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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Remarks:
This (Q)SAR falls within the domain of applicability of the test substance, and is considered suitable for contributing information in a weight-of-evidence approach for the biodegradability endpoint.
Justification for type of information:
QSAR prediction
Guideline:
other: ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.6: QSARs and grouping of chemcials. ECHA, May 2008.
Principles of method if other than guideline:
BIOWIN estimates the probability of rapid aerobic and anaerobic biodegradation of an organic compound in the presence of mixed populations of environmental microorganisms. BIOWIN contains seven separate models:
Rapid Probability Models:
 Biowin1  =  linear probability model
 Biowin2 =  nonlinear probability model
Expert Survey Models:
 Biowin3  =  expert survey ultimate biodegradation model
 Biowin4  =  expert survey primary biodegradation model
MITI Probability Models:
 Biowin5  =  MITI linear model
 Biowin6  =  MITI nonlinear model
Anaerobic Probability Model:
 Biowin7  =  anaerobic biodegradation model

Biodegradability estimates are based upon fragment constants that were developed using multiple linear or non-linear regression analyses, depending on the model.
GLP compliance:
no
Key result
Parameter:
probability of ready biodegradability (QSAR/QSPR)
Remarks on result:
readily biodegradable based on QSAR/QSPR prediction
Details on results:
SMILES : NCC=C
CHEM :
MOL FOR: C3 H7 N1
MOL WT : 57.10
--------------------------- BIOWIN v4.10 Results ----------------------------

Biowin1 (Linear Model Prediction) : Biodegrades Fast
Biowin2 (Non-Linear Model Prediction): Biodegrades Fast
Biowin3 (Ultimate Biodegradation Timeframe): Weeks
Biowin4 (Primary Biodegradation Timeframe): Days
Biowin5 (MITI Linear Model Prediction) : Readily Degradable
Biowin6 (MITI Non-Linear Model Prediction): Readily Degradable
Biowin7 (Anaerobic Model Prediction): Biodegrades Fast
Ready Biodegradability Prediction: YES

------+-----+--------------------------------------------+---------+---------
TYPE | NUM | Biowin1 FRAGMENT DESCRIPTION | COEFF | VALUE
------+-----+--------------------------------------------+---------+---------
Frag | 1 | Aliphatic amine [-NH2 or -NH-] | 0.1538 | 0.1538
MolWt| * | Molecular Weight Parameter | | -0.0272
Const| * | Equation Constant | | 0.7475
============+============================================+=========+=========
RESULT | Biowin1 (Linear Biodeg Probability) | | 0.8742
============+============================================+=========+=========

------+-----+--------------------------------------------+---------+---------
TYPE | NUM | Biowin2 FRAGMENT DESCRIPTION | COEFF | VALUE
------+-----+--------------------------------------------+---------+---------
Frag | 1 | Aliphatic amine [-NH2 or -NH-] | 1.1099 | 1.1099
MolWt| * | Molecular Weight Parameter | | -0.8108
============+============================================+=========+=========
RESULT | Biowin2 (Non-Linear Biodeg Probability) | | 0.9647
============+============================================+=========+=========

A Probability Greater Than or Equal to 0.5 indicates --> Biodegrades Fast
A Probability Less Than 0.5 indicates --> Does NOT Biodegrade Fast

------+-----+--------------------------------------------+---------+---------
TYPE | NUM | Biowin3 FRAGMENT DESCRIPTION | COEFF | VALUE
------+-----+--------------------------------------------+---------+---------
Frag | 1 | Aliphatic amine [-NH2 or -NH-] | 0.0244 | 0.0244
MolWt| * | Molecular Weight Parameter | | -0.1262
Const| * | Equation Constant | | 3.1992
============+============================================+=========+=========
RESULT | Biowin3 (Survey Model - Ultimate Biodeg) | | 3.0974
============+============================================+=========+=========

------+-----+--------------------------------------------+---------+---------
TYPE | NUM | Biowin4 FRAGMENT DESCRIPTION | COEFF | VALUE
------+-----+--------------------------------------------+---------+---------
Frag | 1 | Aliphatic amine [-NH2 or -NH-] | 0.0433 | 0.0433
MolWt| * | Molecular Weight Parameter | | -0.0824
Const| * | Equation Constant | | 3.8477
============+============================================+=========+=========
RESULT | Biowin4 (Survey Model - Primary Biodeg) | | 3.8086
============+============================================+=========+=========

