A note on bleach v. HOCl

Bleach is widely used to disinfect, and the most common form used is sodium hypochlorite, which is usually found in household products at a concentration of around 5 to 10%. To prevent its breakdown it is supplied in a highly alkaline solution of sodium hydroxide (NaOH, or caustic soda).

It is highly irritating to the eyes, skin and lungs, and inhalation over long periods could be carcinogenic. It can also leave a residue and is corrosive to some metals.

In contrast, HOCl has a temporary, mild chlorine smell that dissipates quickly; it is hypoallergenic and completely safe.

Bleach is highly corrosive. Whilst HOCl is considerably less corrosive (depending on the manufacturing process residual salts from electrolysis may cause some corrosion).

It is important to understand that as sodium hypochlorite is supplied in a highly alkaline solution (pH 11 to 13), compared to HOCl it is 80 to 100 times less toxic to microbes at the same chlorine concentration. The pH of bleach does not change with dilution in water.

HOCl is therefore not only far safer than bleach but also a much more powerful disinfectant.

The difference between HOCl and household bleach

Sodium hypochlorite is strongly alkaline and highly corrosive.

Whilst HOCl  is considerably less corrosive, depending on the manufacturing process residual salts from electrolysis may cause some corrosion.

Is NaDCC safer than bleach?

Accidental exposure

“NaDCC solutions resulted in lower airborne chlorine exposures and fewer detections at or above the measuring instrument's limit of detection than bleach solutions.”

NaDCC Disinfectant in Janitorial Cleaning and Comparison to Bleach: Exposure Assessment

Deliberate ingestion

Bleach ingestion is frequently used for suicide which results primarily from caustic effects on upper gastrointestinal tract.

However, when at least 11g of NADCC tablets were ingested deliberately, the resultant respiratory failure was successfully treated by extracorporeal membrane oxygenation (ECMO) and the patient was discharged from hospital after 27 days.

Early ECMO initiation in the emergency department for refractory hypoxemic respiratory failure caused by NaDCC intoxication