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Environmental fate & pathways

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Biodegradation in water

Biodegradability of 1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol (CAS no. 1229 -55 -6) is predicted using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor (2017). Test substance undergoes 29.8% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical

1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol was estimated to be not readily biodegradable in water.

Biodegradation in water and sediment

Biodegradation in water and sediment study was carried out for determining the half-life of test chemical 1-[(2-methoxyphenyl)azo]-2-naphthol (CAS no 1229 -55 -6) under anaerobic conditions (George L. Baughman and Eric J. Weber, 1994). Sediments were obtained from 2 different lakes (i.e, Herrick and Kingfisher) near Athens, GA. The sieved sediment (5-15 cm deep) was stored in the dark, under lake water, in sealed, 2-gal glass or plastic bottles until used.Organic carbon content of sediments was determined at the University of Georgia Soil Testing Laboratory by the Walkley-Black method and by three other combustion methods, including that of Lee and Macalady.Ingeneral, the methods gave comparable results. The percent organic carbon for each lake sediment was as follows: Beef Pond, 3.05 ± 14%(n=9); Herrick, 1.52 :l:56% (n=31); KingfIsher, 7.46:l: 45%(n=10); Oglethorpe, 1.99 :l: 48%(n=7). Sediments were scraped from the top few centimeters of the lake bottom at a water depth of less than about 50 cm and sieved, at the lake, through a 0.5 mm sieve.The desired amount of sediment (based on wet weight and moisture content of filter cake) in lake water was sealed and allowed to remain quiescent for 2-4 days prior to dye addition. During dye addition (in ACN) and mixing, the sediment was maintained under N2 until placement in 20-mL scintillation vials. No attempt was made to measure redox potentials in the compacted sediment of either kinetic or product studies. However, under the study conditions, the reddish Georgia clay sediment quickly became the light gray color that is characteristic of reducing environments.Vials were sacrificed for analysis by shaking, sonicating, and filtering. To a portion of the filter cake was added a volume of ACN equal to twice the sediment moist weight. The vial was then shaken and sonicated and the slurry was filtered.Test chemical was identified by analytical methods such as HPLC and GC. For all kinetic experiments, rate constants for dye loss,kL,were obtained as the slope of a regression of the logarithm of dye concentration versus time.Products of the azo dye, SR 1, were expected to be o-anisidine and l-amino-2-naphthol resulting from reductive cleavage of the azo bond. However, these compounds could not be identified by HPLC because they coeluted. After GPC cleanup, each product was detected by GC-MS with both spectra and retention times identical to those of purchased materials.The half-life value of test chemical 1-[(2-methoxyphenyl)azo]-2-naphthol in sediment obtained from2 different lakes (i.e, Herrick and Kingfisher) was determined to be 4.0 and 2.2 days with an average first order rate constant of 7.2 × 10-3and 1.3 × 10-2, respectively. Based on this half-life value, it indicates that 1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol is not persistent in sediment.

Biodegradation in soil

The half-life period of 1-[(2-methoxyphenyl)diazenyl]-2-naphthol (CAS No. 1229 -55 -6) 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, 74.9% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 1-[(2-methoxyphenyl)diazenyl]-2-naphthol in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of

1-[(2-methoxyphenyl)diazenyl]-2-naphthol, 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

From authorative database HSDB The BCF of oil pink i.e 1-[(2-methoxyphenyl)azo]-2-naphthol in aquatic organisms was reported as 290000 using a measured log Kow of 7.5 and a recommended regression-derived equation. This BCF value indicates that bioconcentration in aquatic organisms will be an important fate process i.e chemical have concern for bioaccumulation in aquatic environment.

Adsorption / desorption

From HSDB authorative database the adsorption coefficient (Koc) of substance Oil pink i.e1-[(2-methoxyphenyl)azo]-2-naphtholwas found to be 290000 using a measured log Kow of 7.5 and regression derived equation.This Koc value indicates that oil pink will be immobile in soil.

Additional information

Biodegradation in water

Various predicted data for the target compound 1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol(CAS No. 1229 -55 -6) and supporting weight of evidence study for its closest read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In a prediction done by SSS (2017) using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor, percentage biodegradability of test chemical1-[(2-methoxyphenyl)diazenyl]-2-naphthol(CAS No. 1229-55-6) was estimated.Test substance undergoes 29.8% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol was estimated to be not readily biodegradable in water.

 

In another prediction using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound 1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol(CAS No. 1229 -55 -6) 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 chemical 1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol is expected to be not readily biodegradable.

