BCDMH Safety Guide


safety guide for BCDMH also known as bromine tablets

What is BCDMH?

BCDMH is short for 1-Bromo-3-Chloro-5,5-DiMethylHydantoin. Many pool cleaning agents sold as “bromine cleaners” or “bromine tablets” have BCDMH as the primary active ingredient.

Since BCDMH is used as a germicide and fungicide in the treatment of water, it is regulated as a pesticide by the EPA and has the associated labeling and disposal requirements.

BCDMH has the CAS Number 16079-88-2.

The CAS Number is used to identify BCDMH as an ingredient on safety data sheets (SDS) and other safety documentation. When looking for BCDMH as an ingredient in pool cleaners, look for the CAS Number within the composition table.

Notable Properties of BCDMH

BCDMH is a white crystalline solid with a halogen odor. When in water, BCDMH releases hypochlorous acid, hypobromous acid, and 5,5-dimethylhydantoin. The hypochlorous acid and hypobromous acid are the active disinfecting components used in water treatment.

What Makes BCDMH Hazardous?

BCDMH has several associated hazards, being an oxidizer, corrosive, an irritant, and hazardous to the environment. Different risks come from each of the different hazardous properties of BCDMH.

As an oxidizer, BCDMH creates a fire risk by having the potential to worsen or intensify fires. Accordingly, BCDMH should not be kept near flammable materials, such as wood or paper.

BCDMH can be hazardous to human health as a corrosive and irritant. BCDMH can cause damage to the skin and eyes, as well as being harmful if swallowed.

The same germicide and fungicide properties that make BCDMH an excellent pool cleaner make it an environmental hazard as it can harm wildlife.

BCDMH Frequently Asked Questions

Are Bromine Tablets the Same as Chlorine Tablets?

No, bromine tablets have BCDMH as the active ingredient and most chlorine tablets have TCCA as the active ingredient. Read more about TCCA.

Do Bromine Tablets Contain Chlorine?

Yes, the “chloro” part of 1-Bromo-3-Chloro-5,5-Dimethylhydantoin indicates the presence of chlorine in the chemical formula of BCDMH. There is one chlorine atom for every bromine atom present in BCDMH.

Do Bromine Tablets Dissolve?

BCDMH will react with water to produce hypochlorous acid, hypobromous acid, and 5,5-dimethylhydantoin. Depending on factors including the size of the tablet and temperature of the water, this reaction can happen quickly or slowly.

BCDMH contains both bromine and chlorine as active ingredients.

6 Steps for Safety

Step 1: Read the Warnings

When working with a product for the first time, always read all the safety documents first. This includes safety data sheets, which should be provided by the manufacturer or importer of the BCDMH product. There may also be an EPA pesticide label, OSHA chemical label, or a Consumer Protection label on the packaging of the BCDMH product. These documents all contain important information on the hazards of the product and instructions on how to mitigate those hazards.

Different compositions in different products may cause additional hazards to be present beyond the properties of the product with BCDMH as the only active ingredient. Be sure to familiarize yourself with the differences between separate BCDMH-based products.

Step 2: Prepare Your Workspace

Creating a safe workspace, sometimes referred to as engineering control, is a key component of working safely with any potentially hazardous substance.

One of the primary routes of exposure for BCDMH is contact with airborne dust, which can then enter the airways or eyes and cause chemical burns. Fans that would blow BCDMH dust around should be avoided. Dust collectors and air filters which draw in and capture any stray BCDMH dust are ideal.

Step 3: Gather Your PPE

For working with BCDMH, you will need the following PPE.

  • Respiratory Protection
    • A respirator rated to handle organic vapors and/or halogens is recommended.
    • A full-facepiece respirator can serve as both respiratory protection and eye protection.
  • Eye and Face Protection
    • Safety goggles which create a seal around the eyes are needed to prevent any airborne BCDMH from reaching the eyes.
    • Open safety glasses, which do not have a sealing surface, will not work in preventing dust from reaching the eyes. A face shield can be used in combination with safety glasses.
  • Gloves
    • Rubber gloves will prevent BCDMH from touching the skin on the hands and causing irritation.
    • As BCDMH is corrosive, be sure to use gloves that are resistant to corrosive substances.
  • Long Sleeves
    • Long sleeves will prevent BCDMH from touching the skin on the arms and causing irritation.
    • Either a long-sleeved shirt, long-sleeved coat, or disposable sleeves will work.
    • Launder any contaminated closing separately to prevent cross-contamination and inform anyone laundering the clothing of the presence of BCDMH so they can take any necessary precautions.

Step 4: Clear Your Workspace

Having a clear workspace is an important part of safety. Clutter can cause accidents and can prevent you from noticing if something has spilled.

This is also a good time to double-check check any engineering controls, like a dust collector, are in proper working order and that no filters need to be changed out.

If you are working in a shared space, make sure anyone around you can also remain safe when you are working with BCDMH. For those working at home, this can include family members and pets.

Step 5: Do The Work

BCDMH has a fire risk due to being an oxidizer. Ensure that proper fire safety precautions are in place in the work area.

If PPE and good work practices are used properly, working with BCDMH has minimal hazards.

If work cannot be completed in one sitting, be sure to properly seal any BCDMH containers to prevent spills or accidental release when not in use.

Step 6: Clean Up

Use large volumes of water to clean up any spilled BCDMH to dilute the resulting solution. Be sure to dispose of any waste in accordance with local regulations.

As BCDMH is an environmentally hazardous substance, take extra precautions so that none is released into the environment during cleanup.

Further Reading

The National Library of Medicine has a PubChem Entry on BCDMH and Hazardous Substances Data Bank Entry.

Check out the Safety Guide Series Hub for more safety guides.

Sources Cited

National Center for Biotechnology Information (2024). PubChem Compound Summary for CID 61828, 1-Bromo-3-chloro-5,5-dimethyl-2,4-imidazolidinedione. Retrieved April 19, 2023 from https://pubchem.ncbi.nlm.nih.gov/compound/1-Bromo-3-chloro-5_5-dimethylhydantoin.

National Center for Biotechnology Information (2024). PubChem Annotation Record for 1-BROMO-3-CHLORO-5,5-DIMETHYLHYDANTOIN, Source: Hazardous Substances Data Bank (HSDB). Retrieved April 19, 2023 from https://pubchem.ncbi.nlm.nih.gov.

Original Posting Date: Aprl. 19, 2023

Last Updated: Feb. 12, 2024


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