UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MAY 2 3 Z0\2 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

MEMORANDUM 

SUBJECT: 

FROM: 

THRU: 

TO: 

BEAD Chemical Profile for Registration Review: Propylene oxide (042501) 

Biological 

Leonard Yourman, 

Analysis 

Plant 

Branch 

Pathologist 

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Sepehr Haddad, Environmental Protection Specialist /;;.__, f/ ' 1 • 

Science Information and Analysis Branch 7 ~~ 

John 

Economic 

Biological 

Faulkner, 

Analysis 

and Economic 

Economist 

Branch 

Analysis Divis

r· Q 

ion 

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(7503P) 

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AmetJones, 

Biological Analysis 

Chief 

B~~ch 

~ . u 

Diann 

Science 

Sims, 

Information 

Chief ~ and Analysis Branch 

Economic 

Timothy Kiely, 

Analysis 

Chief 

BrancH ~ #. ~ 

Biological and Economic Ana ys s Division ( P) 

Andrea Mojica, Chemical Review Manager 

Risk Management and Implementation Branch 4 

Pesticide Re-evaluation Division (7508P) 

Product Review Panel: May 9, 2012 

INTRODUCTION 

The purpose of this 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 of EPA staff currently evaluating the registration status 

of propylene oxide (PPO), and eventually the general public. This document builds upon the 
data already provided in the "Usage and Label Use Data Packages" that are also provided to 

Registration Review teams by BEAD. The document is based on information and data available 

to BEAD as of April, 2012. 

PPO is a fumigant, an epoxide compound that exists at room temperature as a volatile colorless 

liquid (NTP, 2011). It is soluble in water and ethanol and miscible with acetone, benzene, 

carbon tetrachloride, methanol, and ether. PPO is very flammable, but it is stable under normal 

storage conditions. It is very reactive, particularly with chlorine, ammonia, strong oxidants, and 

acids. It may polymerize explosively when heated or involved in a fire. 

PPO has been used in chambers for the sterilization of packaged foods and as a postharvest 

treatment. It is used as an herbicide, microbicide, insecticide, fungicide, and miticide. PPO is 

used primarily as a chemical intermediate in the production of other compounds (NTP, 2011). 

PPO is used to produce industrial polyurethane polyols, propylene glycols, glycol ethers, di- and 

tri-propylene glycols, and miscellaneous compounds. Polyurethane polyols are used to make 

polyurethane foams, and propylene glycols are used primarily to make unsaturated polyester 

resins for the textile and construction industries. PPO is also used in the preparation of 

lubricants, surfactants, and oil emulsifiers. 

COMMON FORMULATIONS AND APPLICATION METHODS 

PPO is formulated as a pressurized gas. It is used in vacuum chambers at full strength (1 00%) 

for nuts, spices, cocoa (cacao) bean, cocoa powder, and cosmetics. According to the label, it 

must be used at a concentration of 8% with an inert gas (carbon dioxide, nitrogen) for figs, dried 

plums (prunes), and raisins. 

USE SITES 

Agricultural Use Sites 

PPO is registered for use on the following agricultural commodities: processed food/feed stored 

products (raisins, grapes, plums, prunes/figs, cocoa beans, cocoa powder, spices, birdseed, 

processed nuts). 

Non-Agricultural Use Sites 

PPO is registered for use on the following non-agricultural sites: transportation vehicles, empty 

containers (processed feed/food, raw agricultural commodities feed/food), airtight chambers, 

shipping commercial transportation (containers, empty trailers, empty railroad boxcars 

feed/food), pharmaceutical materials, tents, and vaults. 

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USAGE 

The Department ofPesticide Regulation (CDPR) reported that in 2010, a total of300,000 lb of 

PPO was used for crops in California, the 57th most used pesticide (by pound) (CDPR, 2011). 

There were no usage data available for PPO from other BEAD data sources, such as private 

market research proprietary data or USDA-NASS. A Re-registration Eligibility Decision (RED) 

document for this chemical was issued in 2006. According to information in the RED an 

estimated 64.8 million pounds of commodities were treated with PPO annually. The RED also 

stated that PPO was used mostly on nutmeats (approximately 1.8% commodity treated) and 

spices (approximately 1% commodity treated) and that EPA has established tolerance limits for 

PPO based on residues from fumigation of cocoa beans, nutmeats, herbs and spices, and some 

fruits (e.g., figs, prunes, and raisins) (EPA, 2006a). 

HISTORY OF BEAD ASSESSMENTS FQR PROPYLENE OXIDE 

BEAD assessed the impact of PPO and alternatives on almonds, pecans, walnuts, and spices 

(EPA, 2006d) and responded to public comments (EPA, 2006b ). 

Almonds. PPO has been used as a fumigant for raw almonds to reduce microbial contamination 

on raw almonds. A potential alternative to PPO for raw almonds are various methods of steam 

heat that can reduce the microbial populations while maintaining the character of raw almonds. 

Operating costs of steam systems are likely to be at least comparable to PPO for treating large 

lots of almonds; however, there is uncertainty to the ease of deployment and use of steam 

pasteurization technology in the almond production system, especially for smaller almond 

handlers. If PPO or steam systems were not available for treating raw almonds, impacts might 

include increased incidence of Salmonella contamination on marketed raw almonds (including 

increased costs associated with recalls) and losses associated with lots that test positive for 

contamination with Salmonella or other microbes unacceptable to customers. 

