3-(2-dodecenyl)succinic anhydride

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Persistence: The results from the ready biodegradability test (screening criterion) indicated 61.56% biodegradation in 28 days, greater than 60% degradation but failing the 10-day window. Although the substance was not determined to be readily biodegradable, the results were indicative of “inherent, ultimate biodegradability”. This information is satisfactory to determine that the substance is not fulfilling the criteria for persistence (Chapter R.11, “PBT Assessment”, version 1.1,Guidance on information requirements and chemical safety assessment, ECHA, November 2012, Section R.11.1.3.1, pp. 24-25). The hydrolysis test (additional consideration) indicated rapid hydrolysis at environmentally relevant pH conditions and temperatures (i.e.; at pH 7, DT₅₀= 76 minutes at 15^oC and DT₅₀= 35 minutes at 25^oC). Each of these hydrolysis half-life values is substantially below the threshold half-life of 24 hours which provides “clear evidence of environmental degradation” (Chapter R.7.b, “Endpoint-specific guidance”, Guidance on information requirements and chemical safety assessment, ECHA, May 2008, Section R.7.9.5.3, p. 193).  Hydrolysis is the most significant abiotic degradation process, as it “may proceed effectively in aquatic, sediment and soil compartments” (Chapter R.11, “PBT Assessment”, version 1.1, Guidance on information requirements and chemical safety assessment, ECHA, November 2012, Section R.11.1.3.1, p. 19). Therefore, based on the information available, the substance is “not Persistent” (“not P”) and “not very Persistent” (“not vP”).

 

Bioaccumulation:  An experimentally-determined octanol-water partitioning coefficient for the substance was not obtained, due to rapid hydrolysis of the substance. In accordance with ECHA guidance, a “computational (in silico) method shall be used in case the test cannot be technically performed” (Chapter R.7.a, “Endpoint-specific guidance”, Guidance on information requirements and chemical safety assessment, ECHA, May 2008, Section R.7.1.8, p. 99). The predicted partition coefficient (log K_ow=4.38) is below the screening criterion (i.e., log K_ow≤4.5) to determine that the substance is “not bioaccumulative” (“not B”) and “not very bioaccumulative” (“not vB”). Additionally, the substance has been shown to undergo rapid hydrolysis at environmentally relevant pH and temperature conditions (i.e., at pH 7, DT₅₀= 76 minutes at 15^oC and DT₅₀= 35 minutes at 25^oC). Each of these hydrolysis half-life values is substantially below the threshold half-life of 12 hours, below which “it can be assumed that the rate of hydrolysis is greater than that for uptake by exposed organisms” (Chapter R.7.c, “Endpoint-specific guidance”, Guidance on information requirements and chemical safety assessment, ECHA, May 2008, Section R.7.10.3.4, p. 24). Therefore, based on the predicted partitioning behaviour of the substance and evidence of rapid hydrolysis at environmentally relevant conditions, the substance is determined to be “not B” and “not vB”.

 

Toxicity: A definitive determination regarding the mammalian toxicity of the substance indicates that the substance is not toxic. With respect to mammalian toxicity, the substance has not been classified as “carcinogenic, mutagenic or toxic for reproductive toxicant” (CMR) and has not been classified as “STOT RE”, T, 48” or “Xn, R48” with respect to chronic exposures; these are definitive determinations of “not T” with respect to mammalian toxicity.

 

The results of the short-term aquatic toxicity tests indicate that that the substance is presumably “not toxic” (“not T”) when compared to the screening criteria for short-term aquatic toxicity.  The LC₅₀for fish (based on read-across from tetrapropenyl succinic anhydride, another substance in the category) was reported at > 100 mg/L, the EC₅₀for daphnids (based on read-across from tripropenyl succinic anhydride, another substance in the category) was reported as > 100 mg/L, and the E_rC₅₀for algae (based on read-across from tetrapropenyl succinic anhydride, another substance in the category) was reported as 110 mg/L (based on cell count). Therefore, all acute toxicity L(E)C₅₀values were four orders of magnitude above the definitive aquatic toxicity criterion of L(E)C₅₀< 0.01 mg/L, and three orders of magnitude above the aquatic toxicity screening criterion of L(E)C₅₀< 0.1 mg/L. Since the substance does not exhibit the potential for bioaccumulation and has been shown to undergo rapid hydrolysis in the environment, the substance may be considered to be presumably "not T" for both acute and chronic exposures. 

 

Conclusions: Any determination based on screening criteria requires that “each of the three properties persistency, bioaccumulation and toxicity need to be considered in conjunction” (Chapter R.11, “PBT Assessment”, Guidance on information requirements and chemical safety assessment, ECHA, May 2008, Section R.11.1.2.2, p. 13). Therefore, the substance is considered to be “not PBT “(not P, not B and presumably not T) and “not vPvB” (not vP, not vB).