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
Acaraben, Akar 338, Folbex, Kop-mite, Benzilan, ECB, Geigy 338, Benz-
Chlorobenzilate has been cancelled and is no longer available in the
United States (20). Previously, the U. S. Environmental Protection Agency
(EPA) had classified all formulations containing chlorobenzilate as
Restricted Use Pesticides (RUPs). RUPs may be purchased and used only by
certified applicators. The criteria used for this classification was its
ability to cause tumors in mice, and its effects on the testes of rats
(18). Aerial and ground foliar sprays were restricted to citrus use in the
states of Arizona, California, Florida and Texas for the control of mites
Chlorobenzilate was introduced in 1952. It is used for mite control
on citrus crops and in beehives (8). It is nonsystemic, meaning that it is
not absorbed or transported throughout a plant. It has little insecticidal
action, killing only ticks and mites (2, 17).
Chlorobenzilate is available as emulsifiable concentrate and as
wettable powder formulations (8).
Chlorobenzilate is slightly to moderately toxic to humans. Symptoms
of acute poisoning from ingestion of chlorobenzilate include
incoordination, nausea, vomiting, fever, apprehension, confusion, muscle
weakness or pain, disturbed sense of balance, dizziness, weight loss,
wheezing and coma. Symptoms may occur within several hours after exposure.
Death may result from discontinued breathing or irregular heartbeats (9,
Chlorobenzilate is a mild skin and eye irritant (19).
The oral LD50 for chlorobenzilate in rats and hamsters is 700 mg/kg,
and 729 mg/kg in mice (2, 19).
Prolonged or repeated exposure to chlorobenzilate may cause the same
effects as acute exposure (19). After continuous exposure to
chlorobenzilate, 16 out of 73 workmen tested had abnormal
electroencephalograms, or EEGs. EEGs are recordings of electrical activity
of the brain. The most severe brain activity changes were seen in those
persons exposed to the herbicide for one to two years (11) . Chronic skin
exposure to chlorobenzilate may cause inflamed skin or rashes, also known
as dermatitis. Chronic eye exposure to this material may cause
The use of chlorobenzilate has been restricted in the U.S. because the
compound is tumor-forming (oncogenic) in rats and mice (3). Atrophy of the
testes was observed in a two-year study of male rats (19). Symptoms of
poisoning in test animals included depression, salivation, tearing,
diarrhea and deep, rapid breathing (11).
In 1979, the EPA recommended that sperm counts be examined in a
selected population of chlorobenzilate applicators (2). A three-generation
rat reproduction study resulted in reduced testicular weights, but did not
affect reproduction. The results of another study indicate that
chlorobenzilate does not adversely affect reproductive performance nor
produce testicular atrophy at dosage levels up to 100 mg/kg per day (15).
Information is incomplete on the potential for chlorobenzilate to
cause birth defects (14).
No information is available.
Chlorobenzilate is a suspected carcinogen in animals and a possible
human carcinogen. It has produced liver tumors in mice, but the evidence
for carcinogenicity in rats is uncertain (2).
Poisoning may effect the central nervous system, the kidneys and the
liver (19). Autopsies revealed intestinal irritation and bleeding in the
lungs of rats poisoned by dietary doses of 25 mg/kg of chlorobenzilate
(11). Liver damage may be caused by repeated or prolonged contact with
this material (9).
Fate in Humans and Animals
Chlorobenzilate is rapidly excreted by humans, usually within 3 to 4
days (19). After daily doses of 12.8 mg/kg to dogs, for 5 days/week for 35
weeks, about 40% of the dose was excreted unchanged or as urinary
metabolites. No significant storage in fat of dogs or rats was reported
Chlorobenzilate has a slight tendency to accumulate in fatty tissues
(3). Intense activity or starvation may mobilize the stored pesticide and
cause the reappearance of toxic symptoms (19). In a study funded by the
National Pesticide Hazard Assessment Program of EPA, detectable traces of
chlorobenzilate were found in urine collected from Texas and Florida
citrus-grove growers and workers. The collected information showed a range
of exposure: from low levels in harvest season pickers, exposed to little
or no chlorobenzilate exposure, to higher levels among permanent or semi-
permanent workers employed during the spraying season. Among all workers,
urinary values ranged from zero to 63.6 ppm (4). This acaricide has not
been found in human milk in the United States (11) .
