O-isopropyl ethylthiocarbamate

Endpoint summary

Additional information

Environmental fate and pathways

 

Environmental Fate/Exposure Summary: 

Environmental exposure

 

IPETC/ O-isopropyl ethylthiocarbamate  is used in the mining industry as flotation agents as a fine collector for minerals such as copper sulfate, lead, zinc, molybdenum and nickel. The IPETC/ O-isopropyl ethylthiocarbamate  is the best collector for copper sulfate. The amount of IPETC/O-isopropyl ethylthiocarbamate used is very small relative to the quantity of ore treated, being approximately 2 to 50 g/tonne of ore.

 

The flotation process is fully automated. The process takes place in open tanks. However, the concentration of IPETC/O-isopropyl ethylthiocarbamate  in the flotation tank is low and, therefore, the release of Carbon monoxide; carbon dioxide; oxides of nitrogen; oxides of sulphur (includes sulphur di and tri oxides) would be expected to be low.

Air monitoring data, although limited and of poor quality, indicate that the atmospheric levels of carbon dioxide; oxides are below 10 ppm in the flotation areas. The risk to workers during the flotation process is considered to be low.

                                                                                                    

 

Environmental fate

 

IPETC/O-isopropyl ethylthiocarbamate was hydrolytically stable (half life > 1 year) specified by the OECD Guidelines. This substance has a limited potential to bioaccumulate (based on log Kow used by BCF estimates: 3.32, and predicted bioconcentration factors, log BCF = 1.86 (EPIWIN/BCF Program). IPETC/O-isopropyl ethylthiocarbamate is not expected to contaminate the environment where ore tailings are confined to well constructed tailings dams. Most will be retained on sulphide minerals and destroyed when they are dried after flotation. Minor residues that remain associated with tailings will be destroyed by hydrolysis intailings dams.

 

Critical Health Effects

The critical health effects for risk characterisation include, a systemic acute effect (acute toxicity from oral exposure) and a local effect (skin irritation and eye irritation).

Public Risk Characterisation

Given that there are no consumer uses identified for the chemical, it is unlikely that the public will be exposed. Hence, the public risk from this chemical is not considered to be unreasonable.

Occupational Risk Characterisation

During product formulation, oral and dermal exposure might occur, particularly where manual or open processes are used. These could include transfer and blending activities, quality control analysis, and cleaning and maintaining equipment. Worker exposure to the chemical at lower concentrations could also occur while using formulated products containing the chemical. The level and route of exposure will vary depending on the method of application and work practices employed.

Given the critical systemic long-term, systemic acute and local health effects, the chemical could pose an unreasonable risk to workers unless adequate control measures to minimise oral and dermal exposure are implemented. The chemical should be appropriately classified and labelled to ensure that a person conducting a business or undertaking (PCBU) at a workplace (such as an employer) has adequate information to determine the appropriate controls.

 

 

 Stability

 

Phototransformation in air

 

If released to air, a vapor pressure of 0.68mm Hg at 25 deg C (0.68 mm Hg is equivalent to vapour pressure of 90.7 Pa ) indicates that O-isopropyl ethylthiocarbamate (IPETC ) will exist solely as a vapor in the atmosphere. Vapor-phase O-isopropyl ethylthiocarbamate will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 0.234 days, calculated from its rate constant of 45.7698 E-12 cm3/molecule-sec at 25 deg.

O-isopropyl ethylthiocarbamate (IPETC) do not contain chromophores that absorb at wavelengths >290 nm and therefore O-isopropyl ethylthiocarbamate (IPETC ) is not expected to be susceptible to direct photolysis by sunlight.

Using the AOPWIN QSAR model, the photochemical degradation rate of O-isopropyl ethylthiocarbamate in the atmosphere is 45.7698 E-12cm3/molecule-sec, with a resultant predicted half live of 2.804 Hrs ( 0.234 Days (12-hr day; 1.5E6 OH/cm3))

 

OVERALL OH Rate Constant = 45.7698 E-12 cm3/molecule-sec

HALF-LIFE = 0.234 Days (12-hr day; 1.5E6 OH/cm3)

HALF-LIFE = 2.804 Hrs

 

Phototransformation in water

It is not applicable for a compound wich is slightly soluble or moderately soluble

 Phototransformation in soil

If released to soil, Isopropyl Ethyl Thionocarbamate (IPETC) is expected to have high mobility based upon an estimated Koc of 79.22 . 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

 

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).

