1-[4-(1,1-dimethylethyl)phenyl]-3-(4-methoxyphenyl)propane-1,3-dione

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Persistence

Experimental data on the hydrolysis of the substance is not available as the study was waived due to the extremely poor water solubility of the test item of 0.027 mg/L. Both a study on anaerobic biodegradability and a study on (aerobic) inherent biodegradability revealed that the substance is not biodegradable. 

Two guideline compliant biodegradation simulation tests were carried out demonstrating that the test item is degrading in the water phase relatively fast. The half-life, DT50, of the parent compound in natural water at 12 °C was determined in accordance with OECD TG 309 to be 10.8 days at high dose (0.015 mg/L) and 10.2 days at low dose (0.005 mg/L). Under sterile conditions the parent compound degraded slower than in non-sterile conditions. The half-life at 12 °C was 54.7 days at a concentration of 0.015 mg/L. The half-life, DT50, of the parent compound in freshwater sediment was determined in accordance with OECD TG 308 to be 111 days at 12 °C in a river water/sediment system. The half-life in the river water phase was 0.13 days at 12 °C and from the entire river water/sediment system the DT50 was determined to be 72.1 days at 12 °C. Using a pond water/sediment system, the DT50 for the parent compound in the sediment phase was 139 days at 12 °C, for the pond water phase 1.4 days at 12 °C and for the entire pond water/sediment system, the DT50 was 99 days at 12 °C. It is thus concluded that the substance fulfils the P criterion since the DT50 in freshwater sediment is > 120 days, but not vP, as the DT50 in freshwater is ≤ 60 days and the DT50 in freshwater sediment is clearly below 180 days. The substance is therefore considered P, but not vP in accordance with the criteria laid down in Annex XIII of Regulation (EC) no 1907/2006 (REACH).

 

Bioaccumulation

Experimental data are available from a GLP-compliant OECD 305-III study (Burri, 2011; please refer to IUCLID Section 5.3.1 for robust summary of this study). The BMF combined corrected for growth and lipid content was BMFkgl = 0.1218. The experimentally determined BMF was translated into BCF values according to ECHA guidances and OECD calculation template. The BCF of BMDBM is considered to be in the range between 2000 and 3000, thus fulfilling the B criterion of BCF ≥ 2000, but not the vB criterion of BCF ≥ 5000. A detailed Weight of Evidence assessment on the bioaccumulation potential of the substance according to REACH Annex XIII criteria and ECHA guidance documents is attached to IUCLID Section 13.2.

 

Toxicity

Neither short-term, nor long-term ecotoxic effects were detected up to and including the water solubility limit of the substance. The criterion of EC10 or NOEC ≥ 0.01 mg/L for non-T properties is thus regarded fulfilled. Further, the substance is not classified as carcinogenic (category 1 or 2), mutagenic (category 1 or 2), or toxic for reproduction (category 1, 2 or 3) according to Directive 67/548/EEC or 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. No other evidence of chronic toxicity, as identified by the classifications T, R48 or Xn, R48 according to Directive 67/548/EEC or specific target organ toxicity after repeated exposure (STOT RE category 1 or 2) according to Regulation (EC) No 1272/2008. In conclusion, the substance does not fulfil the T criteria laid down in Annex XIII of Regulation (EC) 1907/2006 and hence the substance is considered "not T".

 

Conclusion on PBT/vPvB

The substance has been evaluated to be P and B, but not vP, vB or T. The substance is therefore neither classified PBT, nor classified vPvB in accordance with the criteria laid down in Annex XIII of Regulation (EC) 1907/2006 (REACH).