Effects on Birds
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 seven-day LC50 for
chlorobenzilate was 3,375 ppm in bobwhite quail. Its five-day LC50 in
mallard ducks was greater than 8000 ppm (14).
Effects on Fish
Chlorobenzilate is not expected to bioconcentrate in aquatic organisms
(12). Its LC50 is 0.7 mg/l for 95 hours in rainbow trout (14, 11).
Effects on Other Animals (Nontarget Species)
Chlorobenzilate is believed to be non-toxic to beneficial insects
(10). Chlorobenzilate is non-toxic to honey bees (8).
Breakdown of Chemical in Soil and Groundwater
Because chlorobenzilate is practically insoluble in water and it
adsorbs strongly to soil particles (Koc = 1,065) in the upper soil layers,
it is expected to exhibit low mobility in soils, and to therefore be
unlikely to leach to groundwater (12). Its soil half-life in fine sandy
soils was 1.5 to 5 weeks after application of 0.5-1.0 ppm, with the removal
probably due to microbial degradation (12). Due to its strong adsorption
to soil particles and low vapor pressure, chlorobenzilate is not expected
to volatilize from soil surfaces (12, 5).
Following a five-day application of chlorobenzilate to several
different citrus groves employing various tillage treatments,
chlorobenzilate was not found in subsurface drainage waters, nor in surface
runoff waters (5).
Breakdown of Chemical in Water
Chlorobenzilate adsorbs to sediment and suspended particulate material
in water. It is practically insoluble in water (12, 11) . It is not
expected to volatilize or to bioconcentrate in aquatic organisms, but may
be subject to biodegradation (12).
Breakdown of Chemical in Vegetation
Chlorobenzilate is fairly persistent on plant foliage and may be
phytotoxic, or poisonous, to some plants (6).
Chlorobenzilate residues have been found in the peel of citrus fruit.
Its half-life in lemon and orange peels was from 60 to over 160 days (11).
The spraying of 200, 1,000 and 5,000 ppm chlorobenzilate (in emulsions or
suspensions) caused browning of the edges or the veins of leaves on most
treated crops (11) . When chlorobenzilate was applied to the surface of
soybean leaves, the miticide was quite stable and very little was absorbed
and moved, or translocated, from one part of the plant to another (7).
PHYSICAL PROPERTIES AND GUIDELINES
Technical chlorobenzilate contains approximately 90% active compound
(11). It is a brownish liquid. Pure chlorobenzilate is a yellow solid (1,
Chlorobenzilate is stable under normal temperatures and pressures. It
may burn, but does not ignite readily. Breakdown of chlorobenzilate by
heat may create corrosive fumes of hydrogen chloride and toxic oxides of
carbon. Exposure to alkalis or strong acids may cause hydrolysis (19, 9,
Occupational Exposure Limits:
No occupational exposure limits have been established by ACGIH, NIOSH
or OSHA (19).
|CAS #: ||510-15-6
|H2O solubility: ||practically insoluble in water (8, 13)
|Solubility in other solvents: ||soluble in most organic solvents including benzene, acetone, methyl alcohol, toluene, hexane, octan-1-ol, alcohol, ethanol, and petroleum oils (8, 19, 11, 17)
|Melting point: ||35-37 degrees C (95-99 degrees F) for pure chlorobenzilate (13, 17)
|Boiling point: ||313-316 degrees F (156-158 degrees C) (19)
|Flash point: ||104 degrees F (40 degrees C) (19)
|Specific gravity: ||1.2816 (19)
|Koc: ||1065 (12)
|Vapor pressure: ||2.2 x 10 to the minus 6 mm Hg at 20 degrees C (12)
|Chemical Class/Use: ||Chlorinated hydrocarbon; organochlorine miticide
CIBA Plant Protection
P.O. Box 18300
Greensboro, NC 27419-8300
Review by Basic Manufacturer:
Comments solicited: November, 1992
Comments received: January, 1994
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