Metam-sodium

Endpoint summary

Description of key information

Adsorption / desorption

The adsorption coefficient Koc in soil of test chemical Metam-sodium (CAS No. 137-42-8) was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals (from secondary source (Draft Assessment Report, 2007) and authoritative database (AGRITOX - Plant Protection Phentopharmaceuticals Database, 2012)). Metam-sodium was introduced onto a HPLC column in a 10 μl injection containing 507.90 ng (test 1, pH 4), 508.80 ng (test 2, pH4), 501.55 ng (test 1, pH 9) and 530.30 ng (test 2, pH 9). The capacity factor (k) was determined based on the retention time of Metam-sodium and sodium nitrate (inert substance). In order to correlate k with its Koc, six reference compounds (acetanilide, atrazine, triadimenol, naphthalene, pyrazophos and DDT) with log Koc values between 1.25 and 5.63 were selected and injected. Metam-sodium was eluted from the column more quickly than acetanilide (the reference standard with the lowest iterature value for log Koc).The Log Koc value of the test chemical Metam-sodium was determined to be < 1.25 at pH 4 and 9, respectively. This log Koc value indicates that the substance Metam-sodium has a negligible sorption tosoil and sediment and therefore have rapid migration potential to ground water.

Additional information

Adsorption / desorption

Experimental study and various predicted data for the target compound Metam-sodium (CAS No. 137-42-8) and various supporting weight of evidence studies for its structurally and functionally similar read across substance were reviewed for the adsorption end point which are summarized as below:

 

In an experimental weight of evidence study from secondary source (Draft Assessment Report, 2007) and authoritative database (AGRITOX - Plant Protection Phentopharmaceuticals Database, 2012), adsorption coefficient Koc in soil of test chemical Metam-sodium (CAS No. 137-42-8) was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals.Metam-sodium was introduced onto a HPLC column in a 10 μl injection containing 507.90 ng (test 1, pH 4), 508.80 ng (test 2, pH4), 501.55 ng (test 1, pH 9) and 530.30 ng (test 2, pH 9). The capacity factor (k) was determined based on the retention time of Metam-sodium and sodium nitrate (inert substance). In order to correlate k with its Koc, six reference compounds (acetanilide, atrazine, triadimenol, naphthalene, pyrazophos and DDT) with log Koc values between 1.25 and 5.63 were selected and injected. Metam-sodium was eluted from the column more quickly than acetanilide (the reference standard with the lowest iterature value for log Koc).The Log Koc value of the test chemical Metam-sodium was determined to be < 1.25 at pH 4 and 9, respectively.

 

Another adsorption study was conducted for estimating the adsorption coefficient (Koc) value of test chemical Metam-sodium (CAS no. 137-42-8) (Pesticide Properties Database, 2017). The adsorption coefficient (Koc) value of substance Metam-sodium was estimated to be 10 (Log Koc = 1), respectively.

 

In a supporting weight of evidence study from authoritative database (Pesticide Properties Database, 2017) for the test chemical Metam-sodium (CAS no. 137-42-8),adsorption study was conducted for estimating the adsorption coefficient (Koc) value of test chemical Metam-sodium (CAS no. 137-42-8). The adsorption coefficient (Koc) value of substance Metam-sodium was estimated to be 17.8 (Log Koc = 1.25), respectively.

 

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), the adsorption coefficient i.e KOC for test substance Metam-sodium was estimated to be 13.4 L/kg (log Koc = 1.127).The predicted KOC result based on the 5 OECD principles.

 

In a supporting weight of evidence study from authoritative database (HSDB, 2017) for the read across chemical Disodium cyanodithiocarbamate (CAS no. 138-93-2),asorption experiment was conducted for estimating the adsorption coefficient (Koc) value of read across chemical Disodium cyanodithiocarbamate (CAS no. 138-93-2). The adsorption coefficient (Koc) value was calculated using a structure estimation method based on molecular connectivity indices. The adsorption coefficient (Koc) value of test substance Disodium cyanodithiocarbamate was estimated to be 2 (Log Koc = 0.3).

 

For the read across chemical Sodium dimethyldithiocarbamate (CAS no. 128-04-1),adsorption study was conducted for estimating the adsorption coefficient (Koc) value of read across chemical Sodium dimethyldithiocarbamate (CAS no. 128-04-1). The adsorption coefficient (Koc) value was calculated using a water solubility of 1000000 mg/l and a regression derived equation. The adsorption coefficient (Koc) value of test substance Sodium dimethyldithiocarbamate was estimated to be 2.2 (Log Koc = 0.342).

 

On the basis of above overall results for target chemical Metam-sodium (from secondary source, authoritative database AGRITOX - Plant Protection Phentopharmaceuticals Database and Pesticide Properties Database &CompTox Chemistry Dashboard,2017) and for its read across substance (from authoritative database HSDB, 2017), it can be concluded that the log Koc value of test substance Metam-sodiumranges from 1–1.25 indicating that the test chemical Metam-sodium has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.