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PBT assessment

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PBT assessment: overall result

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

Persistency Criterion: 

The results of a ready biodegradability study based on the OECD Guideline 301D, Closed Bottle Test (Madsen, 1994) indicated that the test material was susceptible to biodegradation based upon the O2consumption values of approximately 22% of ThOD by day 28. While these results did not allow for the characterization of “readily biodegradable” the results do indicate that the test material undergoes degradation under test conditions that are less than optimal for biodegradation. Additionally, the data suggested that the inability to achieve the characterization of “ready” was a function of some degree of toxicity of the test material to the activated sludge microorganisms. In a second study, Davis and Hawes, 2010 were unable to demonstrate biodegradability of the test material due to microbial toxicity associated with the amine.

 

With regard to the toxicity of aliphatic amines to sludge microbial biomass, numerous studies have demonstrated toxicity of aliphatic amines at test substance concentrations that are typical for screening assays of biodegradation. More importantly, others (Yoshimura, et al., 1980[1], van Ginkel at al., 2008[2], 1993[3]) have shown that when these aliphatic amines are tested for biodegradability at test concentrations at environmentally realistic concentrations (i.e.,mg/L) which are typically below the toxicity threshold, that biodegradation does occur. In these studies the authors attribute false negative results in biodegradability screening studies to the microbial inhibition at standard testing concentrations (i.e., mg/L). 

 

Further, Matsui and Furuhashi, 1995[4], Watkins and Morgan, 1990[5]and Olson et al., 1999[6]have demonstrated the biodegradability of branched aliphatic hydrocarbons.  These data support the position that branched aliphatics compounds biodegrade when microbial toxicity issues are mitigated.

 

The biodegradation of the test material was also predicted to occur by Quantitative Structure Activity Relationship [QSAR] analysis using the BIOWIN2, 3 and 6 sub-models resident within the USEPA EPIWIN QSAR model. The BIOWIN2 sub-model [Non-linear Model Prediction] estimate was: Biodegradesfast, with a non-linear probability of 0.833. [non-linear probability ≥ 0.5 is indicative of rapid biodegradation]. The BIOWIN3 ultimate biodegradation time frame equaled “Weeks” with a probability of 2.9 [Results classification 2: months; 3 weeks]. Finally, the BIOWIN6 sub-model [MITI Non-linear Model] results were: Biodegrades Fast; the MITI non-linear probability was 0.6864 [MITI non-linear probability ≥ 0.5 is indicative of ready biodegradability].  

 

Based on the measured biodegradation data, the potential for microbial toxicity of the aliphatic amines at typical screening level test substance concentrations, the general biodegradability of linear and branched aliphatic hydrocarbons and finally the QSAR estimates, the weight of evidence indicate that the test material is not persistent.

 

Therefore the test material is not persistent.

 

Bioaccumulation Criterion:

A substance fulfils the bioaccumulation criterion (B-) when:

– the bioconcentration factor () is higher than 2000.

With a LogP (octanol/water) of 2.9 (≤ 4.5) the test material is not predicted to be bioaccumulative and therefore would not be classified as bioaccumulative.

 Because a measured aquaticvalue is not available thefor fish can be predicted from the relationship between Kow and.  For purposes of this analysis the measured Log Kow of 2.9 was used as the basis for thederivation. Equation [74] of the TGD was employed assuming a Log Kow of between 2 and 6 and using the equation illustrated below as developed by Veith et al. (1979)[7]: 

 

Log BCFfish= 0.85 * Log Kow – 0.70

 

           where LogKow = 2.9 based on measured data

 

Based on this equation the calculated Log BCFfishequals: 1.765; 

 

Therefore the estimated BCFfish= 58.21

 

Similarly the terrestrial bioconcentration factor (BCFearthworm) for the test material has been estimated using QSAR according to the model generated by Jager (1998)[8]. The model was supported by data with neutral organic chemicals in soil within the range Log Kow of 3 – 8 and in water only experiments of Log Kow 1 – 6. An application range of Log Kow 1 – 8 is advised. 

 

Therefore the model is appropriate for the test material. For organic chemicals, the main route of uptake into earthworms will be via the interstitial water. Bioconcentration can be described as a hydrophobic partitioning between the pore water and the phases inside the organism and can be modeled according to the following equation [82d in the TGD]: 

 

BCFearthworm= (0.84 + 0.012Kow)/RHOearthworm= 10.4

 

where the default RHOearthwormvalue = 1.0.

 

Based on the estimated BCFfishand BCFearthwormof 58.21 and 10.4, respectively, the test material is not considered bioaccumulative. 

 

Toxicity Criterion:

A substance fulfils the toxicity criterion (T-) when:

– the long-term no-observed effect concentration (NOEC) for marine or freshwater organisms is less than 0.01 mg/l, or

– the substance is classified as carcinogenic (category 1 or 2), mutagenic (category 1or 2), or toxic for reproduction (category 1, 2, or 3), or

        there is other evidence of chronic toxicity, as identified by the classifications: T, R48, or Xn, R48 according to Directive 67/548/.

A long-term toxicity test (early life-stage toxicity test) with rainbow trout (Oncorhynchus mykiss) exposed to the test material and conducted for 96 days under GLPs and following OECD Guideline 210 resulted in a NOEC for the most sensitive endpoint (blotted wet weight) of 0.078 mg/L.

The test material is not classified as carcinogenic (category 1 or 2), mutagenic (category 1or 2), or toxic for reproduction (category 1, 2, or 3).

The test material is not classified as R48, or Xn, R48 according to Directive 67/548/EEC.

 

Therefore, the test material is not considered Toxic.


[1]K. Yoshimura1,1and F. Masuda. 1980. Biodegradation of long chain alkylamines. Journal of the American Oil Chemists' Society 57(7). P 238-240.

[2]van Ginkel, C. G.; Gancet, C.; Hirschen, M.; Galobardes, M.; Lemaire, Ph.; Rosenblom, J. Chemosphere (2008), 73(4), 506-510.

[3]VanGinkel, C. G.; Stroo, C. A.; Kroon, A. G. M. Tenside, Surfactants, Detergents (1993), 30(3), 213-16.

[4]Matsui, Toru; Furuhashi, Keizo; Bioscience, Biotechnology, and Biochemistry (1995), 59(7), 1342-4.

[5]Watkinson, Robert J.; Morgan, Philip.   Biodegradation (1990), 1(2-3), 79-92.

[6]Olson, Jennifer Jean; Mills, Gary L.; Herbert, Bruce Eric; Morris, Pamela J. Environmental Toxicology and Chemistry (1999), 18(11), 2448-2453.

[7]Veith GD, Defoe DL and Bergstedt BV (1979).Measuring and estimating the bioconcentration factor of chemicals in fish. J. Fish Board36, 1040-1048.

[8]Jager T (1998). Mechanistic approach for estimating bioconcentration of organic chemicals in earthworms (Oligochaeta). Environmental Toxicology and Chemistry17(10), 2080-2090.