Health effects of bromoform and dibromochloromethane
Contents
- 1 Introduction
- 2 Pathways for bromoform and dibromochloromethane in the environment
- 3 Exposure to bromoform and dibromochloromethane
- 4 Pathways for bromoform and dibromochloromethane in the body
- 5 Health effects of bromoform and dibromochloromethane
- 6 Reducing risk of exposure to bromoform and dibromochloromethane
- 7 Medical tests for exposure to bromoform and dibromochloromethane
- 8 Further Reading
Introduction
Bromoform (also known as tribromomethane) and dibromochloromethane are colorless to yellow, heavy, nonburnable liquids with a sweetish odor. These chemicals are possible contaminants of drinking water that has been chlorinated to kill bacteria and viruses that could cause serious waterborne infectious diseases. Bromoform and dibromochloromethane may form when chlorine reacts with other naturally occurring substances in water, such as decomposing plant material. Plants in the ocean also produce small amounts of these chemicals. These chemicals are found mainly in water that originally came from surface sources, such as rivers and lakes. Springs and deep drilled wells usually contain very little of the substances that react with chlorine to form these chemicals; therefore, well and spring water is less likely a source of bromoform and dibromochloromethane than water from a reservoir (artificial lake). The amount of bromoform and dibromochloromethane in drinking water can change considerably from day to day, depending on the source, temperature, amount of plant material in the water, amount of chlorine added, and a variety of other factors. In the past, bromoform was used by industry to dissolve dirt and grease and to make other chemicals. It was also used in the early part of this century as a medicine to help children with whooping cough get to sleep. Currently, bromoform is only produced in small amounts for use in laboratories and in geological and electronics testing. Dibromochloromethane was used in the past to make other chemicals such as fire extinguisher fluids, spray can propellants, refrigerator fluid, and pesticides. It is now only used on a small scale in laboratories. In the environment, bromoform and dibromochloromethane are not found as pure liquids, but instead, they are found either dissolved in water or evaporated into air as a gas. Both bromoform and dibromochloromethane are relatively stable in the air, but reactions with other chemicals in the air cause them to break down slowly (about 50% in 1 or 2 months). Bromoform and dibromochloromethane in water or soil may also be broken down by bacteria, but the speed of this process is not known. (Health effects of bromoform and dibromochloromethane)
Pathways for bromoform and dibromochloromethane in the environment
Bromoform and dibromochloromethane enter the environment through the disposal of water that has been disinfected with chlorine or as vapors emitted from chlorinated water. These chemicals are also made naturally by plant-like organisms called algae that are found in the oceans. Some part of bromoform and dibromochloromethane that enters the air is removed by rain. What is left in the air takes about 1-2 months for half of it to degrade. In water, bromoform and dibromochloromethane are slowly broken down at the water surface where oxygen is available, but break down much faster in deep water and in water that is underground where there is a lot less oxygen. Bromoform and dibromochloromethane are mobile in soils and may seep into groundwater. Bromoform and dibromochloromethane do not appear to concentrate in fish.
Exposure to bromoform and dibromochloromethane
You are most likely to be exposed to bromoform and dibromochloromethane by drinking water that has been treated with chlorine. Usually, the levels in chlorinated drinking water are between 1 and 10 parts of bromoform and dibromochloromethane per billion parts of water (ppb). These are levels that are known to be without adverse health effects. Bromoform and dibromochloromethane have also been detected in chlorinated swimming pools.
Exposure can occur at a swimming pool, by breathing bromoform or dibromochloromethane that has evaporated into the air, or by uptake from the water through the skin. Neither dibromochloromethane nor bromoform are likely to be found in food.
If you live near a factory or laboratory that makes or uses dibromochloromethane or bromoform, you might be exposed to dibromochloromethane or bromoform in the air. Currently, bromoform is only used for geological and electronics testing. Dibromochloromethane is used on a small-scale in laboratories. Since neither dibromochloromethane nor bromoform have widespread use in this country, they are usually present in outside air at very low levels (less than 0.01 ppb). Therefore, exposure to bromoform or dibromochloromethane in the air is a minor route. Exposure may occur if you come into contact with water or soil at a chemical waste site where dibromochloromethane or bromoform has been disposed.
Pathways for bromoform and dibromochloromethane in the body
Studies in animals or humans indicate that both bromoform and dibromochloromethane can easily enter your body after swallowing them in water or breathing them in air. They can also enter your body through your skin (for example, by washing or showering in water containing these chemicals). Some portion of bromoform and dibromochloromethane entering your body may be broken down to other compounds. Bromoform, dibromochloromethane, and their breakdown products can be removed from the body by being exhaled from the lungs. These chemicals leave the body fairly rapidly. Bromoform and dibromochlormethane do not tend to build up in the body, 50-90% of the amount that enters the body is removed within 8 hours.
