1.1 What is bromomethane? |
1.2 How might I be exposed to bromomethane? |
1.3 How can bromomethane enter and leave
my body? |
1.4 How can bromomethane affect my health? |
1.5 Is there a medical test to determine
whether I have been exposed to bromomethane? |
1.6 What recommendations has the federal
government made to protect human health? |
1.7 Where can I get more information? |
References |
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September 1992 |
Public Health Statement |
for |
Bromomethane |
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This Public Health Statement is the
summary chapter from the Toxicological
Profile for bromomethane. It is one in a series of Public
Health Statements about hazardous substances and their health
effects. A shorter version, the ToxFAQs™,
is also available. This information is important because this
substance may harm you. The effects of exposure to any hazardous
substance depend on the dose, the duration, how you are exposed,
personal traits and habits, and whether other chemicals are
present. For more information, call the ATSDR Information
Center at 1-888-422-8737.
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This Statement was prepared to give you information about
bromomethane and to emphasize the human health effects that
may result from exposure to it. The Environmental Protection
Agency (EPA) has identified 1,177 sites on its National Priorities
List (NPL). Bromomethane has been found in at least 12 of
these sites. However, we do not know how many of the 1,177
NPL sites have been evaluated for bromomethane. As EPA evaluates
more sites, the number of sites at which bromomethane is found
may change. This information is important for you to know
because bromomethane may cause harmful health effects and
because these sites are potential or actual sources of human
exposure to bromomethane.
When a chemical is released from a large area, such as an
industrial plant, or from a container, such as a drum or bottle,
it enters the environment as a chemical emission. This emission,
which is also called a release, does not always lead to exposure.
You can be exposed to a chemical only when you come into contact
with the chemical. You may be exposed to it in the environment
by breathing, eating, or drinking substances containing the
chemical or from skin contact with it.
If you are exposed to a hazardous chemical such as bromomethane,
several factors will determine whether harmful health effects
will occur and what the type and severity of those health
effects will be. These factors include the dose (how much),
the duration (how long), the route or pathway by which you
are exposed (breathing, eating, drinking, or skin contact),
the other chemicals to which you are exposed, and your individual
characteristics such as age, sex, nutritional status, family
traits, life style, and state of health.
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1.1
What is bromomethane? |
Bromomethane (also called methyl bromide) is a colorless
gas without much smell. Some bromomethane is formed in the
ocean, probably by algae or kelp. However, most is made by
humans to kill various pests (rats, insects, fungus, etc.)
that might be present in homes, foods, or soil. Some bromomethane
is also used to make other chemicals.
Bromomethane is usually stored in sealed containers to keep
it from evaporating. If leaking containers of bromomethane
are put in a waste site, most of the bromomethane will probably
escape into the air. Small amounts might leak into the soil
or pass through the soil and dissolve in underground water.
Bromomethane has been found in underground water at two hazardous
waste sites on the NPL.
Bromomethane breaks down in the environment to other chemicals.
In air, it usually takes about 11 months for half the bromomethane
that was released to disappear. In underground water, it usually
takes about 1 month for half the bromomethane to break down.
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1.2
How might I be exposed to bromomethane? |
Because bromomethane is a gas, you are
most likely to be exposed by breathing it in air. In most
places around the world, levels in air are usually less than
0.025 parts of bromomethane per billion parts of air (ppb).
Some cities have higher levels (up to about 1–2 ppb) because
of releases from chemical factories and automobile exhausts.
You will probably not be exposed to high levels unless you
are near a place where bromomethane is being used for fumigation.
Workers who fumigate homes or fields may be exposed to very
high levels if proper safety precautions are not followed.
Because bromomethane evaporates so quickly, it is usually
not found in food, surface water, or soil.
