E X T O X N E T
Extension Toxicology Network
A Pesticide Information Project of Cooperative Extension Offices of
Cornell University, Michigan State University, Oregon State University, and
University of California at Davis. Major support and funding was provided
by the USDA/Extension Service/National Agricultural Pesticide Impact
Publication Date: 5/94
TRADE OR OTHER NAMES
Basic copper sulfate: BSC Copper Fungicide; CP Basic Sulfate; Tri-
Basic Copper Sulfate. Pentahydrate form: bluestone, blue vitriol,
Salzburg vitriol, Roman vitriol, and blue copperas (17). Bordeaux Mixture
is a combination of hydrated lime and copper sulfate (21).
Copper sulfate is classified as a general use material by the U.S.
Environmental Protection Agency (EPA). The warning signal "DANGER" must
appear on the labels of all copper sulfate end-products containing 99%
active ingredient in crystalline form.
Copper sulfate is a fungicide used to control bacterial and fungal
diseases of fruit, vegetable, nut and field crops. Some of the diseases
that are controlled by this fungicide include mildew, leaf spots, blights
and apple scab. It is used in combination with lime and water as a
protective fungicide, referred to as Bordeaux mixture, for leaf application
and seed treatment. It is also used as an algaecide, an herbicide in
irrigation and municipal water treatment systems, and as a molluscicide, a
material used to repel and kill slugs and snails. Copper sulfate is a
naturally-occurring inorganic salt and copper is an essential trace element
in plant and animal nutrition (5, 6, 7, 13, 16). It is available in the
following formulations: dusts, wettable powders, and fluid concentrates
Copper is one of 26 essential trace elements occurring naturally in
plant and animal tissue. The usual routes by which humans receive toxic
exposure to copper sulfate are through skin or eye contact, as well as by
inhalation of powders and dusts (16). Copper sulfate is a strong irritant
Copper sulfate is only moderately toxic upon acute oral exposure (17).
There have been reports of human suicide resulting from the ingestion of
gram quantities of this material (10). The lowest dose of copper sulfate
that has been toxic when ingested by humans is 11 mg/kg (8). Ingestion of
copper sulfate is often not toxic because vomiting is automatically
triggered by its irritating effect on the gastrointestinal tract. Symptoms
are severe, however, if copper sulfate is retained in the stomach, as in
the unconscious victim. Some of the signs of poisoning which occurred
after 1-12 grams of copper sulfate was swallowed include a metallic taste
in the mouth, burning pain in the chest and abdomen, intense nausea,
vomiting, diarrhea, headache, sweating, shock, discontinued urination
leading to yellowing of the skin. Injury to the brain, liver, kidneys and
stomach and intestinal linings may also occur in copper sulfate poisoning
Copper sulfate can be corrosive to the skin and eyes. It is
readily absorbed through the skin and can produce a burning pain, along
with the same severe symptoms of poisoning from ingestion. Skin contact
may result in itching or eczema (13). It is considered a skin sensitizer
and can cause allergic reactions in some individuals (16). Eye contact
with this material can cause: conjunctivitis, inflammation of the eyelid
lining, excess fluid buildup in the eyelid; cornea tissue deterioration due
to breaks, or ulceration, in the eye's mucous membrane; and clouding of the
The amount of copper sulfate that is lethal to one-half (50%) of
experimental animals fed the material is referred to as its acute oral
lethal dose fifty, or LD50. The LD50 for copper sulfate is 30 mg/kg in
rats. Ingestion by animals of three ounces of a 1% solution of copper
sulfate will produce extreme inflammation of the gastrointestinal tract,
with symptoms of abdominal pain, vomiting, and diarrhea. When copper
sulfate is given intravenously, or injected into the vein, as little as 2
mg/kg copper sulfate is lethal to guinea pigs; and 4 mg/kg is lethal to
Vineyard sprayers experienced liver disease after 3 to 15 years of
exposure to copper sulfate solution in Bordeaux mixture (13). Long-term
effects are more likely in individuals with Wilson's disease, a condition
which causes excessive absorption and storage of copper (11). Chronic
exposure to low levels of copper can lead to anemia (13). The biological
or chemical manner by which excessive doses of copper sulfate work is not
well understood (6).
The growth of rats was retarded when 25 mg/kg of copper sulfate was
included in their diets. 200 mg/kg caused starvation and death (13).
Sheep with access to salt licks that contained five to nine percent copper
sulfate showed signs of absence of appetite (anorexia), anemia, and
degenerative changes, followed by death within one or two days of exposure
(2). This material caused a significant increase in the death rates in
mice that were exposed to an air level equivalent to human inhalation
The EPA limit for copper sulfate in drinking water is 1 ppm (3). This
limit has been set to prevent a disagreeable taste from copper in drinking
water, as well as to provide adequate protection from toxicity (10).
