1.1 What is disulfoton? |
1.2 What happens to disulfoton when it
enters the environment? |
1.3 How might I be exposed to disulfoton? |
1.4 How can disulfoton enter and leave
my body? |
1.5 How can disulfoton affect my health? |
1.6 Is there a medical test to determine
whether I have been exposed to disulfoton? |
1.7 What recommendations has the federal
government made to protect human health? |
1.8 Where can I get more information? |
References |
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August 1995 |
Public Health Statement |
for |
Disulfoton |
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This Public Health Statement is the
summary chapter from the Toxicological
Profile for disulfoton. 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 disulfoton and to emphasize the human health
effects that may result from exposure to it. The Environmental
Protection Agency (EPA) has identified 1,408 hazardous waste
sites as the most serious in the nation. These sites make
up the National Priorities List (NPL) and are the sites targeted
for long-term federal clean-up activities. Disulfoton has
been found in at least 7 of the sites on the NPL. However,
the number of NPL sites evaluated for disulfoton is not known.
As EPA evaluates more sites, the number of sites at which
disulfoton is found may increase. This information is important
because exposure to disulfoton may cause harmful health effects
and because these sites are potential or actual sources of
human exposure to disulfoton.
When a substance 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. This release
does not always lead to exposure. You can be exposed to a
substance only when you come in contact with it. You may be
exposed by breathing, eating, or drinking substances containing
the substance or by skin contact with it.
If you are exposed to substances such
as disulfoton, many 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, gender, nutritional
status, family traits, life-style, and state of health.
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1.1
What is disulfoton? |
Disulfoton is a manufactured substance
used as a pesticide to control a variety of harmful pests
that attack many field and vegetable crops. Disulfoton does
not occur naturally. The common trade names for disulfoton
are Di-syston®, Disystox®, Frumin
AL®, and Solvirex®. Pure disulfoton
is a colorless oil with no identifiable odor and taste. The
technical product is dark yellowish, and has an aromatic odor.
It does not easily dissolve in water or evaporate to air.
It is most likely to be present in hazardous waste sites with
other wastes, either in drums or mixed with soil. Disulfoton
is used to protect small grains, sorghum, corn, and other
field crops; some vegetables, fruit, and nut crops; and ornamental
and potted plants against certain insects. Although it is
used primarily in agriculture, small quantities are used on
home and garden plants. Small quantities also are used for
other purposes, such as mosquito control in swamps. The use
of disulfoton has decreased in recent years.
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1.2
What happens to disulfoton when it enters the environment? |
Disulfoton enters the environment principally
when it is applied as a spray or as granules on field crops,
vegetables, potted plants, and home gardens. Disulfoton also
can enter the environment when it accidentally spills or leaks
during storage and transport. Disulfoton may also enter the
environment from hazardous waste sites. Environmental contamination
by disulfoton mainly affects soil and water. Natural chemical
reactions and bacterial attack remove disulfoton from soil
and water. Such reactions form some by-products that are more
toxic than disulfoton. Fish accumulate disulfoton in their
bodies. The levels of disulfoton in fish can be hundreds of
times higher than the level in water. Disulfoton binds moderately
well to soil and typically does not travel deep into soil
with rainwater. Disulfoton has been detected infrequently
in groundwater from agricultural soil in California and Virginia.
The estimated amount of time required for the concentration
of disulfoton in river water to decrease to half of its initial
level (half-life) is 7 days. The estimated half-life in soil
ranges from 3.5 to 290 days, depending on the nature of the
soil and climatic conditions.
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1.3
How might I be exposed to disulfoton? |
You may be exposed to disulfoton by breathing
contaminated air, drinking contaminated water, and eating
contaminated food. Disulfoton is rarely detected in air. In
1980, a low level of disulfoton was detected in 1 of 123 air
samples collected from 10 locations in the United States.
The average concentration at this site was 0.1 nanogram (ng)
in 1 cubic meter of air (1 ng = 1/1,000,000,000th [one billionth]
of a gram). Disulfoton has not been detected in drinking water.
Low levels of disulfoton (0.05–1.0 milligram in a kilogram
[mg/kg] of food) (1 mg = 1/1,000 [one thousandth] of one gram)
are sometimes found in some grains, fruits, and vegetables
treated with this pesticide. Because the levels in food are
higher than levels in air and water, you are more likely to
be exposed to disulfoton by eating contaminated food. The
Food and Drug Administration (FDA) estimated that the average
intake of disulfoton in food per day for a 14- to 16-year-old
male in the United States from 1986 to 1991 was 0.2 ng/kg
(nanograms per kilogram) of body weight. The FDA estimate
for disulfoton intake from foods is 0.07% or less than 1/1,000th
of the Food and Agriculture Organization/World Health Organization
(FAO/WHO) acceptable daily intake (ADI) value of 300 ng/kg.
The FAO/WHO ADI value is the maximum amount of a chemical
which if ingested over a person's lifetime appears to be without
appreciable health risk. Workers in industries that manufacture
and formulate disulfoton are at a higher risk of exposure.
