Bis(isopropyl)naphthalene

PBT assessment

PBT assessment: overall result

PBT status:

the substance is handled as if it were a PBT/vPvB

Justification:

The criteria given in the “Guidance on information requirements and chemical safety assessment, chapter R.11: PBT Assessment” (ECHA, 2017) are used to decide if the substance fulfils the PBT or vPvB criteria.

Persistence Assessment

Bis(isopropyl)naphthalene (DIPN) is an isomeric mixture, which consist of seven isomers (1,3-, 1,4-, 1,5-, 1,6-, 2,6- and 2,7-DIPN).Biodegradation potential differs between the isomers.The isomers 1,3-DIPN and 1,4-DIPN which were less degradable on screening test level were also stable in surface water simulation tests according to OECD 309. However, based on volatility the dissipation time from water phase was very short. The determined DisT50 values were below 2 days indicating a rapid evaporation from the water phase, which means that the results of the OECD 309 studies are not sufficient for a final persistence assessment. Therefore, QSAR estimates for the degradation of DIPN in the sediment and soil compartments were considered additional in a weight of evidence approach. For degradation in sediment the QSAR prediction is persistent (P) and/or very persistent (vP). For the soil compartment the QSAR prediction leads to a “borderline result” with a DT50 close to the P threshold of 120 days. Both QSARs can be considered as reliable since the constituents are in the applicability domain of the model. Based on experimental study results and QSAR estimates, it can be assumed that bis(isopropyl)naphthalene (CAS 38640-62-9) contains persistent and/or very persistent isomers. Therefore the isomeric mixture bis(isopropyl)naphthalene (CAS 38640-62-9) needs to be assessed as potentially persistent (P) and/or very persistent (vP).

 

Bioaccumulation Assessment

Bis(isopropy)naphthalene (DIPN) is an isomeric mixture, which consist of seven isomers (1,3-, 1,4-, 1,5-, 1,6-, 2,6- and 2,7-DIPN). Bioaccumulation potential differs between the isomers. According to OECD 305 the lipid normalized BCF values were determined to range between 810 -2500 (low dose group; 0.47 µg/L) and 2200-7800 (high dose group; 4.85 µg/L), respectively. Hence, some isomers of bis(isopropyl)naphthalene fulfil the criterion of being bioaccumualtive (BCF > 2000). Although the environmental relevance of the results from the high exposure concentration is questionable the highest measured BCF value of 7800 was used as an worst case assumption for the bioaccumulation assessment. Therefore, the isomeric mixture bis(isopropyl)naphthalene (CAS 38640-62-9) was assessed as bioaccumulative (B) and potentially very bioaccumulative (vB) under environmental conditions.

Toxicity Assessment

In a long-term toxicity study on Daphnia magna following OECD guideline 211 a NOEC (21d) of 0.0118 mg/L (measured, TWA) based on the reproduction rate was determined. Based on available data, the substance is not classified as carcinogenic (category 1A or 1B), germ cell mutagenic (category 1A or 1B), or toxic for reproduction (category 1A, 1B or 2) according to Regulation EC No 1272/2008. Hence, the T criterion is not fulfilled.

In conclusion, the substance is handled as if it were a vPvB substance