Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Environmental Exposure and Fate

The high water solubility and low vapour pressure indicate that Potassium oxide will be found predominantly in the aquatic environment. Potassium oxide is present in the environment as potassium and Oxygen ions, which implies that it will not adsorb on particulate matter or surfaces and will not accumulate in living tissues. It is obvious that both potassium and Oxygen ions have a wide natural occurrence (UNEP, 1995).

Atmospheric emissions as Potassium oxide aerosols should be rapidly neutralized by carbon dioxide, or other acids and the salts (e.g. potassium carbonate) will be washed out by rain. For this reason potential atmospheric emissions of Potassium oxide are considered of no concern. Significant emissions to the terrestrial environment are not expected during normal handling and use of Potassium oxide. Small terrestrial emissions will be neutralized by the buffer capacity of the soil. For this reason the environmental assessment can be limited to the aquatic compartment.

Because Potassium oxide does occur in the environment as Potassium and Oxygen a separate environmental assessment of both the potassium and the Oxygen ion is needed.

Oxygen is the most abundant chemical element by mass in the Earth's biosphere, air, sea and land. Oxygen is the third most abundant chemical element in the universe, after hydrogen and helium.

Potassium is essential constituent and one of the most abundant ions in all animal species. In adult humans, the total body potassium is approx. 3.5 mol (135 g). 98 % of this is located intracellular (150 mmol/l), the extracellular potassium concentration is approx. 4 mmol/l.

Both K+ and O- ions are normal constituents of the body fluids. K+ plays an essential role in the human physiology but starts to be toxic at levels exceeding 200 – 250 mg/l. Its concentration in the blood is regulated principally by renal excretion/reabsorption and controlled by an efficient feedback auto-regulation system. An excessive pH of the blood is prevented by the bicarbonate buffer system, respiration and renal compensation mechanisms.

Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions.

Hydrolysis is a chemical reaction during which molecules of water (H2O) are split into hydrogen cations (H+, conventionally referred to as protons) and hydroxide anions (OH−) in the process of a chemical mechanism).

Potassium oxide is a basic oxide and reacts with water violently to produce the caustic potassium hydroxide

When water is added to Potassium oxide, KOH is produced.

K2O+H2O→KOH

On this basis, Potassium oxide does not have a potential for Hydrolysis and Potassium ion will not hydrolise.

Stability

 

Phototransformation in air

  

Dipotassium oxide/ Potassium oxide has low vapor pressure (3.03E-014 Pa) indicating significant amounts of Dipotassium oxide/ Potassium oxide are unlikely to be present in the atmosphere for photodegradation.

If released to air, a vapor pressure of 2.27E-016 mm Hg  at 25 deg C (2.27E-016 mm Hg is equivalent to a vapour pressure of 3.03E-014 Pa) indicates significant amounts of Dipotassium oxide/ Potassium oxide are unlikely to be present in the atmosphere for photodegradation and therefore Dipotassium oxide/ Potassium oxide is not expected to be susceptible to direct photolysis by sunlight. 

 

   

Phototransformation in water

 

If released into water, Dipotassium oxide/ Potassium oxide is not expected to adsorb to suspended solids and sediment based upon the estimated Koc value of 13.22 L/kg. Volatilization from water surfaces is not expected to be an important fate process based upon this compound's estimated Henry's Law constant is 2.814E-023 atm-m3/mole (2.851E-018 Pa-m3/mole).

On this basis phototransformation in water is not expected .

Therefore testing for Phototransformation in water does not need to be performed.

 

Phototransformation in soil

If released to soil, Dipotassium oxide/Potassium oxide is expected to have very high mobility based upon an estimated Koc of 13.22. Volatilization from moist soil surfaces is not expected to be an important fate process.

    

Therefore testing for Phototransformation in soils does not need to be performed. 

 

Hydrolysis

 According to “ANNEX VIII- STANDARD INFORMATION REQUIREMENTS FOR SUBSTANCES MANUFACTURED OR IMPORTED IN QUANTITIES OF 10 TONNES OR MORE , study for Hydrolysis as a function of pH does not need to be conducted if:

-the substance is ready biodegradable.

 As Dipotassium oxide/Potassium oxide is ready biodegradable a Hydrolysis study does not need to be conducted.

Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions.

Hydrolysis is a chemical reaction during which molecules of water (H2O) are split into hydrogen cations (H+, conventionally referred to as protons) and hydroxide anions (OH−) in the process of a chemical mechanism).