 The hydrolysis of the substance was less than 10% over the 5 days, so a definitive test was not performed. Based on these results, IPETC/O-isopropyl ethylthiocarbamate was hydrolytically stable (half life > 1 year) specified by the OECD Guidelines .

 

  

    Biodegradation

Biodegradation in water: screening tests

 

Propan-2-ol (Isopropyl alcohol) and Butan-1-ol (Butyl alcohol) are both reagents used in the manufacture of IPETC/O-isopropyl ethylthiocarbamate . Therefore, the Biodegradation in water of Propan-2-ol (Isopropyl alcohol) and Butan-1-ol (Butyl alcohol) need to be considered in the assessment of IPETC/O-isopropyl ethylthiocarbamate .

The results suggest that Propan-2-ol (Isopropyl alcohol) and Butan-1-ol (Butyl alcohol) are readily biodegradable and therefore IPETC/O-isopropyl ethylthiocarbamate will be readily biodegradable and it is not expected to persist in the environment.

The ready biodegradability of n-butanol was examined. After 5 days, approximately 68% of the test material was degraded. After 10 and 15 days, approximately 87 and 92% of the test material was degraded. Butan-1-ol (Butyl alcohol) is both reagents used in the manufacture of Reaction mass of O-isopropyl ethylthiocarbamate and n-butanol and propan-2-ol. Therefore, the Biodegradation in water of Butan-1-ol (Butyl alcohol) need to be considered in the assessment of IPETC/O-isopropyl ethylthiocarbamate.

These results suggest that IPETC/O-isopropyl ethylthiocarbamate will be readily biodegradable and it is not expected to persist in the environment.

A 5-day aerobic test with isopropyl alcohol/ propan-2-ol  reported 53 % biooxidation.

A BOD5/COD ratio ≥ 0.5 for propan-2-ol is considered as indicative of rapid degradation. Thus, a substance which passes this screening test is considered likely to biodegrade 'rapidly' in the aquatic environment, and is thus unlikely to be persistent.

The results suggest that Propan-2-ol (Isopropyl alcohol) and Butan-1-ol (Butyl alcohol) are readily biodegradable and therefore IPETC/O-isopropyl ethylthiocarbamate will be readily biodegradable and it is not expected to persist in the environment.

 

  

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.

Propan-2-ol (Isopropyl alcohol) and Butan-1-ol (Butyl alcohol) are both reagents used in the manufacture of IPETC/O-isopropyl ethyl thiocarbamate.Therefore, the Biodegradation in water of Propan-2-ol (Isopropyl alcohol)and Butan-1-ol (Butyl alcohol) need to be considered in the assessment of IPETC/O-isopropyl ethyl thiocarbamate .

The results suggest that Propan-2-ol (Isopropyl alcohol) and Butan-1-ol (Butyl alcohol) are readily biodegradable and therefore IPETC/O-isopropyl ethylthiocarbamate will be readily biodegradable and it is not expected to persist in the environment.

As IPETC/O-isopropyl ethylthiocarbamate 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

 

If released to soil, O-isopropyl ethylthiocarbamate (IPETC) is expected to have very high mobility based upon an estimated Koc of 79.22. 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

 

This substance has a limited potential to bioaccumulate (based on log Kow used by BCF estimates: 3.32, and predicted bioconcentration factors, log BCF = 1.86 (EPIWIN/BCF Program).

The estimated BCF of 71.82 L/kg wet-wt was measured by calculation from EPI SuiteTM v4.1 Program.

These values would suggest very low bioaccumulation potential.

This is Exposure Assessment Tools and Models made from EPA (Environmental Protection Agency).

 

BCFBAF Program (v3.01) Results:

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

SMILES : O(C(=NCC)S)C(C)C

CHEM  : Carbamothioic acid, ethyl-, O-(1-methylethyl) ester

MOL FOR: C6 H13 N1 O1 S1

MOL WT : 147.24

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

Summary Results:

 Log BCF (regression-based estimate): 1.86 (BCF = 71.8 L/kg wet-wt)

 Biotransformation Half-Life (days) : 0.471 (normalized to 10 g fish)

 Log BAF (Arnot-Gobas upper trophic): 2.02 (BAF = 104 L/kg wet-wt)

 

Log Kow (experimental): not available from database

Log Kow used by BCF estimates: 3.32

 

Equation Used to Make BCF estimate:

  Log BCF = 0.6598 log Kow - 0.333 + Correction

 

     Correction(s):                   Value

      No Applicable Correction Factors

 

  Estimated Log BCF = 1.856 (BCF = 71.82 L/kg wet-wt)

 

  

Bioaccumulation: terrestrial

 

This substance has a limited potential to bioaccumulate (based on log Kow used by BCF estimates: 3.32, and predicted bioconcentration factors, log BCF = 1.86 (EPIWIN/BCF Program).

