coefficient (log Kow) of 6.69, which is above the screening criterion (log Kow ≤ 4.5) for both “not B” and “not vB”. However, available information indicates that the substance exhibits a low potential for aquatic exposure, based on its very low water solubility (estimated at 0.08994 mg/L) and moderate adsorption to soils, sediment and activated sludge (estimated log Koc = 3.5638).  Additional information indicates that the substance exhibits a low potential for bioaccumulation. The substance is composed of a methyl ester of a fatty acid, and is expected to be rapidly metabolised in vertebrates, indicating that the potential for bioaccumulation may be much lower than that predicted by the partition coefficient. The bioconcentration factor (BCF = 511 L/kg w.w.) predicted by a validated QSAR model (EPI Suite BCFBAF v3.01) is substantially below the criteria for both bioaccumulative (BCF > 2000) and very bioaccumulative (BCF > 5000).  Therefore, although there are multiple lines of evidence (including toxicokinetics and QSAR modeling) indicating that the substance is unlikely to be bioaccumulative, the substance is considered “potentially B” and “potentially vB”, in the absence of a definitive determination.

The evaluation of short-term aquatic toxicity tests indicates that the substance does not exhibit aquatic toxicity. Toxicity studies conducted on an analogue substance (methyl myristate) through read-across reported values of 96-h NOEC = 1000 mg/L, 48-h NOELR = 100 mg/L and 72-h NOErLR = 100 mg/L from acute fish toxicity, acute daphnid immobilisation and algal growth inhibition studies. These studies revealed an absence of observed toxicity to aquatic organisms, indicating that the short-term toxicity of the substance is substantially above the screening criterion for potential aquatic toxicity (EC50 or LC50 < 0.1 mg/L).  These results support the finding that the substance is "not T" to aquatic life. The substance does not exhibit the properties of a carcinogenic, mutagenic or reproductive toxicant (CMR), nor does the substance exhibit specific target organ toxicity in a repeated-dose study (STOT-RE). These results provide a definitive determination that the substance is "not T" with respect to mammalian endpoints.

Therefore, although a complete definitive determination cannot be made with respect to all endpoints, it has been shown by definitive criteria that the substance is “not T” (mammalian toxicity); by screening criteria that that the substance is “not P”, “not vP and “not T” (based on aquatic toxicity); and in the absence of definitive information, assumed that the substance is “potentially B” and “potentially vB”.  It is not necessary to have definitive criteria for all five endpoints to make the determinations as to whether the substance is “not PBT” and “not vPvB”. The determination only 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, Version 1.1, ECHA, November 2012, Section R.11.1.2.2, p. 15).  In summary, based on data available to date, the substance is “not PBT” (not P, potentially B, and not T based on aquatic and mammalian endpoints) and is “not vPvB” (not vP, potentially vB).