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1.3
How can bromomethane enter and leave my body? |
If bromomethane is present at a waste
site, you are most likely to be exposed to it by breathing
the vapors in contaminated air. You might also be exposed
by drinking water from contaminated wells, although this is
less likely. If you breathe in bromomethane, about half of
it will pass through your lungs and enter your blood. Studies
in animals suggest that if you swallow bromomethane in water,
nearly all of it will pass through your stomach or intestines
and enter your body. Bromomethane that enters your body either
from your lungs or stomach is quickly spread throughout your
body by your blood. Most bromomethane in your body is broken
down into other chemicals, and these chemicals leave your
body in the urine or in the air you breathe out. This usually
begins happening within minutes, and is usually nearly complete
within several days. We do not know how much bromomethane
can enter your body through the skin, but the amount is probably
small.
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1.4
How can bromomethane affect my health? |
If you breathe bromomethane, you may develop a headache and
begin to feel weak and nauseated several hours later. If you
breathe a large amount, fluid may build up in your lungs and
it may be hard to breathe. You may have muscle tremors, and
sometimes even seizures. Your kidneys may also be injured,
and urine production may slow or stop. In severe cases, these
effects can lead to death. In less serious cases, most of
these effects usually disappear after several weeks, but some
of the effects may never go away.
Studies in animals suggest that if you swallow bromomethane,
you might experience stomach irritation but would probably
not experience lung, kidney, or brain injury. Bromomethane
that gets on your skin can cause itching, redness, and blisters.
Studies in animals also suggest that bromomethane does not
cause birth defects and does not interfere with normal reproduction
except at high exposure levels. Animals that breathed bromomethane
for 2 years did not develop cancer. Animals that swallowed
bromomethane for 25 weeks had changes in their stomachs that
could have been an early sign of cancer, but we do not know
if swallowing bromomethane for a longer time would cause cancer.
Both the International Agency for Research on Cancer and the
EPA have determined that bromomethane is not classifiable
as to its carcinogenicity in humans.
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1.5
Is there a medical test to determine whether I have been exposed
to bromomethane? |
Several tests are available to tell whether
you have been exposed to bromomethane, but each has limitations.
The most direct test measures bromomethane in your blood or
in the air you breathe out. However, this test is not usually
used because most bromomethane does not stay in the body very
long (see Section 1.3) and special
measuring equipment is needed. More often, the main breakdown
product of bromomethane (bromide) is measured in blood samples.
Bromide is normally present in the blood of all people, but
the levels of bromide increase when people are exposed to
bromomethane. The amount of increase depends on the level
of exposure. Tests for bromide are only useful if done within
1-2 days following exposure, and are not very helpful in predicting
if exposed persons will have health effects or how serious
the effects will be, because not all people respond to bromomethane
the same way.
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1.6
What recommendations has the federal government made to protect
human health? |
Concentrated bromomethane can be very
dangerous, so the EPA allows only licensed professional fumigators
to buy or use bromomethane. The government does not have any
regulations at present about how much bromomethane can be
present in outdoor air or water, but EPA requires water companies
to test for this chemical in their water. The Food and Drug
Administration (FDA) has set limits of 125–400 parts of bromide
per million parts of food (ppm) for how much bromide may remain
in food after the food is treated with bromomethane. The Occupational
Safety and Health Agency (OSHA) limits the average level of
bromomethane in workplace air to 5 ppm, and recommends that
exposures be reduced to the lowest level feasible.
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1.7
Where can I get more information? |
If you have any more questions or concerns, please contact
your community or state health or environmental quality department or:
Agency for Toxic Substances and Disease Registry
Division of Toxicology
1600 Clifton Road NE, Mailstop F-32
Atlanta, GA 30333
Information line and technical assistance:
Phone: 888-422-8737
FAX: (770)-488-4178
ATSDR can also tell you the location of occupational and environmental health
clinics. These clinics specialize in recognizing, evaluating, and treating illnesses
resulting from exposure to hazardous substances.
To order toxicological profiles, contact:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Phone: 800-553-6847 or 703-605-6000
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References |
Agency for Toxic Substances and Disease
Registry (ATSDR). 1992. Toxicological
profile for bromomethane. Atlanta, GA: U.S. Department
of Health and Human Services, Public Health Service.
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