Developing embryos were resorbed in pregnant hamsters given copper
salts intravenously on the eighth day of gestation. Testicular atrophy
increased in birds as they were fed larger amounts of copper sulfate.
Sperm production was also interrupted to varying degrees (13).
Reproduction and fertility was affected in pregnant rats given this
material on the third day of pregnancy (8). EPA does not require data on
the reproductive effects of copper sulfate in mammals (16).
Heart disease occurred in the surviving offspring of pregnant hamsters
given intravenous copper salts on the eighth day of gestation (13). EPA
does not require data on the teratogenic effects of copper sulfate (16).
At 400 and 1,000 ppm, copper sulfate caused mutations in two types of
microorganisms (8). Data on the potential mutagenic effects of this
material is not required by the EPA.
Ten mg/kg of copper sulfate caused endocrine tumors in chickens given
the material parenterally, that is, outside of the gastrointestinal tract
through an intravenous or intramuscular injection (8). EPA does not
require this data for copper sulfate (16).
Examinations of copper sulfate-poisoned animals showed signs of acute
toxicity in the spleen, liver and kidneys (13). Injury may also occur to
the brain, liver, kidneys and gastrointestinal tract in response to
overexposure to this material (2).
Fate in Humans and Animals
Absorption of copper sulfate into the blood occurs primarily under the
acidic conditions of the stomach; the mucous membrane lining of the
intestines acts to some extent as a barrier to absorption of ingested
copper (13). After ingestion, more than 99% of copper is excreted in the
feces. Copper is an essential trace element that is strongly
bioaccumulated (3, 13). It is stored primarily in the liver, brain, heart,
kidney and muscles. About one-third of all the copper in the body is
contained in the liver and brain. Another third is contained in the
muscles. The remaining third is dispersed in other tissues.
Effects on Birds
Copper sulfate poses less of a threat to birds than to other animals.
The lowest lethal dose (LDLo) for this material in pigeons and ducks is
1,000 mg/kg and 600 mg/kg, respectively (13). The oral LD50 for Bordeaux
mixture in young mallards is 2,000 mg/kg (14).
Effects on Aquatic Organisms
Copper sulfate is very toxic to fish. Its toxicity to fish varies
with the species and the physical and chemical characteristics of the water
(12). Even at recommended rates of application, this material may be
poisonous to trout and other fish, especially in soft or acid waters. Its
toxicity to fish generally decreases as water hardness increases. Fish
eggs are more resistant than young fish fry to the toxic effects of copper
sulfate (3). Very small amounts of this material can have damaging effects
on fish. Permits are being required in some situations for application of
copper sulfate to water bodies. Further field studies have been required
by the EPA (16). Direct application of copper sulfate to water may cause a
significant decrease in populations of aquatic invertebrates, plants and
Effects on Other Animals (Nontarget Species)
Copper sulfate is toxic to aquatic invertebrates, such as crab, shrimp
and oysters. Based on data on the potential hazards posed by this material
to the slackwater darter, freshwater mussels, and Solano grass, and in an
effort to minimize exposure of endangered species to this material,
applicators in some counties are required to consult EPA endangered species
bulletins before applying copper sulfate (16). It is a Federal violation
to use any pesticide in a manner that results in the death of an endangered
species or adverse changes to their natural habitat (17). Bees are
endangered by strong, water-based copper compounds, such as a Bordeaux
mixture of copper sulphate, lime and water (5). Copper sulfate and similar
fungicides have been poisonous to sheep and chickens on farms at normal
application rates. Most animal life in soil, including large earthworms,
have been eliminated by the extensive use of copper-containing fungicides
in orchards (12). Frogs died after being given intravenous doses of 25
mg/kg of copper sulfate. The lethal concentration fifty, or LC50, is that
concentration of a chemical in air or water that kills half of the
experimental animals exposed to it for a set time period. The 96-hour LC50
of copper sulfate to pond snails is 0.39 mg/l, at 20 degrees C. Higher
concentrations of the material caused some behavioral changes, such as
secretion of mucous, and discharge of eggs and embryos (13).