Potassium oxide is a basic oxide and reacts with water violently to produce the caustic potassium hydroxide

When water is added to Potassium oxide, KOH is produced.

K2O+H2O→KOH

On this basis, Potassium oxide does not have a potential for Hydrolysis and Potassium ion will not hydrolise.

 

Biodegradation

 

Biodegradation in water:screening tests

 

The estimated Biodegradetion in Water was measured by calculation from EPI SuiteTM v4.1/BIOWIN v4.10Program and Ready Biodegradation was predicted. This is Exposure Assessment Tools and Models made from EPA (Environmental Protection Agency).

 

BIOWIN v4.10 Results:

 

 Biowin1 (Linear Model Prediction)   : Biodegrades Fast

 Biowin2 (Non-Linear Model Prediction): Biodegrades Fast

 Biowin3 (Ultimate Biodegradation Timeframe): Weeks

 Biowin4 (Primary Biodegradation Timeframe): Days

 Biowin5 (MITI Linear Model Prediction)   : Biodegrades Fast

 Biowin6 (MITI Non-Linear Model Prediction): Biodegrades Fast

 Biowin7 (Anaerobic Model Prediction): Biodegrades Fast

 Ready Biodegradability Prediction: YES

 

Biodegradation in water and sediment: simulation tests

According to “ANNEX IX- STANDARD INFORMATION REQUIREMENTS FOR SUBSTANCES MANUFACTURED OR IMPORTED IN QUANTITIES OF 100 TONNES OR MORE”, a simulation testing on ultimate degradation in surface water, the study does not need to be performed if the substance is ready biodegradable. As Dipotassium oxide/Potassium oxide is ready biodegradable a ready biodegradability study does not need to be conducted.

Therefore testing for Biodegradation in water does not need to be performed

 

Biodegradation in soil

 

Expert Judgement

If released to soil, Dipotassium oxide/Potassium oxide is expected to have very high mobility based upon an estimated Koc of 13.22. Volatilization from moist soil surfaces is not expected to be an important fate process.

Therefore testing for biodegradation in soil does not need to be performed.

Bioaccumulation

Potassium oxide has not bioaccumulation potential.

Potassium is essential constituent and one of the most abundant ions in all animal species. In adult humans, the total body potassium is approx. 3.5 mol (135 g). 98 % of this is located intracellular (150 mmol/l), the extracellular potassium concentration is approx. 4 mmol/l.

Oxygen is the most abundant chemical element by mass in the Earth's biosphere, air, sea and land. Oxygen is the third most abundant chemical element in the universe, after hydrogen and helium

Both K+ and O- ions are normal constituents of the body fluids. K+ plays an essential role in the human physiology but starts to be toxic at levels exceeding 200 – 250 mg/l. Its concentration in the blood is regulated principally by renal excretion/reabsorption and controlled by an efficient feedback auto-regulation system. An excessive pH of the blood is prevented by the bicarbonate buffer system, respiration and renal compensation mechanisms.

Bioconcentration/bioaccumulation was estimated using QSAR estimation software (EPISUITE v4.1 BCFBAF v3.01), in accordance with REACH Annex XI. The estimated log BCF is 0.5 (BCF = 3.16 L/kg wet-wt) using the regression-based method.

The estimated log BAF is -0.05 (BAF = 0.894 L/kg wet-wt) using the Arnot-Gobas upper trophic method.

--------------------------------- BCFBAF v3.01 --------------------------------

Summary Results:

 Log BCF (regression-based estimate): 0.50 (BCF = 3.16 L/kg wet-wt)

 Biotransformation Half-Life (days) : 0.00627 (normalized to 10 g fish)

 Log BAF (Arnot-Gobas upper trophic): -0.05 (BAF = 0.894 L/kg wet-wt)

 

Log Kow (experimental): -1.38

Log Kow used by BCF estimates: -1.38

 

Equation Used to Make BCF estimate:

  Log BCF = 0.50

 

     Correction(s):                   Value

      Correction Factors Not Used for Log Kow < 1

 

  Estimated Log BCF = 0.500 (BCF = 3.162 L/kg wet-wt)

 

 

Bioaccumulation: terrestrial

  This substance has a limited potential to bioaccumulate (based on log Kow used : -1.38, Log Kow (experimental): -1.38 , and predicted bioconcentration factors, log BCF = 0.5 (EPIWIN/BCF Program).

