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Classification & Labelling & PBT assessment

PBT assessment

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Administrative data

PBT assessment: overall result

Reference
Name:
potassium methanolate
Type of composition:
legal entity composition of the substance
State / form:
solid: bulk
Reference substance:
potassium methanolate
PBT status:
the substance is not PBT / vPvB
Justification:

Data for the definitive conclusion on the PBT or vPvB properties of potassium methanolate are not available. Thus, the screening criteria given in the “Guidance on information requirements and chemical safety assessment, chapter R.11: PBT assessment” (ECHA, 2017) are used as surrogate information to decide whether the substance may potentially fulfil the PBT or vPvB criteria. In water, potassium methanolate rapidly hydrolyses to methanol and potassium hydroxide (OECD, 2002). Due to the rapid hydrolysis of potassium methanolate, the PBT/vPvB-assessment is based on the products of hydrolysis i.e. methanol and potassium hydroxide.

 

Persistence

The screening criterion for persistence is the potential of a substance for degradation. The substance potassium methanolate reacts readily with water to form potassium hydroxide and methanol. Methanol is readily biodegradable whereas potassium hydroxide as an inorganic substance is no subject to biodegradation. Hence, potassium methanolate does not fulfil the criteria for persistence.

 

Bioaccumulation

A test on bioconcentration in aquatic organisms is not needed due to the very low potential for bioaccumulation of potassium methanolate. The substance reacts readily with water to form potassium hydroxide and methanol.

The available experimentally observed BCF values for methanol are <10 L/kg. According to “Guidance on information requirements and chemical safety assessment, chapter R.11: PBT assessment” (ECHA, 2017), the screening criterion for bioaccumulative substances which have to be classified as “B” or “vB”, is a BCF > 2000 L/kg. As the BCF for the surrogate of potassium methanolate is well below this trigger, the substance is not considered to have bioaccumulative properties in the frame of a PBT assessment.

 

Toxicity

The screening for the “T” in support of the PBT assessment is based on acute toxicity tests with aquatic organisms.

The substance potassium methanolate reacts readily with water to form potassium hydroxide and methanol.

Low toxicity was observed in all organisms with LC50 values >100 mg/L for all endpoints (with methanol). Further, in an early-life-stage bioassay conducted with Oryzias latipes by Gonzales-Doncel et al. (2008), NOEC values for methanol between 7900 - 15800 mg/L were determined. This result indicates that methanol has a very low long-term toxicity to fish. Toxic effects of the hydrolysis product potassium hydroxide are not expected.

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 being relevant for aquatic toxicity.

Since the endpoint of methanol is well above the trigger of 0.01 mg/L, potassium methanolate is not classified as toxic (“T”) related to the environment. The substance is not classified as carcinogenic, mutagenic or toxic for reproduction nor is there any evidence of chronic toxicity according to Regulation (EC) No 1272/2008. Therefore, potassium methanolate does not meet the T-criterion.

 

In conclusion, the substance is not PBT/vPvB.