Washing soda is not non-toxic. It’s a strong alkaline substance with a pH of about 11.4, which makes it a genuine irritant to skin, eyes, and lungs. That said, it’s far from the most dangerous chemical in your home. It has low acute toxicity if swallowed in small amounts, the FDA recognizes food-grade sodium carbonate as safe for use in food processing, and it won’t produce poisonous fumes. The real risks come from direct, unprotected contact and from treating it as casually as baking soda.
How It Compares to Baking Soda
The confusion is understandable. Washing soda (sodium carbonate) and baking soda (sodium bicarbonate) sound similar and even look alike as white powders. But their pH levels tell a very different story. Baking soda sits at a mild 8.3 on the pH scale. It’s safe to eat, safe on skin, and harmless around pets. Washing soda comes in at 11.4, making it roughly 1,000 times more alkaline than baking soda. That jump matters because alkaline substances dissolve organic material, which is exactly why washing soda cleans so well and why it can damage living tissue.
Baking soda is genuinely non-toxic. Washing soda is an industrial-strength cleaning agent that earned a “Warning” signal word on its official safety classification and carries a formal hazard statement for causing serious eye irritation. Some regulatory bodies classify it even more strictly: Australia’s chemical assessment system flags it for causing severe skin burns and eye damage. The bottom line is that these two products should not be used interchangeably, especially in any recipe that touches your body.
What It Can Do to Skin and Eyes
Washing soda’s high pH means it can cause chemical irritation on direct contact. Brief, incidental contact with dry powder or a dilute solution is unlikely to cause serious harm, but prolonged or repeated exposure to concentrated solutions can lead to redness, drying, cracking, and in severe cases, chemical burns. The mechanism is the same one that makes it effective at cutting grease: it breaks down organic compounds, and your skin is an organic compound.
Eye contact is the more serious concern. Safety data sheets for Arm & Hammer Super Washing Soda specifically warn against contact with eyes, and the product’s formal hazard classification centers on serious eye irritation. Getting washing soda powder or solution in your eyes can cause significant pain, redness, and potential damage to the surface of the eye. If this happens, flushing immediately with water for several minutes is the standard first response.
Inhalation Risks
Washing soda is sold as a fine, lightweight powder that becomes airborne easily when you pour or scoop it. Breathing in that dust irritates the respiratory tract, potentially causing coughing, throat irritation, and discomfort. The official safety data sheet from Church & Dwight explicitly states to “avoid breathing dust” and recommends adequate ventilation during use.
For typical household tasks like adding a scoop to your washing machine, the exposure is minimal. The risk increases when you’re working with larger quantities in a confined space, like mixing a big batch of homemade cleaner in a small laundry room. Pouring slowly and keeping a window open or a fan running eliminates most of the concern.
What Happens If It’s Swallowed
Washing soda has low acute oral toxicity. Animal studies put the median lethal dose at 2,800 mg per kilogram of body weight for a related form, which places it well outside the range of substances considered highly toxic. For context, table salt has a comparable toxicity profile in animal studies. A small accidental taste is not a medical emergency.
Larger amounts are a different matter. Because washing soda is a strong alkaline, swallowing a significant quantity can burn the lining of the mouth, throat, and esophagus. Alkaline burns are particularly insidious because they penetrate deeply into tissue without always causing immediate pain, meaning the damage can be worse than it initially feels. The NIH lists sodium carbonate poisoning as a recognized condition requiring medical evaluation when ingestion is more than trivial.
Safety Around Pets
Dogs and cats are more vulnerable to washing soda than adults, partly because of their smaller body weight and partly because they can’t tell you what they got into. Alkaline substances like washing soda cause tissue damage at the point of contact. In animals, ingestion can lead to drooling, vomiting (sometimes with blood), difficulty swallowing, abdominal pain, and lethargy. Burns to the esophagus are especially common with alkaline agents, and these burns can develop over hours, meaning an animal may look fine initially and worsen later.
Skin and eye contact in pets follows the same pattern as in humans: redness, swelling, and potential for deeper burns with prolonged exposure. If you use washing soda for cleaning, store it in a sealed container out of reach. Residue on floors or surfaces is unlikely to cause problems, but an open box a curious pet can nose into is a genuine hazard.
Environmental Impact
Washing soda is often promoted as an eco-friendly cleaning alternative, and in many ways it is. It contains no synthetic fragrances, phosphates, or surfactants. However, it does affect aquatic environments. According to an OECD assessment, the primary environmental hazard is its ability to raise the pH of water. Sensitive freshwater species like amphipods (small crustaceans) showed lethal effects at concentrations as low as 67 mg per liter, while hardier species like mosquitofish tolerated concentrations above 700 mg per liter.
Sodium carbonate is an inorganic substance, so it doesn’t biodegrade. It simply dissolves and dissociates in water. In practice, the small amounts used in household cleaning are heavily diluted by the time they reach waterways and are unlikely to shift the pH enough to cause ecological harm. It’s a far better option for waterways than many conventional detergents, but calling it completely benign to aquatic life would be an overstatement.
How to Use It Safely
For routine household cleaning, like boosting laundry detergent, scrubbing greasy stovetops, or unclogging drains, a few practical habits eliminate most of the risk. Wear rubber gloves whenever you’re working with washing soda solutions, especially for tasks that involve soaking your hands. Keep the area ventilated when scooping powder, and pour slowly to minimize dust. Store it in a clearly labeled, sealed container away from children and pets.
You don’t need a respirator or safety goggles for adding a scoop to your washing machine. But if you’re mixing large batches of cleaning paste, scrubbing with a concentrated solution, or working in a small, poorly ventilated space, goggles and a dust mask are reasonable precautions. The Arm & Hammer safety data sheet draws a distinction between casual consumer use and occupational exposure, noting that workplace safety requirements go beyond what a typical consumer needs. For most people using it at home in normal amounts, gloves and common sense are sufficient.