The estimated BCF of 71.82 L/kg wet-wt was measured by calculation from EPI SuiteTM v4.1 Program.

These values would suggest very low bioaccumulation potential.

This is Exposure Assessment Tools and Models made from EPA (Environmental Protection Agency).

 

BCFBAF Program (v3.01) Results:

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

SMILES : O(C(=NCC)S)C(C)C

CHEM  : Carbamothioic acid, ethyl-, O-(1-methylethyl) ester

MOL FOR: C6 H13 N1 O1 S1

MOL WT : 147.24

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

Summary Results:

 Log BCF (regression-based estimate): 1.86 (BCF = 71.8 L/kg wet-wt)

 Biotransformation Half-Life (days) : 0.471 (normalized to 10 g fish)

 Log BAF (Arnot-Gobas upper trophic): 2.02 (BAF = 104 L/kg wet-wt)

 

Log Kow (experimental): not available from database

Log Kow used by BCF estimates: 3.32

 

Equation Used to Make BCF estimate:

  Log BCF = 0.6598 log Kow - 0.333 + Correction

 

     Correction(s):                   Value

      No Applicable Correction Factors

 

  Estimated Log BCF = 1.856 (BCF = 71.82 L/kg wet-wt)

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

Whole Body Primary Biotransformation Rate Estimate for Fish:

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

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

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

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

Frag | 3 | Methyl [-CH3] | 0.2451 | 0.7353

Frag | 1 | -CH2- [linear] | 0.0242 | 0.0242

Frag | 1 | -CH- [linear] | -0.1912 | -0.1912

L Kow| * | Log Kow = 3.32 (KowWin estimate) | 0.3073 | 1.0198

MolWt| * | Molecular Weight Parameter | | -0.3776

Const| * | Equation Constant | | -1.5058

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

RESULT | LOG Bio Half-Life (days) | | -0.3266

RESULT | Bio Half-Life (days) | | 0.4714

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

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

Biotransformation Rate Constant:

kM (Rate Constant): 1.47 /day (10 gram fish)

kM (Rate Constant): 0.8268 /day (100 gram fish)

kM (Rate Constant): 0.465 /day (1 kg fish)

kM (Rate Constant): 0.2615 /day (10 kg fish)

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

Estimated Log BCF (upper trophic) = 2.016 (BCF = 103.7 L/kg wet-wt)

Estimated Log BAF (upper trophic) = 2.016 (BAF = 103.7 L/kg wet-wt)

Estimated Log BCF (mid trophic) = 1.970 (BCF = 93.32 L/kg wet-wt)

Estimated Log BAF (mid trophic) = 1.970 (BAF = 93.38 L/kg wet-wt)

Estimated Log BCF (lower trophic) = 1.944 (BCF = 87.96 L/kg wet-wt)

Estimated Log BAF (lower trophic) = 1.946 (BAF = 88.34 L/kg wet-wt)

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

Estimated Log BCF (upper trophic) = 2.346 (BCF = 221.7 L/kg wet-wt)

Estimated Log BAF (upper trophic) = 2.452 (BAF = 282.9 L/kg wet-wt)

 

 

   

Transport and distribution

Adsorption / desorption

 

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

— based on the physicochemical properties the substance can be expected to have a low potential for adsorption (e.g. the substance has a low octanol water partition coefficient), or

— the substance and its degradation products decompose rapidly.

The log of the adsorption coefficient (KOC) ofIsopropyl Ethyl Thionocarbamate (IPETC )was estimated to be log KOC = 1.8988which is equal to a KOC value of 79.22 using theKOCWIN v2.00 QSARmethod.

This value indicates thatIsopropyl Ethyl Thionocarbamate (IPETC )will be adsorbed by organic carbon in soil.Isopropyl Ethyl Thionocarbamate (IPETC )can be classified to be of very high mobility in soilaccording these resultsand does not have a high potential for adsorption to soil. Isopropyl Ethyl Thionocarbamate (IPETC )adsorbs strongly to sulphide minerals but has less affinity for surfaces in general. The KOC value of 79.22 also suggest thisconclusion.