Pecans and Walnuts. PPO treatment of shelled pecans and walnuts is important for the portion 

marketed for use as ingredients in dairy and bakery products. Available information suggests 

that there are limited alternatives (e.g. heat treatments) to PPO for treating pecans and walnuts 

for this purpose. If PPO is no longer available in pecan production, the impact on the pecan and 

walnut producers and industries that use pecans may be high. 

Spices. PPO is registered for use on spices to reduce insect, bacterial and mold infestations. It 

has a small use on spices (approximately 1% of spices used in the U.S.), mostly for insect 

management. It is not considered by the industry as effective in reducing high microbial 

populations. PPO has been banned throughout the European Union. Alternatives, depending on 

the particular spice being treated, include improved management and agricultural practices, 

product selection, heat treatments, and irradiation. Based on low use patterns and the availability 

of alternatives that have been effective in other countries, BEAD anticipates that the spice 

industry would experience only minor impacts if PPO was unavailable for-use on spices. Similar 

conclusions were made in a BEAD alternatives assessment (EPA 2006c ). 

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BIOLOGICAL ASPECTS RELEVANT TO PROPYLENE OXIDE 

After outbreaks of Salmonella, in 2001 and 2004, that were traced to raw almonds there has been 

an ongoing effort by the almond processing industry to avoid future incidences of contaminated 

almonds. The almond industry considers PPO an important treatment to that end (ABC, 2012). 

Most almonds are oil roasted, dry roasted or blanched and do not require additional treatment. A 

small portion of the nearly 2 billion pounds produced annually is currently marketed as "raw'' 

and the Almond Board of California (ABC) requires surface treatment with PPO or other 

pasteurization treatments for ensuring the safety of these almonds (Federal Register, 2007). PPO 

treatment of raw almonds both maintains the "raw" characteristics and reduces populations of the 

Salmonella pathogen. Steam pasteurization is also a surface treatment and is used primarily for 

organic almonds (ABC, 2012). Specialized steam equipment reduces any "cooked" effect on 

raw almonds. 

Similar to its use on almonds, PPO is also considered important by walnut and pecan processors 

to reduce the microbial and insect populations in harvested pecans, especially when the nuts will 

be included as an ingredient in dairy or bakery items. PPO pasteurization of shelled pecans or 

walnuts is important to preserve nut quality for end use products, such as ice cream and bakery 

goods. Available information suggests that there are limited alternatives to PPO for this purpose. 

PPO may have an increased role as an alternative to some previous uses of methyl bromide, but 

according to the U.S. Nomination for critical use exemption of methyl bromide, "U.S. EPA has 

established tolerances for propylene oxide on prunes, figs, and raisins, but no comparative 

efficacy data for commodity fumigation seems to be currently available" (UNEP, 2011). 

INFORMATION THAT MAY BE USEFUL FOR BEAD'S FUTURE WORK ON 

PROPYLENE OXIDE 

The various nut industries have indicated that PPO is important to public health to reduce 

incidences of Salmonella or other pathogens for raw nut consumption. Information on advanced 

alternatives to PPO (e.g., heat treatment facilities) is limited and may be helpful in the future for 

any further assessments required by BEAD. 

REFERENCES 

ABC (Almond Board of California). 2012. The Food Safety Program and Almond 

Pasteurization. 

http://www.almondboard.com/Handlers/FoodQualitySafety/Pasteurization/Pages/Default.aspx 

CDPR (California Department of Pesticide Regulation). 2011. The top 100 pesticides usedpounds of active ingredients statewide in 2010 (all sites combined). 

http://www.cdpr.ca.gov/docs/pur/pur10rep/top 100 ais lbslO.pdf 

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EPA. 2006a. Reregistration Eligibility Decision for Propylene Oxide, July 2006 

http:/ /www.epa. gov I oppsrrd 1 /reregistration/propylene oxide/ 

EPA. 2006b. BEAD Response to Phase 3 Public Comments Concerning the Reregistration of 

Propylene Oxide (PPO) for Uses on Almonds, Pecans, and Walnuts 

EPA. 2006c. Propylene Oxide (PPO) Alternatives Assessment for Use on Spices to Reduce 

Bacterial and Mold Contamination. 

EPA. 2006d. Impact Assessment of Propylene Oxide and Alternatives on Almonds, Pecans, 

Walnuts and Spices (DP# 316567) 

Federal Register. 2007. Almond grown in California; Outgoing Quality Control Requirement. 

Final Rule. Agricultural Marketing Service, USDA. 7CFR Part 981. Docket: FV06-981-1 FR. 

http://www.almondboard.com/Handlers/Documents/Outgoing-Quality-Control-Rule.pdf 

NTP (National Toxicology Program). 2011. Propylene Oxide. Report on Carcinogens, Twelfth 

Edition (2011). Pp 367-368. U.S. Department of Health and Human Services. 

http://ntp.niehs.nih.gov/ntp/roc/twelfth/profiles/PropyleneOxide.pdf 

UNEP (United Nations Environment Programme). 2011. Summary: Nomination for Critical Use 

Exemptions for Methyl Bromide Submitted by the United States of America on February 4, 

2011. 

http://ozone.unep.org/Exemption Information/Critical use nominations for methyl bromide/M 

eBr Submissions/USA-CUN-Dec%20Ex1-4-para7-201l.pdf 

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