Tetrabutylammonium bromide

PBT assessment

PBT assessment: overall result

Reference

Name:

tetra butyl ammonium bromide

Type of composition:

boundary composition of the substance

State / form:

solid: bulk

Reference substance:

tetra butyl ammonium bromide

PBT status:

the substance is not PBT / vPvB

Justification:

Classification of Tetrabutylammonium bromidefor effects in the environment:

 

The chemical Tetrabutylammonium bromide (CAS no. 1643-19-2) is used as a phase transfer catalyst, antimicrobial and antistat in cosmetics. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for Tetrabutylammonium bromide. 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

On the basis of the available information as per OECD TG for the test chemical Tetrabutylammonium bromide (CAS no. 1643-19-2), it indicates that chemical Tetrabutylammonium bromide as inherently biodegradable in water and thus likely to be not persistent (not P) in nature.

 

Environmental fate

Aerobic mineralisation of test chemical in water was studies as per the principles of the OECD Guideline 309 (Aerobic Mineralisation in Surface Water - Simulation Biodegradation Test) (Adopted 13th April 2004) under aerobic conditions. The surface water was collected from Kaveri River, Sangama, Ramnagar District, Karnataka State, India in a thoroughly cleansed container. The sampling site for collection of the surface water was selected ensuring that no known history of its contamination with the test item or its structural analogues within the previous four years considering the history of possible agricultural, industrial or domestic inputs. The pH and temperature of the water was measured at the site of collection and the depth of sampling and the appearance of the water sample. (e.g. color and turbidity) was also noted. Oxygen concentration of the surface layer was measured in order to demonstrate aerobic conditions. Depth of sampling was 1-2 feet and surface water was clear with no turbidity. The test water was stored at 4 to 6°C with continuous aeration prior use for a period not more than 4 weeks. Temperature (°C) at time of collection was 21.8°C, pH of temperature was 6.83, Oxygen concentration (mg/l) of 4.8 mg/l,  Dissolved organic carbon (%) of 3.9 mg/l, colony count consists of 4500 CFU/ml, Total organic carbon (TOC) of 3.8 mg/l, Nitrate (NO3- ) of 4.5 mg/l, Nitrite (NO2- ) of 0.62 mg/l, P of <0.1 mg/l, Orthophosphates (PO43-) of 0.19 mg/l, Total ammonia tot (NH4+ ) of <0.3 mg/l and BOD of <2.0 mg/l, respectively. Prior to use of surface water, the coarse particles were removed by filtration through a 100 μm mesh sieve. Test chemical conc. used in the study was 10 μg/L as low dose and 100 μg/L as high dose, respectively. Study was performed in duplicates in a 250 ml conical flasks which was covered with cotton plugs under continuous darkness. Test conditions involve a temperature of 12±2°C, pH of  6.83. Test vessel was kept in an incubator shaker at 12 ± 2°C in dark. Aerobic condition was maintained in the test system by continuous shaking. Agitation was provided to facilitate oxygen transfer from the headspace to the liquid so that aerobic conditions were adequately maintained. Additional to test vessels, 1 blank test vessel containing only the test water for all sampling intervals was included, 1 blank test vessel containing only the sterile test water was also treated at 10 µg/L (0.01 µg/mL) and 100 µg/L (0.1 µg/mL) conc. and duplicate test vessels with reference (aniline) (conc. 10 μg/l i.e. 0.01 mg/l) was also kept in the study. The concentration of test chemical residues in samples collected at different pre-determined interval zero-time (immediately after treatment day 0), day 1, day 3 day 7, day 14, day 28, day 45 and day 60 were diluted suitably with acetonitrile and at each sampling occasion, duplicate aliquots from each test concentration were subjected to analysis by a validated LC-MS/MS method. Simutaneously, samples were removed at regular intervals, measured pH and oxygen concentration. After that the samples were diluted at 1:1, v/v ratio with methanol to prevent further degradation prior to LC-MS/MS analysis. Shaking was continued at 12 ± 2°C in dark for using in other sampling intervals. The surface water samples were analyzed for the residues of test item by liquid chromatography with positive-ion electrospray ionization (ESI) tandem mass spectrometry using the mass ion transition m/z 244.1 -> 143.2 for primary quantification and the mass ion transition m/z 244.1 -> 101.1 for qualitative confirmation. High performance liquid chromatograph (Exion HPLC) equipped with a mass spectrometer (TQ 5500) was used with a column of  Phenomenex Luna, C18 (2), 4.6mm×150mm i.d., 3.0µm, column oven temperature of 40°C, mobile phase consists of Solvent A : 5 mM ammonium formate in Milli-Q® water and Solvent B : Acetonitrile in a ratio of 15 : 85, v/v, flow rate of 0.6 mL/min with splitter, respectively. Detection method involve the use of MS. Linearity range was evaluated to be in the range of 0.00026-0.02064 µg/ml, respectively. During method validation, acceptable recoveries were generated for the samples fortified at LOQ and 10 LOQ level. The % RSD (precision) was ≤20% at each fortification level. Recovery data from these samples demonstrated that test chemical was stable during analysis. The recoveries of all the samples analyzed were in the range of 70-110% with %RSD ≤ 20%. Analysis of the Day 0 samples at 10 μg/L and 100 μg/L test concentrations demonstrated quantitative recovery of test chemical. The average amount of test chemical present was 107.5% and 2.8% & 96.9% and 3.0% at Day 0 and Day 60, respectively following application of test chemical to test water at 10 μg/L (low dose) and 100μg/L (high dose). The average amount of test chemical present was 105.1% and 61.6% & 108.0% and 59.1% at Day 0 and Day 60, respectively following application of test chemical to sterile test water at 10 μg/L (low dose) and 100μg/L (high dose). The DT50 value was determined to be 10.2 d and 10.4 d at test chemical conc. of 10 μg/l and 100 μg/l at 12°C, respectively. 90% of test chemical in natural surface water was determined after 33.7 d and 34.5 d at test chemical conc. of 10 μg/l and 100 μg/l, respectively. Based on the these results, test chemical was degraded in surface water and sterile surface water. Hence, test chemical was considered to be not persistent in water.

