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Environmental fate & pathways

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Biodegradation in water

Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test substance Nonylphenol ethoxylates (CAS no. 127087 -87 -0) (NTRL report no. OTS0558989, 1997). The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)). Concentration of inoculum i.e, sludge used was 30 mg/l. During the 28 day period the biological oxygen demand is measured and at the end of the 28 day period the level of organic carbon remaining in the aqueous phase is also measured. The percentage degradation of test substance was determined to be 81% by DOC removal parameter in 28 days. Thus, based on percentage degradation, Nonylphenol ethoxylates is considered to be readily biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface (EPI) Suite (2017) prediction model was run to predict the half-life in water and sediment for the test compound4-Nonylphenol, branched, ethoxylated(CAS No. 127087 -87 -0). If released in to the environment, 9.39% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of4-Nonylphenol, branched, ethoxylatedin water is estimated to be 60 days (1440 hrs). The half-life (60 days) indicates that the chemical is persistent in water and the exposure risk to aquatic animals is moderate to high whereas the half-life period of4-Nonylphenol, branched, ethoxylatedin sediment is estimated to be 541.66 days (13000 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.631%), it can be considered that4-Nonylphenol, branched, ethoxylatedis not persistent in sediment.   

Biodegradation in soil

The half-life period of 4-Nonylphenol, branched, ethoxylated (CAS No. 127087 -87 -0) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 90% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 4-Nonylphenol, branched, ethoxylated in soil is estimated to be 120 days (2880 hrs). Based on this half-life value of 4-Nonylphenol, branched, ethoxylated, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

Bioaccumulation: aquatic / sediment:

The bioconcentration factor (BCF) was estimated by BCFBAF (v3.01) model using regression-based estimate for test substance 4-Nonylphenol, branched, ethoxylated. The BCF value was reported as 7.86 L/kg wet-wt which does not exceed the bioconcentration threshold of 2000. Thus it is concluded that 4-Nonylphenol, branched, ethoxylated is not expected to bio accumulate in the food chain.

Adsorption / desorption:

The adsorption coefficient Koc in soil and in sewage sludge 4-Nonylphenol, branched, ethoxylated(CAS No.127087-87-0) was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The chosen reference substances were having Koc value ranging from 1.239 to 2.47. The Log Koc value was found to be 2.6311 ± 0.0001 at 25°C.

Additional information

Biodegradation in water

1 experimental study for the target compound Polyethylene glycol mono(branched p-nonylphenyl) ether(CAS No. 127087-87-0) which is supported further by the 2 weight of evidence studies (from peer reviewed journal and authoritative database) for its closest read across substance with logKow as the primary descriptor were reviewed for the biodegradation end point which are summarized as below:

 

In a weight of evidence study for target chemical Polyethylene glycol mono(branched p-nonylphenyl) ether(CAS No. 127087-87-0), biodegradation experiment was conducted for 28 days (NTRL report no. OTS0558989, 1997) The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)). Concentration of inoculum i.e, sludge used was 30 mg/l. During the 28 day period the biological oxygen demand is measured and at the end of the 28 day period the level of organic carbon remaining in the aqueous phase is also measured. The percentage degradation of test substance was determined to be 81% by DOC removal parameter in 28 days. Thus, based on percentage degradation, Nonylphenol ethoxylates is considered to be readily biodegradable in nature.

Another weight of evidence study of biodegradation for read across substance Triethylene glycol ethyl ether (CAS no. 112 -50 -5) (having a 50 -60% similarity with the target chemical Polyethylene glycol mono(branched p-nonylphenyl) ether) was carried out for 20 days for evaluating the percentage biodegradability of chemical Triethylene glycol ethyl ether (Kenneth S. Price et. al; 1974) . Initial test substance conc. used in the study was 3, 7 and 10 mg/l, respectively. Domestic wastewater was used as a test inoculum.The BOD bottles were half filled with aerated dilution water containing the specified minerals and buffer. Small aliquots of the test chemicals were added to these bottles from 0.1% stock solutions yielding conc. of 3, 7 and 10 mg/l. At least two of these concentrations were tested in duplicate. These concentrations gave a potential oxygen demand of 3 to 30 mg/l over the 20 days duration of test. Dissolved oxygen was monitored periodically in the individual bottles through the use of a commercial DO meter filled with an agitated probe. The bottles were opened for sampling and DO measurements about five times during the course of the 20 day test.The percentage degradation of test substance was determined to be8, 47, 63 and 71% degradation in 5, 10, 15 and 20 days, respectively.Thus, based on percentage degradation,Triethylene glycol ethyl etheris considered to be readily biodegradable in nature.

For the same read across chemical Triethylene glycol ethyl ether (CAS no. 112 -50 -5) from authoritative database (J-CHECK, 2016), biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test substanceTriethylene glycol ethyl ether (CAS no. 112 -50 -5). 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 substance was determined to103, 99 and 100% by BOD, TOC removal and GC parameter in 28 days. Thus, based on percentage degradation,Triethylene glycol ethyl ether is considered to be readily biodegradable in nature

On the basis of above results for target chemical Polyethylene glycol mono(branched p-nonylphenyl) ether(from NTRL report) and for its read across substance (from peer reviewed journal and authoritative database J-CHECK) , it can be concluded that the test substance Polyethylene glycol mono(branched p-nonylphenyl) ether can be expected to be readily biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface (EPI) Suite (2017) prediction model was run to predict the half-life in water and sediment for the test compound4-Nonylphenol, branched, ethoxylated(CAS No. 127087 -87 -0). If released in to the environment, 9.39% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of4-Nonylphenol, branched, ethoxylatedin water is estimated to be 60 days (1440 hrs). The half-life (60 days) indicates that the chemical is persistent in water and the exposure risk to aquatic animals is moderate to high whereas the half-life period of4-Nonylphenol, branched, ethoxylatedin sediment is estimated to be 541.66 days (13000 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.631%), it can be considered that4-Nonylphenol, branched, ethoxylatedis not persistent in sediment.   

