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Pesticide Reregistration

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 its
decision and explains why in a Reregistration Eligibility Document, or
RED.  This fact sheet summarizes the information in the RED for 10, 10'-
Oxybisphenoxarsine (OBPA).

Use Profile

OBPA is a bacteriostat, disinfectant (bacteriocide/germicide) and fungicide.  
It is registered to prevent the growth of microorganisms in plastics which are 
fabricated into shower curtains, floor coverings, wall coverings, coated 
fabrics, marine upholstery, automotive vinyl trim, vinyl molding, tarpaulins, 
awnings, gaskets, weather stripping, caulking, ditch liners and swimming pool 
liners.  OBPA also is used as a preservative in adhesives, coatings and 
specialty products, in paper and paper and plastic products, in textiles, 
fibers and cordage, in carpets, and in othcr pesticides.

OBPA is formulated as an emulsifiable concentrate, pelleted/tableted, soluble 
concentrate/liquid and ready-to-use liquid.  The concentration varies from 1 
to 5 percent, based on the total weight of formulation.

Regulatory History

OBPA was initially registered as a pesticide in the United States in 1965.  
EPA issued a Registration Standard for OBPA in October 1981 (N-IlS PB82-
172271).  The Registration Standard required additional product chemistry 
data, a hydrolysis study and an activated sludge metabolism study, which was 
later waived. In September 1991, EPA issued a Data Call-In (DCI) requinng 
product chemistry data and a repeat of the hydrolysis study (which was later 

EPA has now completed its rcview of the OBPA data base, including the data 
submitted in response to the 1991 DCI.

Human Health Assessment

OBPA shows a high degree of acute toxicity when administered orally and to the 
skin and eyes.  It has been placed in Toxicity Category I indicating the 
highest degree of acute toxicity for these effects.

In subacute feeding studies using rats, animals fed the highest dose levels 
had retarded growth, liver effects and an accumulation of arsenic in the liver 
and kidneys.  In a subacute inhalation study rats and guinea pigs sacrificed 
48 hours after their last exposure to OBPA had mild to moderate effects and 
the rats had liver effects.  Animals kept four months longer with no further 
exposure showed no effects of OBPA.

OBPA does not appear to cause developmental or reproductive toxicity, and 
shaws no mutagenic activity.  Metabolism studies show that arsenic accumulates 
in the liver and kidneys as a result of exposure to OBPA, however this arsenic 
is cleared from the body after two weeks.

Dietary Exposure

OBPA is not registered for use on food, feed or processed commodities.  
Therefore, dietary exposure or risk is not expected.

Occupational and Residential Exposure

Although occupational and residential exposure to OBPA occurs, such exposure 
is indirect and/or extremely low level. Dilect occupational exposure during 
production of pesticide or plastic products containing OBPA is mitigated by 
the use of closed systems and appropriate protective gloves and eyewear.  
Indirect residential and other human exposure to OBPA in treated plastics is 
low because only a small percent of OBPA is added to these products, and only 
small amounts of OBPA are released, very slowly.

Human Risk Assessment

OBPA does not pose human dietary risks since no food-related uses are 
registered and dietary aposure is not anticipated.

The potential for occupational cxposure to OBPA is minimal provided that OBPA 
is used in a closed system and that appropriate Personal Protective Equipment 
(PPE) is worn.  Residential exposure to OBPA is indirect and low level.  No 
additional uses are proposed that would significantly increase human exposux 
to OBPA.  Therefore, the potential human risks from exposure to OBPA 
pesticides are likely to be minimal.