Workers who spray the pesticide in fields and some farm workers
who enter the fields following spraying also are at a higher
risk of exposure than the general population. Among the general
population, people who frequently use the pesticide in their
homes and gardens are potentially at higher risk. People who
live near hazardous waste sites that contain disulfoton also
are potentially at a higher risk of exposure. Children playing
at or near these hazardous waste sites may be exposed by touching
and eating soil that contains disulfoton.
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1.4
How can disulfoton enter and leave my body? |
Disulfoton can easily enter your body
when you breathe it in, swallow it, or have skin contact with
it. The amount of disulfoton that enters your body depends
on the amount in air, food, and water, and the length of time
you are exposed to it. In an oily mixture, disulfoton may
enter the body through the skin, lungs, or stomach more easily
than it would in a water mixture. After disulfoton enters
your body, the blood carries it to your organs and tissues.
Disulfoton generally does not build up in your organs and
tissues, but is initially changed to more harmful substances,
which quickly break down to harmless by-products. The harmful
breakdown products inhibit important enzymes (cholinesterases)
in the nervous system, and this action can cause neurological
effects. The harmless breakdown products do not have any known
effects on the body. Studies in animals show that disulfoton
and/or the breakdown products completely leave the body through
the urine, feces, and exhaled air in about 10 days or less.
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1.5
How can disulfoton affect my health? |
In people, disulfoton mainly causes harmful
effects to the nervous system. The harmful breakdown products
of disulfoton inhibit cholinesterase activity in the nervous
system, which results in neurological effects. Depending on
the amount of disulfoton that enters the body, neurological
effects, such as inhibited cholinesterase activity, narrowing
of the pupils, vomiting, diarrhea, drooling, difficulty in
breathing, tremors, convulsions, and even death may occur.
These effects can occur if you breathe in, swallow, or have
skin contact with disulfoton. Exposure to small amounts of
disulfoton can sometimes inhibit cholinesterase activity without
causing obvious neurological effects. If you take in disulfoton
from food or water for long periods, you may also become nearsighted.
You are less likely to die from skin contact with disulfoton
than from swallowing it, but you may become weak and tired
after skin contact.
Breathing in, swallowing, or having skin
contact with high levels of disulfoton can cause similar neurological
effects in animals. The neurological effects of disulfoton
are the most common effects. Animals that swallowed disulfoton
for long periods became nearsighted, and the structures of
their eyes were further damaged. Results of animal studies
suggest that female rats and mice are more sensitive to disulfoton
than male rats and mice.
We do not know whether disulfoton causes
reproductive or birth defects, or cancer in people. However,
some studies suggest that disulfoton may cause reproductive
effects in animals. Some animals that swallowed disulfoton
during pregnancy had newborns with underdeveloped bones, damaged
livers and kidneys, and underdeveloped testes. Animals that
swallowed disulfoton for long periods did not develop cancer.
Disulfoton has not been classified for carcinogenic effects
by the Department of Health and Human Services (DHHS), the
International Agency for Research on Cancer (IARC), or the
EPA.
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1.6
Is there a medical test to determine whether I have been exposed
to disulfoton? |
Disulfoton and its breakdown products
can be measured in the blood, urine, feces, liver, kidney,
or body fat of exposed people. In cases of occupational or
accidental exposure to disulfoton, the breakdown products
are often measured in the urine. The breakdown products are
relatively specific for disulfoton and a few other similar
organophosphate pesticides and can be detected in urine for
up to one week after people were last exposed. Because disulfoton
inhibits cholinesterase in blood and in blood cells, inhibition
of this enzyme activity may also suggest exposure to disulfoton.
Cholinesterase activity in blood and in blood cells may remain
inhibited for as long as 1–2 weeks after the last exposure.
Because other organophosphate pesticides also inhibit cholinesterase
activity in blood and blood cells, this test is not specific
for disulfoton. The measurement of cholinesterase in blood
and blood cells and the amount of disulfoton breakdown products
in the urine cannot always predict how much disulfoton you
were exposed to. Your doctor can send samples of your blood
or urine to special laboratories that perform these tests.
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1.7
What recommendations has the federal government made to protect
human health? |
The National Institute for Occupational
Safety and Health (NIOSH) recommends an exposure limit of
0.1 mg disulfoton/m³ of air for a 10-hour workday within
a 40-hour workweek.
EPA recommends that no more than 10 parts
of disulfoton per billion parts (ppb) of water be present
in drinking water that children drink for periods of up to
10 days. Disulfoton in drinking water should not exceed 3
ppb for children or 9 ppb for adults if they drink the water
for longer periods, and should not exceed 0.3 ppb for
adults who will drink the water during an average lifetime.
EPA has designated disulfoton as a hazardous substance, but
it does not intend to cancel or restrict registration of pesticide
products containing disulfoton. Federal regulations limit
the amount of disulfoton that factories can release into waste
water. EPA requires industries to report releases or spills
of 1 pound or more.
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1.8 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). 1995. Toxicological
profile for disulfoton. Atlanta, GA: U.S. Department of
Health and Human Services, Public Health Service.
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