Reaction products of 2,2'-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane with maleic anhydride and methacrylic acid

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Modified Small Vinyl Ester is a highly viscous prepolymer, which is placed on the market for industrial use only as an approximately 50% solution in a reactive diluent. Modified Small Vinyl Ester solutions are used under controlled conditions to ensure safe use and to avoid release of primarily the reactive diluent to the environment. Direct and indirect exposure of water is assessed to be negligible and long-term effects in aqueous species are judged to be unlikely.

Persistent: In case of incidental release to the environment, when exposed to light, Modified Small Vinyl Ester will polymerise to an extremely stable polymer that is highly insoluble in water. This property means the substance meets the persistent (P) and very persistent (vP) criteria based on biodegradation and hydrolysis. Ready biodegradability of Modified Small Vinyl Ester was assessed in a modified Sturm test compliant with GLP and, although Modified Small Vinyl Ester did not inhibit microbial activity in the toxicity control, no significant biodegradation occurred. The longest hydrolysis half-life in freshwater of the constituents of Modified Small Vinyl Ester is 85 days at 20 °C (at pH=7), which is greater than the P-criterion (half-life of < 40 days).

Bioaccumulation: In case of incidental release to the environment, Modified Small Vinyl Ester is considered unlikely to bioaccumulate in aquatic organisms. The octanol-water partition coefficient (Kow) for Modified Small Vinyl Ester was determined using the HPLC method at neutral pH and at pH = 1.5 to be 4.3, which is below the Bioaccumulation (B) criterion of <4.5 and on this basis the substance does not meet the B-criterion.

Toxicity: In case of incidental release to the environment, Modified Small Vinyl Ester is unlikely to be toxic to aquatic organisms at the water solubility of the substance, which is above the T-criterion of < 0.01 mg/L NOEC for freshwater or marine organisms.

In conclusion, Modified Small Vinyl Ester meets the P-criterion, but is not considered to be a PBT substance based on its unlikely potential for bioaccumulation and low toxicity.

Likely routes of exposure:

Modified Small Vinyl Ester is produced in closed systems under controlled conditions and is used by industrial and professional users, only. Release to the environment is evaluated to be incidental only. If Modified Small Vinyl Ester is incidentally released to the environment, it will polymerise to an extremely stable polymer, binding all Modified Small Vinyl Ester covalently in the polymer matrix that is highly insoluble in water. The final articles manufactured from Modified Small Vinyl Ester are extremely stable at normal temperature and pressure. Thus, exposure of the aqueous environment is evaluated to be negligible.