UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON , D
.C
. 20460 

## JUN 15 2DG

l\1EMORANDUM OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION



### SUBJECT: BEAD Chemical Profile for Registration Review : Diphacinone (067701) and Diphacinone, sodium salt (067705) 

### FROM: Colwell Cook, Biologist

## C~ Biological Analysis Branch



### THRU:

TO: Cynthia Doucoure, Environmental Protection Specialist Science Information and Analysis Branch Elizabeth Hill, Economist Economic Analysis Branch Biological and Economic Analysis Division (7 Amet Jones, Chief Biological Analysis Branc -) Diann Sims, Chief

# (~**~~** Science Information and Analysis Branch

Rus sell Wasem, Chemical Review Manager Risk Management and Implementation Branch I Pesticide Re-evaluation Division (7508P) 

### Product Review Panel date: May 27, 2015

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## c.~SUMMARY Diphacinone was registered in 1960 and diphacinone, sodium salt was registered in 1962 as vertebrate control agents. Diphacinone is an indandione and considered a first generation anticoagulant rodenticide. Based on available proprietary data, diphacinone is reportedly used by consumers and Pest Control Operators (PCOs) in very small quantities (55-200 lbs a.i.).
INTRODUCTION The purpose ofthis document is to convey usage information and a broad overview of the pest management roles of pesticides that are beginning to undergo registration review. The anticipated audience consists of the team ofEPA staff current!y evaluating the registration status of diphacinone and diphacinone, sodium salt, and eventually the general public
. This document builds upon the data BEAD provides in the Label Use Information System (LUIS) reports. The document is based on information and data available to BEAD as of April 2015
HISTORY OF BEAD ASSESSMENTS FOR DIPHACINONE BEAD conducted an analysis ofrodenticide bait use in 2006 (Chiri, 2006) which examined nine rodenticide products, including diphacinone. Diphacinone is considered a first-generation anticoagulant for use against commensal rats and mice and other rodents
. This analysis concluded that rodenticides are necessary for managing rodents, which are a significant public health risk and are capable of causing significant economic damage and that rodenticide active ingredients are typically interchangeable and can be considered alternatives to one another. To date, BEAD has not reviewed any Section 18 Emergency Exemption Requests for the use of diphacinone; this should not be interpreted as a lack ofbenefits associated with the chemical. There are eight special local need labels for diphacinone, indicating that is needed for rodent control.
COMMON FORMULATIONS AND APPLICATION METHODS Diphacinone is formulated as pelletized and granular baits, as well as powder formulations. These are applied via aircraft, bait boxes, cloth bags, hand bulb dusters, hand probes, spoons, spreaders, and trap/bait staions. Diphacinone sodium salt is formulated as a liquid and applied only indoors via bait stations.

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### USE SITES Agricultural Use Sites: Diphacinone is registered to control rodents in orchards, cropland, rangeland, and forest. Diphacinone, sodium salt is not registered for use in crops. Non-Agricultural Use Sites : Diphacinone is registered for use in and around animal burrows and buildings (industrial, commercial, agricultural and public) , as well as noncrop areas (sewers, dumps, irrigation ditches, along fences, gullies, etc.)
. Diphacinone, sodium salt is registered for use inside of industrial, commercial, agricultural and public buildings.


### DIPHACINONE USAGE BEAD reviewed available public and proprietary agricultural data sources and found small quantities (55-200 lbs a.i
.) of diphacinone reported to be used by consumers and Pest Control Operators (PCOs) in 2009 and 2011 as shown in Table 1 below. T bl 1 D. h
.

a e tpl acmone Non-agncu turaIU 

### Sector
Consumer Markets Consumer Markets PCO Sources : Klme & Company, 2009 Proprietary Data, 2011 

### Year
2009 2011 2011 sage 

### Lbs A.I. Applied % 

### ofTotal Lbs AI ofRodenticides Applied 201 1.3 185 1.2 55 5
.2

BEAD also reviewed California data to determine if use of first generation anticoagulant rodenticides is increasing. Based on California DPR data from 2009-2013, diphacinone use increased by nearly 200% due to an increase in the area treated, while diphacinone sodium salt use has remained relatively low due in part to its sole use on non-agricultural sites as shown in Table 2 below. T bl 2 D
. h

a e IQJ acmone 

## u 

## . c rf sage m a 1 ornta: A ,g andNon-ag 

### Chemical Pounds A.I
. Applied 

### 2009 2010 2011 2012 2013 Diphacinone 44 .9 1 52.67 72
.63 96.36 133.54 Diphacinone, <0
.01 2.59 12
.63 2.12 2.07 Sodium Salt Source: California DPR, Pesticide Use Reporting, Summary Data, 2009-2013 Page 3 of 5BIOLOGICAL ASPECTS RELEVANT TO DIPHACINONE Diphacinone is an anticoagulant rodenticide. Anticoagulants work by inhibiting the formation of prothrombin, a critical component in blood clotting, leading to bleeding at capillaries, internal bleeding, and even death. Diphacinone, like other first generation anticoagulant rodenticides, requires multiple feedings for the rodent to acquire a lethal dose.
ROLE OF DIPHACINONE IN PEST MANAGEMENT Diphacinone is registered for control of commensal rodents in and around homes, industrial and agricultural buildings and similar man-made structures, as well as in sewers; in wet or damp areas such as river banks, irrigation ditches, gullies, railroad tracks, loading areas, along fences, under granaries, garbage dumps, and landfills. Diphacinone is also used to control pocket gophers in rangeland, grain fields, forage crops, hay and alfalfa crops, vegetable crops, forest, nurseries, and noncrop areas, such as parks. Diphacinone is a critical component to a rodent management strategy. For a homeowner, along with sanitation and exclusion, diphacinone may be used in bait traps. Rodenticide baits, along with a variety ofhabitat modification and other pest management techniques, are used to reduce the damage caused by native and introduced rodents, as well as other pest mammals. Rodenticide baits are especially useful for rapidly reducing rodent numbers in cases of major infestations, including island eradication of introduced rodents.
INFORMATION THAT MAY BE USEFUL FOR BEAD'S FUTURE WORK ON DIPHACINONE For future BEAD assessments, the following information would be helpful: usage data for nonag sites (lbs a.i. applied, typical number of applications per year, and maximum dose per year); and more detail about how diphacinone is used in agricultural to control vertebrate pests.
REFERENCES California Department of Pesticide Regulation, Pesticide Use Reporting, Summary Data, 2009- 2013 Chiri, A. 2006. Analysis of Rodenticide Bait Use. U.S. Environmental Protection Agency, Office of Chemical Safety and Pollution Prevention. Page 4 of 5

### Kline & 

### Company, 2009 Proprietary Data, 2011

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