Tris(2-ethylhexyl) phosphate

Additional information on environmental fate and behaviour

Administrative data

Endpoint:

additional information on environmental fate and behaviour

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

Not stated

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Experiment not conducted to a specific guideline or to GLP. Experimental result supports evidence that TEHP, when bound to particles, is more persistent in the environment than when in gaseous state- allowing long distance travel of the molecule.

Data source

Reference

Reference Type:

publication

Title:

Heterogeneous OH Initiated Oxidation: A Possible Explanation for the Persistence of Organophosphate Flame Retardants in Air

Author:

Liu et al

Year:

2014

Bibliographic source:

Environ. Sci. Technol., 48, 1041-1048.

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

TEHP coated on ammonium sulphate particles and exposed to OH radicals at specific temperature and relative humidity. Degradation of TEHP measured using compact time-of-flight aerosol mass spectrometer (C-ToF-AMS) and second order rate constant determined.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Tris(2-ethylhexyl) phosphate

EC Number:

201-116-6

EC Name:

Tris(2-ethylhexyl) phosphate

Cas Number:

78-42-2

Molecular formula:

C24H51O4P

IUPAC Name:

tris(2-ethylhexyl) phosphate

Test material form:

other: liquid

Details on test material:

- Name of test material (as cited in study report): tris-2-ethylhexyl phosphate (TEHP)
mass to charge: 435 mz
vapor pressure: 2.7 × 10^−4 pa
No other information stated.

Results and discussion

Any other information on results incl. tables

Mass spectra of unreacted and reacted TEHP coated particles compared kinetic degradation derived from results (second order rate constant) to determine atmospheric lifetime (4.3 days).

Table 1. Reaction kinetics of TEHP Coated on (NH₄)₂SO₄ at 298K

k2 (10^13cm^3molecule^−1s^−1)
exp 1	exp 2	exp 3	exp 4	exp 5	average k2,obs	diffusion corrected k2
17	15	20	29	23	21 ± 5.5	27 ± 1.9

Table 2. Comparisons between measured and estimated k2 and lifetimes for TEHP

k2 (10^13cm^3molecule^−1s^−1)		Atmospheric Lifetime (days)
Laboratory^a	AOPWIN^b	Laboratory^a	AOPWIN^b
2.7 x 10^-12	9.8 x 10^-11	4.3 (3.5 -5.6)	0.1

a       this study

b       structure activity relationship method (SAR)

Applicant's summary and conclusion

Conclusions:

Atmospheric lifetime of TEHP is estimated to be 4.3 days. The data indicates that TEHP is more persistent in the atmospheric environment when it is in particle form versus gas form, potentially facilitating long distance travel of the molecule. This process has been put forward as a potential reason for observation of organophosphate esters in polar regions and other pristine environments.

Executive summary:

TEHP was coated onto ammonium sulphate particles and exposed to OH radicals in a photochemical flow tube at 298K and 38 % RH. The degradation of this particle-bound form of TEHP was observed as a result of OH exposure, as measured using a time-of-flight aerosol mass spectrometer. The derived second order rate constant for the heterogenous loss of TEHP was 2.7 x 10^12 cm3 molecule-1 s-1. Normalised values indicated an atmospheric lifetime of 4.3 days, potentially facilitating long distance atmospheric travel of the molecule.