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Classification & Labelling & PBT assessment

PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB
Justification:

Parent compound:


DTDA (CAS 101012-97-9)is not readily biodegradable. Therefore, the substance is assessed to be potentially P/vP from a precautionary point of view.


The substance has a log Kow of > 4.5 (log Kow > 7.5; see IUCLID CH. 4.7); therefore, the substance fulfils the screening criteria for B/vB substances. However, as the log Kow is not a relevant measure for ionising substances, the bioaccumulation factors were estimated for the constituents of DTDA using a valid QSAR model (BCF base-line model v04.11, OASIS Catalogic v5.14.1.5). All BCF values were clearly below the critical value of 2000. Therefore, the substance does not fulfil the criteria for B/vB substances.


Referring to the available ecotoxicity data, the lowest acute EC50 was clearly larger than the screening value of 0.01 mg/L for T substances. The only available chronic value for algae is also above the critical value for T substances. The substance does not hold any relevant classification according to Regulation EC no 1272/2008. A long-term toxicity study on aquatic invertebrates is planned to fulfil the information requirements. Therefore, the assessment should be regarded as preliminary.


It can be concluded that the substance is assessed to be neither PBT nor vPvB.


 


Predicted metabolites of the branched and linear isomers C26H54 -NH:


The model CATALOGIC 301C v11.16 (OASIS Catalogic v5.14.1.5) was used to predict potential metabolites of the isomer C26H54-NH, which represents the isomer with the highest percentage of the Substance (92 to 94%). In order to take account of the effect of linear and branched structures, a linear isomer and a highly branched molecule were used for the prediction. Both isomers were completely within the applicability domain of the model (100%).


In case of the linear isomer 51 metabolites were predicted with 4 metabolites with a fraction of > 0.001 mol/mol parent, which is equivalent to > 0.1% (see IUCLID Ch. 5.2.1, 5.3.1 for more details). All four metabolites were predicted to be readily biodegradable (63–76% BOD of ThOD in 28 d). Therefore, the relevant metabolites of the linear isomer are assessed to be neither P nor vP.


In addition, the log Kow of these relevant metabolites and their BCF were also predicted to assess their bioaccumulation potential. The log Kow was > 3 for two of these metabolites indicating that bioaccumulation is possible; however, the predicted BCF values were < 2000 L/kg with a maximum BCF of 1549. Three out of these four metabolites were within the applicability domain of the BCF model. The metabolite “CCN” was out of the AD; however, the substances log Kow is very low indicating no significant potential for bioaccumulation. Therefore, it can be concluded that these metabolites do not meet the criteria for B/vB substances.


The number of metabolites was higher for the branched isomer (n = 95) with 24 reaching a quantity of > 0.001 mol/mol parent (see IUCLID Ch. 5.2.1, 5 .3.1 for more details). Four of the relevant metabolites are predicted to be readily biodegradable. The remaining 20 relevant metabolites reach a BOD between 35 to 56% BOD of ThOD in 28 d and should be regarded as not readily biodegradable. 14 of these metabolites have a log Kow < 3 (range: -1.7 to 2.9) as well as a low BCF (max. BCF = 5.25 L/kg). Six of these non-readily biodegradable metabolites have a log Kow > 3; however, the BCF was predicted to be < 2000 (range: 5.5 to 107 L/kg). It should be noted that 3 out of these 6 metabolites were not within the applicability domain of the BCF base-line model. However, the deviation from the applicability domain is minimal. These metabolites were completely within the parametric, structural, and mechanistic subdomains. In case of the metabolic domain, 100% of the atom-centered fragments (ACF) were identified as fragments present in the training chemicals. More than 93% of the metabolites’ ACF were identified as “fragments in correctly predicted training chemicals” (93.3 to 96.3%) and only the remainder of the ACF were identified as “non-correctly predicted training chemicals” (3.7 to 6.7%). Therefore, the predicted BCF values can be regarded as sufficiently reliable for this screening assessment. The metabolites are assessed to be potentially P/vP from a precautionary point of view, but they do not meet the criteria for B/vB substances.


Besides QSAR modelling, the relevant degradation products were also checked if they were registered under the REACH Regulation 1907/2006. None of the substances were registered in the ECHA disseminated database. It can be concluded that none of the predicted and relevant metabolites meet the criteria for P/vP as well as B/vB substances; therefore, they are not PBT and not vPvB.


Their toxicity (T) was not further assessed as no critical combination of potential P/vP (= not readily biodegradable) and potential B/vB (log Kow > 3) properties was observed.


 


In conclusion, DTDA (CAS 101012-97-9) and its predicted metabolites are assessed to neither fulfill the PBT criteria (not PBT) nor the vPvB criteria (not vPvB).

Likely routes of exposure:

Because the substance does not fulfill the PBT and vPvB criteria, no emission characterisation is performed.