Potassium methanolate

Toxicity to soil microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil microorganisms

Data waiving:

other justification

Justification for data waiving:

other:

Additional information

In contact with water, potassium methanolate rapidly hydrolyses to methanol and potassium hydroxide (OECD, 2002). Thus, the degradation products of potassium methanolate are of relevance for the assessment of environmental toxicity.

No studies on the toxicity to soil microorganisms are available for potassium methanolate or the degradation products methanol and potassium hydroxide. All available data on terrestrial organisms as well as activated sludge microorganisms do not indicate a need to investigate the effects of the substance and relevant degradation products on soil microorganisms.

 

Potassium hydroxide

Potassium hydroxide further dissociates in the environment to potassium (K+) and hydroxyl ions (OH-). Potassium belongs to the alkali metals and is one of the most common elements in the earth crust. Together with sodium ions (Na+), potassium ions (K+) are responsible for maintaining the cell membrane potential and essential for the function of all living cells (Clausen&Poulsen, 2013). Many physiological processes in organisms are driven by the influence of potassium. Thus, potassium ions are not considered to be relevant for aquatic toxicity. Hydroxyl ions may cause a change (increase) of pH of the receiving environmental compartment. This may result in effects on aquatic organisms in case the pH is changed outside of the tolerable pH-range. Thus, hydroxyl ions do not have an intrinsic toxicity but may cause physical effects depending on the buffer capacity of the aqueous medium (OECD, 2002). It has to be noted that effluents from sewage treatment plants are measured frequently for its pH and are appropriately adapted before release if needed. In addition, due to the dilution effects and buffer capacity of natural aquatic ecosystems significant pH changes followed by effects on aquatic species are not expected (OECD, 2002). In conclusion, any observed effects after exposure of terrestrial organisms to potassium hydroxide is considered to be solely caused by a potential change of pH. Potassium ions are not considered to contribute to terrestrial toxicity.

 

Methanol

Data on methanol investigating the long-term toxicity to soil organisms are available for terrestrial plants, earthworms and terrestrial arthropods (Stantec 2006).

All available studies indicate a low toxicity of methanol to terrestrial organisms with NOEC values≥1000 mg/kg.

 

Thus, no further testing on soil microorganisms is deemed necessary for potassium methanolate.