United States               Prevention, Pesticides          EPA-738-F-95-006A
                  Environmental Protection        And Toxic Substances          June 1995
                  Agency	(7508W)	

                  R.E.D.   FACTS
      PGStJCJdG       All pesticides sold or distributed in the United States must be
R0TGClistration  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
                  appropriate 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 2645, terbuthylazine.

    USG ProfilG       Terbuthylazine is an algicide, microbicide and microbiostat used to
                  control slime-forming algae, fungi, and bacteria. It is registered for use in
                  commercial and industrial water cooling systems, and in residential and
                  commercial ornamental ponds, fountains and aquaria. Terbuthylazine is
                  formulated as a soluble concentrate/liquid, and is applied as a continuous
                  feed or intermittent slug treatment, using either open pouring or closed
                  system methods.
                       Use practice limitations  currently require users to preclean systems
                  before applying the pesticide,  and prohibit:  discharge of effluent containing
                  the pesticide into sewage systems without notifying the sewage treatment
                  plant authority; discharging effluent containing the pesticide into lakes,
                  streams, ponds, estuaries,  oceans, or public waters;  use where treated
                  water will come into contact with lawns, trees, shrubs, or other desirable
                  plants since injury may result; and using water from treated systems for
                  irrigation or spraying of agricultural crops, lawns, or  ornamental plants, or
                  for watering cattle, goats,  hogs, horses, poultry or sheep, or for human

Human Health
      Initially, in 1975, terbuthylazine was registered as a herbicide in the
U.S., and several tolerances for residues in food and feed were established.
However, since no end-use products were registered for these uses, the
tolerances were revoked in 1992.  Meanwhile, in 1986, algicide and
microbicide/microbistat end-use products were registered. EPA has issued
four Data Call-In notices for terbuthylazine.  Five products currently are

      Terbuthylazine generally is of relatively low acute toxicity.  It has
been placed in Toxicity Category III, the second-to-lowest of four
categories,  for acute oral, dermal, and inhalation effects. Terbuthylazine is
mildly to moderately irritating to the eyes, and slightly irritating to the skin,
and has also been placed in Toxicity Category III for these effects.  It is not
a skin sensitizer.
      In a subchronic toxicity study using rats, terbuthylazine caused
decreased body weight gain as well as decreased thymic,  kidney and liver
weights.  A study using rabbits resulted  in decreased body weight gain and
food consumption, and mortality in one  female.  In another rabbit study, all
the animals developed difficulty in breathing, piloerection, sedation,  curved
body posture, dermal irritation, and decreased body weight gain and food
      In chronic toxicity and carcinogenicity studies using mice and rats,
decreases in body weight gain and food  consumption were observed. Two
studies using mice and rats caused no increase in tumors. However, a third
study using rats caused an increased incidence of testicular tumors in males
and mammary gland carcinomas in females, but only at a dose at which
excessive systemic toxicity also was observed. Based on this study, EPA's
Carcinogenicity Peer Review Committee has classified terbuthylazine as a
Group D carcinogen—one for which there is inadequate evidence to
determine carcinogenicity in humans.
      Terbuthylazine caused no signs of  developmental toxicity in a study
using rabbits.  However, in a study using rats, maternal toxicity was
observed as reduced body weight gain and food intake, and developmental
toxicity was observed in the  litter as a lack of bone formation in one toe.
Reproductive toxicity data is not available, but will be  required if food uses
are proposed in the future. Available studies  indicate that terbuthylazine is
not mutagenic.
Dietary Exposure
      Dietary exposure to terbuthylazine is not expected since no products
with food uses currently are registered.

                     Occupational and Residential Exposure
                           Workers may be exposed to terbuthylazine during applications in
                     commercial/industrial settings.  In addition, workers may be exposed to this
                     pesticide after application, while cleaning or maintaining water cooling
                     towers, and other people (including children) may be exposed while wading
                     or swimming in treated  ornamental ponds or fountains. Because of the use
                     patterns and dilution factors involved, however, EPA believes that post-
                     application exposure to terbuthylazine in both commercial and residential
                     settings is minimal.
                           Since terbuthylazine is associated with developmental toxicity effects,
                     EPA assessed the risks to workers who apply this pesticide using the open
                     pouring method compared to the metering pump method. The Agency
                     found that the risk to commercial applicators who routinely use the open
                     pouring method is unacceptable. Margins of Exposure (MOEs) for these
                     workers are very  low for both typical and high use rates, both short- and
                     intermediate-term.  However, MOEs for workers using closed pump
                     systems are well above 100, the margin generally considered acceptable.
                     MOEs for workers using both open pouring and metering pump methods in
                     residential  settings also are acceptably high.
                           EPA  therefore is prohibiting commercial applications of terbuthylazine
                     using the open pouring method, and is requiring use of closed systems along
                     with certain personal protective equipment (PPE), to reduce exposure and
                     risk to acceptable levels for all commercial uses.
                     Human Risk Assessment
                           Terbuthylazine is of relatively low acute toxicity, and is classified as a
                     Group D carcinogen because there is inadequate evidence to determine its
                     carcinogenicity in humans.  However, it is associated with developmental
                     toxicity in a study using rats.
                           Terbuthylazine has no food-related uses at present so dietary exposure
                     is not of concern.  However, workers are exposed while applying this
                     pesticide in commercial/industrial and residential settings, using open
                     pouring and closed system methods.  EPA has found that the risk  to
                     commercial/industrial workers using  open pouring methods is unacceptable.
                     The Agency is prohibiting open pouring methods for commercial/industrial
                     uses of terbuthylazine, and  requiring  use of closed systems with PPE in
                     commercial/industrial settings.

