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Biodegradation in water

Biodegradability of 6-Methoxy-2-naphthaldehyde (CAS no. 3453 -33 -6) is predicted using OECD QSAR toolbox version 3.3 (2017) with logKow as the primary descriptor. Test substance undergoes 92.6% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 6-Methoxy-2-naphthaldehyde was estimated to be readily biodegradable in water.

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 compound 6-Methoxy-2-naphthaldehyde (CAS No. 3453 -33 -6). If released in to the environment, 29.1% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 6-Methoxy-2-naphthaldehyde in water is estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of 6-Methoxy-2-naphthaldehyde in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.142%), indicates that 6-Methoxy-2-naphthaldehyde is not persistent in sediment.

 

Biodegradation in soil

The half-life period of 6-Methoxy-2-naphthaldehyde (CAS No. 3453 -33 -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, 70.2% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 6-Methoxy-2-naphthaldehyde in soil is estimated to be 30 days (720 hrs). Based on this half-life value of 6-Methoxy-2-naphthaldehyde, 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.

Additional information

Biodegradation in water

Various predicted data for the target compound 6-Methoxy-2-naphthaldehyde (CAS No. 3453-33-6) and supporting weight of evidence studies for its 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 chemical 6-Methoxy-2-naphthaldehyde(CAS No. 3453-33-6) was estimated.Test substance undergoes 92.6% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 6-Methoxy-2-naphthaldehyde was estimated to be readily biodegradable in water.

 

In another prediction using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound 6-Methoxy-2-naphthaldehyde(CAS No. 3453-33-6) 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  6-Methoxy-2-naphthaldehyde is expected to be readily biodegradable.

 

In a supporting weight of evidence study from authoritative database (J-CHECK and HSDB, 2017) for the read across chemical 1-butoxypropan-2-ol (CAS no. 121-33-5), biodegradation experiment was conducted for 14 days for evaluating the percentage biodegradability of read across substance 1-butoxypropan-2-ol. 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 and initial test substance conc. used in the study was 100 mg/l, respectively. The percentage degradation of substance 1-butoxypropan-2-ol was determined to be 97, 99 and 100% by BOD, TOC removal and HPLC parameter in 14 days. Thus, based on percentage degradation,1-butoxypropan-2-ol is considered to be readily biodegradable in nature.

 

For the read across substance 2-Methoxybenzaldehyde (CAS no. 135-02-4) from peer reviewed journal (Gerhard Zellner et. al; 1990), biodegradation study was conducted under anaerobic conditions for 28 days for evaluating the percentage biodegradability of read across substance 2-methoxybenzaldehyde. Test chemical 2-methoxybenzaldehyde were of analytical grade and were purchased from Serva (Heidelberg, Federal Republic of Germany), Merck, or Aldrich Chemie GmbH & CoKG (Steinheim, Federal Republic of Germany). Desulfovibrio vulgaris Marburg DSM 2119 and Desulfovibrio sp. strain MP47 was used as an inoculum for the study. Desulfovibrio vulgaris Marburg DSM 2119 was obtained from Hans Hippe, Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Braunschweig, Federal Republic of Germany and Desulfovibrio sp. strain MP47 was isolated from a laboratory digester. Strain MP47 is presumably another strain of Desulfovibrio vulgaris. Desulfovibrio vulgaris Marburg DSM 2119 and Desulfovibrio sp. strain MP47 were routinely cultured in a medium that contained the following (per liter): 4.25 g of Na2SO4, 0.255 g of K2HPO4, 0.255 g of KH2PO4, 0.255 g of (NH4)2S04, 0.45 g of NaCl, 0.10 g of MgSO4 - 7H20, 2.0 g of yeast extract, 60 mg of CaCl2, 4 mg of FeSO4, 24 mg of Ni(NH4)2(SO4)2, and 1 mg of resazurin. The medium was supplemented with 10 ml each of vitamin and mineral solutions and reduced by the addition of 0.5 g of L-cysteine hydrochloride and 0.5 g of Na2S 9H20 per liter.The pH of the medium was adjusted to 7.0. Cultures were grown at 37°C on a rotary shaker at 100 rpm. Utilization of yeast extract components as electron donors was tested in the same medium with an N2-CO2 (80:20%; 300 kPa) gas atmosphere.Serum bottles was used as a test vessel for the study. Initial test substance conc. used in the study was 250 mg/l. Parallel cultures in serum bottles containing 20 ml of medium and 250 mg of substrate per liter were incubated under N2-CO2 (80:20%, 300 kPa) at 37°C on a shaker (100 rpm) for 4 weeks. Biotransformation of the substrates was analyzed by at least two methods, including HPLC with two detector systems, UV spectroscopy at 254 nm and thin-layer chromatography. The percentage degradation of substance 2-methoxybenzaldehyde was determined to be 80% by HPLC, UV-Vis and TLC parameter in 28 days. The chemical was transformed into the respective benzoic acids. Thus, based on percentage degradation, 2-methoxybenzaldehyde is considered to be readily biodegradable in nature.