According to “ANNEX IX- STANDARD INFORMATION REQUIREMENTS FOR SUBSTANCES MANUFACTURED OR IMPORTED IN QUANTITIES OF 100 TONNES OR MORE , a bioaccumulation study need not be conducted if:

— the substance has a low potential for bioaccumulation (for instance a log Kow ≤ 3) and/or a low potential to cross biological membranes, or

— direct and indirect exposure of the aquatic compartment is unlikely.

The estimated Log BCF of Potassium oxide is 0.5 (BCF = 3.162 L/kg wet-wt)

 

BCFBAF Program (v3.01) Results:

==============================

SMILES : KOK

CHEM  : Potash (potassium oxide)

MOL FOR: O1

MOL WT : 94.20

--------------------------------- BCFBAF v3.01 --------------------------------

Summary Results:

 Log BCF (regression-based estimate): 0.50 (BCF = 3.16 L/kg wet-wt)

 Biotransformation Half-Life (days) : 0.00627 (normalized to 10 g fish)

 Log BAF (Arnot-Gobas upper trophic): -0.05 (BAF = 0.894 L/kg wet-wt)

 

Log Kow (experimental): -1.38

Log Kow used by BCF estimates: -1.38

 

Equation Used to Make BCF estimate:

  Log BCF = 0.50

 

     Correction(s):                   Value

      Correction Factors Not Used for Log Kow < 1

 

  Estimated Log BCF = 0.500 (BCF = 3.162 L/kg wet-wt)

 

===========================================================

Whole Body Primary Biotransformation Rate Estimate for Fish:

===========================================================

------+-----+--------------------------------------------+---------+---------

 TYPE | NUM | LOG BIOTRANSFORMATION FRAGMENT DESCRIPTION | COEFF | VALUE 

------+-----+--------------------------------------------+---------+---------

 L Kow| * | Log Kow = -1.38 (experimental  )       | 0.3073 | -0.4241

 MolWt| * | Molecular Weight Parameter               |        | -0.2415

 Const| * | Equation Constant                        |        | -1.5371

============+============================================+=========+=========

  RESULT  |       LOG Bio Half-Life (days)           |        | -2.2027

  RESULT  |           Bio Half-Life (days)           |        | 0.00627

  NOTE    | Bio Half-Life Normalized to 10 g fish at 15 deg C  |

============+============================================+=========+=========

 

Biotransformation Rate Constant:

 kM (Rate Constant): 110.6 /day (10 gram fish)

 kM (Rate Constant): 62.17 /day (100 gram fish)

 kM (Rate Constant): 34.96 /day (1 kg fish)

 kM (Rate Constant): 19.66 /day (10 kg fish)

 

Arnot-Gobas BCF & BAF Methods (including biotransformation rate estimates):

  Estimated Log BCF (upper trophic) = -0.049 (BCF = 0.8939 L/kg wet-wt)

  Estimated Log BAF (upper trophic) = -0.049 (BAF = 0.8939 L/kg wet-wt)

  Estimated Log BCF (mid trophic)  = -0.030 (BCF = 0.9325 L/kg wet-wt)

  Estimated Log BAF (mid trophic)  = -0.030 (BAF = 0.9325 L/kg wet-wt)

  Estimated Log BCF (lower trophic) = -0.026 (BCF = 0.9412 L/kg wet-wt)

  Estimated Log BAF (lower trophic) = -0.026 (BAF = 0.9412 L/kg wet-wt)

 

Arnot-Gobas BCF & BAF Methods (assuming a biotransformation rate of zero):

  Estimated Log BCF (upper trophic) = -0.047 (BCF = 0.8975 L/kg wet-wt)

  Estimated Log BAF (upper trophic) = -0.047 (BAF = 0.8975 L/kg wet-wt)

 

 

Transport and distribution

Adsorption / desorption

 

The log of the adsorption coefficient (KOC) of Dipotassium oxide/Potassium oxide was estimated to be log KOC = 1.1211which is equal to a KOC value of 13.22 using the KOCWIN v2.00 QSAR method.