Health effects of bromoform and dibromochloromethane
You should know that one way to learn whether a chemical will harm people is to determine how the body absorbs, uses, and releases the chemical. For some chemicals, animal testing may be necessary. Animal testing may also help identify such health effects as cancer or birth defects. Without laboratory animals, scientists would lose a basic method for getting information needed to make wise decisions that protect public health. Scientists have the responsibility to treat research animals with care and compassion. Scientists must comply with strict animal care guidelines because laws today protect the welfare of research animals.
Additionally, there are vigorous national and international efforts to develop alternatives to animal testing. The efforts focus on both in vitro and in silico approaches and methods. For example, the National Toxicology Program (NTP) at the National Institute of Environmental Health Sciences (NIEHS) created the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM) in 1998. The role of NICEATM is to serve the needs of high quality, credible science by facilitating development and validation—and regulatory and public acceptance—of innovative, revised test methods that reduce, refine, and replace the use of animals in testing while strengthening protection of human health, animal health and welfare, and the environment. In Europe, similar efforts at developing alternatives to animal based testing are taking place under the aegis of the European Centre for the Validation of Alternative Methods (ECVAM).
Studies in animals or humans indicate that both bromoform and dibromochloromethane can easily enter your body after swallowing them in water or breathing them in air. They can also enter your body through your skin (for example, by washing or showering in water containing these chemicals). Some portion of bromoform and dibromochloromethane entering your body may be broken down to other compounds. Bromoform, dibromochloromethane, and their breakdown products can be removed from the body by being exhaled from the lungs. These chemicals leave the body fairly rapidly. Bromoform and dibromochlormethane do not tend to build up in the body, 50-90% of the amount that enters the body is removed within 8 hours.
Health effects in children
This section discusses potential health effects in humans from exposures during the period from conception to maturity at 18 years of age.
In the early 1900s, bromoform was given to children suffering from whooping cough, resulting in several deaths when children were accidentally overdosed. Children appeared drowsy, then lifeless, just before dying.
There are no studies in humans or laboratory animals that examine whether the effects of bromoform and dibromochloromethane change with age. Based on current knowledge of body function, and metabolism in the body, there is no indication that children will be affected more than adults.
Reducing risk of exposure to bromoform and dibromochloromethane
If your doctor finds that you have been exposed to substantial amounts of bromoform and/or dibromochloromethane, ask whether your children might also have been exposed. Your doctor might need to ask your state health department to investigate.
The chance of consuming bromoform or dibromochloromethane in chlorinated public drinking water varies with season, water temperature, water chemistry, disinfection method, and other factors. However, the health risks associated with drinking non-disinfected water when there is evidence of disease-causing contamination (i.e., bacteria, viruses, etc.) are much greater than the risk of adverse health effects from exposure to bromoform or dibromochloromethane.
There are water treatment methods that people can be used in the home to reduce exposure to bromoform and dibromochloromethane from chlorinated tap water. These include simple do-it-yourself methods such as connecting solid carbon black filters to faucets and shower taps. Homeowners may discuss other home water treatment methods, including filtering, aeration or boiling, distillation, and/or activated charcoal, with a professional plumber or water well contractor. The chance of exposure to bromoform and dibromochloromethane may be reduced by minimizing contact with water expected to have higher levels of these chemicals, such as chlorinated swimming pool water. When bathing or showering some portion of dibromochloromethane and/or bromoform may evaporate into the air. Opening bathroom windows, and taking shorter baths and showers may reduce the amount of chemical vapor that is inhaled or absorbed through the skin.
Medical tests for exposure to bromoform and dibromochloromethane
If your doctor finds that you have been exposed to substantial amounts of bromoform and/or dibromochloromethane, ask whether your children might also have been exposed. Your doctor might need to ask your state health department to investigate.
The chance of consuming bromoform or dibromochloromethane in chlorinated public drinking water varies with season, water temperature, water chemistry, disinfection method, and other factors. However, the health risks associated with drinking non-disinfected water when there is evidence of disease-causing contamination (i.e., bacteria, viruses, etc.) are much greater than the risk of adverse health effects from exposure to bromoform or dibromochloromethane.
There are water treatment methods that people can be used in the home to reduce exposure to bromoform and dibromochloromethane from chlorinated tap water. These include simple do-it-yourself methods such as connecting solid carbon black filters to faucets and shower taps. Homeowners may discuss other home water treatment methods, including filtering, aeration or boiling, distillation, and/or activated charcoal, with a professional plumber or water well contractor. The chance of exposure to bromoform and dibromochloromethane may be reduced by minimizing contact with water expected to have higher levels of these chemicals, such as chlorinated swimming pool water. When bathing or showering some portion of dibromochloromethane and/or bromoform may evaporate into the air. Opening bathroom windows, and taking shorter baths and showers may reduce the amount of chemical vapor that is inhaled or absorbed through the skin.
Further Reading
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