United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508W)
EPA-738-F-95-023
May 1996
R.E.D. FACTS
Dimethoxane
Pesticide
Reregi strati on
Use Profile
Regulatory
History
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 reregi strati on, 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 reregi strati on, EPA announces this and
explains why in a Reregi strati on Eligibility Decision (RED) document. This
fact sheet summarizes the information in the RED document for reregi strati on
case 3064, dimethoxane.
Dimethoxane is a fungicide, microbiocide/microbiostat used to preserve
emulsions and water-based industrial processes.
This biocidal product is used in the manufacturing process to control
spoilage microorganisms encountered in industrial emulsions and specialty
industrial products, textiles, jet fuels, adhesives and leather processing liquors.
Dimethoxane is a preservative used in industrial settings only.
Dimethoxane is formulated as a liquid soluble concentrate. It is applied
by the open-pouring method and by closed delivery system.
Use practice limitations preclude combining dimethoxane with systems
containing amides or amines, because dimethoxane products may cause
discoloration in these systems.
Dimethoxane was first registered as a pesticide in the U.S. in 1962. In
1987, an antimicrobial Data Call-In (DCI) required the submission of a variety
of subchronic and chronic toxicology and occupational exposure studies. A
Phase IV DCI was issued in 1992, which required product chemistry,
ecological effects and environmental fate data. There is currently one product
registered for the incorporation into emulsion paints, emulsion inks, jet fuels,
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leather processing liquors, coatings, specialty industrial products, and use in
textile and adhesive production.
Human Health
Assessment
Toxicity
In studies using laboratory animals, dimethoxane generally has been
shown to be of minor acute toxicity. It is slightly toxic by the oral, dermal and
inhalation routes and has been placed in Toxicity Category III (the second
lowest of four categories) for these effects. It was found to cause mild eye
irritation and was placed in toxicity category III for eye irritation.
Dimethoxane caused only slight irritation in the dermal irritation study and was
placed in toxicity category IV (the lowest of four categories). However,
dimethoxane is a strong skin sensitizer.
In a subchronic toxicity test using rats, dermal irritation was observed in
the highest dose levels. Other effects found at the highest dose levels include
reduced body weight gains in males and increased incidence of liver changes in
females.
The National Toxicology Program (NTP) conducted carcinogenicity
studies on dimethoxane. The results indicated an increased incidence of
tumors of the forestomach in the high dose male mice. NTP therefore
concluded that there was equivocal evidence of carcinogenicity for male mice.
However, there was no evidence of dimethoxane carcinogenicity in female
mice or in male or female rats. The Agency has completed a qualitative
assessment of exposure and cancer risk based on the NTP studies and
conservative occupational exposure assumptions and concluded that there is no
significant human cancer risk from the registered uses of dimethoxane.
In a developmental toxicity study using rats, dimethoxane produced
some maternal toxicity effects at the highest dose level. Dimethoxane is not
mutagenic.
Based on the toxicology data base for dimethoxane, neither short term (1
to 7 days) nor intermediate term (1 week to several months) toxicological
endpoints for occupational/residential risk assessment were identified due to
low toxicity and minor effects.
Dietary Exposure
There are no food uses of dimethoxane, therefore, people will not be
exposed to residues through the diet.
Occupational and Residential Exposure
Based on current use patterns, handlers (mixers, loaders, and applicators)
may be exposed to dimethoxane during and after application of the pesticide
product in industrial settings. For those handlers using open pouring
application methods, there is a potential for respiratory, dermal and eye
exposure. Potential for exposure to handlers using closed delivery systems is
expected to be significantly reduced. Due to the chemical properties of
dimethoxane, including low vapor pressure, post-application inhalation
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Environmental
Assessment
exposure to workers is expected to be minimal. Also, exposure to individuals
who use dimethoxane products (such as paints) is possible; however, the
amount of dimethoxane contained in these products is so small that resulting
effects are expected to be negligible.
There are no residential uses of dimethoxane, so no exposure to the
general public is expected.
Human Risk Assessment
Dimethoxane generally is of low acute toxicity. Based on a review of the
data, the Agency has determined that there is no significant cancer risk from
the registered uses of dimethoxane.
There are no food uses of dimethoxane, so people will not be exposed to
the chemical through their diet. Dimethoxane is only used in industrial
settings, so there is no exposure anticipated for the general public.
Dimethoxane handlers may be exposed to the chemical during open
pouring application methods. Use of closed systems should significantly
reduce handlers exposure. Based on dimethoxane's low toxicity and use
patterns, risks to applicators are not believed to be significant.
All uses of dimethoxane are outside of the scope of the Agency's Worker
Protection Standard and there are no special toxicological concerns about
dimethoxane that warrant the establishment of active ingredient based personal
protective equipment (PPE).
Environmental Fate
The major route of degradation of dimethoxane is abiotic hydrolysis.
Dimethoxane is highly unstable in water over 50% is hydrolyzed in two
hours It reacts with water to form acetic acid and dioxinol; the latter breaks
down into acetaldehyde and aldol in 14 hours.