SMILES : KOK

CHEM  : Potash (potassium oxide)

MOL FOR: O1 K2

MOL WT : 94.20

----------------------- KOCWIN v2.00 Results ---------------------------

Koc Estimate from MCI:

 ---------------------

        First Order Molecular Connectivity Index ........... : 1.000

        Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 1.1211

        Fragment Correction(s) --> NONE                     :  ---

        Corrected Log Koc .................................. : 1.1211

 

                        Estimated Koc: 13.22 L/kg  <===========

 

 

Henry's Law constant

 

The estimated Henrys Law Constant (25 deg C) measured by calculation from EPI SuiteTM v4.1, HENRYWIN v3.20 Program was 2.814E-023 atm-m3/mole (2.851E-018 Pa-m3/mole) This is Exposure Assessment Tools and Models made from EPA (Environmental Protection Agency).

Distribution modelling.

 

Dipotassium oxide/ Potassium oxide has no affinity to be in air and sediment. The direct emissions to soil and surface water are significant, therefore Dipotassium oxide/ Potassium oxide will be almost exclusively be found in soil and surface water.

Mackay fugacity modelling (level 3) indicates that, taking into account degradation and using inflow parameters which are consistent with the known production tonnage of this substance in, fugacity coefficient indicates that environmental concentrations in water are predicted to be 8.49e-028 (atm), in air (atm) 2.99e-026 and soil 3.73e-026 (atm) and sediment to be  7.69e-028 (atm).

These are negligible low levels. This can be considered a worse case prediction as it assumes all product is emitted with no emission control systems used.

 

Other distribution data

These results suggest for Dipotassium oxide/Potassium oxide that direct and indirect exposure from distribution in media is unlikely.

Based on low vapor pressure and low estimated log Pow, expected to partition to water and soil. Not expected to partition to air, sediments or biota.

 

Therefore testing for distribution in media does not need to be performed.

 

The estimated STP Fugacity Model and Volatilization From Water were measured by calculation from EPI SuiteTM v4.1 Program. This is Exposure Assessment Tools and Models made from EPA (Environmental Protection Agency) .

 

                                         

                         Volatilization From Water

                           =========================

 

Chemical Name: Potash (potassium oxide)

 

Molecular Weight   : 94.20 g/mole

Water Solubility      : 1E+006 ppm

Vapor Pressure      : 2.27E-016 mm Hg

Henry's Law Constant: 2.81E-023 atm-m3/mole (calculated from VP/WS)

 

                                 RIVER            LAKE

                                  ---------        ---------

Water Depth    (meters):   1                1         

Wind Velocity   (m/sec):   5                0.5       

Current Velocity (m/sec): 1                0.05      

 

     HALF-LIFE (hours) : 2.02E+019        2.203E+020

     HALF-LIFE (days ) :  8.415E+017       9.18E+018 

     HALF-LIFE (years) :  2.304E+015       2.513E+016

 

 

STP Fugacity Model: Predicted Fate in a Wastewater Treatment Facility

======================================================================

  (using 10000 hr Bio P,A,S)

PROPERTIES OF: Potash (potassium oxide)

-------------

Molecular weight (g/mol)                              94.2

Aqueous solubility (mg/l)                             1E+006

Vapour pressure (Pa)                                  3.02642E-014

               (atm)                                              2.98684E-019

               (mm Hg)                                        2.27E-016

Henry 's law constant (Atm-m3/mol)      2.8136E-023

Air-water partition coefficient                  1.15068E-021

Octanol-water partition coefficient (Kow)      8.31764E-006

Log Kow                                                          -5.08

Biomass to water partition coefficient                0.800002

Temperature [deg C]                                   25

Biodeg rate constants (h^-1),half life in biomass (h) and in 2000 mg/L MLSS (h):

         -Primary tank        0.04       15.97      10000.00

         -Aeration tank      0.04       15.97      10000.00

         -Settling tank        0.04       15.97      10000.00

 

                                     STP Overall Chemical Mass Balance:

                                      ---------------------------------

                                                g/h              mol/h         percent

 

Influent                                1.00E+001        1.1E-001       100.00

 

Primary sludge                   2.50E-002        2.6E-004        0.25

Waste sludge                      1.50E-001        1.6E-003        1.50

Primary volatilization        1.53E-020        1.6E-022        0.00

Settling volatilization        4.18E-020        4.4E-022        0.00

Aeration off gas                 1.03E-019        1.1E-021        0.00

 

Primary biodegradation     1.76E-003        1.9E-005        0.02

Settling biodegradation     5.27E-004        5.6E-006        0.01

Aeration biodegradation   6.93E-003        7.4E-005        0.07

 

Final water effluent            9.82E+000        1.0E-001       98.15

 

Total removal                      1.85E-001        2.0E-003        1.85

Total biodegradation         9.22E-003        9.8E-005        0.09