Result Classification: 5.00 -> hours 4.00 -> days 3.00 -> weeks
(Primary & Ultimate) 2.00 -> months 1.00 -> longer

------+-----+--------------------------------------------+---------+---------
TYPE | NUM | Biowin5 FRAGMENT DESCRIPTION | COEFF | VALUE
------+-----+--------------------------------------------+---------+---------
Frag | 1 | Aliphatic amine [-NH2 or -NH-] | 0.0333 | 0.0333
Frag | 1 | -CH2- [linear] | 0.0494 | 0.0494
Frag | 3 | -C=CH [alkenyl hydrogen] | 0.0062 | 0.0186
MolWt| * | Molecular Weight Parameter | | -0.1699
Const| * | Equation Constant | | 0.7121
============+============================================+=========+=========
RESULT | Biowin5 (MITI Linear Biodeg Probability) | | 0.6435
============+============================================+=========+=========

------+-----+--------------------------------------------+---------+---------
TYPE | NUM | Biowin6 FRAGMENT DESCRIPTION | COEFF | VALUE
------+-----+--------------------------------------------+---------+---------
Frag | 1 | Aliphatic amine [-NH2 or -NH-] | -0.2845 | -0.2845
Frag | 1 | -CH2- [linear] | 0.4295 | 0.4295
Frag | 3 | -C=CH [alkenyl hydrogen] | 0.0285 | 0.0855
MolWt| * | Molecular Weight Parameter | | -1.6483
============+============================================+=========+=========
RESULT |Biowin6 (MITI Non-Linear Biodeg Probability)| | 0.7517
============+============================================+=========+=========

A Probability Greater Than or Equal to 0.5 indicates --> Readily Degradable
A Probability Less Than 0.5 indicates --> NOT Readily Degradable


------+-----+--------------------------------------------+---------+---------
TYPE | NUM | Biowin7 FRAGMENT DESCRIPTION | COEFF | VALUE
------+-----+--------------------------------------------+---------+---------
Frag | 1 | Aliphatic amine [-NH2 or -NH-] | 0.1773 | 0.1773
Frag | 1 | -CH2- [linear] | 0.0260 | 0.0260
Frag | 3 | -C=CH [alkenyl hydrogen] | -0.0735 | -0.2206
Const| * | Equation Constant | | 0.8361
============+============================================+=========+=========
RESULT | Biowin7 (Anaerobic Linear Biodeg Prob) | | 0.8188
============+============================================+=========+=========

A Probability Greater Than or Equal to 0.5 indicates --> Biodegrades Fast
A Probability Less Than 0.5 indicates --> Does NOT Biodegrade Fast

Ready Biodegradability Prediction: (YES or NO)
----------------------------------------------
Criteria for the YES or NO prediction: If the Biowin3 (ultimate survey
model) result is "weeks" or faster (i.e. "days", "days to weeks", or
"weeks" AND the Biowin5 (MITI linear model) probability is >= 0.5, then
the prediction is YES (readily biodegradable). If this condition is not
satisfied, the prediction is NO (not readily biodegradable). This method
is based on application of Bayesian analysis to ready biodegradation data
(see Help). Biowin5 and 6 also predict ready biodegradability, but for
degradation in the OECD301C test only; using data from the Chemicals
Evaluation and Research Institute Japan (CERIJ) database.

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The ready biodegradability of allylamine was predicted using the BIOWIN model, part of the EPISUITE group of programs. BIOWIN predicted allylamine as readily biodegradable.
Executive summary:

The ready biodegradability of allylamine was investigated using the (Q)SAR BIOWIN v 4.10 (2011, US EPA). BIOWIN estimates the probability of rapid aerobic and anaerobic biodegradation of an organic compound in the presence of mixed populations of environmental microorganisms. BIOWIN contains seven separate models:

Rapid Probability Models:

 Biowin1  =  linear probability model

 Biowin2 =  nonlinear probability model

Expert Survey Models:

 Biowin3  =  expert survey ultimate biodegradation model

 Biowin4  =  expert survey primary biodegradation model

MITI Probability Models:

 Biowin5  =  MITI linear model

 Biowin6  =  MITI nonlinear model

Anaerobic Probability Model:

 Biowin7  =  anaerobic biodegradation model

Biodegradability estimates are based upon fragment constants that were developed using multiple linear or non-linear regression analyses, depending on the model.

