2,2',6,6'-tetrabromo-4,4'-isopropylidenediphenol

Distribution modelling

Administrative data

Endpoint:

distribution modelling

Type of information:

calculation (if not (Q)SAR)

Remarks:

Migrated phrase: estimated by calculation

Adequacy of study:

key study

Study period:

2010

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Derived using calculation method software recommended by REACH Guidance (e.g. EPIwin).

Data source

Reference

Reference Type:

other: Estimation software

Title:

Unnamed

Year:

2007

Materials and methods

Model:

calculation according to Mackay, Level III

Calculation programme:

EPI Suite v3.20; modeling based on chemical structure

Release year:

2 007

Media:

other: air, water, soil, sediment

Test material

Test material information

Constituent 1

Results and discussion

Percent distribution in media

Air (%):

0

Water (%):

0.632

Soil (%):

53.2

Sediment (%):

46.2

Aerosol (%):

0

Any other information on results incl. tables

TBBPA's transport and distribution between environmental compartments was modeled using EPI v3.20, and based on the chemical's structure. Over 99% of TBBPA released to the environment is predicted to partition to soil (53%) and sediment (46%). Negligible amounts are predicted to partion to water (0.6%) and air (0.00008%) (Level III Fugacity Model; Emissions of 1000 kg/hr to each of air, water and soil). In soil and sediment, TBBPA is expected to bind extensively to organic carbon (estimated Koc soil = 6.5 x 10E6). Movement into groundwater is not expected based on this Koc and measured water solubility. TBBPA is expected to partition from water to organic carbon (Koc = 5.6 x 10E5). TBBPA is not expected to volatilize from water (Volatilization half-life in rivers = 6.7 x 10E5, in lakes = 7.3 x 10E6). In air, TBBPA is expected to be be bound to particulates; the fraction sorbed to particulates is estimated to be 1 at 25 degrees C (AEROWIN v1.00). Its movement in the atmosphere will be goverened by the particles to which it is bound. Sewage treatment plants are predicted to remove TBBPA from the influent to a high degree (94%), but biodegradation in the treatment plant is not expected. Removal in the treatment plant will be by partitioning to sludge. Leaching from polymers is not expected, in part because its primary use is as a reactive flame retardant in printed circuit boards but also due to its physical/chemical properties.

Distribution modelling results are summarised in the following table. EPI v3.20 was used because later versions of this software included incorrect values in its reference library for certain brominated flame retardants.

Estimated properties for TBBPA using EPI (v3.20).

Property	Result	EPI Module
Henry’s Law Constant (25°C)	2.31 x 10E-13 atm-m3/mole	HENRY v3.10
	9.43 x 10E-12 unitless	HENRYWIN v3.10
	2.47 x 10E-8 atm-m3-mole	VP/Wsol Estimate using EPI values
Liquid/Subcooled Vapor Pressure	1.95 x 10E-7 Pa	AEROWIN v1.00
Koa (octanol/air partition coefficient	1.678 x 10E18	KOAWIN v1.10
Log Kaw (air/water partition coefficient)	18.22	KOAWin v1.10
Particle/gas Partition Coefficient (Kp) (m3/ug)	15.4 (Mackay model) 4.12 x 10E5 (Koa model)	AEROWIN v1.00
Reaction with Hydroxyl Radicals in the Atmosphere	Overall OH Rate Constant = 2.9584 x 10E-12 cm3/molecule-sec; Half-life = 3.615 days (12-hr day; 1.56 x 10E6 OH/cm3)	AOP v1.92
Koc	5.62 x 10E5	PCKOC v1.66
Koc-soil	6.5 x 10E6	Level III Fugacity Model
Biomass to water partition coefficient	3.169 x 10E6	STP Fugacity Model
Sorption to airborne particulates (25°C)	1	Octanol/Air Model
	0.998	Junge-Pankow Model
	0.99	Mackay Model
Environmental Partitioning	At Emissions to Air, Water, Soil and Sediment of 1000, 1000, 1000 and 0 kg/hr, respectively:   Distribution (%): Air 8.93 x 10E-5; Water 0.632; Soil 53.2; Sediment 46.2   Fugactity (atm): Air 4.24 x 10E-7; Water 5.17 x 10E-20; Soil 3.58 x 10E-21; Sediment 1.4 x 10E-19   Reaction (kg/hr): Air 0.317; Water 45.1; Soil 1.9 x 10E-3; Sediment 366   Advection (kg/hr): Air 0.397; Water 281; Soil 0; Sediment 410   Reaction (%): Air 0.01; Water 1.5; Soil 63.2; Sediment 12.2   Advection (%): Air 0.01; Water 9.37; Soil 0, Sediment 13.7	Level III Fugacity Model

Applicant's summary and conclusion

Conclusions:

In the environment, TBBPA is expected to partition mainly to sediment and soil, where it will be bound to particulate matter. Partioning to air and water will be negligble, and that present in these matrixes will also be bound to particulate matter. TBBPA's movement in the atmosphere will be associated with that of the particulates to which it is bound.

Executive summary:

In the environment, TBBPA is expected to partition mainly to sediment and soil, where it will be bound to particulate matter. Partioning to air and water will be negligble, and that present in these matrixes will also be bound to particulate matter. TBBPA's movement in the atmosphere will be associated with that of the particulates to which it is bound.