 

Hence it has been concluded that Tetrabutylammonium bromide 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 experimental BCF value from study report as per OECD TG 305 was determined to 0.8394 and 0.4624 for 0.1 mg/L and 1.0 mg/L concentrations, respectively  and the octanol water partition coefficient of the test chemical was determined to be 0.839 ± 0.032 at 25°C, respectively, which is less than the threshold of 4.5. 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 fulfils the T criterion within Annex XIII based on the assessment that here follows:

 

Mammals

The tested chemical is regarded to be classified for reprotoxicity in ‘Category 2’ as per the CLP Regulation.

Further, there is not evidence of chronic toxicity, as identified by the classifications STOT (repeated exposure) as per the CLP Regulation.

The tested chemical is regarded to be not classified for carcinogenicity and mutagenicity.

 

Aquatic organisms

All of the available short-term eco-toxicity data for fish, invertebrates and algae for the substance Tetrabutylammonium bromide indicates the LC50/EC50 value to be in the range 50 to 1542.94 mg/L, respectively. These value suggest that the substance is likely to be hazardous to aquatic organisms at environmentally relevant concentrations and can be considered to be classified in ‘aquatic chronic category 3’ as per the CLP regulation.

 

On the basis of the experimental study result of long term eco-toxicity data for fish and aq. Invertebrates, the NOEC value was determined to be 1.6  mg/l and 10 mg/l, respectively.

Thus, long-term NOEC for aquatic organisms were not exceeded for the substance at concentration below 0.01 mg/L based on the data mentioned above.

 

The chemical was therefore not considered as hazardous to aquatic environments as per the criteria set out in Annex XIII.

 

Conclusion

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