Octadecyl stearate

Endpoint summary

Description of key information

Hydrolysis:

The study does not need to be conducted because the substance is highly insoluble in water

Biodegradation in water: screening tests.:

Estimation Programs Interface Suite was run to predict the biodegradation potential of the test compound in the presence of mixed populations of environmental microorganisms. The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI LInear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that test chemical is expected to be not readily biodegradable.

Bioaccumulation: aquatic / sediment:

From BCFBAF (v3.00) model of EPI suite the estimated bio concentration factor (BCF) for test chemical is 3.2 L/kg wet-wt which does not exceed the bioconcentration threshold of 2000.Thus it is concluded that test chemical is not expected to bio accumulate in the aquatic environment.

Adsorption:

The Soil Adsorption Coefficient i.e Koc value of test chemical was estimated using EPI suite  KOCWIN Program (v2.00) as Koc 1281000000 L/kg (log Koc = 9.10)  by means of MCI method at 25 deg.C. This Koc value indicates that the substance has a very strong sorption to soil and sediment and therefore have negligible migration potential to groundwater.

Additional information

Hydrolysis:

The study does not need to be conducted because the substance is highly insoluble in water

Biodegradation in water: screening tests:

Predicted data for the target compound and various supporting weight of evidence studies for its closest read across substance were reviewed for the biodegradation end point which are summarized as below:

The first study was predicted data study in this the Estimation Programs Interface Suite was run to predict the biodegradation potential of the test compound in the presence of mixed populations of environmental microorganisms. The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI LInear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that test chemical is expected to be not readily biodegradable.

In a supporting weight of evidence study from authoritative database, biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test chemical. The study was performed according to OECD Guideline 301 B "Ready Biodegradability: Modified Sturm Test (CO2 evolution)" at a temperature of 22±2°C. Bacteria collected from activated sludge of the sewage treatment plant of CH 4153 Reinach on 2/6/89 was used as a test inoculum. Initial test substance conc. used in the study was 11.3 and 23.9 mg/l, respectively. The test medium was prepared according to the method described in the guideline. 2-liter flasks equipped with gas inlet and magnetic stirrers were used as the test vessels. Aeration consisted of approx. 25 ml/min air free of carbon dioxide. 1200 ml of the mineral solution with the inoculum was aerated for 24 hours in the test vessel. In 300 ml mineral solution 0.5 ml nonylphenol 10E05PO (solution of 30 mg in 100 ml bidist. Water) and 16.3 rsp. 29.9 mg of test substance were added and homogenized. This solution was given to the test vessel which was immediately connected to the CO2 traps. The biodegradation was calculated on the basis of the theoretical carbon content of the test substance and the cumulative quantities of carbon dioxide determined on the days of measurements. Determination of the initial CO2 of the 0.05 N sodium hydroxide and the C02, absorbed in the absorbers filled with 200 ml 0.05 N sodium hydroxide on the days 7, 10, 13, 17, 20, 24, 27, and 28. Blank consisted of water as specified in the guideline containing 0.5 ml of the nonylphenol 10E05PO solution. 20 mg/L with 0.5 ml of the nonylphenol 10E05PO was used as a reference substance in the study. The percentage degradation of test substance was determined to be 15 and 2% by CO2 evolution parameter in 28 days at a chemical conc. of 11.3 and 23.9 mg/l, respectively. Thus, based on percentage degradation, test chemical is considered to be not readily biodegradable in nature.

 

The next biodegradation study was conducted in accordance with OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test) for 28 days for evaluating the percentage biodegradability of test substance. Mixed culture was used as test inoculum for the study. Inoculum was collected form waste water treatment plant. Initial test substance conc. used in the study was 5-10 mg/l based on ThOD .  The percentage degradation of test substance 18 % by oxygen uptake parameter in 28 days. Thus, based on percentage degradation, test chemical is considered to be not readily biodegradable in nature.

On the basis of above results for target chemical and for its read across substance, it can be concluded that the test substance can be expected to be not readily biodegradable in nature.

