United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508W)
EPA-738-F-96-011
June 1996
R.E.D. FACTS
Pesticide
Reregistration
DIBROMODICYANO-
BUTANE
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 before November 1, 1984, 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 develops
any mitigation measures or regulatory controls needed to effectively reduce
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 explains the basis
for its decision in a Reregi strati on Eligibility Decision (RED) document.
This fact sheet summarizes the information in the RED document for
reregi strati on case 2780, dibromodicyanobutane.
US6 Profile Dibromodicyanobutane (1, 2-dibromo-2, 4-dicyanobutane) is a
microbiocide/microbiostat used to control slime-forming bacteria and fungi
in commercial/industrial water cooling systems (recirculating), oil recovery
-------
Regulatory
History
drilling muds/packer fluids, pulp/paper mill water systems, secondary oil
recovery rejection water, industrial adhesives and coatings,
resin/latex/polymer emulsions, metalworking cutting fluids, paints,
specialty industrial products (including fiber processing fluids, waxes,
polishes and inks), and wet-end additives/industrial processing chemicals.
Formulations include soluble concentrates both liquid and solid, pellets and
tablets. Dibromodicyanobutane is applied by metering pump and chemical
pump. The use practice limitations include NPDES permit restriction.
There are no residential products registered.
Dibromodicyanobutane was first registered as a pesticide in the U.S.
in 1980. Data Call-Ins were issued by the Agency in March, 1987
(Antimicrobial Data Call-In) and during the Phase IV Reregi strati on process
in June of 1991. Currently eight products formulated with
dibromodicyanobutane are registered by the Agency. Indirect food additive
tolerances have been established for dibromodicyanobutane as a
preservative in food grade adhesives (see 21 CFR § 175.105) and as a
slimicide in the manufacture in food grade paper and paperboard at a
maximum level of 0.005% of dry weight fiber (see 21 CFR § 176.300).
These tolerances are under the jurisdiction of the U.S. Food and Drug
Administration and are not directly regulated by EPA.
Human Health
Assessment
Toxicity
In studies using laboratory animals, dibromodicyanobutane generally
has been shown to be slightly to practically non-toxic for acute toxicity and
has been placed in Toxicity Category III. However, it is a severe eye
irritant and a human skin sensitizer. In subchronic studies using
dibromodicyanobutane conducted in several mammalian species, no
unusual compound related effects were observed except for thyroid
follicular cell hyperplasia observed in the high dose group in dogs. This
finding was further studied in a special study conducted at the lowest dose
tested in the dog study (4.8 mg/kg/day). While the thyroid effect was
considered significant by the oral route, dietary exposure to
dibromodicyanobutane is expected to be negligible. Several developmental
toxicity studies showed no compound-related external, visceral or skeletal
abnormalities. Dibromodicyanobutane was positive in one mutagenicity
assay, however, this positive finding was not confirmed in multiple other
mutagenicity studies.
Dietary Exposure
The use of dibromodicyanobutane as an indirect food additive to
adhesives or food grade paper and paperboard is expected to be negligible.
There are no registered uses of dibromodicyanobutane directly on food,
therefore, a dietary exposure and risk assessment are not applicable.
-------
Occupational and Residential Exposure
No toxicological endpoints of concern were determined for short-term
and intermediate term occupational/residential risk, except skin
sensitization and eye irritation. A subchronic dermal toxicity study
indicated that dibromodicyanobutane is not absorbed via the dermal route
because no systemic toxicity was observed following repeated dermal
application.
Human Risk Assessment
No subchronic endpoints of concern were triggered for
dibromodicyanobutane. Its use pattern would not typically result in chronic
exposure, and there are no registered direct food uses, therefore, a dietary
exposure and risk assessment are not applicable.
No toxicological endpoints of concern, except for skin sensitization
and eye irritation from acute exposures, were identified for occupational
exposures. Therefore, an applicator exposure analysis and quantitative risk
assessment are not warranted. To protect occupational handlers
(mixers/loaders/applicators) from potential exposure, appropriate personal
protective equipment (PPE) will be required based on the acute toxicity
category of the end-use product.
Additionally, secondary occupational and residential handler
exposure from treated paint, ink and wax products Are not expected to
pose a significant risk because of the low concentration/dilution factor
associated with these products.
Environmental
Assessment Environmental Fate
Dibromodicyanobutane is expected to be very mobile and non-
persistent in aquatic and soil environments. Dissipation is expected to be
controlled by rapid alkaline-catalyzed hydrolysis and microbially-mediated
degradation. However, there is little information on the identity and
environmental behavior of degradates.
Ecological Effects
Dibromodicyanobutane is slightly toxic to avian species on an acute
oral and subacute dietary basis. It is also moderately toxic to fish and
aquatic invertebrates on an acute basis. Because the fish studies conducted
in 1975 provided only supplemental information and were not upgradeable
to the current standards, a new freshwater acute toxicity fish study in
bluegill sunfish has been required.
-------
Additional Data
Required
Product Labeling
Changes
Required
Ecological Effects Risk Assessment
Only a limited set of ecotoxicology and environmental fate studies for
microbiocides such as dibromodicyanobutane are required. The
information available on ecological effects of dibromodicyanobutane
indicates slight toxicity to birds on an acute oral and subacute dietary basis
and moderate toxicity to aquatic invertebrates and estuarine/marine animals.
The chemical is expected to degrade rapidly in aquatic environments.
While the hazard to aquatic organisms has been characterized to a limited
extent, a quantitative risk assessment has not been conducted. The Agency
currently requires that labels for dibromodicyanobutane products specify
that discharges to aquatic environments must comply with NPDES
permitting requirements.