 

The estimated Soil Adsorption Coefficient was 79.22 L/kg measured by calculation from EPI SuiteTM v4.1 Program. This is Exposure Assessment Tools and Models made from EPA (Environmental Protection Agency

KOCWIN Program (v2.00) Results:

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

SMILES : O(C(=NCC)S)C(C)C

CHEM : Carbamothioic acid, ethyl-, O-(1-methylethyl) ester

MOL FOR: C6 H13 N1 O1 S1

MOL WT : 147.24

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

Koc Estimate from MCI:

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

First Order Molecular Connectivity Index ........... : 4.164

Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 2.7704

Fragment Correction(s):

1 Ether, aliphatic (-C-O-C-) .......... : -0.8716

Corrected Log Koc .................................. : 1.8988

Estimated Koc: 79.22 L/kg <===========

Koc Estimate from Log Kow:

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

Log Kow (Kowwin estimate) ......................... : 3.32

Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 2.7615

Fragment Correction(s):

1 Ether, aliphatic (-C-O-C-) .......... : -0.0906

Corrected Log Koc .................................. : 2.6709

Estimated Koc: 468.7 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 4.71E-006 atm-m3/mole (4.78E-001 Pa-m3/mole) , which is almost zero.

This is Exposure Assessment Tools and Models made from EPA (Environmental Protection Agency).

 

Distribution modelling.

 

Isopropyl Ethyl Thionocarbamate (IPETC ) has no affinity to be in air and sediment. The direct emissions to soil and surface water are significant, therefore Isopropyl Ethyl Thionocarbamate (IPETC ) 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 5.95e-011 (atm), in air (atm)  1.29e-011and soil  7.32e-010 (atm) and sediment to be  5.18e-011 (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 Isopropyl Ethyl Thionocarbamate (IPETC) 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: Carbamothioic acid, ethyl-, O-(1-methylethyl) ester

 

Molecular Weight   : 147.24 g/mole

Water Solubility   : -----

Vapor Pressure     : -----

Henry's Law Constant: 4.71E-006 atm-m3/mole (estimated by Bond SAR Method)

 

                                              RIVER          LAKE  

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

Water Depth    (meters):              1                1         

Wind Velocity   (m/sec):             5                0.5       

Current Velocity (m/sec):            1                0.05      

 

     HALF-LIFE (hours) :         152.1            1761      

     HALF-LIFE (days ) :         6.336            73.36     

 

 

STP Fugacity Model: Predicted Fate in a Wastewater Treatment Facility

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

  (using 10000 hr Bio P,A,S)

PROPERTIES OF: Carbamothioic acid, ethyl-, O-(1-methylethyl) ester

 

Molecular weight (g/mol)                              147.24

Aqueous solubility (mg/l)                               0

Vapour pressure (Pa)                                   0

               (atm)                                             0

               (mm Hg)                                        0

Henry 's law constant (Atm-m3/mol)             4.71E-006

Air-water partition coefficient                       0.000192625

Octanol-water partition coefficient (Kow)             2089.3

Log Kow                                                             3.32

Biomass to water partition coefficient                418.659

Temperature [deg C]                                   25

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

         -Primary tank       0.00     4557.29      10000.00

         -Aeration tank      0.00     4557.29      10000.00                     

         -Settling tank        0.00     4557.29      10000.00

 

                              STP Overall Chemical Mass Balance:

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

                                        g/h              mol/h         percent

 

Influent                        1.00E+001        6.8E-002       100.00

 

Primary sludge             4.85E-001        3.3E-003        4.85

Waste sludge                4.52E-001        3.1E-003        4.52

Primary volatilization    2.32E-003        1.6E-005        0.02

Settling volatilization    6.27E-003        4.3E-005        0.06

Aeration off gas            1.58E-002        1.1E-004        0.16

 

Primary biodegradation    2.97E-003        2.0E-005        0.03

Settling biodegradation     8.82E-004        6.0E-006        0.01

Aeration biodegradation   1.16E-002        7.9E-005        0.12

 

Final water effluent          9.02E+000        6.1E-002       90.23

 

Total removal                   9.77E-001        6.6E-003        9.77

Total biodegradation        1.55E-002        1.1E-004        0.15