Environmental Assessment 
Environmental Fate

No further environmental fate data are needed because of the very limited 
environmental exposure expected from current uses of OBPA.  The Registration 
Standard required an activated sludge study, which was later waived, and a 
hydrolysis study.  The hydrolysis study was found deficient, but the Agency 
later determined that an additional hydrolysis study was not needed based on 
the fact that OBPA-treated materials will not result in significant levels of 
residues being released into the environment.  An extractability study on pool 
liners and vinyl baby pants showed that leaching would not result in residues 
that exceed the 50 ppb maximum limit established for arsenic in drinking 

Ecological Effects

Studies usually required to determine effects on birds, fish and other 
nontarget organisms are waived because of OBPA's indoor, industrial use 
pattern.  Avian and aquatic toxicity information is needed only to assess the 
need for precautionary label statements.

Since OBPA is highly corrosive, it would be very highly toxic to birds.  
Existing acute oral rat studies confirm that OBPA is highly toxic to 
terrestrial organisms.

Aquatic studies show that OBPA is very highly toxic to both freshwater and 
marine fish, and to freshwater aquatic and marine invertebrates, on an acute 

Ecological Effects Risk Assessment

OBPA is an indoor, non-food, industrial use pesticide which is incorporated 
into plastics, textiles, adhesives, etc.  The Agency does not conduct risk 
assessments for nontarget organisms for indoor uses without effluent.  Should 
residues of OBPA in effluent ever exceed 1.75 ppb, aquatic organisms would be 
acutely at risk.

Additional Data Required

EPA is requiring product-specific data, including product chemistry and acute 
toxicity studies, as well as rcvised Confidential Statements of Formula and 
reviscd labeling for reregistration of pesticide products containing OBPA.

Product Labeling Changes Required

The labels of all registered pesticide products containing OBPA must comply 
with EPA's current pesticide labeling requirements.  End-use and manufactunng 
use products also must bear the following label statement in the Environmental 
Hazards section:

This pesticide is toxic to fish, aquatic invertebrates, birds, and mammals.  
Do not discharge effluent containing this product into lakes, streams, ponds, 
estuaries, oceans, or other waters unless in accordance with the requirements 
of a National Pollutant Discharge Elimination System (NPDES) pennit and thc 
permitting authority has been notified in writing prior to discharge.  Do not 
discharge effluent containing this product into sewer systems without 
previously notifying the local sewaage treatment platn authority.  For 
guidance contact your state Water Board or Regional Office of EPA

In addition, labels must consistently reflect any potential eye and skin  
hazard (Danger, Warning or Caution Signal Words) and recommend appropriate 
protective equipment (protective eyeware tgoggles or face shield], waterproof 
glaves, long sleeved shirs and long-legged pans, shoes and socks).

Regulatory Conclusion

The use of currently registered pesticide producs containing OBPA in 
accordance with approved labeling will not pose unreasonable risks or adverse 
effecs to humans or the ermironment.  Therefore. all uses of these products 
are eligible for reregistration.

These OBPA products will be reregistered once the required product-specific 
data, revised Confidential Statements of Formula and revised labeling are 
received and accepted by EPA.  Products which contain other active ingredients 
in addition to OBPA will be eligible for reregistration only when all of their 
other active ingrediens also are determined to be eligible.

For More Information

EPA is requesting public comments on the Reregistration Eligibility
Document (RED) for OBPA 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 Pesticide Docket, Public 
Response and Program Resources Branch, Field Operations Division (H-7506C), 
Office of Pesticide Programs (OPP), US EPA, Washington, DC  20460, telephone 

Following the comment period, the OBPA 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 OBPA or about EPA's pesticide reregistration 
program, please contact the Special Review and Reregistration Division (H-
7508W), OPP, US EPA, Washington, DC  20460, telephone 703-308-8000.  For 
information about reregistration of individual products containing OBPA, 
please contact Product Manager - Cynthia Giles-Parker, Registration Division 
(H-7505C), OPP, US EPA, Washington, DC  20460, telephone 703-305-5540.

For information about the health effects of pesticidcs, or for assistance in 
recognizing and managing pesticide poisoning symptoms, please contact the 
National Pesticides Telecommunications Network (NPIN). Call toll-free 1-800-
858-7378, between 8:00 am and 6:00 pm Central Tlme, Monday through Friday.