Potassium carbonate

Endpoint summary

Additional information

There are some reliable data available for acute toxicity on fish (Oncorhynchus mykiss) and Daphnia (Daphnia magna and Daphnia pulex)

In a 96-h acute toxicity study according to national standard (US), comparable to guideline FIFRA Guideline 72-1 the 96-h LC50 for Rainbow trouts (Oncorhynchus mykiss) was 68 mg a.i./L. The NOEC, based on mortality, was 33 mg a.i./L.

In a second 96-h acute toxicity study under the same conditions the toxicity to Bluegill sunfish (Lepomis macrochirus) was considerably lower. The 96-h LC50 was determined to be 230 mg a.i./L (95% CL: 140 - 240 mg a.i./L). The NOEC, based on mortality, was 140 mg a.i./L.

 

In a 48-h acute toxicity study according to national standard (US), comparable to guideline FIFRA 72-2 the 48-h EC50 for Daphnia pulex and Daphnia magna were determined. The 48-h EC 50 for Daphnia pulex was 200 mg a.i./L and the 48-h EC50 for Daphnia magna was 430 mg a.i./L . The NOEC, based on mortality, was 120 mg a.i./L and 190 mg a.i./L for Daphnia pulex and Daphnia magna, respectively. Daphnia pulex was more sensitive than Daphnia magna.

 

Toxicity tests on aquatic plants and sediment organisms as well as long-term toxicity tests are not available.

 

The abiotic dissociation of potassium carbonate and potassium hydrogen carbonate in water results in the formation of potassium and carbonate ions. Potassium and carbonate are essential for almost all living organisms including aquatic plants and algae and natural components in their habitats. Furthermore potassium as well as carbonate are ubiquitously present in the environment, occurring naturally in minerals, soils and sediments, natural waters (oceans, lakes, rivers), biota and human beings. This is in line with the fact that standard guidelines, e.g. OECD 201, aquatic test media should be enriched with potassium (e.g. as KH2PO4) and carbonate (e.g. as NaHCO3) to ensure appropriate living conditions. Therefore, potassium carbonate is not expected to have an intrinsic toxic activity to aquatic organisms and sediment organisms.

 

However, the only possible effect of potassium carbonate would result from the pH effect. The pH is expected to remain between environmentally acceptable ranges. A significant increase of the pH of the receiving water is not expected. Generally, the change in pH of the receiving water should stay within a tolerated range of the pH at the effluent side and for this reason no adverse effects on the aquatic environment are expected due to the production or use of potassium carbonate, if emissions of waste water are controlled by appropriate pH limits and/or dilutions in relation to the natural pH and buffering capacity of the receiving water.

 

A generic PNEC cannot be derived from single-species toxicity data for potassium carbonate, as the pH of natural waters as well as the buffer capacity of natural waters show considerable differences and aquatic organisms/ecosystems are adapted to these specific natural conditions, resulting in different pH optima and pH ranges that are tolerated (See: EU RAR NaOH (2007). European Union Risk Assessment Report sodium hydroxide. Office for Official Publications of the European Union. Luxembourg.; section 3.2.1.1.4, page 30 and Hera (2005).HERA (2005). Sodium carbonate (CAS 597-19-8) Ed. 2.0, April 2005, http:www.heraproject.com; section 2.2.2, page 11). According to the OECD SIDS (2002a). Screening Information Data Set (SIDS) Initial Assessment report for sodium hydroxyde. Organisation for Economic Co-operation and Development, UNEP Publication (Available on internet: http://www.chem.unep.ch/irptc/sids/OECDSIDS/INDEXCHEMIC.htm) and (OECD (2002b).OECD SIDS (2002b) OECD (2002) Screening Information Data Set (SIDS) Initial Assessment report for potassium hydroxyde. Organisation for Economic Co-operation and Development, UNEP Publication (Available on internet:http://www.inchem.org/documents/sids/sids/POTASSIUMHYD.pdf), a lot of information is available on the relationship between pH and ecosystem structure and also natural variations in pH of aquatic ecosystems have been quantified and reported extensively in ecological publications and handbooks.