Registration Dossier

Classification & Labelling & PBT assessment

PBT assessment

Administrative data

PBT assessment: overall result

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

The assessment of PBT and vPvB is performed by comparison of the relevant intrinsic properties of MBS with the criteria of the REACH regulation (Annex XIII) as shown in the following table:

PBT and vPvB criteria and the corresponding properties of MBS

 Criterion

 PBT criteria  vPvB criteria  MBS  Criterion fulfilled?
 P  Half-life in marine water > 60 d, or half-life in fresh- or estuarine water > 40 d, or half-life in marine sediment > 180 d, or half-life in fresh- or estuarine water sediment > 120 d, or half-life in soil > 120 d Half-life in marine, fresh or esturarine water > 60 d, or half-life in marine, fresh or esturarine sediment > 180 d, or half-life in soil > 180 d   Not readily biodegradable (Bayer AG, 1988a) Fast hydrolysis (Monsanto, 1984) The main hydrolysis products MBT, BT and morpholine are also not readily biodegradable (MITI, 1979, 1990 and 1992) yes 
 B  BCF > 2000  BCF > 5000  The estimated BCF of MBT is 81.34 l/kg (Currenta, 2010b). The BCFs of the main hydrolysis products of MBS: -The experimentally determined BCF of MBT is lower than 8 (MITI, 1992) -The experimentally determined BCF of BT is lower than 7.5 (EU-risk assessment, 2008) -The experimentally determined BCF of morpholine is lower than 2.8 (MITI, 1979) no 
 T  Long-term NOEC for marine or freshwater organisms    Most sensitive NOEC (96h, fish) with the hydrolysis product (e.g. MBT) of MBS 0.041 mg/L  no
 T  CMR  n.a.  Not classified as CMR  no
 T  Other evidence of chronic toxicity, as identified by the classifications: T, R48, or Xn, R48 according to Directive 67/548/EEC n.a.  Not classified as T, R48, or Xn, R48 according to Directive 67/548/EEC  no 

Persistence Assessment:

MBS is not readily biodegradable, but it hydrolyzes with a half-life of ca. 24 hours at pH 7.0 and 25°C. The main hydrolysis products of MBS are MBT, BT and morpholine, and they are also not readily biodegradable. Therefore MBS is considered as persistent.

Bioaccumulation Assessment:

MBS is not bioaccumulative with an estimated BCF of 81.34 l/kg. The hydrolysis products of MBS, such as MBT, BT and morpholine, also have no bioaccumulation potential with the experimentally determined BCFs all below 10.

Toxicity Assessment

The lowest NOEC of 0.041 mg/L is reported to fish after 96 hour exposure to MBT as the main hydrolysis product of MBS, which is above 0.01 mg/l; and hence MBS does not fulfil the T criteria.

Summary and overall Conclusions on PBT or vPvB Properties

Due to both the B and T criteria are not fulfilled; MBS is neither PBT nor a vPvB substance.