Environmental   Environmental Fate
   AsSGSSITIGnt         Terbuthylazine is stable to hydrolysis,  and to aqueous photolysis. It
                     degrades very slowly under aerobic aquatic conditions, and will persist
                     under most aquatic conditions.

 Risk Mitigation
Additional Data
Ecological Effects
      Terbuthylazine is practically nontoxic to birds on an acute and
subacute dietary basis. However, it is moderately toxic to both cold and
warm water fish, slightly toxic to aquatic invertebrates, and highly toxic to
estuarine/marine invertebrates from acute exposures.  Terbuthylazine is
expected to be phytotoxic to aquatic plants because it belongs to the triazine
family (which includes many herbicides), is released to waterways, and
dissipates slowly in the environment.
Ecological Effects Risk Assessment
      No significant risks to birds or mammals are expected from use of
terbuthylazine. Although terbuthylazine is  moderately toxic to fish and
slightly toxic to freshwater  invertebrates, these species are not expected to
be at risk under  typical use and exposure scenarios.  In high exposure
situations, however, levels of concern for high risk, restricted use, and
endangered species are met or exceeded. Because  its use patterns are not
associated with estuarine or marine environments,  significant risk to
estuarine/marine invertebrates is not expected.  Phytotoxicity to aquatic
plants is anticipated, and EPA has required relevant studies as confirmatory

      EPA is requiring the following risk mitigation measures for
terbuthylazine, as discussed earlier:
°     To reduce  risks to commercial/industrial applicators, EPA will
prohibit open pouring methods and require that only closed system methods
of application, with specified PPE, be used for commercial application of
°     To adequately mitigate potential risks to fish, freshwater invertebrates,
and aquatic plants from release of effluent to waterways:
      •  EPA will coordinate regulatory oversight of terbuthylazine under
      FIFRA,  the federal pesticide law administered by the Agency's Office
      of Pesticide Programs,  and the National Pollutant Discharge
      Elimination System (NPDES) administered by the Office of Water in
      conjunction with the states.
      •  EPA will require compliance with the Endangered Species
      Protection Program when it goes into effect.

      The generic database supporting terbuthylazine is substantially
complete. Confirmatory data measuring the toxicity of this pesticide to
aquatic plants were recently required of registrants, and must be  submitted
to EPA by January 1996. The Agency also is requiring product-specific
data including product chemistry and acute toxicity studies, revised
Confidential Statements of Formula (CSFs), and revised labeling for

 Product LabGling         All terbuthylazine end-use products must comply with EPA's current
            ChanQGS   pesticide product labeling requirements,  and with the following:
Red UJ r0d               Effluent Discharge Labeling Statements
                                All end-use products that  may be contained in an effluent discharged
                          to the waters of the U.S. or municipal sewer systems must bear the effluent
                          discharge labeling statements described in PR Notice 93-10.
                          Other Labeling Requirements
                                Except where indicated otherwise,  the following statements must
                          appear on all end-use products containing terbuthylazine that are intended
                          primarily for industrial use:
                                Application Restrictions:
                          For products intended for industrial use:
                                "Open pouring of this product is prohibited."
                                "Mixing, loading, and application  must be with a closed system (one
                                that prevents the chemical from contacting handlers or other persons)
                                and during handling of the chemical personal protective equipment
                                must be worn.  Personal protective equipment includes a long-sleeved
                                shirt, long pants, shoes, socks, and chemical-resistant gloves. A
                                chemical-resistant apron must be immediately available during loading
                                and application and must  be worn  in case of a leak, spill, or other
                                exposure to the concentrate. "
                          For products intended for homeowner use:
                                "Persons that mix, load, or apply this product must wear a long-
                                sleeved shirt, long pants, shoes, socks, and chemical-resistant gloves. "
                                User Safety Requirements:
                                "Follow manufacturer's instructions for cleaning/maintaining Personal
                                Protective Equipment. If no such  instructions for washables exist,  use
                                detergent and hot water.  Keep and wash personal protective
                                equipment 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."
                                "Users should remove personal protective equipment immediately
                                after handling this product.  Wash  the outside of gloves before
                                removing. As  soon as possible, wash thoroughly and change into
                                clean clothing."
                                Currently registered pesticide products containing the active ingredient
         Conclusion   terbuthylazine, labeled and used as specified in the RED document, will not
                          pose unreasonable risks or adverse effects to humans or the environment.

                 Therefore, all uses of these products are eligible for reregistration.
                 Terbuthylazine products will be reregistered once the required product
                 specific data, revised Confidential Statements of Formula, and revised
                 labeling are received and accepted by EPA.

   For MOTG         EPA is requesting public comments on the Reregistration Eligibility
Information   Decision (RED) document for terbuthylazine 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
                       Electronic copies of the RED and this fact sheet can be downloaded
                 from the Pesticide Special Review and Reregistration  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 terbuthylazine RED document also
                 will be available from the National Technical Information Service (NTIS),
                 5285 Port Royal Road, Springfield, VA 22161, telephone         703-487-
                       For more information about EPA's pesticide reregistration program,
                 the terbuthylazine RED, or reregistration of individual products containing
                 terbuthylazine, please contact the Special Review and Reregistration
                 Division (7508W), OPP, US EPA, Washington, DC 20460,  telephone
                       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 8:00 am and 6:00 pm  Central Time, Monday
                 through Friday.