Icosanoic acid

Endpoint summary

Additional information

Stability

Phototransformation in air

The atmospheric oxidation half-life of Eicosanoic acid was estimated using the level III multimedia model. It was estimated that the substance is not persistent in air medium as the half life period of Eicosanoic acid in air is 0.62 days. This indicates that Eicosanoic acid is easily phototransformed in air.

OVERALL OH Rate Constant =0.000000000025cm3/molecule-sec.

Media	Half-Life (days)	Percent in Each Medium
Air	0.62	1%

Hydrolysis

The Hydrolysis rate constant of Eicosanoic acid is estimated to be 0.0000000000253065 cm3/molecule-sec. at half life of 5.072 hrs.The estimated half life of the substance indicates that the substance is moderately hydrolysable.

Phototransformation in water

No experimental data available. As this study is not a standard information requirement in REACH and there is no indication from the CSA on the need to investigate further the fate and behaviour of the substance (Annex X requirement), no further testing is considered necessary.

Phototransformation in soil

No experimental data available. As this study is not a standard information requirement in REACH and there is no indication from the CSA on the need to investigate further the fate and behaviour of the substance (Annex X requirement), no further testing is considered necessary.

Biodegradation

Biodegradation in water: screening tests

The half life period of Eicosanoic acid in water is 15 days and based on this value it can be concluded that the chemical is not persistent in water medium since the half life is less than the threshold of 60 days (to qualify the chemical as persistent). Also the diffusion percentage of Eicosanoic acid in water medium is 24%.This coupled with the dilution of water shall result in ready biodegradabililty of the chemical.

PBT Profiler Database

Media	Half-Life (days)	Percent in Each Medium
Water	15	24%

Fugacity Model by EPI Suite estimation database

	Mass Amount (percent)	Half-Life (hr)	Emissions (kg/hr)
Water	24.5	360	1000

	Fugacity (atm)	Reaction (kg/hr)	Advection (kg/hr)	Reaction (percent)	Advection (percent)
Water	8.16e-012	658	342	21.9	11.4

Biodegradation in water and sediment: simulation tests

Based on the Level III Fugacity Model, the half life period of the Eicosanoic acid was estimated. The half life period of Eicosanoic acid in water is 15 days (360 hrs) therefore it is considered that the substance will qualify as not persistent as the half life does not exceed the threshold of 60 days. So, it can be confirmed that the substance is readily biodegradable in water medium where as in sediment the half life is 140 days (3360 hrs).

Based on this value, it can be inferred that the substance is persistent in sediment medium and is not readily biodegradable probably due to the anaerobic conditions existing in most sediments.However, it can be observed that  there is no diffusion of the substance in the sediment medium as evident from the reported data (0%) and hence persistence in the sediment compartment is not likely to be critical.

Media	Half-Life (days)	Percent in Each Medium
Water	15	24%
Sediment	140	0%

Biodegradation in soil

The PBT Profiler & EPI Suite has estimated that Eicosanoic acid is expected to be found predominantly in soil and its persistence estimate is based on its availability in this medium. Its half-life in soil, 30 days (720 hrs).,does not exceeds the threshold of 120 days as per Annex XIII of REACH.Therefore, Eicosanoic acid is estimated to be not persistent in the soil environment.

PBT Profiler Estimate

Media	Half-Life (days)	Percent in Medium
Soil	30	74%

Fugacity Model by EPI Suite estimation database

	Mass Amount (percent)	Half-Life (hr)	Emissions (kg/hr)
Soil	74.3	720	1000

	Fugacity (atm)	Reaction (kg/hr)	Advection (kg/hr)	Reaction (percent)	Advection (percent)
Soil	2.91e-011	999	0	33.3	0

Bioaccumulation

Bioaccumulation is the process by which the chemical concentration in an aquatic organism achieves a level that exceeds that in the water, as a result of chemical uptake through all possible routes of exposure. The relationship between bioaccumulation and bio-concentration is that, chemicals that have the potential to bioconcentrate also have the potential to bioaccumulate. Bioaccumulation is closely related to the Bioconcentration factor (BCF).

The estimated BCF of the key study was obtained to be 3.2.Supporting study also indicate the same BCF value as the key study.This low value of BCF of Eicosanoic acid indicates its non bioaccumulative nature as the BCF factor is less than the bio-concentration threshold of 2000.

Transport and distribution

Adsorption / desorption

The Soil Adsorption Coefficient i.e Koc value of Eicosanoic acid was estimated as 38850 L/kg by means of MCI method. This indicates that Eicosanoic acid will have a very strong tendency of sorption to soil and sediment and therefore havenegligiblemigration potential to groundwater.This Koc value when converted at 20 degC is equivalent to 31080.

Henry's Law constant

Henry's Law states that at a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.Henrys Law Constant of Eicosanoic acid at 25 deg C is 9.1 Pa m³/mol.