The BIOWIN models produced the following probabilities of rapid biodegradability:

BIOWIN 1 (Linear Model): 0.8742

BIOWIN 2 (Non-linear Model): 0.9647

BIOWIN 3 (Ultimate Survey Model): 3.0974 (weeks)

BIOWIN 4 (Primary Survey Model): 3.8086 (days)

BIOWIN 5 (MITI Linear Model): 0.6435

BIOWIN 6 (MITI Non-Linear Model): 0.7517

BIOWIN 7 (Anaerobic Linear Model): 0.8188

As the probability of "fast biodegradation" was >0.5, the model indicates that allylamine is rapidly biodegradable and can be considered as readily biodegradable.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
This study was conducted in accordance with international guidelines, and in accordance with the principles of GLP. The study has been given a reliability rating of 2, due to extreme variability observed between sample point replicates. The variability observed makes it difficult to draw conclusions on the ready biodegradabilty of this substance.
Qualifier:
according to
Guideline:
OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic, non-adapted
Details on inoculum:
A sample of activated sludge was obtained from the aeration tank of Worlingworth sewage treatment works (Suffolk, UK), which treats predominantly domestic waste, three days before the start of the test. On the day of collection, the sample was passed through a sieve with a mesh of ca. 1 mm2. A sub-sample (ca. 1 litre) was removed and centrifuged at ca. 2500 rpm for ca. 1 minute and the supernatant removed. The sample was then made up to volume with mineral salts medium (MSM) and centrifuged. This procedure was repeated twice and the sample was then aerated until required. Aliquots (10 mL) of a homogenised sample of the washed activated sludge were filtered through dried (approximately 105°C) and pre-weighed Whatman GF/C filter papers. The filters were dried for at least one hour, allowed to cool and re-weighed. The solids level in the sludge was determined and then an appropriate volume used to inoculate control and test media to give a final suspended solids concentration (MLSS) of 4 mg/L. The sample of activated sludge was not adapted to the test substance before the start of the definitive test.
Duration of test (contact time):
28 d
Initial conc.:
10 mg/L
Based on:
ThIC
Parameter followed for biodegradation estimation:
inorg. C analysis
Details on study design:
Three days before test substance addition, ultrapure water (Appendix 2) was added to each of four, 10-litre glass vessels, followed by the volumes of each of the stock solutions required to prepare ten litres of MSM. Each culture bottle was then inoculated and a magnetic stirring bar was added. The bottles were stoppered, then each was placed on an electrically-operated magnetic stirrer. The vessels were aerated until the day of test initiation (Day 0) with a supply of air that had been treated to remove carbon dioxide by passing it through cylinders containing fused calcium chloride and soda lime.
On Day 0 of the test, the pH of the three-day old inoculated MSM was determined and adjusted with HCl to 7.4 ± 0.2 as required.
The reference substance sodium benzoate was added as an aqueous stock solution (1.72 g/L) to a reservoir of the pre-aerated inoculated MSM labelled reference to give a nominal concentration of 10 mg C/L. Blank-controls contained inoculated MSM alone. Aliquots (100 mL) of each MSM were added to the respective (160 ml) vials.
Information from the Sponsor indicated that the test substance was a volatile liquid. Therefore the test substance was added directly to vials (160 mL) containing 100 mL of the inoculated MSM as a volume (2.1 µL calculated based on specific gravity of 0.763) to give a final, nominal test concentration of 10 mgC/L. The liquid volume to headspace ratio was approximately 1 : 1.7.
An inhibition assay was prepared by adding aliquots (2.1 µL) of the test substance to vials (160 mL) containing 100 mL of the inoculated MSM plus the reference substance. The nominal concentration for both the test and reference substance was 10 mg C/L.
The vials were immediately sealed with PTFE tape, Teflon coated bungs and aluminium crimp seals. The vials were incubated horizontally on an enclosed reciprocating shake at a speed of ca. 150 - 200 rpm. The final volume of each culture was 100 mL.
Reference substance:
benzoic acid, sodium salt
Preliminary study:
No preliminary study was conducted
Test performance:
The study met Guideline validity criteria. However, extreme variability was observed between replicate vessels containing test item, leading to an inconclusive test result.
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
31.2
St. dev.:
37.4
Sampling time:
7 d
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
52.2
St. dev.:
33.7
Sampling time:
11 d
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
49.7
St. dev.:
29.7
Sampling time:
14 d
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
58
St. dev.:
7
Sampling time:
21 d
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
35.9
St. dev.:
7.4
Sampling time:
28 d
Details on results:
The production of CO2 in the control cultures, expressed as a percentage of the nominal organic carbon load as test substance in the test system (at most, 14.6% on Day 28) was acceptable for this assay system (recommended maximum, 15%). These results confirm that the inoculum was viable and that the test was valid.
Biodegradation of allylamine was calculated as 5.8% on Day 3, increased to 52.2% by Day 11, with a maximum of 58.0% degradation on Day 21, although the increase in biodegradation was not monotonic (see Figure 1 and Table 5). Substances are considered to be readily biodegradable in this test if CO2 production is equal to or greater than 60% of the theoretical value within ten days of the level achieving 10% (the 10 day window). Allylamine, therefore, cannot be considered to be readily biodegradable based on the results of this study. However, the levels of biodegradation observed in individual vessels were highly variable, which was likely a reflection of the vessels having been spiked individually with small volumes of test substance, required because of the volatile nature of the test substance; this may have had an impact on the mean levels of biodegradation observed and therefore this study is considered to not be conclusive regarding the ready biodegradability of allylamine.
The pH of the test/control and reference MSM at the start of the test were 7.75 and 7.80, respectively. The temperature of a 100 mL volume of water held under test conditions ranged from 21.3 to 22.9°C during the test period.
Results with reference substance:
Sodium benzoate alone had biodegraded by 64.1% on Day 3, by 78.6% on Day 14 and by, at most, 80.4% on Day 21. In the presence of allylamine (the inhibition assay), sodium benzoate had been degraded by 57.8% on Day 3 and by 85.8% on Day 7, demonstrating that allylamine had no inhibitory effect on the activity of the microbial inoculum.

