Hexylamine

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Classification of Hexylamine for effects in the environment:

 

The chemical Hexylamine (CAS no. 111-26-2) is used as an intermediate. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for Hexylamine. The PBT criterion was herein assessed based on experimental data in conjunction with standardized environmental fate models. Here follows a description of the PBT assessment.

 

 

Persistence assessment

The tested substance does not fulfil the P criterion within Annex XIII based on the assessment that here follows:

 

Biotic degradation

Various study for the test compound Hexylamine (CAS No. 111-26-2) and for its read across substances were reviewed for the biodegradation end point which are summarized as below:

 

Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test substance Hexylamine by bacteria as a test inoculum (Takashi Kameya et. al; 1995). Two tests were carried out for studying the biodegradation of test substance Hexylamine. They are standard tests and low conc. tests. Seeding bacteria was used as a test inoculum. The concentration of organic compound was determined by dissolved organic carbon (DOC) in the standard test and by chromatography in low conc. test. Biodegradation ratio is determined by analysing the decrease of DOC in the standard test. Reproducibility is confirmed by the biodegradation ratio of benzoic acid being > 78% after 14 days.

The percentage degradation of the test compound was determined to be less than 30% in > 28 days in standard test and 100% degradation in 21 days in low conc. test, respectively. Thus, based on the percentage degradation, the test chemical was considered to be non-biodegradable in standard test and readily biodegradable in low conc. test.

 

Estimation Programs Interface Suite (EPI suite, 2016) was run to predict the biodegradation potential of the test compound Hexylamine (CAS no. 111- 26 -2) in the presence of mixed populations of environmental microorganisms. The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that Hexylamine is expected to be readily biodegradable.

 

28-days Manometric respirometry test following the OECD guideline 301Fto determine the ready biodegradability of the test item n-hexylamine (CAS No. 111-26-2) (UERL study report, Sustainability Support Services (Europe) AB, Report no. 111-26-2/01/2015/RBD, 2015). % Degradation was calculated using the values of BOD and ThOD for test item and reference item. The BOD28value of n-hexylamine (CAS No. 111-26-2) was observed to be 1.447mgO2/mg. ThOD was calculated as 2.846 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to manometric respirometry test was found to be 50.84%.Based on the results, the test item, under the test conditions, was found to be inherently biodegradable at 20 ± 1°C over a period of 28 days.

 

Biodegradation study was conducted for > 28 days for evaluating the percentage biodegradability of test substance Hexylamine by anaerobic bacteria (Takashi Kameya et. al; 1995). Two test were carried out by using different conc. of test chemical and inoculum. Anaerobic bacteria was used as a test inoculum. The concentration of organic compound was determined by dissolved organic carbon (DOC) or chromatography. Biodegradation ratio is determined by analysing the decrease of DOC. The percentage degradation of the test compound was determined to be 50% in test 1 and 47% in > 28 days test 2, respectively. Thus, based on the percentage degradation, the test chemical was considered to be undergoes slow biodegradation under the given test conditions.

 

In addition to the above studies for the test chemical, various studies for the read across substances (CAS: 109-73-9; 107-10-8; 124-09-4 and 110-58-7) were also reported which indicate ready biodegradability of the substance.

 

In addition to the above, a study was carried out to determine the effects of microbial utilization of sorbed amines and to establish whether the rate of biodegradation of a sorbed substrate is equal to its rate of desorption. The incubation time was 0.3 and 0.42 days. The inoculum was a mixed culture of bacteria grown on the individual amines as sole carbon source to give an initial level of about 106cells/ml. The original source of the organisms was Lima Loam. The tests were carried under aerobic conditions at a pH of 7.2 and concentration of 71 and 63 ppm at 30°C and 22°C. The rate of biodegradation of n-hexylamine under aerobic conditions is 100%. It can be conducted that n-hexylamine biodegrades fast with acclimation.

 

Environmental fate

According to the fugacity model levels III, the most likely environmental fate for this test chemical is soil (i.e.estimated to 70.3%). In soil, Hexylamine was expected to have moderate mobility based upon a Log KOC of 2.16. The half-life in soil (17.33 days estimated by EPI suite) indicates that the chemical is not persistent in soil and the exposure risk to soil dwelling animals is low.

 

If released in to the environment, 28.3 % and 0.18% of the chemical will partition into water and sediment respectively, according to the Mackay fugacity model level III in EPI suite version 4.1 (2016). However, the half-life (8.66 days in water and 77.91 days in sediment as estimated by EPI suite) indicates that the chemical is not persistent in these medium.

Hence it has been concluded that Hexylamine is not persistent in nature.  

 

 

Bioaccumulation assessment

The tested substance does not fulfil the B criterion within Annex XIII based on the assessment that here follows:

 

The BCF value is determined as 10.63 at 25ºC (Dissertation report, 2001) and the log octanol-water partition coefficient (log Kow) was determined to 2.06-2.31. If this chemical is released into the aquatic environment, there should be a low risk for the chemical to bioaccumulate in fish and food chains.

 

Toxicity assessment

The tested substance does not fulfil the T criterion within Annex XIII based on the assessment that here follows:

 

Mammals

The tested chemical is regarded to be not classified for carcinogenicity, mutagenicity and reprotoxicity, Further, there is no evidence of chronic toxicity, as identified by the classifications STOT (repeated exposure), category 1 (oral, dermal, inhalation of gases/vapours, inhalation of dust/mist/fume) or category 2 (oral, dermal, inhalation of gases/vapours, inhalation of dust/mist/fume).

 

Aquatic organisms

The predicted and experimental EC50/LC50 values were in the range of 15 to 56.60 mg/L. Based on the lowest available EC50/LC50, Hexylamine was suggested to be classified as ‘Aquatic chronic Category 3’.

 

There are no available long-term toxicity evaluations for Hexylamine. The short-term evaluations for algae of read across substance (CAS: 129-09-4) report the NOEC values as 10mg/L. By speculation, although the substance is classified as per the CLP criterion, classification for aquatic toxicity will not be applicable as per Annex XIII criteria for all of the tropic levels and the same is based on the above mentioned studies.

 

 

Conclusion

Based on critical, independent and collective evaluation of information summarized herein, the tested compound does not fulfil the P, B and T criterion and has therefore not been classified as a PBT compound within Annex XIII.