United States <
: Environmental Protection
Agency
Prevention/Pesticides
And Toxic Substances
(75Q8W)
ERA-738-F-99-001
February 1999
SERA R.E.D. FACTS
Pesticide
Reregistcation
Use Profile
Chlorine gas
All pesticides sold or distributed in the United States must be registered
by EPA, based on 'scientific studies showing that they can be used without
posing unreasonable risks to people or the environment. Because of advances
in scientific knowledge/the law requires that pesticides which were first
registered years ago be reregistered to ensure that they meet today's more
stringent standards. ,
In evaluating pesticides for reregistration, EPA obtains and reviews a-
complete set of studies from pesticide producers, describing the human health
and environmental effects of each pesticide. The Agency imposes any
regulatory controls that are needed to effectively manage each pesticide's risks.
, EPA then reregisters pesticides that can be used without posing unreasonable
risks to human health or the environment.
When a pesticide is eligible for reregistration, EPA announces this and
explains why in a Reregistration Eligibility Decision (RED) document. This
fact sheet summarizes the information in the RED document, for reregistration
Case 4022, chlorine gas.
Chlorine gas is used in water treatment to disinfect drinking water,
swimming pools, ornamental ponds and aquaria, sewage and wastewater, and
other types of water reservoirs. Chlorine gas also is used as a disinfectant,
microbistat/microbicide and algicide in food processing systems, pulp and
paper mill systems, and commercial and industrial water cooling systems.' It is
used in washing meat, fresh produce and seeds to control decay-causing
microorganisms. - ,
Chlorine is formulated as a pressurized gas and distributed in large
stationary containers such as tank cars or trucks and 150-pound to 1-foB
cylinders. It is intended for use only by trained, experienced persosanel, under
the supervision of the registrant and in accordance with state and municipal
regulatory requirements. ,'...'-
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Regulatory
History
Human Health
Assessment
Chlorine gas was first registered in the U.S. in 1948, as a disinfectant for
use i*1 swimming pools, drinking water, cooling towers arid sewage systems.
In 1976, chlorine gas was classified for general use based on the premise that
industrial users already were adequately trained in its use. Chlorine gas was
declared exempt from the requirement of a tolerance when used in solution on
raw agricultural commodities in 1991 because measurable residues are not
expected. EPA required additional generic data in a Data Call-In notice issued
in November 1.993. Currently, 97 pesticide products containing the active
ingredient chlorine gas are registered. .
The Food and Drug Administration (FDA) regulates the use of chlorine
gas hi solution as a food contact surface sanitizer. EPA's Qffice of Water
regulates its use in potable water systems.
i
Toxicity
In human poisoning incidents involving accidental ingestion of household
bleach, chlorine has caused a burning sensation hi the mouth and throat,
irritation to the digestive tract and stomach, and vomiting. Exposure to
chlorine gas causes effects ranging from bronchitis, asthma and swelling of the
lungs, to headaches, heart disease and meningitis. Acute exposure causes more
severe respiratory and lung effects, and can result in fatalities. More often,
however, the effects are not permanent; complete and rapid recovery generally
occurs with treatment.
Chlorine disinfectants have been shown to cause occupational dermatitis
or irritation of the skin. People who are asthmatic or allergic to chlorine may
be at high risk for adverse reactions after inhaling or ingesting chlorine, for
example, after drinking treated water.
Technical grade chlorine (gas and liquid) and its byproducts,
hypochlorous acid and hypochlorite ions, are highly toxic and corrosive, and
have been placed hi Toxicity Category I (indicating the highest degree of acute
toxicity) for oral, dermal, eye and inhalation effects. EPA waived several acute
toxicity studie^ ,; .; ijbchronic toxicity studies for chlorine due to its known
acute toxic;* , . rrc(?;veness.
Pr , j 4 2 ;; tar chronic inhalation study showed effects consistent
igs. Even the lowest exposures resulted in measurable cell
; ~rily as pulmonary lesions. Additional long-term testing is not
asce: ;; ;i uie likelihood of additional effects being identified for chlorine
per I; Demote.
Diverse results have been reported for chronic, exposure to chlorine in
drinking water. EPA has classified chlorine as a Group D carcinogen (not
classifiable as to human carcinogenicity), based on a 1990 National Toxicology
Program (NTP) study. That study showed equivocal evidence of cancer in
female rats (increased leukemia) and no evidence hi male rats or hi male and
witl ^it*
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female mice. The International Agency for Research on Cancer (I ARC) also
determined in 1991 that chlorinated drinking water is not classifiable as to
human carcinogenicity. Chlorine has not been shown to cause reproductive,
developmental or mutagenic effects.