Table 1. Raw data on test item vessels

 Day Replicate  Contrl Mean IC (mg C/L)  Mean Control IC (mg C/L)  Test Mean IC (mg C/L)  Biodegradation (%)  Mean Biodegradation (%)  SD
 0  1  1.1    1.0  0.0    
 0  2  1.0  1.0  1.1  0.0  0.0  0.0
 0  3  1.0    1.1  0.0    
 3  1  1.3    1.9  5.7    
 3  2  1.3  1.3  1.7  4.0  5.8  2.0
 3  3  1.4    2.1  7.9    
 7  1  1.7    7.5  57.6    
 7  2  1.8  1.7  2.2  4.7  31.2  37.4
 7  3  1.7    *  *    
 11  1  1.7    3.2  14.5    
 11  2  1.7  1.7  8.0  62.9  52.2  33.7
 11  3  1.7    9.6  79.3    
 14  1  1.9    3.6  16.5    
 14  2  2.1  2.0  9.4  73.8  49.7 29.7
 14  3  1.9    7.8  58.6    
 21  1  2.0    8.1  60.3    
 21  2.1  2.1  7.1  50.0  58.0  7.0
 21  2.1    8.5  63.6    
 28  1  2.3    6.0  35.1    
 28  2  2.5    5.5  30.3    
 28  3  2.4  2.5  7.0  45.1  35.9  7.4
 28  4  2.4    5.2  27.4    
 28  5  2.7    6.6  41.5    

