Sodium carbonate (soda ash) is used as a builder in detergent powders and tablets for water softening in the washing process. Sodium carbonate is also used in laundry additives, machine dishwashing products, surface cleaners, toilet cleaners and other household cleaning products. The product sodium carbonate is available for consumers and solutions of sodium carbonate in water have been used in the past for soaking of clothes, dishwashing, floor washing, degreasing operations and for personal care. These applications may still occur. The amount of sodium carbonate, which is used in household cleaning products in Europe, is estimated to be 550,000 tonnes per year.
After use of the household cleaning product, the water (containing the sodium carbonate) will be disposed via the drain. However, the carbonate will not be discharged to aquatic ecosystems but will be neutralized in the waste water treatment plant. Sodium has a low toxicity and the emitted amount of sodium is relatively low compared to background concentrations and therefore the emitted amount of sodium will not have an effect on the aquatic organisms of the receiving water.
The available acute ecotoxicity data with fish and water fleas revealed LC50 values which were higher than 68 mg/l. The increase in pH of the receiving water was used to obtain an idea of the acceptable amount of sodium carbonate which can be added to aquatic ecosystems. Depending on the buffer capacity of the aquatic ecosystem, an estimate of the acceptable amount ranges between 2 and 20 mg/l.
When humans are exposed to sodium carbonate, via the use of household cleaning products, the concentration of sodium in the blood and the pH of the blood will not be increased and therefore the exposure to sodium carbonate will not increase the normal physiological levels of sodium and carbonate/bicarbonate. Therefore there is no concern about a possible systemic toxic effect after short term or repeated exposure to the substance. No genotoxic effects in bacteria or teratogenic effects in rabbits, rats and mice have been reported. The only critical endpoint for sodium carbonate seems to be local irritation.
Consumers will be exposed to sodium carbonate due to direct skin contact with solutions which contain sodium carbonate, which can be laundry hand washing or use of a carbonate solution for personal care (e.g. skin treatment). However, the concentrations of sodium carbonate in these solutions are too low to cause local irritation.
Accidental or intentional overexposure to sodium carbonate may occur via oral uptake or via exposure of the eyes (e.g. due to splashing). The available animal data do not indicate severe adverse effects when accidental or intentional overexposure to sodium carbonate occurs. Although sodium carbonate is widely available for consumers and has been used for a long time, cases of oral poisoning or effects on human eyes have not been reported in the literature. Apparently accidental or intentional overexposure to sodium carbonate does not result in severe adverse effects on humans or does simply not occur.
Based on the available data, the use of sodium carbonate in household cleaning products has neither an adverse effect on the aquatic ecosystem nor an adverse effect on consumers.