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Environmental fate & pathways

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The preliminary study showed that at each of pH 4, 7 and 9 and 50±0.5ºC, greater than 50% hydrolysis had occurred after 2.4 hours, equivalent to a half-life of less than 1 day under environmental conditions (25°C).

As a consequence, when release into water 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate will rapidly be transformed into due to its instability. That is the reason why the assessment of the bioaccumulation potential will be based on the bioaccumulation potential of degradation substances: neodecanoic acid and 2-methyl-2,4-pentanediol.

A computer simulation via EPI Suite TM (using an experimental log Kow of 4.2, coming from the Klimisch-1-rated study of GRL 2009, see section 4.7 “Partition coefficient”) gave a BCF for the concerned substance of 274 L/kg wet-wt, which is below the trigger value of BCF = 500 for classification with respect to chronic aquatic toxicity:

Bioaccumulation Estimates (BCFBAF v3.00):

  Log BCF from regression-based method = 2.438 (BCF = 274.3 L/kg wet-wt)

  Log Biotransformation Half-life (HL) = -0.2198 days (HL = 0.6029 days)

  Log BCF Arnot-Gobas method (upper trophic) = 2.345 (BCF = 221.4)

  Log BAF Arnot-Gobas method (upper trophic) = 2.345 (BAF = 221.4)

      log Kow used: 4.20 (user entered)

 

With regards to the two breakdown substances: neodecanoic acid and 2-methyl-2,4-pentanediol a computer simulation via EPI Suite TM was also done.

Neodecanoic acid:

Bioaccumulation Estimates (BCFBAF v3.00):

  Log BCF from regression-based method = 0.500 (BCF = 3.162 L/kg wet-wt)

  Log Biotransformation Half-life (HL) = 0.1593 days (HL = 1.443 days)

  Log BCF Arnot-Gobas method (upper trophic) = 2.548 (BCF = 353.1)

  Log BAF Arnot-Gobas method (upper trophic) = 2.548 (BAF = 353.4)

      log Kow used: 3.90 (estimated)

 

2-methyl-2,4-pentanediol

Bioaccumulation Estimates (BCFBAF v3.00):

  Log BCF from regression-based method = 0.500 (BCF = 3.162 L/kg wet-wt)

  Log Biotransformation Half-life (HL) = -1.4535 days (HL = 0.0352 days)

  Log BCF Arnot-Gobas method (upper trophic) = 0.052 (BCF = 1.127)

  Log BAF Arnot-Gobas method (upper trophic) = 0.052 (BAF = 1.127)

      log Kow used: 0.58 (estimated)

 

Based on the available information it is therefore proposed that the study on bioaccumulation of 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate and its degradation substances can be waived, which is in accordance to the intention of the REACH regulation to minimize animal consumption by conducting unnecessary vertebrate studies.