Halogenated Hydrocarbons

Halogenated hydrocarbons, also known as halocarbons, are hydrocarbon compounds in which at least one hydrogen atom is replaced by a halogen (Group VII A of the Periodic Table) atom, such as fluorine, chlorine, or bromine. Common examples of halogenated hydrocarbons include: 1-bromopropane (C3H7Br), methylene chloride (CH2Cl2), chloroform (CHCl3), tetrachloroethylene (C2Cl4) and carbon tetrachloride (CCl4).

Halogenated Hydrocarbons

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What are some common uses of halogenated hydrocarbons?

Halogenated hydrocarbons have a wide variety of uses. Tetrachloroethylene, also known as perchloroethylene or “perc,” has been traditionally used as a solvent for dry cleaning clothes. Methylene chloride has been used as an effective degreasing solvent for cleaning metals and as a solvent for the spray application of adhesives. More recently, 1-bromopropane has been introduced as a substitute for perc in dry cleaning and for methylene chloride in spray adhesives.

Freon, which is a registered trademark name of The Chemours Company, refers to a class of halogenated hydrocarbons known as chlorofluorocarbons. These have been used as refrigerants, but are also known to cause ozone depletion in the atmosphere.

Several chlorinated hydrocarbons have been used as insecticides and herbicides. DDT (dichlorodiphenyltrichloroethane) and chlordane (octachloro-4,7-methanohydroindane) have been used as insecticides, and 2,4-D (2,4-dichlorophenoxyacetic acid) and 2,4,5-T (2,4,5-trichlorophenoxyacetic acid) have been used as herbicides.

What are the hazards associated with halogenated hydrocarbons?

Because the scope of occupational safety and health regulations does not encompass environmental impact, the discussion of hazards associated with halogenated hydrocarbons will be limited to the physical and health hazards these chemicals pose to employees who use them or are exposed to them.

Physical hazards associated with the use of halogenated hydrocarbons arise from the flammability of the low-molecular-weight chemicals in this group. Higher molecular weight members of this group that have more halogen atoms tend to be nonflammable and have been used as fire retardants or for fire suppression.

Other physical hazards associated with the use of halogenated hydrocarbons arise from the high reactivity of low molecular weight members of this group. Contact with aluminum metal and other incompatible materials have resulted in violent reactions.

Health hazards associated with halogenated hydrocarbons depend on the specific chemical, route of exposure, the airborne concentration and duration of exposure. The group of compounds known as halomethanes (e.g., Halon 1211) are derivatives of methane where one or more hydrogen atoms have been replaced with halogen atoms (F, Cl, Br, or I) and have been used a refrigerants and as fire extinguishing media. These compounds when released in large quantity can act as simple asphyxiants by reducing the oxygen concentration in the air.

Long term exposure to many chlorinated hydrocarbons through inhalation can result in liver and kidney toxicity. Exposure of unprotected skin to the solvents used can cause defatting of the skin resulting in dermatitis. Methylene chloride and vinyl chloride have also been shown to be human carcinogens and are regulated under substance-specific standards.

Another health hazard arises from the inadvertent formation of phosgene (or dichlorocarbonyl) from chlorinated hydrocarbons. Phosgene, which is used industrially as an intermediate in the production of isocyanates, is formed when remaining trace amounts of chlorinated degreasing solvents used to clean metals are exposed to ultraviolet radiation that is emitted during arc welding. Phosgene is also formed by the thermal decomposition of chlorinated hydrocarbons (e.g., chlorodifluoromethane), for example, during a fire. Inhalation of phosgene in sufficient concentration can result in pulmonary edema which can lead to death.

What can I do to protect myself and others?

Engineering and Work Practice Controls. When possible, substitute halogenated hydrocarbons with less hazardous chemicals. Work involving the use of halogenated hydrocarbons should be conducted in well ventilated areas and away from heat sources.

Personal Protective Equipment. When substitution is not feasible and engineering controls are not adequate to maintain airborne exposures below permissible exposure limits (PELs) or, in the absence of applicable PELs recommended exposure limits, appropriate respiratory protection must be used in conjunction with an effective respiratory protection program. In addition, appropriate skin protection, especially chemical resistant gloves, should be worn when contact with halogenated hydrocarbons is reasonably anticipated.

What resources are available to assist employers?

Training and Outreach Services

he presentations on hazard communication, respiratory protection and personal protective equipment are available to assist employers in training their staff. Each of these presentations should be modified to address site-specific conditions and hazards. Other example presentations are available along with pre-recorded webinars

The education, training and technical assistance bureau provides free online safety and health training and outreach services (i.e., speaker's bureau requests, safety booths) upon request. 

In addition, the NCDOL Library offers free safety and health videos (including streaming video services) and related research assistance on consensus standards (i.e., ANSI, NFPA, NEC).

Safety and Health Programs

A hazard communication program, hazardous chemical programrespiratory protection program, 1-bromopropane program and personal protective equipment hazard assessment are available for employers to download and adapt to their specific conditions. Other example safety and health programs are available for employers to download and adapt to their specific conditions. 

Safety and Health Topics

More information related to halogenated hydrocarbons can be found on the safety and health topics pages for hazard communication, personal protective equipment (PPE), respiratory protection, 1-bromopropane and methylene chloride.

Consultation Services

The consultative services bureau provides free and confidential onsite consultation regarding worksite safety and health hazards.

Which standards apply?

OSH has adopted the following standards which are applicable to halogenated hydrocarbons in North Carolina. This is not all inclusive.

Note: Please also check the standards information and activity webpage to see if there has been any recent or upcoming regulatory activity on this topic. 

General Industry




Other Applicable Standards

The Which OSHA Standards Apply webpage can also help identify other standards that may be applicable to this topic.

Where can I learn more?

Industry Guides

Technical Assistance

Inquiries about workplace safety and health requirements can be submitted to Ask OSH through the online form, by email to ask.osh@labor.nc.gov, or by phone at 919-707-7876.