Metam-sodium

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data is from peer reviewed journal

Justification for type of information:

Data is from peer reviewed journal

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Principles of method if other than guideline:

Aim of this study was to determine the effect of chemical Metam-sodium on the growth of aquatic cladoceran crustacean Daphnia magna by utilizing Toxkits (culture/maintenance-free microbiotests).

GLP compliance:

not specified

Specific details on test material used for the study:

- Name of test material : Metam-sodium
- Molecular formula : C2H4NNaS2
- Molecular weight : 129.1826 g/mol
- Smiles notation : C(=S)(NC)[S-].[Na+]
- InChl : 1S/C2H5NS2.Na/c1-3-2(4)5;/h1H3,(H2,3,4,5);/q;+1/p-1
- Substance type: Organic
- Physical state: Solid

Analytical monitoring:

not specified

Vehicle:

not specified

Details on test solutions:

- Method: Standard freshwater was prepared with the concentrated salt solutions provided in the kit. 1 : 1 toxicant dilution series of the blind water samples was prepared.

Test organisms (species):

Daphnia magna

Details on test organisms:

Details on test organisms
TEST ORGANISM
- Common name: Water Flea
- Age at study initiation (mean and range, SD): Neonate daphnids that were younger than 24 h were used.
- Method of breeding: Dormant Daphnia eggs are protected by a chitinous capsule called ephippium and can be stored for long periods of time in the refrigerator at 4 °C without losing their viability. When ephippia are placed under specific environmental conditions and triggers, the eggs develop in 3–4 days into neonates that can be used for the toxicity tests. Hatching of the ephippia was initiated 3–4 days prior to the start of the toxicity tests by incubating the dormant eggs in petri dishes with ISO medium at 20 °C under a constant illumination of 6000 lux.

Test type:

static

Water media type:

freshwater

Total exposure duration:

24 h

Test temperature:

20 °C

Details on test conditions:

Details on test conditions
TEST SYSTEM
- Test vessel: Multiwell test plates
- Type (delete if not applicable): closed
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: Multiwells had a column of ‘rinsing wells’ to prevent dilution of the toxicant in the multiwell cups during transfer of the test organisms from the hatching petri dish to the test plate. The transfers were performed with the aid of a micropipette, on a light table. In the first step about 25 daphnids were transferred from the petri dish into the ‘rinsing wells’. Then exactly five neonates were brought from the ‘rinsing wells’ into each test well containing 5 ml of test medium. On completion of the transfers, each multiwell plate was sealed with a strip of parafilm and covered with its lid. Plates then were placed in an incubator set at 20 °C in darkness for 24 h.


OTHER TEST CONDITIONS
- Light intensity: constant illumination of 6000 lux.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : The wells of each row were checked and the number of dead or immobilized neonates was recorded versus that of the actively
swimming test organisms in each well

Reference substance (positive control):

not specified

Key result

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

0.61 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95 % CI was 0.49-0.75 mg/l

Reported statistics and error estimates:

Manually by ‘graphical interpolation’ Or by probit analysis.

Validity criteria fulfilled:

not specified

Conclusions:

Based on the immobility of daphnia magna due to the exposure of chemical Metam-sodium for 24 hrs of exposure, the EC50 was determine to be 0.61 mg/l.

Executive summary:

Aim of this study was to determine the effect of chemical Metam-sodium on the growth of aquatic cladoceran crustacean Daphnia magna by utilizing Toxkits (culture/maintenance-free microbiotests). Test conducted according to the OECD and ISO test protocols for the acute Daphnia magna toxicity tests for 24 hrs of total exposure period. Toxicant dilution series of the blind water samples was prepared with the test chemical.

 

Neonate daphnids that were younger than 24 h were used. Hatching of the ephippia was initiated 3–4 days prior to the start of the toxicity tests by incubating the dormant eggs in petri dishes with ISO medium at 20 °C under a constant illumination of 6000 lux. Multiwell test plates were used in the study. In the plate rinsing wells present contain 5 daphnia per well with 5 ml of test solution. The wells of each row were checked and the number of dead or immobilized neonates was recorded versus that of the actively swimming test organisms in each well.

