The toxicity of sodium carbonate

ADI (acceptable daily intake) make no restrictions (FAO/WHO in 1985). LD50 (median lethal dose) is about 6 g/kg (mice-oral). 

Soda ash dust has irritation effects on the skin, respiratory and eyes. Long-term exposure to soda solution may cause eczema and dermatitis. Its concentrated solutions can cause burns, necrosis, and even corneal opacity. The maximal allowable concentration of soda ash dust in the air is 2 mg/m3. The operators should wear overalls, door cover, gloves, boots and other protective clothing to protect the respiratory system and skin.