Ecological Effects
There is no direct use or application of dimethoxane outdoors. Any
significant hazard would presumably result from a transportation accident,
spill, or purposeful discharge into the environment. Any such environmental
contamination would have minimal impact on avian and aquatic species, due to
the low toxicity of dimethoxane to these species.
Dimethoxane was found to be slightly toxic to practically nontoxic to
avian species on an acute oral and subacute dietary basis. Results from the
acute freshwater fish studies indicated that dimethoxane is slightly toxic to both
cold and warm water fish. The study submitted to the Agency indicating the
effects of dimethoxane on freshwater invertebrates did not fulfill the guideline
requirement. However, it did provide adequate information indicating that
dimethoxane is only slightly toxic to freshwater invertebrates. This study is not
required to be resubmitted due to the low level of toxicity to freshwater
invertebrates and due to the fact that dimethoxane is only registered for indoor
uses.
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Ecological Effects Risk Assessment
Risk assessments are not conducted on nontarget organisms for
microbiocides having indoor non-food uses without effluents. The preservative
uses of dimethoxane in emulsion paints, emulsion inks, jet fuels, leather
processing liquors, coatings, specialty industrial products, textiles and
adhesives are expected to result in minimal to no exposure to the environment.
The jet fuel use of dimethoxane, however, is associated with periodic releases
into the environment based on purging of jet fuel storage tanks of "water
bottoms" (small areas of condensation on the bottom of the tank, which if not
removed could cause leakage from rust formation weakening the tank wall).
The hazard to wildlife and aquatic organisms from these registered indoor non-
food uses is expected to be minimal because dimethoxane is not more than
slightly toxic to fish and aquatic invertebrates, and is slightly to practically
nontoxic to birds.
Endangered Species
Limitations in the use of dimethoxane may be required to protect
endangered and threatened species, but these limitations have not been defined
and may be formulation specific. The jet fuel use of dimethoxane is associated
with periodic releases into the environment based on purging of jet fuel storage
tanks. The hazard to wildlife and aquatic organisms from this use is expected
to be minimal because dimethoxane is not more than slightly toxic to fish and
aquatic invertebrates, and birds. The Endangered Species Protection Program
is expected to become final in the near future, at which time registrants will be
informed if any required label modifications are necessary. Such modifications
would most likely consist of the generic label statement referring pesticide
users to use limitations contained in county Bulletins.
Additional Data The Agency is requiring product-specific data including product
chemistry and acute toxicity studies, revised Confidential Statements of
Formula (CSFs), and revised labeling for reregi strati on.
Product Labeling
Changes Required
All dimethoxane end-use products must comply with EPA's current
pesticide product labeling requirements, and with the following. For a
comprehensive list of labeling requirements, please see the dimethoxane RED
document.
The Agency is requiring that the following labeling statements be
included on dimethoxane end-use products as appropriate, given the acute
toxicity and use patterns of each product.
Handler (Mixer, Loader, Applicator, Etc.) Personal Protective
Equipment (PPE): The PPE for pesticide handlers will be based on the acute
toxicity of the end-use product.
Application Restrictions:
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"Do not apply this product in an way that will contact workers or other
persons. Only protected handlers may be in the area during application."
Engineering Controls:
"When handlers use closed metering systems, the handler requirements
may be reduced or modified to long-sleeved shirt, long pants, shoes and
socks."
Use Safety Requirements:
"Follow manufacturer's instructions for cleaning/maintaining PPE. If
no such instructions for washing, use detergent and hot water. Keep and wash
PPE separately from other laundry."
User Safely Recommendations:
"Users should wash hands before eating, drinking, chewing gum, using
tobacco, or using the toilet."
"Users should remove clothing immediately if pesticide gets inside. Then
wash thoroughly and put on clean clothing."
"Users should remove PPE immediately after handling this product. Wash
the outside of gloves before removing. As soon as possible, wash thoroughly and
change into clean clothing."
Skin Sensitization Statement:
"This product may cause skin sensitization reaction in some people."
Regulatory
Conclusion
For More
Information
The use of currently registered products containing dimethoxane in
accordance with approved labeling will not pose unreasonable risks or adverse
effects to humans or the environment. Therefore, all uses of these products are
eligible for reregi strati on.
Dimethoxane products will be reregistered once the required product-
specific data, revised Confidential Statements of Formula, and revised labeling
are received and accepted by EPA.
EPA is requesting public comments on the Reregi strati on Eligibility
Decision (RED) document for dimethoxane 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, Public Response and Program Resources
Branch, Field Operations Division (7506C), Office of Pesticide Programs
(OPP), US EPA, Washington, DC 20460, telephone 703-305-5805.
Electronic copies of the RED and this fact sheet can be downloaded
from the Pesticide Special Review and Reregi strati on Information System at
703-308-7224. They also are available on the Internet on EPA's gopher
server, GOPHER.EPA.GOV, or using ftp on FTP.EPA.GOV, or using WWW
(World Wide Web) on WWW.EPA.GOV.
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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 dimethoxane RED document also
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 EPA's pesticide reregi strati on program, the
dimethoxane RED, or reregi strati on of individual products containing
dimethoxane, please contact the Special Review and Reregi strati on 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 symptoms, 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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