 

In a supporting weight of evidence study for the read across chemical 1-(phenyldiazenyl)-2-naphthol (CAS no. 842-07-9), the carbon dioxide evolution test (former Sturm test) is a static method used for evaluating the ultimate aerobic biodegradability of a read across substance 1-(phenyldiazenyl)-2-naphthol in water (Sustainability Support Services (Europe) AB has letter of access, 2003). Activated sludge was obtained from laboratory wastewater plant treating municipal sewage. Activated sludge of a concentration of 30 mg/I dry substance was pre-aerated for about two days before the start of the test. Mixtures of the test substance, a defined inorganic medium and a non pre-adapted inoculurn (e .g. activated sludge or effluent of a municipal or laboratory waste water treatment plant) are incubated and aerated at room temperature up to 28 days. The biologically produced carbon dioxide is trapped in a 0,25 mol. potassium hydroxide solution. The production of carbon dioxide (C02) is a clear indication of biodegradation. The measured amount of carbon dioxide at the end of the test is compared with the calculated maximal theoretical production (ThC02) and indicated as biodegradation degree in percent. The conductivity shift of the absorption solution is used for calculating of the C02 production. Biodegradation degree of the reference substance after 14 days (% CO2/ThCO2): 60 - 70%. The percentage degradation of the read across substance was determined to be <10% in 28 days by CO2/ThCO2 parameter. Thus, the substance 1 -(phenyldiazenyl)-2 -naphthol is considered to be not readily biodegradable according to OECD criteria.

 

On the basis of above results for target chemical1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol (from OECD QSAR toolbox version 3.3 and EPI suite, 2017) and for its read across substance (from experimental report), it can be concluded that the test substance 1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol can be expected to be not readily biodegradable in nature.

Biodegradation in water and sediment

Biodegradation in water and sediment study was carried out for determining the half-life of test chemical 1-[(2-methoxyphenyl)azo]-2-naphthol (CAS no 1229 -55 -6) under anaerobic conditions (George L. Baughman and Eric J. Weber, 1994). Sediments were obtained from 2 different lakes (i.e, Herrick and Kingfisher) near Athens, GA. The sieved sediment (5-15 cm deep) was stored in the dark, under lake water, in sealed, 2-gal glass or plastic bottles until used.Organic carbon content of sediments was determined at the University of Georgia Soil Testing Laboratory by the Walkley-Black method and by three other combustion methods, including that of Lee and Macalady.Ingeneral, the methods gave comparable results. The percent organic carbon for each lake sediment was as follows: Beef Pond, 3.05 ± 14%(n=9); Herrick, 1.52 :l:56% (n=31); KingfIsher, 7.46:l: 45%(n=10); Oglethorpe, 1.99 :l: 48%(n=7). Sediments were scraped from the top few centimeters of the lake bottom at a water depth of less than about 50 cm and sieved, at the lake, through a 0.5 mm sieve.The desired amount of sediment (based on wet weight and moisture content of filter cake) in lake water was sealed and allowed to remain quiescent for 2-4 days prior to dye addition. During dye addition (in ACN) and mixing, the sediment was maintained under N2 until placement in 20-mL scintillation vials. No attempt was made to measure redox potentials in the compacted sediment of either kinetic or product studies. However, under the study conditions, the reddish Georgia clay sediment quickly became the light gray color that is characteristic of reducing environments.Vials were sacrificed for analysis by shaking, sonicating, and filtering. To a portion of the filter cake was added a volume of ACN equal to twice the sediment moist weight. The vial was then shaken and sonicated and the slurry was filtered.Test chemical was identified by analytical methods such as HPLC and GC. For all kinetic experiments, rate constants for dye loss,kL,were obtained as the slope of a regression of the logarithm of dye concentration versus time.Products of the azo dye, SR 1, were expected to be o-anisidine and l-amino-2-naphthol resulting from reductive cleavage of the azo bond. However, these compounds could not be identified by HPLC because they coeluted. After GPC cleanup, each product was detected by GC-MS with both spectra and retention times identical to those of purchased materials.The half-life value of test chemical 1-[(2-methoxyphenyl)azo]-2-naphthol in sediment obtained from2 different lakes (i.e, Herrick and Kingfisher) was determined to be 4.0 and 2.2 days with an average first order rate constant of 7.2 × 10-3and 1.3 × 10-2, respectively. Based on this half-life value, it indicates that 1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol is not persistent in sediment.

Biodegradation in soil

The half-life period of 1-[(2-methoxyphenyl)diazenyl]-2-naphthol (CAS No. 1229 -55 -6) 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, 74.9% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 1-[(2-methoxyphenyl)diazenyl]-2-naphthol in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of

1-[(2-methoxyphenyl)diazenyl]-2-naphthol, 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 1 -[(2 -methoxyphenyl)diazenyl]-2 -naphthol can be considered to be not readily biodegradable in nature.

