Registration Dossier

Administrative data

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:
PNEC aqua (freshwater)
PNEC value:
0.001 mg/L
Assessment factor:
1 000

Marine water

Hazard assessment conclusion:
PNEC aqua (marine water)
PNEC value:
0 mg/L
Assessment factor:
10 000

STP

Hazard assessment conclusion:
PNEC STP
PNEC value:
2 mg/L
Assessment factor:
10

Sediment (freshwater)

Hazard assessment conclusion:
PNEC sediment (freshwater)
PNEC value:
0.001 mg/kg sediment dw
Extrapolation method:
equilibrium partitioning method

Hazard for air

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:
PNEC soil
PNEC value:
0 mg/kg soil dw
Extrapolation method:
equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:
PNEC oral
PNEC value:
3 300 g/kg food
Assessment factor:
90

Additional information

Sodium methanethiolate (CAS No. 5188-07-8) is the sodium salt of methanethiol (CAS No. 74-93-1) and is safer and easier to handle. Upon addition to water, sodium methanethiolate dissociates to the methanethiolate anion and sodium cation. Depending on pH, equilibrium then exists between the methanethiolate anion and methanethiol itself (protonated, neutral form). At environmentally relevant pHs, the substance exists almost entirely in the protonated form, methanethiol. Because the compounds are identical at environmental and biological pH values, toxicity and fate data from either compound can be used to read across to the other compound.

Conclusion on classification

Methanethiol environmental classification is based on data available for sodium methanethiolate. Methanethiol is considered as toxic for fish (LC50 -96h = 1.8 mg/L) and Daphnia (EC50 -48h = 1.5 mg/L). Methanethiol is harmful to algae with a growth rate toxicity value of 15 mg/L. Methanethiol is not considered as a bioaccumulative substance with a log Kow below 4 and an estimated bioconcentration factor for fish also below 4.

On this basis methanethiol environmental classification is not required neither according to the dangerous substance directive, nor according to the globally harmonized system.