The generic data base supporting the reregi strati on of
dibromodicyanobutane for the above eligible uses has been reviewed and
determined to be substantially complete. No new additional studies on
dibromodicyanobutane are being required at this time. However, additional
information about the identity of the hydrolysis degradates has been required
because hydrolysis appears to be the major route of degradation.
The Agency is also requiring product-specific data including product
chemistry and acute toxicity studies, revised Confidential Statements of Formula,
and revised labeling for reregi strati on for product reregi strati on.
All dibromodicyanobutane end-use products must comply with EPA's
current pesticide product labeling requirements. The Agency believes it is
prudent to require additional use precautions to afford product users increased
protection from unnecessary exposure to dibromodicyanobutane. For similar
reasons the Agency is retaining current worker and environmental restrictions and
precautions for risk reduction as specified below and in Section V of the
dibromodicyanobutane RED.
To remain in compliance with FIFRA, manufacturing use product (MP)
labeling must be revised to comply with all current EPA regulations, PR Notices
and applicable policies. The MP labeling must bear the following statement
under Directions for Use:
-------
"Only for formulation into a microbiocide/microbiostat/ bacteriostat
for use as an additive for industrial adhesives, emulsions, resin/latex
and polymer systems, metalworking cutting fluids, secondary oil
recovery injection water, drilling muds, wet-end additives/industrial
processing chemicals, specialty industrial products (includes fiber
processing fluids, waxes, polishes, and inks), and latex and oil paints
(varnish applied film).
A MP registrant may, at his/her discretion, add one of the following statements to
a MP label under "Directions for Use" to permit the reformulation of the product
for a specific use or all additional uses supported by a formulator or user group:
(a) "This product may be used to formulate products for specific
use(s) not listed on the MP label if the formulator, user group,
or grower has complied with U.S. EPA submission requirements
regarding support of such use(s)."
(b) "This product may be used to formulate products for any
additional use(s) not listed on the MP label if the formulator,
user group, or grower has complied with U.S. EPA submission
requirements regarding support of such use(s)."
Effluent Discharge Labeling Statements
"Do not use in facilities discharging directly or indirectly to the
estuarine or marine environment."
To reduce environmental risk from dibromodicyanobutane 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.
Personal Protective Equipment for Occupational Uses
The minimum handler labeling requirements for occupational uses of
dibromodicyanobutane end-use products is:
"Mixers, loaders, applicators and other handlers must wear:
— Long-sleeve shirt and long pants,
— Shoes plus socks."
-------
If the end-use product is classified as toxicity category I or II for eye
irritation potential, add:
— "Protective eyewear."
If the end-use product is classified as toxicity category I or II for skin
irritation potential, add:
— "Chemical-resistant apron, and
— Chemical-resistant gloves*."
If the end-use product is classified as toxicity category I or II for acute
inhalation toxicity, a respirator requirement must be added. The type of
respirator must be specified in the statement and is based on the acute toxicity
category and the vapor pressure.
*For the glove statement, use the statement established for dibromodicyanobutane
through the instructions in Supplement Three of PR Notice 93-7. However, the
corrosiveness and penetration of dibromodicyanobutane must be considered and
appropriate chemical-resistant materials must be listed.
Placement in Labeling
The personal protective equipment requirements must be placed on the end-
use product labeling in the location specified in PR Notice 93-7, and the format
and language of the PPE requirements must be the same as is specified in PR
Notice 93-7.
The agency is requiring the following labeling statements to be located on
all end-use products containing dibromodicyanobutane that are intended
primarily for occupational use.
Application Restrictions
"Do not use this product in a way that will contact workers or other
persons."
User Safety Requirements
Registrant: add the following statements only if gloves or protective
eyewear are required PPE on the end-use product:
-------
"Follow manufacturer's instructions for cleaning/maintaining PPE. If
no such instructions for washables, use detergent and hot water. Keep
and wash PPE separately from other laundry."
User Safety 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."
Registrant: add the following statements only if gloves are required
PPE on the end-use product:
- "Users should remove PPE immediately after handling this
product. Wash the outside of gloves before removing. As soon
as possible wash thoroughly."
Skin Sensitizer Statement
"This product may cause skin sensitization reactions in some people."
Clarification of Oil Drilling Mud Use
To clarify the intent of the oil recovery drilling muds/packer fluids use (as
an aquatic or terrestrial non-food use pattern), the following statement must be
added to the labels for terrestrial non-food oil/gas drilling muds and packer fluids:
"For use in terrestrial wells only"
And the following statement must be added to the precautionary labeling:
"Do not apply in marine and/or estuarine oil fields."
The following statement must be added to the labels for aquatic non-food
industrial oil/gas drilling muds and packer fluids:
"For use in offshore wells only."
-------
For use in both terrestrial and offshore oil/gas drilling muds and packer
fluids, the following statement must be added:
"This product may be used for terrestrial and off-shore oil/gas drilling
muds and packer fluids."
Additional Directions for Use
Registrants must specify on labeling the complete directions for use for
each use pattern: site of application, type of application, timing of application,
equipment used for application, and the rate of application (dosage)."
Regulatory
Conclusion
The use of currently registered products containing
dibromodicyanobutane 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.
Dibromodicyanobutane 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 dibromodicyanobutane 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.
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 dibromodicyanobutane 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 dibromodicyanobutane RED, or reregi strati on of individual products
-------
containing dibromodicyanobutane, 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.
-------
10
------- |