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PBT assessment

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PBT assessment: overall result

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

The target substance 2 -butyloctanoic acid was demonstrated to be readily biodegradable in an OECD guideline 301 B-test.


 


Therefore the substance is not considered to be persistent (P).


 


2 -butyloctanoic acid has been calculated BCF of 3.162, meaning the BCF, meaning the BCF << 2000, therefore the substance is considered not to be bioaccumulative according to the PBT-criteria.


 


A reliable QSAR model (Ecological Structure-Activity Relationship (ECOSAR) version 1.00) was used to predict the aquatic toxicity of the test item 2 -butyl octanoic acid to fish. The 96 hour LC50 was 13.297 mg/L.


In the key study (Daphnia magna, OECD 202, GLP compliant) with the target substance 2-butyloctanoic acid the 48h-EL50 was 41.7 mg/l (95% confidence interval between 34.1 and 50.9 mg/l). In the supporting study (Daphnia magna, OECD 202, GLP compliant) the 48h-EC50 was 31 mg/l (95% confidence interval between 22 and 42 mg/l). In the ECOSAR calculation a value of 48 h-EC50 of 9.363 mg/L is predicted for an acute daphnia test with 2-butyl octanoic acid. An algae test for 2-butyl octanoic acid was conducted according to OECD 201 guidelines with Pseudokirchneriella subcapitata. The test was GLP compliant. The results of the GLP test showed that under the test conditions with Pseudokirchneriella subcapitata, the ErL50, ErL20 and ErL10 values for 2-butyloctanoic acid obtained from the 0-72 hour growth rate analyses, based on geometric mean measured loading rates, were >10.6, 8.33, and 5.46 mg/L, respectively.  In addition, the toxicity of the Source substance 1, Reaction mass of n-undecanoic-acid and 2-methyl-decanoic-acid and 2 -ethyl-nonanoic-acid and 2-propyl-octanoic-acid and 2 -butyl-heptanoic-acid, was assessed in a fresh water algal growth inhibition test with Pseudokirchnerella subcapitata according to OECD guideline 201. The ErC10 of 2.7 mg/L (95% CL 2.0 – 3.5 mg/L), NOErC of 1.3 mg/L and the ErC50 of 13 mg/L (95% CL 11 – 15 mg/L) after 72 hours of exposure can be considered reliable without restrictions. The ECOSAR calculation of the test substance 2-butyl octanoic acid confirms that range of toxicity with a 96 h EC50 value of 16.975 mg/L and a calculated 96 h NOEC of 5.067 mg/L.


 


A reliable QSAR model (Ecological Structure-Activity Relationship (ECOSAR) version 1.11) was used to predict the chronic aquatic toxicity of 2 -butyloctanoic acid to fish. The 30 day chronic value (the geometric mean of the NOEC and LOEC) was 1.675 mg/L for the neutral organic class. As per REACH Guidance Ch 10, a NOEC can be calculated from the chronic value. Therefore, the calculated NOEC = 1.184 mg/L and will be used in the assessment.


 


A reliable QSAR model (Ecological Structure-Activity Relationship (ECOSAR) version 1.11) was used to predict the chronic aquatic toxicity of 2 -butyloctanoic acid to daphnids. The 21 day chronic value (the geometric mean of the NOEC and LOEC) was 1.662 mg/L for the neutral organic class. As per REACH Guidance Ch 10, a NOEC can be calculated from the chronic value. Therefore, the calculated NOEC = 1.175 mg/L and will be used in the assessment as the key value for long-term toxicity to aquatic invertebrates.


Toxicity Aquatic toxicity tests do not indicate that 2 -butyloctanoic acid meets the criteria to be regarded as toxic (T). Furthermore the substance is not classified as carcinogenic, germ cell mutagenic, or toxic for reproduction or STOT.


 


Hence the substance does not meet the criteria to be regarded as a PBT or vPvB substance.


 


An emission characterisation for 2 -butyloctanoic acid is not needed because it is not a PBT.