 

In a supporting weight of evidence study from authoritative database (J-CHECK, 2017) and secondary source (OECD SIDS, 2009) for the read across chemical 4-Methoxybenzaldehyde (CAS no. 123-11-5),biodegradation experiment was conducted for 14 days for evaluating the percentage biodegradability of read across substance 4-methoxybenzaldehyde.The study was performed according to OECD Guideline 301C “Ready biodegradability: Modified MITI Test (I)” under aerobic conditions. Activated sludge was used as a test inoculum. Sludge and surface water including surface soil were collected from ten different places in Japan which includes water treatment plants, rivers, lake and inner bays. These sludge and water/soil were mixed and cultivated with glucose and peptone as nutrient in a testing laboratory. 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. Aniline was used as a reference substance for the study. Portion of the test solution was taken out followed by the centrifuge separation. Then, the supernatant solution was employed for the quantitative analysis for HPLC and TOC. BOD was continuously measured by BOD analysis over 14 days. Direct analysis by HPLC and TOC analysis were conducted after 28 days. The percentage degradation of substance 4-methoxybenzaldehyde was determined to be 99, 98 and 100% by BOD, TOC removal and HPLC parameter in 28 days. Thus, based on percentage degradation, 4-methoxybenzaldehyde is considered to be readily biodegradable in nature.

 

Another biodegradation studywas conducted for 28 days for evaluating the percentage biodegradability of read across substance 4-methoxybenzaldehyde (CAS no. 123-11-5) (HPVIS, 2017). The study was performed according to OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test) under aerobic conditions at a temperature range of 17-22°C. Activated sludge was used as a test inoculum for the study. Initial test substance conc. used in the study was 10 mg/l. Concentration of inoculum used was10% by volume of secondary effluent from an unacclimatised activated sludge. The mean percentage biodegradation was calculated from 4 vessels on day 28. The percentage degradation of substance 4 -methoxy benzaldehyde was determined to be 94.9% by CO2 evolution parameter in 28 days. Thus, based on percentage degradation, 4 -methoxybenzaldehyde is considered to be readily biodegradable in nature.

 

On the basis of above results for target chemical 6-Methoxy-2-naphthaldehyde (from OECD QSAR toolbox version 3.3 and EPI suite, 2017) and for its read across substance (from authoritative database J-CHECK, HSDB, peer reviewed journals and secondary source), it can be concluded that the test substance 6-Methoxy-2-naphthaldehyde 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 compound 6-Methoxy-2-naphthaldehyde (CAS No. 3453 -33 -6). If released in to the environment, 29.1% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 6-Methoxy-2-naphthaldehyde in water is estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of 6-Methoxy-2-naphthaldehyde in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.142%), indicates that 6-Methoxy-2-naphthaldehyde is not persistent in sediment.

 

Biodegradation in soil

The half-life period of 6-Methoxy-2-naphthaldehyde (CAS No. 3453 -33 -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, 70.2% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 6-Methoxy-2-naphthaldehyde in soil is estimated to be 30 days (720 hrs). Based on this half-life value of 6-Methoxy-2-naphthaldehyde, 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 6-Methoxy-2-naphthaldehyde can be considered to be readily biodegradable in nature.