* Vessel broken prior to analysis and contents lost, no analysis possible

Table 2. Raw Data on Reference Vessels

Day Replicate  Contrl Mean IC (mg C/L)  Mean Control IC (mg C/L)  Reference Mean IC (mg C/L)  Biodegradation (%)  Mean Biodegradation (%)  SD
 0  1  1.1    0.9  0.0    
 0  2  1.0  1.0  0.8  0.0  0.0  0.0
 0  3  1.0    0.9  0.0    
 3  1  1.3    7.8  64.8    
 3  2  1.3  1.3  7.8  64.6  64.1  1.1
 3  3  1.4    7.6  62.8    
 7  1  1.7    9.1  74.2    
 7  2  1.8  1.7  9.5  77.6  74.6  2.9
 7  3  1.7    8.9  71.8    
 11  1  1.7    9.6  79.1    
 11  2  1.7  1.7  9.8  81.1  79.4  1.6
 11  3  1.7    9.5  77.9    
 14  1  1.9    9.8  78.0    
 14  2  2.1  2.0  9.7  77.7  78.6 1.3
 14  3  1.9    10.0  80.1    
 21  1  2.0    10.0  79.2    
 21  2.1  2.1  10.1  80.2  80.4  1.2
 21  2.1    10.3  81.7    
 28  1  2.3    10.2  76.7    
 28  2  2.5    10.0  75.1    
 28  3  2.4  2.5  9.9  74.0  76.7 3.3 
 28  4  2.4    10.7  82.4    
 28  5  2.7    10.0  75.4    


Table 3. Raw Data for Inhibition Vessels (Test Item + Reference Item)

Day Replicate  Contrl IC (mg C/L)  Mean Control IC (mg C/L)  Inhibituin Mean IC (mg C/L)  Biodegradation (%)  Mean Biodegradation (%)  SD
 0  1  1.1    1.1  0.0    
 0  2  1.0  1.0  1.0  0.0  0.0  0.0
 0  3  1.0    1.0  0.0    
 3  1  1.3    7.7  58.4    
 3  2  1.3  1.3  7.6  57.1  57.8  0.7
 3  3  1.4    7.7  57.8    
 7  1  1.7    14.5  96.1    
 7  2  1.8  1.7  12.6  77.2  85.8  9.6
 7  3  1.7    13.3  84.1    

* Vessel broken prior to analysis and contents lost, no analysis possible.

Validity criteria fulfilled:
yes
Interpretation of results:
other: Inconclusive
Conclusions:
Allylamine cannot be considered as readily biodegradable, or readily biodegradable but failing the 10 day window as biodegradation did not reach 60 % (based on ThIC) during the test.
The levels of biodegradation observed in individual vessels were highly variable, with some indicating that >60 % degradation was achieved on days 11, 14 and 21. The high variability was likely a reflection of the vessels having been spiked individually with small volumes of test substance, a situation necessitated by the volatile nature of the test substance; this may have had an impact on the mean biodegradation values derived in the test and therefore this study is considered to not be conclusive regarding the ready biodegradability of Allylamine.
The results obtained for the biodegradation of sodium benzoate alone (78.6% of the theoretical maximum after 14 days and 76.7% by the end of the test on Day 28) fulfil the validity criteria for this test.
The biodegradation of sodium benzoate in the presence of Allylamine was monitored in order to assess whether any inhibitory effects were exerted on the activity of the microbial inoculum. None were observed.
Executive summary:

The ready biodegradability of allylamine was assessed in the Sealed-Vessel CO2 Evolution test using International Standard ISO 14593 (adopted March 1999) and Test Guideline OECD 310 (CO2 in sealed vessels (Headspace Test)). It also included aspects of the US Environmental Protection Agency (EPA), Office of Prevention, Pesticides and Toxic Substances, (OPPTS) Method 835.3120, Sealed-Vessel Carbon Dioxide Production test, adopted January 1998.

Appropriate volumes of inoculated mineral salts medium (MSM) were prepared in five-litre clear glass vessels and aerated for five days with CO2-free air. On the day of test initiation, control vessels containing inoculated MSM, reference vessels containing inoculated MSM and the reference substance, sodium benzoate at a nominal concentration of 10 mg C/L, and the test vessels containing inoculated MSM and the test substance were prepared. For the test cultures, aliquots (100 mL) of MSM were transferred to the appropriate number of Wheaton vials (160 mL), allylamine was added by gas tight syringe at a nominal concentration of 10 mg C/L to individual vials and due to the volatile nature of the test substance immediately sealed with PTFE tape, a Teflon-coated septa and aluminium crimp seal. The remaining culture medium for the other groups were also transferred to Wheaton vials (160 mL) and sealed with PTFE tape, a Teflon-coated septa and aluminium crimp seal.

Test, control and reference vessels were incubated for 28 days on a reciprocating shaker at ca. 150 - 200 rpm at a temperature of 22 ± 2°C. On each analysis occasion, the appropriate vials were injected with 1 mL of NaOH (nominally 7M) and shaken for at least one hour. The total inorganic carbon content of the liquid phase of each sample was then determined using a carbon analyser.