Copper is strongly bioaccumulated. Biological activity is a major
factor in determining the occurrence and distribution of copper in the
Breakdown of Chemical in Soil and Groundwater
Copper sulfate is: (a) partly washed down to lower soil levels by
water percolating through the ground, called groundwater; (b) partly bound
to soil components; and (c) partly changed into different metabolites, or
breakdown products (5). Copper is considered to be among the more mobile
of the heavy metals in surface environments. Copper is bound, or adsorbed,
to organic materials, and to clay and mineral surfaces. The degree of
copper adsorption to soils depends on the level of acidity or alkalinity of
the soil. The distance that it can travel in soil is limited by its strong
adsorption to many types of surfaces (13). All applied copper will become
a part of the soil copper content (19). Although copper sulfate is highly
water soluble-that is, it dissolves very easily in water-the copper ions
are strongly adsorbed or precipitated to soil particles when it is applied
to soil (13). The leaching potential of this material is low in all but
When applied to irrigation water, copper sulfate does not accumulate
in the surrounding soils. 60% of applied copper was deposited in the
sediments at the bottom of the irrigation ditch, where it became adsorbed
to clay, mineral and organic particles. Copper compounds, or precipitates,
also settle out of solution, in a process called precipitation. This
occurs less often than adsorption. Usually, precipitates are biologically
inactive, meaning that they do not undergo further biological changes (3).
Breakdown of Chemical in Water
Due to its high water solubility, excessive amounts of copper sulfate
should be kept out of lakes, streams and ponds (1). Water can be
contaminated by inappropriate cleaning of application equipment, or
disposal of waste associated with this material (16). High concentrations
of this type of copper are toxic to aquatic organisms and may cause a
significant decrease in populations of aquatic invertebrates, plants, and
fish (13, 16). A state Fish and Game Agency should be consulted before
copper sulfate application to public waters, as permits may be required for
such treatment (17).
Copper sulfate products should not be used to treat more than half of
a lake or pond at one time, in order to avoid depletion of oxygen caused by
decaying vegetation. One to two weeks should be allowed between copper
sulfate treatments to allow water oxygen levels to recover (16).
The effectiveness of copper sulfate decreases as water hardness
increases. As a naturally-occurring substance, copper can persist
indefinitely. No evidence has been found to show that this material gets
removed from water through volatilization (13).
Breakdown of Chemical in Vegetation
One of the limiting factors in the use of copper compounds is their
serious potential for phytotoxicity, or poisonous activity in plants (17).
Copper sulfate can kill plants by disrupting photosynthesis. 200 ppm of
copper was found in grass five months after it was sprayed with copper
sulfate to control liver fluke (13). Blue-green algae in some copper
sulfate-treated Minnesota lakes appeared to become increasingly resistant
to the algaecide after 26 years of use (12).
PHYSICAL PROPERTIES AND GUIDELINES
Boots, protective gloves, and goggles should be worn by anyone
handling this material (13, 17). Skin should be washed immediately if
contaminated, and work clothing should be changed daily if it is reasonably
likely that it is contaminated with copper sulfate.
Copper sulfate is blue and odorless. It gives off moisture when
exposed to air (22). Copper sulfate is classified for shipping purposes as
a hazardous substance or hazardous waste. It may pose unreasonable risk to
health, safety, or property, when transported (13). Copper sulfate is
highly corrosive to plain steel, iron and galvanized pipes. All metal in
contact with solutions of this material should be 304 stainless steel,
monel or plastic (6). It should not be stored in metal containers. Copper
sulfate is also incompatible with acetylene gas and with magnesium metal
(13). Containers of this material should be kept tightly sealed (20). It
is indefinitely stable when kept dry and is stable to heat, cold, or light
(19). However, there is slight decomposition of copper sulfate at
temperatures above 200 degrees C. Above 400 degrees C, it decomposes,
giving off sulfur trioxide gas (13).
Burning copper sulfate may produce irritating or poisonous gases, and
pollution may be caused by runoff from fire control or dilution water (15).
Occupational and Exposure Limits:
|TWA: ||1.0 mg/m3 for all copper dusts or mists (1).
|H20 solubility: ||anhydrous form: 14.3 g/100 cc at 0 degrees C; 75.4 g/100
cc at 100 degrees C; copper sulfate pentahydrate:31.6 g/100 cc at 0 degrees C; 203.3 g/100 cc at 100 degrees C (17); 23.05 g/100 g at 25 degrees C; 14.8 g/100 g at 0 degrees C (5); 75.4 g/100 cc at
100 degrees C (13); 143,000 ppm (18)
|Solubility in other solvents: ||1.04 g/100 cc at 18 degrees C in methanol
(13); Insoluble in ethanol and most organic solvents (6)
|Melting point: ||Above 100 degrees C, copper sulfate loses water from
crystallization with formation of the monohydrate; above 200 degrees C it loses all water of crystallization (5)
|Vapor pressure: ||0 (5)
|Koc: ||Copper is strongly adsorbed by clay and humus. It is precipitated on
clay particles as insoluble copper hydroxides, phosphates, or carbonates (19)
|Chemical Class/Use: ||Inorganic fungicide, algaecide, herbicide,
CP Chemical Inc.
P.O. Box 1979
Sumter, SC 29151
Review by Manufacturer:
Comments solicited: October, 1991
Comments received: December, 1993
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Review by CP Chemicals, Inc. December 27, 1993.