Dietary Exposure
Pursuant to 40 CFR 180.1095, Chlorine gas is exempt from the
requirement of a tolerance when used pre- or postharvest on all raw
agricultural commodities. Use of chlorine in food processing water systems to
prevent decay of raw agricultural commodities may result in residues on treated
produce; however, finite residues or residues abbve naturally occurring
background levels are not expected. Similarly, if livestock ingest chlorine-
treated water, finite residues or residues above background levels are not
expected to occur in meat, milk or eggs. ~
Chlorine gas used as a food contact surface sanitizer on food, meat or
poultry processing premises and equipment is under FDA's regulatory purview.
EPA regulates contaminants hi drinking water under the Safe Drinking Water
Act (SDWA). The Office of Drinking Water .has recently established a
Maximum Residual Disinfectant Level (MRDL) of 4 mg/L for chlorine. An
MRDL is an enforceable Federal Standard.
Occupational and Residential Exposure
Chlorine gas is metered into water through closed systeriis hi
manufacturing processes or from large stationary containers such as tank cars,
tank trucks and cylinders. Given current use patterns of chlorine gas, there is
potential for dermal and inhalation exposure to applicators and other people
exposed to chlorinated water including swimmers, bystanders and workers in
food processing plants and water/sewage treatment plants.
Occupational exposure guidelines have been established by OSHA and
other domestic and foreign sources. Post-application exposure to chlorine
while swimming in treated pools is not believed to be significant, if label
requirements are followed. .-:.-
- A significant number of accidents and injuries resulting from the use of
chlorine gas as a pesticide have been reported by the American Association of
Poison Control Centers, .the Chlorine Institute, the California Pesticide Illness
Surveillance Program and others. In California, most accidents involved
, maintenance or equipment failure of chlorinator systems. The most common
FIFRA use-related exposures occurred at food processing plants. A significant
number of the incidents reported were attributed to application error. While
there were some residential pool incidents, most occurred in connection with
public/commercial pool chlorinator systems. In Florida, four applicators have
died as a result of incorrectly apply ing chlorine gas, <
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Human Risk Assessment
Risk to the public is not anticipated from consuming food or water
treated with chlorine. Although residues may remain on fruits and vegetables
as a result of their treatment with chlorine solution, these residues are exempt
from tolerance requirements and are not believed to pose risks. Residues
above background levels are not expected in meat, milk or eggs as a result of
chlorine use in drinking water. Use of chlorine to sanitize food contact
.surfaces and food .processing equipment presumably does not result in residues
of concern in foods (this use is under FDA's jurisdiction). EPA's Office of
Drinking Water regulates chlorine hi drinking water supplies under the SDWA.
The Agency has concluded that there is a need to better characterize the
reproductive a developmental risks associated with drinking water in order to
assure that children, infants and fetuses not face unreasonable risk from chronic
exposure to drinking water byproducts. Because of the high levels of
exposure, both in terms of population (greater than 200,000,000) and
individual consumption of chlorinated drinking water, it is necessary to assess
the associated risks with greater certainty. , . .
Three water treatment byproducts hi particular have been identified for
which the health effects need to be better characterized.
Bromodichloromethane, dichloroacetic acid, and dibromoacetic acid have been
identified as having health effects in laboratory studies. Because these
compounds are the most common toxicologically significant halogenated
hydrocarbons that have not been completely characterized, additional testing
on these compounds will improve the Agency's ability to assess chronic risks
from drinking water exposure.
EPA has significant concerns about applicator and post-application
exposure to chlorine gas because it is highly toxic for all routes of exposure.
The greatest risk of poisoning accidents from chlorine is to applicators and
bystanders from accidental exposures resulting from use of chlorine gas hi
public/commercial swimming pools, and to applicators and workers hi
industrial food settings. Two other uses, pulp/paper mills and cooling towers,
also pose a significant risk because of chlorinator system failure and
maintenance operations. The reported poisoning incidents strongly suggest
that the use of chlorine gas hi these situations presents a significant risk of
acut >xicity to applicators, other workers and bystanders. To mitigate this
. r' ,/: PA is requiring Restricted Use Pesticide classification for the use of
i i i ifte gas in food processing plants, public/commercial swimming pools,
"," Jp,"paper mills and cooling towers so that in the future these uses will be
mite ! to trained, certified applicators. In addition, EPA is requiring
igiiificant revisions to product labeling through the RED, so labels will contain
sufficient specific use information. The labeling improvements are expected to
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adequately address the risks: associated with water/sewage treatment and
residential pool use, which will, still be classified as general use.
