United States
Environmental Protection
Agency
Office of Prevention, Pesticides
And Toxic Substances
(7508W)
EPA-738-F-92-008
September 1992
R.E.D. FACTS
Pesticide
Reregistration
Use Profile
Regulatory
History
Sodium Hydroxide
All pesticides sold or used 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 undue hazards to human health or the environment.
When a pesticide is eligible for reregistration, EPA announces this and
explains why in a Reregistration Eligibility Document, or RED. This fact
sheet summarizes the information in the RED for sodium hydroxide.
Sodium hydroxide is registered for use as a herbicide to control tree
roots in sewer systems; as a fungicide and algicide for use on water-well
casings; and as a disinfectant in various indoor settings. Also known as
caustic soda, this corrosive substance also has many non-pesticidal uses,
particularly in the rayon, film and chemical industries.
Sodium hydroxide first was registered as a pesticide in 1951.
Currently, seven products are registered which contain sodium hydroxide,
most in combination with other pesticide active ingredients. The Food and
Drug Administration (FDA) considers sodium hydroxide generally
recognized as safe (GRAS) for use in food.
Under a memorandum of understanding issued in 1971, FDA
evaluates the dietary risks of sanitizers used on food contact surfaces while
EPA assesses the product chemistry, efficacy and applicator risks. Since
sodium hydroxide is included under this agreement, EPA has deferred to
FDA's assessment of dietary risks in preparing this RED.
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Human Health
Assessment
Environmental
Assessment
Toxicity
Sodium hydroxide is a widely used chemical whose toxicity has been
well known for some time. It is corrosive and irritating to the skin, eyes
and mucous membranes, and has been placed in Toxicity Category I
(indicating the highest degree of toxicity) for acute eye and skin irritation
effects.
A subchronic inhalation study showed bronchial and lung effects in
rats. Chronic carcinogenicity studies using mice and rats showed no cancer
effects. The chemical is not mutagenic. Human poisoning cases indicate
that less than 10 grams taken orally is fatal.
Dietary Exposure
Sodium hydroxide is not used directly on food or feed, but is used on
food contact surfaces and well-head casings. These uses have been
evaluated by FDA under the memorandum of understanding described
earlier, and have been found not to pose unacceptable dietary risks.
Occupational and Residential Exposure
Based on approved product formulation types and application
methods, mixers, loaders and applicators in commercial and institutional
settings may be exposed to sodium hydroxide. However, as long as label
directions and precautions are followed, exposure of eyes and skin should be
minimal.
Human Risk Assessment
Sodium hydroxide is corrosive and irritating to the skin, eyes and
mucous membranes but does not appear to cause chronic health effects.
Dietary exposure to the chemical is minimal and has been cleared by FDA.
The potential for significant eye and skin exposure to mixers, loaders and
applicators in commercial and institutional settings exists. However, if
products are used in accordance with label precautions for eye and skin
protection, worker exposure should be minimal. Therefore, the most
significant human health risks posed by use of sodium hydroxide are
adequately mitigated by product labeling.
Environmental Fate
Sufficient information is available in the public literature on the fate of
sodium hydroxide in the environment. No further environmental fate data
are required for reregistration.
Ecological Effects
One outdoor use of sodium hydroxide, to treat sewage systems, also is
regulated by State agencies through the National Pollution Discharge
Elimination System (NPDES) permit program; therefore, EPA did not
conduct a risk assessment for this use. Current product labeling warns that
sewer treatment effluent containing sodium hydroxide may not be
discharged into lakes, streams, ponds, estuaries, oceans, or public waters
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Additional Data
Required
Product Labeling
Changes Required
without an NPDES permit. The water well casings use of sodium
hydroxide is believed to result in only minimal exposure of birds, mammals
and other terrestrial organisms. Current product labeling helps protect
wildlife from undue exposure to sodium hydroxide.
EPA has waived all generic data requirements for sodium hydroxide
except basic product identity and chemistry information. Generic data on
the composition, manufacturing process and impurities of each technical
source used in registered pesticide products is required for reregistration.
Product-specific data, including product chemistry and efficacy
studies, also are required for reregistration.
The labels of all registered sodium hydroxide products must comply
with EPA's current pesticide labeling requirements.
• In addition, manufacturing- and end-use products registered to
control roots in sanitary sewer lines (except products intended solely for
residential use, which are exempt) must bear the following statement:
"This pesticide is toxic to wildlife. Do not discharge effluent
containing this product into lakes, streams, ponds, estuaries, oceans,
or public waters unless this product is specifically identified and
addressed in an NPDES permit. Do not discharge effluent containing
this product to sewer systems without previously notifying the sewage
plant authority. For guidance contact your State Water Board or
Regional office of the U.S. Environmental Protection Agency."
• For end-use products for use on well-head casings the Agency
requires label statements concerning wildlife toxicity and prohibition against
contamination of water by disposal of equipment, wash water, or rinsate.
• The Agency is requiring the following label statement on all end-
use products to mitigate the potential for irreversible eye tissue damage:
"When using this product, wear eye goggles or safety glasses."
• None of the registered pesticide products containing the active
ingredient sodium hydroxide are likely to cause unreasonable adverse effects
in people or the environment, and all are eligible for reregistration. These
products will be reregistered once the required generic data, product-
specific data and revised labeling are received and accepted by EPA.
• Registered products containing sodium hydroxide as well as other
active ingredients will be reregistered once the other active ingredients also
are determined to be eligible for reregistration.
For More EPA is requesting public comments on the Reregistration Eligibility
Information Document (RED) for sodium hydroxide 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 or to submit written comments, please contact the
Regulatory
Conclusion
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Public Response and Program Resources Branch, Field Operations Division
(7506C), Office of Pesticide Programs (OPP), US EPA, Washington, DC
20460, telephone 703-305-5805.
In the future, the sodium hydroxide RED will be available from the
National Technical Information Service (NTIS), 5285 Port Royal Road,
Springfield, VA 22161, telephone 703-487-4650.
For more information about sodium hydroxide or about EPA's
pesticide reregistration program, please contact the Special Review and
Registration Division (7508W), OPP, US EPA, Washington, DC 20460,
telephone 703-308-8000. For information about reregistration of individual
sodium hydroxide products, please contact the Registration Division
(7505C), OPP, US EPA, Washington, DC 20460, telephone 703-305-7830.
For information about the health effects of pesticides, or for assistance
in recognizing and managing pesticide poisoning symptoms, please contact
the National Pesticides Telecommunications Network (NPTN). Call toll-
free 1-800-858-7378, 24 hours a day, seven days a week, or fax your
inquiry to 806-743-3094.
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