Bioaccumulation: aquatic / sediment:

Three results including different predicted data from validated models and experimental data from authoritative database for bioaccumulation (BCF) endpoint of target chemical Octadecyl stearate (CAS no. 2778-96-3) were summarized as follows:

 

First data from BCFBAF (v3.00) model of EPI suite the estimated bio concentration factor (BCF) for test chemical is 3.2 L/kg wet-wt which does not exceed the bioconcentration threshold of 2000.Thus it is concluded that test chemical is not expected to bio accumulate in the aquatic environment.

Above predicted result of target supported by experimental data of test chemical from authoritative database in this study the

BCF value of test chemical was estimated to be 3.0 dimensionless by using an estimated log Kow of 17.7 and a regression derived equation. On the basis of this estimated BCF value it can be concluded that test chemical in non bioaccumulative in nature.

Next study was also reviewed from same data source as mentioned above in this the BCF value of test chemical was estimated to be 3.0 dimesionless by using an estimated log Kow of 13.45 and a regression derived equation. On the basis of this estimated BCF value it can be concluded that test chemical in non bioaccumulative in nature and the potential for bioconcentration in aquatic organisms (fish) is low.

In another study bioaccumulation of test chemical was conducted on test organism Lepomis macrochirusfor 49 days for evaluating the bioconcentration factor (BCF value) of test chemical. Lepomis macrochirus was used as a test organism for the study. The test was conductedin aerated carbon–filtered well water and Town River water under flow-through system. The BCF after exposure in the contaminated river water was detected with BCF <5 in the filet 94 in the viscera and 13 in the whole body. After 14 days in clear water 93 % of test chemical was detected to be eliminated. It was concluded that bluegill concentrated test chemical in well water about three times more than in river water. 49 days of exposure phase followed by a depuration phase that ranged from 21–35 days. During both phases edible (filets) and inedible (visceral) tissues of 5 fish were analyzed in duplicate for both total radioactivities at least once a week. The bioconcentration factor (BCF value) of test chemicalonLepomis macrochiruswas determined to be 13 at concentration of0.023 mg/l which does not exceed the bioconcentration threshold of 2000, indicating that the test chemicalisnot expected to bioaccumulate in the food chain.

Thus based on the above information for bioaccumulation endpoint, it can be concluded that the test substance is expected to be non bioaccumulative in aquatic environment.

Adsorption:

Four studies including predicted data from validated models and experimental study from authoritative database for adsorption (KOC) endpoint of target chemical with relevant read across chemicals which is structurally similar to target were summarized as follows:

 

First study from prediction using KOCWIN model (v2.00) of EPI suite which indicated the adsorption value of test chemical was estimated as Koc 1281000000 L/kg (log Koc = 9.10) by means of MCI method at 25 deg.C. This Koc value indicates that the substance has a very strong sorption to soil and sediment and therefore have negligible migration potential to groundwater.

 

Another prediction model i.e Chemspider - ACD/PhysChem Suite and Scifinder database for target indicate the soil adsorption coefficient i.e Koc value of test substance was estimated to be 10000000(Log koc-7) at pH 1-10 and temperature 25 deg.C. Koc values at mentioned range of pH indicates that the substance has very strong sorption to soil and sediment and therefore have negligible migration potential to groundwater. 

Above predicted value for target chemical supported by experimental data of test chemical in which the average Koc of test chemical using three standard USEPA sediments (supplied and characterized by the EPA) was measured as 1200000 (Log Koc-6.07).This Koc value suggests that test chemmical is expected to has a very strong sorption to soil and sediment and therefore have negligible migration potential to groundwater.

Another study was also experimental study from same source as mentioned in above study (HSDB) in this study the KOC value was estimated by using a structure estimation method based on molecular connectivity indices, the Koc of test cheemical was estimated to be 10000000000 (Log Koc-10).This estimated Koc value suggests that test chemical is expected to has a very strong sorption to soil and sediment and therefore have negligible migration potential to groundwater.

Last Adsorption study was conducted for estimating the adsorption coefficient (Koc) value of test chemical. The adsorption coefficient (Koc) value of test chemical was estimated to be 9X106(Log Koc = 6.95). This Koc value indicates that thetest chemical has very strong sorption to soil and sediment and therefore has negligible migration potential to groundwater.

Thus all available studies for target chemicaland its structurally smilar read across chemicals of adsorption endpoint gives the common conclusion that the test substance is expected to has a very strong sorption to soil and sediment and therefore have negligible migration potential to groundwater.