Environmental EnvironmentalFate
Assessment Chlorine hydrolyses in water to form hypochlorite and hypochlorous
, acid. Hypochlorous acid is an oxidizing agentit has a sanitizing effect on
organic and inorganic contaminants. Disinfection by chlorination is achieved
1 by maintaining a "free residual chlorine" concentration in solution. -'
When treated effluent is released into receiving waters, free residual
chlorine dissipates rapidly (it has a half-life of 1.3 to 5 hours). The ultimate
'fate of chlorine-containing effluent is site specific, and depends on factorsi such
s as the chemical constituents of the receiving waters, their -temperature, the
' dilution ratio and the intensity of sunlight.
Ecological Effects
, Studies on lithium hypochlorite were used to satisfy the data ',.
requirements for chlorine used as an industrial biocide, since both form
hypochlorous acid when dissolved in water.
Lithium hypochlorite is practically non-toxic to birds on a subacute
dietary basis. However, chlorine is very highly toxic to fish and freshwater
'. ' , invertebrates.
' ' '" "'-. .''!''
Ecological Effects Risk Assessment
. ( In receiving waters from facilities using chlorine, if acute, levels of
concern are exceeded, a significant risk to aquatic organisms and endangered
aquatic organisms can be expected. Levels of concern (equaling one-half of
the EC50) are 0.009 ppm for aquatic invertebrates, 0.023 ppm for freshwater
fish, and 0;013 ppm for esloiarine organisms. Levels of concern for endangered
species (equaling one twentieth of the EC50) are 0.85 ppb for aquatic
invertebrates, 2-3 ppb for freshwater fish, and 1.3 ppb for estuarine
invertebrates. .
Uses of chlorine that are not regulated under the NPDES permit
program, including swimming pool, aquaria and indoor use patterns (fruit arid
'.." vegetable rinsing and food processing), should produce only intermittent
discharges of minimal concentration into lakes or streams, resultingin minimal
.environmental exposure. .
Other chlorine uses, including water cooling tower, sewage treatment
plant, and pulp and paper mill uses, are mcluded in the NPDES permit
programs administered by EPA's Office of Water. Effluent discharges
. containing chlorine are regulated under NPDES permits to reduce the impact
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on water bodies. The maximum concentration of chlorine allowed in each
effluent stream is set on a site-specific and use-specific basis, to achieve the
lowest possible concentrations of chlorine in each receiving stream. No '
significant adverse effects to aquatic organisms are anticipated from discharges
of chlorine under the NPDES permitting system.
Additional Data
Required
Product Labeling
Changes Required
Endangered Species
If acute levels of concern are exceeded in receiving waters from facilities
using chlorine, a significant risk to endangered aquatic organisms can be
expected. EPA is working with the U.S.- Fish and Wildlife Service to develop a
program to avoid jeopardizing the continued existence of identified species by
the use of pesticides. When this program goes into effect, endangered species
labeling may be required.
The generic data base for chlorine is substantially complete to
characterize acute risks. For the majority of exposure scenarios, enough data
exists to adequately characterize chronic risks, also. Regarding the drinking"
water treatment use, although the quality of data is sufficient to reregister this
public health use, there is some uncertainty regarding the health effects of
halogenated byproducts that may be present. The Agency will be requiring the
submission of reproductive and developmental studies on
bromidichloromethane, dichloroacetic acid, and dibromoacetic acid. The
Agency also is requiring product-specific data, including product chemistry, as
well as revised Confidential Statements of Formula (CSF) and revised labeling
for reregistration. ,
All end-use products containing chlorine must comply with EPA's
current regulations and labeling requirements. The table containing the specific
labelling requirements is included in the RED document and as a supplement to
this Fact Sheet. It specifies detailed labeling requirements and guidance,
covering the following areas:
Use Directions - The end use label must indicate specific intended uses,
and must provide specific directions for each use. Products must be
labeled for restricted use sites or general use sites, not both. The
standard Precautionary Statements and Statement of Practical Treatment
have been reworded (please see the RED).
