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PBT assessment

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PBT assessment: overall result

Type of composition:
legal entity composition of the substance
State / form:
solid: particulate/powder
Related composition:
Reference substance:
PBT status:
the substance is PBT / vPvB

An evaluation of the inherent properties of T003421 is performed against the ANNEX XIII criteria. If insufficient data were available, the screening criteria as laid down in ECHA Guidance on information requirements and chemical safety assessment Chapter R.11: PBT Assessment (2014) were applied.



The persistency assessment is based on the screening criteria in Annex XIII of the REACH Regulation. The biodegradation potential of the test substance has been assessed in a OECD 301B study (Desmares-Koopmans, 2016). The substance is considered to be not readily biodegradable, no signifcant biodegradation was observed (<3% under the conditions of the test). No hydrolysis study has been performed with the substance. The water solubility of the test item is <0.020 mg/L, no analytical method was available to support the hydrolysis test at this low concentration level. The test on the hydrolysis could therefore not be performed.

The low level of biodegradation observed in a modified Sturm test may be misleading since the test used a concentration higher than the expected water solubility of the test substance and so most of the added substance would most likely not be available for biodegradation (the test item tended to float on the water surface). However, a conservative approach was followed and the substance has been classified as potentially P/vP.



The bioaccumulation assessment is based on the screening criteria in Annex XIII of the REACH Regulation. The measured log n-octanol/water partition coefficient (log Pow) of the test substance was determined to be > 7.2 in the study performed (Ciric, 2017) which may indicate a potential for bioaccumulation.

Octanol-water partitioning has become a common method for evaluating the potential of a substance to bioaccumulate; however, a major disadvantage of octanol-water partitioning is that experimental determination can be subject to very large measurement errors. For hydrophobic substances such as T003421, the screening log Kow value of > 7.2 should be treated with care as log Pow>4.5 suggests potentially B or vB properties in aquatic organisms; however, at very high log Pow (>6), a decreasing relationship between the two parameters is observed.

No full bioaccumulation test with T003421 is available but the estimated BCF value (using the measured log Kow value) is 1.06 E+4 L/kg ww (BCFBAF v3.01 program; Estimation Programs Interface Suite™ for Microsoft® Windows v 4.11., US EPA), which indicates that the substance fulfills the screening criteria in Annex XIII of the REACH Regulation for bioaccumulation assessment (BCF > 2000 L/kg ww). Moreover as the BCF is > 5000 L/Kg, the substance is considered to have potentially very bioaccumulative properties (vB).

Based on the structure of the parent molecule, predictions of the structures of the breakdown products/metabolites were made using the QSAR model/expert system EAWAG-BBD Pathway Prediction System.

The prediction showed that the 2,2 -dimethylpropanoic acid (CAS 75-98-9) parts split off from the parent compound leading to a remaining part (C(O)(=O)C1C(O)(C(O)(C(O)(C(O1)Br))) of which the predicted log Kow value was -1.74 (KOWWIN v1.68). The aerobic likelihood of the prediction was “very likely”. Therefore, the breakdown product/metabolite of the substance is considered not to meet the B/vB criterion.




The toxicity assessment is based on the criteria in Annex XIII of the REACH Regulation. The lowest reported chronic toxicity data is above the cutoff value of 0.01 mg/L (21d-NOEC = 0.0276 mg/L for daphnia). The test substance is not classified as carcinogenic (Cat. 1 or 2), as mutagenic (Cat. 1 or 2), or as reproductive toxicant (Cat. 1, 2 or 3), nor as STOT RE Cat. 1 or 2 according to the Regulation EC N° 1272/2008. Hence, it does not fulfill the criteria to be considered as Toxic.


The substance is considered to be potentially P/vP and vB but does meet the T criteria. To conclude, T003421 should be considered a PBT or a vPvB substance according to the EU criteria.