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PBT assessment

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PBT assessment: overall result

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

1.   Persistence Assessment

Biological oxygen demand (BOD) measurements after 28 days incubation of the test substance with sewage sludge indicated a maximum of 6 % degradation, and analytical determinations of the residual compound in the BOD bottles indicated a maximum of 3 % degradation. The result of this test indicates that the BDP is not readily biodegradable.

In addition, hydrolytic degradation study of BDP indicates that the half-life for BDP is estimated to be >1 years based on a hydrolysis rate constant at pH 4, 7, 9 and 25 °C. Thus, BDP is stable in water.

According to the available information, we can not reach a conclusion that BDP is persistence or not. In order to obtain a definite result, inherent biodegradation and simulation testshould be furtherperformed.However, the initialCSAshows that in theinvestigateduse scenarios, BDPisused in a closed processwithno likelihood of exposureand the calculated risk of BDP is low (see section 10).Therefore, currently there is no concern of further information.

2.   Bioaccumulation Assessment

The criterion used in the risk assessment for bioaccumulation is a bioconcentration factor (BCF) >2,000L/kgaccording toChapter R.11ofGuidance on information requirements and chemical safety assessment(2008),Based on the QSAR,bioconcentration factor(BCF) values of BDP vary from/kg to66.07L/kg (please refer to section4.3), which is much low than “B” criteria.

Furthermore,BCF was determined via a Bioconcentration Test (Semi-Static System) to Zebra-fish (Brachydanio rerio) in accordance with OECD Test Guideline 305.The study was conducted under semi-static conditions with the nominal concentration of 0.4 mg/L and solvent control for a period of 33 days. 250 test fish were used for each treatment and equally divided into 10 test containers. The test solution was renewed once every two days. During the exposure time, the mortality, number of abnormal fish and abnormal behavior of fish was observed and recorded once a day. The water sample and fish sample were taken to analyze the concentration of the test substance (BDP). The bioconcentration factor (BCF) value was calculated as the ratio (as BCFss) of concentration in the fish (Cf) and in the water (Cw) at the apparent steady-state. BDP was stable under test condition.During the test, based on the nominal concentration of 0.4 mg/L, the mean measured concentration of BDP test solution was 0.37 mg/Land standard deviation was 0.04.The steady state bioconcentration factorBCFsswas determined to be 5, which therefore showed BDP is not bioaccumulative in Zebra fish (Brachydanio rerio).

Thus, BDP is regarded as a non-bioaccumulative substance.

3.   Toxicity Assessment

A reliable report named Flame Retardant Alternatives, which wasconducted by Syracuse Research Corporation for the Washington State Departments of Ecology and Health, indicates that Experimental fish NOEC values of BDP was 5 mg/L (Syracuse Research Corporation,2006), which was much greater than the estimated water solubility for pure BDP. So it suggested that BDP has no effect to fish at saturation.

 

The acute tests on rainbow trout, Daphnia magna and algal were all Static Limit Tests for the low solubility of BDP. The tests were all performed with nominal concentration of the test material of 1.0 mg/L.The results of these tests indicate that the BDP is not toxic to this species up to the limits of its water solubility.

Furthermore, two long-term tests on fish and daphnia were conducted respectively in accordance with OECD TG 210 and 211. The results of both tests showed the NOECs were both over 0.4 mg/l, which were also above the water solubility of BDP.

The criterion used in the risk assessment for toxicity assessment is NOEC<0.01mg/L. In addition, BDP is not CMR substance. Therefore based on the current knowledge, BDP is not classified as toxic.

4.   Summary and overall Conclusions on PBT or vPvB Properties

BDP is neither PBTnor vPvB substance.

Likely routes of exposure:

Not likely to be exposed to either worker or public population.