What Is It?

Sodium hypochlorite, or chlorine bleach, is a chlorinated inorganic disinfectant and antimicrobial agent commonly used in household cleaning products to kill bacteria, fungi, and viruses or to whiten or brighten fabric. In 1957, it was registered for use as a pesticide.[6] Household bleach may contain up to 10% sodium hypochlorite, while industrial bleaches have higher concentrations of up to 50%.[5]

Why It Matters

Chlorine bleach is used to whiten paper towels, toilet paper, and feminine care products. Chlorine bleach is widely used by households, businesses, and medical facilities for its ability to disinfect surfaces or whiten fabrics and materials like paper. It is also used to kill pathogens in swimming pools or to treat wastewater and therefore is a prevalent contaminant in drinking water. The interactions between chlorine bleach and other constituents in aquatic environments can result in the formation of harmful by-products, not to mention, chlorine bleach is toxic to aquatic life. Finally, chlorine bleach is linked to asthma.

Where It’s Found

Chlorine bleach is found in cleaning products or is used in isolation with the purpose of disinfecting surfaces. It can also be found in laundry detergents and treatments as a stain “removal” and whitening agent. It is used in swimming pools, drinking water, and other water and wastewater systems. It is even used to treat various crops, seeds, and/or soil and for turning certain items white, such as period care products and other toiletries, or in treating wood pulp to create white paper.

Found In

Cleaning products
Paper products
Period care products

The Health Concern

Chlorine bleach is acutely toxic for being corrosive. It can cause severe skin burns and eye damage and is toxic to aquatic life.[1]

Toxicity via inhalation is primarily due to the gases that result from mixing chlorine bleach with acidic compounds. Under normal conditions, significant amounts of chlorine gas are not emitted from sodium hypochlorite. When chlorine bleach is mixed with acidic cleaning agents, it releases chlorine gas. If mixed with ammonia-based cleaning agents, it releases chloramine compounds, both of which are respiratory irritants, and in extreme cases, can cause death.[4][5]

When chlorine bleach enters aquatic environments, the release of free chlorine reacts with natural organic matter to form potentially harmful disinfection by-products. The by-product that forms is dependent on various physical environmental factors, in addition to the type of organic and/or inorganic matter present in the reaction. These by-products can fall into chemical classes that are potential carcinogens, developmental and reproductive toxicants, or may interfere with or damage DNA. It is also possible for disinfection by-products to contaminate soils and groundwater.[3] Notably, chlorine bleach in wastewater can form trihalomethanes, a potential carcinogen, which subsequently contaminates drinking water.[3]

Chlorine bleach in cleaning products can even react with the other ingredients (e.g., surfactants, fragrances, etc.) in the product to form halogenated volatile organic compounds (VOCs). VOCs can also be emitted from the reaction of chlorine bleach with organic matter on dirty surfaces it is used to clean.[2] Halogenated VOCs are linked to various adverse health effects, and some are potential carcinogens. Other by-products of chlorine bleach include dioxins. Dioxins are formed from chlorine bleaching processes used to treat wood pulp to make white paper or for turning period products and other toiletries white. Dioxins are linked to cancer, reproductive toxicity, and hormone disruption. Finally, chlorine bleach is linked to asthma. It is considered an asthmagen, a substance that can cause asthma.[7] It is also recognized as an asthma trigger, which means it can trigger an asthma attack in those that already have asthma.[8]

A thorough safety review evaluates the ingredients used at all stages of a product’s life cycle, from its manufacture to its final formulation. On that basis, chlorine bleach is best avoided as a treatment or cleaning agent in consumer products.

How to Avoid It

Consumers can avoid using chlorine bleach when possible. If you must use bleach, try to limit its usage for scenarios when a serious disinfectant is necessary. Otherwise, cleaning or sanitizing surfaces with safer alternatives is best. For a quick and easy DIY household cleaner that’s safe and effective, combine one part filtered water to one part distilled white vinegar.

For safer cleaning when you can’t avoid it:
Wear gloves and eye protection when handling chlorine bleach or other bleach products.

Dilute chlorine bleach with water to limit the amount of exposure. Follow instructions on the bottle for preparing dilutions, or use the CDC’s recommendations for preparing dilutions if bottle instructions are not available to you.

Never mix bleach with any other cleaning products and avoid buying bleach cleaners that contain other inactive ingredients, like surfactants or fragrances.