Bioaccumulation: aquatic / sediment

Two results including predicted data from authorative database and validated models for bioaccumulation (BCF) endpoint of target chemical 1-[(2-methoxyphenyl)azo]-2-naphthol (Cas no. 1229-55-6) were summarized as follows:

 

First study from authorative database HSDB; 2017 suggest The BCF of oil pink i.e 1-[(2-methoxyphenyl)azo]-2-naphthol in aquatic organisms was reported as 290000 using a measured log Kow of 7.5 and a recommended regression-derived equation. This BCF value indicates that bioconcentration in aquatic organisms will be an important fate process i.e chemical have concern for bioaccumulation in aquatic environment.

Above result assist by prediction done using Bio-concentration Factor (v12.1.0.50374) module from ACD (Advanced Chemistry Development)/I-Lab to determine Bio-concentration Factor over the entire pH scale 1-14 of the test substance 1-[(2-methoxyphenyl)azo]-2-naphthol.BCF  estimated to be in the range 1066 to 3662 (dimentionless). This value indicates that the test substance 1-[(2-methoxyphenyl)azo]-2-naphthol was likely to be Bioaccumulative in aquatic organisms. 

Thus based on the above information for bioaccumulation endpoint, it can be concluded that the test substance 1-[(2-methoxyphenyl)azo]-2-naphthol (Cas no. 1229-55-6)is expected to be Bioaccumulative in aquatic environment as both studies indicate the chemical 1-[(2-methoxyphenyl)azo]-2-naphthol exceed the BCF threshold of 2000.

Adsorption / desorption

Five results including experimental data from authorative database and different predicted values from validated models for adsorption (KOC) endpoint of target chemical 1-[(2-methoxyphenyl)azo]-2-naphthol (Cas no. 1229-55-6) with relevant read across which is structurally similar to target were summarized as follows:

 

First study from HSDB authorative database which suggest the adsorption coefficient (Koc) of substance Oil pink i.e 1-[(2-methoxyphenyl)azo]-2-naphthol was found to be 290000 using a measured log Kow of 7.5 and regression derived equation. This Koc value indicates that oil pink will be immobile in soil.

 

 Followed prediction by KOCWIN model (v2.00) of EPI suite which indicate the adsorption value of 1-[(2-methoxyphenyl)azo]-2-naphthol was estimated as 34820 L/kg(log Koc=4.54) by means of MCI method at 25 deg.C. This Koc value indicates that the substance 1-[(2-methoxyphenyl)azo]-2-naphthol has a very strong sorption to soil and sediment and therefore have negligible migration potential to groundwater. 

Above result is assist by result from CompTox Chemistry Dashboard using OPERA (OPEn (quantitative) structure-activity Relationship Application) V1.02 model in which calculation based on PaDEL descriptors (calculate molecular descriptors and fingerprints of chemical) indicate the adsorption coefficient i.e KOC for test substance 1-[(2-methoxyphenyl)azo]-2-naphthol was estimated to be 4610 L/Kg.The predicted KOC result based on the 5 OECD principles. Thus based on the result it is concluded that the test substance 1-[(2-methoxyphenyl)azo]-2-naphthol is immobile in soil compartment.

And Scifinder database suggest the soil adsorption coefficient i.e Koc value of test substance 1-[(2-methoxyphenyl)azo]-2-naphthol was estimated to be 5690 (Log koc =3.75) at pH range 1-10 at temperature 25 deg.C. This Koc value at all range of pH condition indicates that the substance 1-[(2-methoxyphenyl)azo]-2-naphthol has Strong sorption to soil and sediment and thus negligible to slow migration potential to groundwater.

 

Last study from authorative database HSDB; 2017 for read across chemical Solvent Red 23 (Cas no. 85-86-9) suggest Log Koc values for test substance Solvent Red 23 are based on calculations by Baughman and Perenich (1988) using a range of measured solubility for commercial dyes and an assumed melting point of 200 deg.C.During experiment the Log Koc (Organic carbonwater partition coefficient) (dimensionless) was reported to be 3.4 to 4.2. Based on the result it is concluded that the Solvent Red 23 has low water solubility and a relatively high Koc it is not likely to leach from sediments and soils means solvent Red 23 is immobile in soil and sediment.

Thus all above available studies for adsorption endpoint come to conclusion that the test substance chemical 1-[(2-methoxyphenyl)azo]-2-naphthol (Cas no. 1229-55-6) is expected be immobility in soil and sediment compartment.