 

Based on the immobility of daphnia magna due to the exposure of chemical Metam-sodium for 24 hrs of exposure, the EC50 was determine to be 0.61 mg/l. thus chemical was consider as toxic and can be consider to be classified as aquatic acute category 1 as well as chronic 1 as per the CLP classification criteria.

Description of key information

Aim of this study was to determine the effect of chemical Metam-sodium on the growth of aquatic cladoceran crustacean Daphnia magna by utilizing Toxkits (culture/maintenance-free microbiotests). Test conducted according to the OECD and ISO test protocols for the acute Daphnia magna toxicity tests for 24 hrs of total exposure period. Toxicant dilution series of the blind water samples was prepared with the test chemical. Neonate daphnids that were younger than 24 h were used. Hatching of the ephippia was initiated 3–4 days prior to the start of the toxicity tests by incubating the dormant eggs in petri dishes with ISO medium at 20 °C under a constant illumination of 6000 lux. Multiwell test plates were used in the study. In the plate rinsing wells present contain 5 daphnia per well with 5 ml of test solution. The wells of each row were checked and the number of dead or immobilized neonates was recorded versus that of the actively swimming test organisms in each well. Based on the immobility of daphnia magna due to the exposure of chemical Metam-sodium for 24 hrs of exposure, the EC50 was determine to be 0.61 mg/l. thus chemical was consider as toxic and can be consider to be classified as aquatic acute category 1 as well as chronic 1 as per the CLP classification criteria.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.61 mg/L

Additional information

Based on the various experimental data for the target chemical Metam-sodium (137-42-8) study have been reviewed to determine toxic nature of on the growth and other activity of invertebrates. The studies are as mentioned below: 

In the first key experimental study for the Metam-sodium (137-42-8) from peer reviewed journal (Journal of applied toxicology, 2004). Aim of this study was to determine the effect of chemical Metam-sodium on the growth of aquatic cladoceran crustacean Daphnia magna by utilizing Toxkits (culture/maintenance-free microbiotests). Test conducted according to the OECD and ISO test protocols for the acute Daphnia magna toxicity tests for 24 hrs of total exposure period. Toxicant dilution series of the blind water samples was prepared with the test chemical. Neonate daphnids that were younger than 24 h were used. Hatching of the ephippia was initiated 3–4 days prior to the start of the toxicity tests by incubating the dormant eggs in petri dishes with ISO medium at 20 °C under a constant illumination of 6000 lux. Multiwell test plates were used in the study. In the plate rinsing wells present contain 5 daphnia per well with 5 ml of test solution. The wells of each row were checked and the number of dead or immobilized neonates was recorded versus that of the actively swimming test organisms in each well. Based on the immobility of daphnia magna due to the exposure of chemical Metam-sodium for 24 hrs of exposure, the EC50 was determine to be 0.61 mg/l. thus chemical was consider as toxic and can be consider to be classified as aquatic acute category 1 as well as chronic 1 as per the CLP classification criteria.

 

Similarly in the second experimental study for Metam-sodium (137-42-8) from (Journal of Economic Entomology 1967), toxicity was measured. Aim of this study was to determine the nature of chemical Metam-sodium on the growth of aquatic invertebrate daphnia magna by providing the total exposure of 26 hrs. Standard solution was prepared in acetone and exactly I ml of each of these standard solutions was placed in 1 liter of Standard Test Medium in a 2-liter Erlenmeyer flask and mixed thoroughly. 100 ml of this mixture were placed in each of the ten 4-oz bottles. Thus each rack contained 10 bottles of the chemical to be tested at a concentration of 1.0, 0.1, 0.01 or 0.001/ppm. A rack containing 10 bottles of water to which 1 ml of acetone was added was always included in every test run, to serve as a control. 10 daphnia <24 h Larvae (1ST INSTAR) were added in 4-oz round glass bottles. Test repeated 10 times for exact effect determination. After the exposure of chemical, lethal dose at which 50 % mortality observed were recorded. Based on the mortality of test organism daphnia magna by the chemical Metam-sodium for the period of 26 hrs, the LD50 was observed at 0.33 mg/l. Thus based on the effect chemical was consider as toxic and can be consider to be classified as aquatic acute 1 as well as chronic 1 category as per the CLP classification criteria.

