[[4-[[2-(4-cyclohexylphenoxy)ethyl]ethylamino]-2-methylphenyl]methylene]malononitrile

Endpoint summary

Description of key information

Hydrolysis

In accordance with column 2 of Annex VIII of the REACH regulation, testing for this endpoint is technically not feasible and does not need to be conducted since the test chemical is insoluble in water.

Biodegradation in water

Estimation Programs Interface Suite (2018) was run to predict the biodegradation potential of the test chemical 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 chemical is expected to be not readily biodegradable.

Bioaccumulation in aquatic/sediments:

The observed BMF was 0.0026 of test chemical on fish Danio rerio  in 20 days. On the basis of this BMF value it is concluded that this test chemical is non bioaccumuative in nature.

Adsorption / desorption

Adsorption study was conducted for estimating the adsorption coefficient (Koc) value of test chemical (from handbook, 2008 and secondary source, 2011). The adsorption coefficient (Koc) value of test chemical was estimated to be 1995262.3 dimensionless (Log Koc = 6.3) at 25°C. This Koc value indicates that the test chemical hasa very strong sorption tosoil and sediment and therefore have negligible migration potential to ground water.

Additional information

Hydrolysis

In accordance with column 2 of Annex VIII of the REACH regulation, testing for this endpoint is technically not feasible and does not need to be conducted since the test chemical is insoluble in water.

Biodegradation in water

Predicted data for the test chemical and various supporting weight of evidence studies for its structurally similar read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In a prediction using the Estimation Programs Interface Suite (2018), the biodegradation potential of the test chemical in the presence of mixed populations of environmental microorganisms was estimated. 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 (2018) for the test chemical, biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of test chemical. Activated sludge was used as a test inoculums for the study. Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l, respectively. The percentage degradation of test chemical was determined to be 0% by BOD and HPLC parameter in 28 days. Thus, based on percentage degradation, test chemical is considered to be not readily biodegradable in nature.

For the test chemical,biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test chemical (secondary source, 2017). The study was performed according to OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test) under aerobic conditions. Activated sludge was used as a test inoculums for the study. Sodium benzoate was used as a reference substance for the study which undergoes 61% biodegradation within 28 days confirming the suitability of the inoculum and the culture conditions. The percentage degradation of test chemical was determined to be 1-2% byCO2 Evolution parameter in 28 days. Thus, based on percentage degradation, test chemical is considered to be not readily biodegradable in nature.

 

Another biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test chemical (secondary source, 2017). The study was performed according to OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test) under aerobic conditions. Activated sludge was used as a test inoculums for the study. Sodium benzoate was used as a reference substance for the study which undergoes 89% biodegradation within 28 days. The percentage degradation of test chemical was determined to be 5% within 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 test chemical, it can be concluded that the test chemical can be expected to be not readily biodegradable in nature.

Bioaccumulation in aquatic/sediments:

For determination bioaccumulation factor an experiment was conducted with food instead of water as the exposure route (Experimental study report, 2009). Apart from that, the general provisions of OECD TG 305 – Bioconcentration: Flow-through Fish Test (June 1996) which is equivalent to the Council regulation (EG) 440/2008 EU method C.13, Bioconcentration: Flow-Through Fish Test (2008) were used to conduct the study. The “Background document to the Fish Dietary Study-Protocol” and “Fish Dietary Bioaccumulation Study - Basic Protocol” was used as guidance. This study consists of two phases the exposure phase and post exposure phase(depuration).During the uptake phase, separate groups of fish of one species are fed with a special diet of fish food mixed with at least two concentrations (100 and 1000 μg/g fish food) of the test item. As a reference compound hexachlorobenzene is also added to the fish diet at a nominal concentration of 100 μg/g. The uptake phase is run for 20 days. The concentration of the test item in control and test diets are analysed one day prior to the uptake phase, at the beginning of the uptake phase and 10 days thereafter. The test item and reference compound concentration in fish is followed by HPLC analysis and UV/VIS-detection 10 days after beginning of the uptake phase and at the end of the uptake phase. A tissue specific analysis was also carried out on dissected fish and the separated guts of the fish at the end of the uptake phase. The test dilution water was measured one day prior to the beginning of the uptake phase and on day 10 and 20 of the uptake phase for the control and both test item concentrations. After 20 days the depuration period is begun by feeding the fish with a diet free from the test item and the reference compound. During the depuration phase fish samples were taken at several times for analysis. Fish for tissue specific analysis were also taken, the guts were removed and both, dissected fish and guts were analysed separately. After a period of 28 days, the concentration of test item in fish was below the LOQ of of test chemical of 0.401 μg/g fish wet weight and that was the last data point to be included in the regression to estimate the depuration rate constant. The lipid cocntent of fish at start of exposure was 8.5 % and at end of exposure was 13.1 %. The test item was shown to be stable in spiked fish food with recoveries ranging from 97.5 to 99.8% at the test item concentration 100 μg/g and 99.2 to 105.2% at the test item concentration 1000 μg/g (3 repeat determinations during uptake phase). The recoveries for the reference compound hexachlorobenzene in spiked fish food ranged from 86.9 to 97.1% at the test item concentration 100 μg/g and from 70.3 to 106.7% at the test item concentration 1000 μg/g, respectively. The uptake efficiency (α) for HCB was 0.548 (54.8%) at a HCB concentration of 100 μg/g (and a test item concentration 1000 μg/g) indicating suitability of the test system. For the test item an uptake efficiency of 0.063 (6.3%) for the test item concentration 1000 μg/g was calculated. Because of limited uptake, at a test item concentration of 100 μg/g the concentration in fish tissue after 20 days uptake was below the LOQ and therefore no assimilation efficiency could be determined. The mean recovery of test item from spiked fish tissue was 97.5%, while the mean recovery of the reference compound hexachlorobenzene was 93.2%. Some fish were dissected and fish tissue and gut samples were analysed separately. From the data, correcting for fish growth during the test, a BMF of 0.0026 was determined for the test item concentration 1000 μg/g. After 28 days of depuration (i.e. feeding unspiked food), no test chemical could be determined any more. At a concentration of 100 μg/g the bioaccumulation was too low to allow quantification. The calculated half life of the test item from the above data was 9.706 days. The observed BMF was 0.0026 of test chemical on fish Danio rerio  in 20 days. On the basis of this BMF value it is concluded that this test chemical is non bioaccumuative in nature.

Adsorption / desorption

Various predicted data of the test chemical were reviewed for the adsorption end point which are summarized as below:

 

Adsorption study was conducted for estimating the adsorption coefficient (Koc) value of test chemical (from handbook, 2008 and secondary source, 2011). The adsorption coefficient (Koc) value of test chemical was estimated to be 1995262.3 dimensionless (Log Koc = 6.3) at 25°C. This Koc value indicates that the test chemical has a very strong sorption to soil and sediment and therefore have negligible migration potential to ground water.

 

In aprediction done using theKOCWIN Programof Estimation Programs Interface (2018) was used to predict the soil adsorption coefficient i.e Koc value of test chemical. The soil adsorption coefficient i.e Koc value of test chemical was estimated to be 338300 L/kg (log Koc= 5.529) by means of MCI method (at 25 deg C). This Koc value indicates that the test chemical has a very strong sorption to soil and sediment and therefore have negligible migration potential to ground water.

 

The Soil Adsorption Coefficient i.e Koc value of test chemical was estimated using Adsorption Coefficient module program as Koc 4999, 36135, 190677, 340864, 370104, 373307, 373630, 373663 and 373666 at pH range 0, 1, 2, 3, 4, 5, 6, 7 and 8-14, respectively (logKoc value ranges from 3.7 ± 1.0 to 5.6 ± 1.0) (ACD (Advanced Chemistry Development)/I-Lab predictive module, 2017)). The logKoc value (at pH 7.0) indicates that the test chemical has a very strong sorption to soil and sediment and therefore have negligible migration potential to ground water.

 

On the basis of above overall results for test chemical, it can be concluded that the log Koc value (at pH 7.0) of test chemical was estimated to be ranges from 5.529 to 6.3, respectively, indicating that the test chemicalhas a very strong sorption to soil and sediment and therefore have negligible migration potential to ground water.