Standard Labeling for Chlorine Products - Please see the RED for
exact label language pertaining to:
The Restricted Use Pesticide legend and usage paragraphs;
Statement of Practical Treatment/First Aid;
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Precautionary Statements/Hazards to Humans and Domestic Animals
.-.' (includes Personal Protective Equipment requirements);
Environmental Hazards; ... . .
Chemical and Physical Hazards;
Directions for Use;
N " ' , v t
Spill and Leak Procedures;
Storage and Disposal;
Disposal of Container.
Guidance for Specific Directions for Use - See the RED for guidance
and sample directions, including: - ' '
What specific directions for use should include;
Use directions for swirnrning pool water treatment products;
Directions for treating sewage and waste water;
Directions for control of microbiological slimes in cooling towers or
pulp and paper mill process water systems;
Directions for treatment of municipal water supplies;
.-''-..- * Directions for treating raw fruits and vegetables;
Directions for various methods used for sanitization of hard,
nonporous food contact surfaces;
Directions for treatment of other hard surfaces.
Effluent Discharge Statement - All end-use (or manufacturing use)
products that may be contained in ah effluent discharged to the waters of the
U.S. or municipal sewer systems must bear the following statement:
"Do not use in facilities discharging directly or indirectly to the
, estuarine or marine environment."
To reduce environmental rjsk from chlorinated water discharge and
disposal, product labels must include the statements pertaining to effluent
discharge under the NPDES permitting system (refer to PR Notice 93 -10) and
, disposal under any applicable federal laws after the above statement.
Regulatory AlLCurrently registered pesticide products containing chlorine can be
Conclusion usec^ without causing unreasonable adverse effects to humans or the
environment, in accordance with the revised labeling specified in this RED.
Therefore, all chlorine products and uses are eligible for reregistration.
. '. Chlorine products registered for use hi non-residential swimming pools,
pulp and paper mill processes, and industrial food processing plants and
,. cooling towers are being reclassified as Restricted Use Pesticides due to
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chlorine's extreme acute toxicity plus many associated human poisoning
incidents. These products must bear Restricted Use Pesticide labeling no
sooner than October 1, 2000, and no later than April 1, 2001.
Chlorine products registered for drinking water, sewage and wastewater
treatment uses and residential pool use will be considered unclassified. The
Agency does not support classifying commercial applications of residential
pools as a Restricted Use because few related accidents or incidents have been
reported. Additionally for water treatment, applicators already are trained and
certified by the states to perform these uses.
Products containing chlorine as the sole active ingredient will be
reregistered once the required product-specific data, CSF and revised labeling
are received and accepted by EPA. Products containing other active
ingredients will be reregistered only after the other active ingredients also are
determined to be eligible for reregistration.
For MorG EPA is requesting public comments on the Reregistration Eligibility
Information Decision (RED) document for Chlorine Gas, during a 60-day time period, as
announced in a Notice of Availability published in the Federal Register. To
obtain a copy of the RED document or to submit written comments, please
contact the Pesticide Docket, Information and Record Integrity Branch,
Information Resources Services Division (7502C), Office of Pesticide
Programs (OPP), US EPA, Washington, DC 20460, telephone 703-305-5805.
, Electronic copies of the RED and this fact sheet are available on the ,
internet. See http://www.epa.gov/REDs.
Printed copies of the RED and fact sheet can be obtained from EPA's
National Center for Environmental Publications and Information
(EPA/NCEPI), PO Box 42419, Cincinnati, OH 45242-0419, telephone 513-
489-8190, fax 513.-489-8695.
- Following the comment period, the Chlorine Gas RED document also
will be available from the National Technical Information Service (NTIS),
5285 Port Royal Road, Springfield, VA 22161, telephone 703-605-6000 or
800-553-6847.
For more information about EPA's pesticide reregistration program, the
Chlorine Gas RED, or reregistration of individual products containing chlorine
gas, please contact the Special Review and Reregistration Division (7508W),
OPP, US EPA, Washington, DC 20460, telephone 703-308-8000.
For information about the health effects of pesticides, or for assistance in
recognizing and managing pesticide poisoning symptomsj please contact the
National Pesticides Telecommunications Network (NPTN). Call
toll-free 1 -800-858-7378, between 9:30 am and 7:30 pm Eastern Standard
Time, Monday through Friday.
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