 

Above studies was supported by another handbooks and authoritative database for the Metam-sodium (137-42-8). Aim of this study was to determine the toxic effect of chemical Metam-sodium on the growth of Cypridopsis vidua (Ostracod, Seed Shrimp). Test were conducted in the static system for total exposure period of 48 hrs. Mature Cypridopsis vidua used in the study. After the incubation period of 48 hrs lethal concentration at which 50 % mortality was observed were recorded. Based on the mortality of Cypridopsis vidua (Ostracod, Seed Shrimp) by the chemical Metam-sodium for 48 hrs, the LC50 was determine at 0.035 mg/l. thus based on the LC50, chemical was consider as toxic and can be consider to be classified as aquatic acute 1 as well as chronic 1 category as per the CLP classification criteria.

 

Similarly the fourth study from secondary source ECOTOX 2018, was conducted to determine the effect of chemical Metam sodium (137-42-8) on the growth of aquatic invertebrate daphnia magna for 48 hrs. Test conducted under the static system in which > 24 hrs old daphnia magna exposed with the chemical and effect were determine by observing the immobility. Based on the immobility of daphnia magna because of the chemical Metam sodium exposure for 48 hrs, the EC50 was determine to be 2.36 mg/l. Thus chemical was consider as toxic and can be consider to be classified as aquatic chronic category 2 as per the CLP classification criteria.

 

In the fifth supporting study for the target chemical Metam sodium (137-42-8) from secondary source ECOTOX 2018 observed that the chemical was toxic to the invertebrates. Aim of this study was to determine the toxic effect of chemical Metam-sodium on the growth of Penaeus aztecus. Test conducted under the flow-through system for 48 hrs of duration. Salter water 35-75 MM Juvenile Penaeus aztecus was used as a test organism. During the time of exposure effect on the mobility (on 50 % test organisms) were observed. Based on the immobility of Penaeus aztecus due to the chemical Metam-sodium for 48 hrs of exposure the EC50 was determine at 10 mg/l. Thus chemical was consider as toxic and classified as aquatic chronic 3 as per the CLP classification criteria.

 

Similarly sixth study from Pesticide Properties Database (PPDB) 2017 for target chemical also supports the classification of target chemical. Aim of this study was to determine the effect of chemical Metam-sodium on the growth of aquatic invertebrate daphnia magna. Test conducted for 48 hrs and the effect were measured at which chemical effect on 50 % daphnia magna. Based on the immobility of daphnia magna by the chemical Metam-sodium for 48 hrs of exposure, the EC50 was determine at 0.99 mg/l. Thus chemical was consider as toxic and classified as aquatic acute 1 as well as chronic 1 as per the CLP classification criteria.

 

According to another supporting study for Metam-sodium (137-42-8) from Plant Protection Phentopharmaceuticals Database, 2012 chemical was toxic. Aim of this study was to determine the effect of chemical Metam-sodium on the growth of aquatic invertebrate daphnia magna. Test conducted for 48 hrs for observing the toxic effect of chemical. Based on the immobility of daphnia magna by the chemical metam-sodium, the EC50 was determine at 2.34 mg/l. Based on the EC50. Chemical was consider as toxic and classified as aquatic chronic 2 as per the CLP classification criteria.

 

 

As the above studies conducted on different invertebrates, environmental conditions and exposure time was also different, thus toxicity was observed in the range of 0.035 to 10 mg/l. But as the experimental full studies conducted according to the standard conditions and maximum studies supports the toxicity nature of chemical thus on that basis, chemical was consider as toxic to aquatic invertebrates and can be consider to be classified as aquatic acute category 1 as well as chronic 1 as per the CLP classification criteria.