Sodium benzoate, alone had biodegraded by 64.1% on Day 3, by 78.6% on Day 14 and by, at most, 80.4% on Day 21. In the presence of allylamine (the inhibition assay), sodium benzoate had been degraded by 57.8% on Day 3 and by 85.8% on Day 7, demonstrating that allylamine had no inhibitory effect on the activity of the microbial inoculum. The production of CO2 in the control cultures, expressed as a percentage of the nominal organic carbon load as test substance in the test system (at most, 14.6% on Day 28) was acceptable for this assay system (recommended maximum, 15%). These results confirm that the inoculum was viable and that the test was valid.

Biodegradation of allylamine was calculated as 5.8% on Day 3, increased to 52.2% by Day 11, with a maximum of 58.0% degradation on Day 21, although the increase in biodegradation was not monotonic. Substances are considered to be readily biodegradable in this test if CO2 production is equal to or greater than 60% of the theoretical value within ten days of the level achieving 10% (the 10 day window). Allylamine, therefore, cannot be considered to be readily biodegradable based on the results of this study. However, the levels of biodegradation observed in individual vessels were highly variable, with some indicating that >60 % degradation was achieved on days 11, 14 and 21. The high variability was likely a reflection of the vessels having been spiked individually with small volumes of test substance, a situation necessitated by the volatile nature of the test substance; this may have had an impact on the mean biodegradation values derived in the test and therefore this study is considered to not be conclusive regarding the ready biodegradability of allylamine.

Description of key information

Readily Biodegradable: No (max. of 58 % between days 7-21, study ongoing); OECD 310; Allen (2013);

BIOWIN Prediction of Biodegradability: Readily Biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

A study on the ready biodegradability of allylamine (OECD 310; Allen, 2013) indicated that the substance was not readily biodegradable. However, this conclusion was drawn based on mean results from a triplicate sampling regime at each timepoint, and the high variability noted in the replicates casts doubt on the use of mean values for the assessment of ready biodegradability.

The following results were used to draw the conclusion from the OECD 310 study:

 Day  Day 0 % Biodegradation  Day 3 % Biodegradation  Day 7 % Biodegradation  Day 11 % Biodegradation  Day 14 % Biodegradation  Day 21 % Biodegradation Day 28 % Biodegradation 
 Replicate 1  0.0  5.7  57.6  14.5 16.5   60.3  35.1
 Replicate 2  0.0  4.0  4.7 62.9   73.8  50.0  30.3
 Replicate 3  0.0  7.9  *  79.3  58.6  63.6  45.1
 Replicate 4  -  -  -  -  -  27.4
Replicate 5  -  -  -  -  -  - 41.5 
 Mean  0.0  5.8  31.2  52.2  49.7  58.0  35.9
 SD 0.0   2.0  37.4  33.7  29.7  7.0  7.4

* Vessel broken prior to analysis and contents lost, no analysis possible.

Over the duration of the study, biodegradation in individual vessels ranged from 4.7 to 79.3 %, and if the extremely low replicate values were not used (replicate 2 on day 7, replicate 1 on days 11 and 14 and replicate 2 on day 21), the substance would be considered readily biodegradable. This is in agreement with the prediction made by BIOWIN (US EPA, 2011). OECD 310 is the only applicable method for assessing the ready biodegradability of volatile substances, but even using the sealed vessels with headspace test, may have contributed to the variability observed between replicates at each sampling point (equivalent variability was not observed in the reference vessels). Allylamine has a vapour pressure of 32 kPa, and is considered extremely volatile. Losses from the aqueous phase for this substance were demonstrated in the method development work for the aquatic toxicity studies, with almost complete losses observed in sampling vials with a small headspace, left for short periods of time (ca. 1hr). Despite the continued rotary shaking of test vessels in this study, it may have been very difficult to keep allylamine in the aqueouse phase, and available for the microorganisms to degrade.

In a weight-of-evidence approach, considering that many test vessel replicates at each time point achieved the desired degradation levels to consider allylamine and readily biodegradable, supported by the high probability of ready biodegradability predicted by BIOWIN, the registrant has considered allylamine as readily biodegradable for the purpose of the Chemical Safety Assessment.