Biodegradation in soil

The half-life period of 4-Nonylphenol, branched, ethoxylated (CAS No. 127087 -87 -0) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 90% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 4-Nonylphenol, branched, ethoxylated in soil is estimated to be 120 days (2880 hrs). Based on this half-life value of 4-Nonylphenol, branched, ethoxylated, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

On the basis of available information, the test substance Polyethylene glycol mono(branched p-nonylphenyl) ether can be considered to be readily biodegradable in nature.

Bioaccumulation: aquatic / sediment:

Four studies including Experimental and Predicted data for Bioaccumulation endpoint of the target chemical 4-Nonylphenol, branched, ethoxylated (Cas no. 127087-87-0) and its relevant read across chemical which are structurally similar to target were reviewed to summarize as follows:  

 

First study from prediction report by BCFBAF (v3.00) model which indicate the estimated bio concentration factor (BCF) for 4-Nonylphenol, branched, ethoxylated (Cas no. 127087-87-0) is 7.86 L/kg wet-wt which does not exceed the bioconcentration threshold of 2000.Thus it is concluded that 4-Nonylphenol, branched, ethoxylated is not expected to bio accumulate in the food chain.

Above predicted result for target chemical is supported by experimental evidence from reliable data source Japan chemicals collaborative knowledge database (J-check) of read across 4-Nonylphenol, ethoxylated (Cas no. 26027-38-3) suggest the Bioconcentration value i.e BCF range of 7.6-12.4 and 9.09-16 was calculated in fish for 4-Nonylphenol, ethoxylated using Cyprinus carpio which were exposed over to 0.1 and 1 mg/L over a 6-week period. This BCF range suggests bioconcentration in aquatic organisms is low.

Data from same source i.e Japan chemicals collaborative knowledge database (J-check) for another read across chemical Nonylphenol, ethoxylated (Cas no. 9016-45-9) indicate the Bioconcentration value i.e BCF range of <0.2 to <1.4 was calculated in fish for Nonylphenol, ethoxylated using Cyprinus carpio which were exposed over to 0.2 and 2 mg/L over a 6-week period.This BCF range suggests bioconcentration in aquatic organisms is low.

Last evidence for one another read across 2-(2-(2-butoxyethoxy)ethoxy)ethanol (Cas no. 143-22-6) gives close result to above all BCF data i.e BCF of 3 was calculated in fish for triethylene glycol monobutyl ether, using an estimated log Kow of 0.02 and a regression derived equation. This BCF suggests the potential for bioconcentration in aquatic organisms is low.

All predicted and experimental values for bioaccumulation is in the range of <0.2 -12.4 (L/kg or dimensionless) concluded that the target chemical 4-Nonylphenol, branched, ethoxylated (Cas no. 127087-87-0) is non bioaccumulative in aquatic environment

Adsorption / desorption:

Four studies for adsorption in soil/sediment endpoint including experimental and valid predicted model data of test chemical 4-Nonylphenol, branched, ethoxylated (Cas no. 127087-87-0) with relevant read across chemicals which is 90-80 % structurally similar to target were reviewed as follows:

 

First study from experimental report of UERL (2017) indicates that the adsorption coefficient Koc in soil and in sewage sludge 4-Nonylphenol, branched, ethoxylated(CAS No.127087-87-0) was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The chosen reference substances were having Koc value ranging from 1.239 to 2.47. The Log Koc value was determined to be 2.6311 ± 0.0001 at 25°C.

And supporting data of target indicate the Soil Adsorption Coefficient i.e Koc value of 4-Nonylphenol, branched, ethoxylated was estimated using EPI suite KOCWIN Program (v2.00) as Koc 1035 L/kg(log Koc=3.014) by means of MCI method at 25 deg.C. This Koc value indicates that the substance 4-Nonylphenol, branched, ethoxylated has a moderate sorption to soil and sediment and therefore have slow migration potential to groundwater.

 

Whereas experiment result (HSDB database by US EPA) for read across chemical 4-Nonylphenol, ethoxylated (Cas no. 26027-38-3) indicate that using a structure estimation method based on molecular connectivity indices, the Koc of 4-Nonylphenol, ethoxylated can be estimated to be 1300 This estimated Koc value suggests that 4-Nonylphenol, ethoxylated is expected to have low mobility in soil.

 

Study from another read across substance Nonylphenol, ethoxylated (Cas no. 9016-45-9) suggest that the Adsorption of nonylphenol polyethoxylates is dependent upon the number of ethoxylate units present; Sludge adsorption was greatest for nonylphenol (44-48% of the added compound adsorbed) followed by nonylphenol ethoxylate (n=1) (14-15% of the added compound adsorbed to sludge), and nonylphenol diethoxylate (67% of the added compound adsorbed to sludge). Adsorption of nonylphenyl ethoxylate (n=6) to sediment was dependent on the organic matter concentration. A Koc of 6.1 was measured in sediment. Polyethyleneglycol nonylphenyl ether (n=13) was observed to Kd values ranging from 450-1460 L/kg in sediment, 230-590 L/kg in sediment without organic carbon, 25-92L/kg in silica, and 12000-13000 L/kg in sludge, suggesting strong sorption may occur to the solid phase in soil.

 

Thus all above studies for target and read across reports from authorative databases arrive at a conclusion as the test substance 4-Nonylphenol, branched, ethoxylated (Cas no. 127087-87-0) has low mobility in soil/sediment compartment.