The Application of Irradiation to Phytosanitary Problems

SUMMARY: This document sets forth a policy statement that shares

positions and policies of the Animal and Plant Health Inspection

Service (APHIS) concerning the use of irradiation as a treatment for

plant pests of quarantine significance.

In preparing this document, we have reviewed and evaluated

pertinent and contemporary information concerning irradiation as a

phytosanitary treatment or potential treatment. We have examined this

information against the background of regulatory and operational

parameters associated with APHIS, Plant Protection and Quarantine's

(PPQ's) mission and authority. The objective of this effort has been to

generate a reference document that describes policies, procedures, and

regulations specifically related to irradiation as a phytosanitary

treatment. This document is designed for review and comment.

ADDRESSES: There are several ways to comment on this document. Because

we hope to develop a dialogue among persons interested in contributing

to the improvement of these policies, the preferred method of

commenting is to subscribe to an e-mail mailing list we are

establishing for the discussion of the policy issues. After you

subscribe, on an ongoing basis you will receive e-mail copies of all

comments submitted to the mailing list. Those wishing to subscribe to

this service should send an e-mail message to

``[email protected]''--without the quotation marks--and

leave the subject area empty. In the body of the message, type

``subscribe irrad''--again without the quotes--and then send the

message.

You can also subscribe to this mailing list or file individual e-

mail comments using a form contained in a World Wide Web site devoted

to this document. The site also contains downloadable copies of this

document and may also have additional background documents on

irradiation, and links to other sites concerning radiation and the

irradiation of products. The address (URL) of the World Wide Web site

is: www.aphis.usda.gov/ppd/irrad.

You may also submit comments by postal mail. To do so, please send

an original and three copies of your comments to Docket No. 95-088-1,

Regulatory Analysis and Development, PPD, APHIS, Suite 3C03, 4700 River

Road Unit 118, Riverdale, MD 20737-1238. Please state that your

comments refer to Docket No. 95-046-1. Postal and e-mail comments

received may be inspected at USDA, room 1141, South Building, 14th

Street and Independence Avenue SW., Washington, DC, between 8 a.m. and

4:30 p.m., Monday through Friday, except holidays. Persons wishing to

inspect comments are requested to call ahead on (202) 690-2817 to

facilitate entry into the comment reading room.

FOR FURTHER INFORMATION CONTACT: Mr. Robert Griffin, Senior Plant

Pathologist, USDA, APHIS, PPD, 4700 River Road Unit 117, Riverdale, MD

20737-1228; (301) 734-3576; e-mail [email protected].

SUPPLEMENTARY INFORMATION:

Development of Policy Statement

The first draft of these positions and policies was introduced in

October 1994 during the annual meeting of the North American Plant

Protection Organization (NAPPO). Subsequent review has included NAPPO

participants and a broadening circle of individual experts,

organizations, and agencies interested in, involved in, or impacted by

irradiation as a phytosanitary treatment. Numerous modifications have

been made as additional information has been collected and reviewed.

This document is not final or authoritative, and does not establish any

agency requirements. Any requirements concerning irradiation that APHIS

develops will be promulgated through rulemaking published in the

Federal Register.

Since 1989, the only formally adopted regulatory policy for

irradiation as a phytosanitary treatment in the United States has been

based on Title 7 of the Code of Federal Regulations (7 CFR 318.13-4f,

``Administrative instructions for approving an irradiation treatment as

a condition for certification of papayas for movement from Hawaii'').

This authorization is specific for a commodity, place of origin, and

program, but is designed for a complex of fruit flies rather than a

single pest. While routine commercial shipments were never realized

under this regulation due to the lack of a treatment facility in

Hawaii, the authorization has proven useful from the standpoint of

beginning to establish policies for irradiation as a phytosanitary

treatment in the United States.

Six years later, PPQ remains dedicated to using the most up-to-

date, appropriate and least intrusive technology to provide quarantine

security, and the need for alternative treatments and pest mitigation

systems is greater than ever. Global trade pressures and the possible

loss of methyl bromide as a fumigant for regulatory pest treatments

make it imperative that practical treatment options be explored.

At the same time, irradiation treatment has matured significantly.

Technological advances, greater experience, and an increasingly larger

body of research indicate that irradiation has important potential as a

treatment for quarantine pest problems.

It is in this light that PPQ now seeks to expand the regulatory

framework addressing irradiation treatment and develop comprehensive

policy statements that will facilitate the development and

formalization of new treatments for phytosanitary applications. This

policy statement provides a sketch from which final policies can be

codified after broad review and input.

Position Summary

The regulations at 7 CFR 318.13-4f provide administrative

instructions for an irradiation treatment as a condition for the

certification of fresh papayas

[[Page 24434]]

moving to the mainland States from Hawaii. These were the first

regulations authorizing the use of irradiation as a quarantine

treatment, and the regulations set a number of policy precedents. The

regulations included the following five basic principles or policies

for irradiation:

1. Requirement that irradiation facilities meet certain APHIS

standards;

2. Monitoring based on inspection of treatment records and

unannounced visits;

3. Policy that the Department is not responsible for damage

resulting from intolerance to the prescribed dose;

4. Reliance on the authority and regulations of the United States

Nuclear Regulatory Commission to ensure U.S. facilities are constructed

and operated in a safe manner; and

5. Reliance on the authority and regulations of the United States

Food and Drug Administration (FDA) to ensure irradiated foods are

wholesome for human consumption.

The precedents described above remain valid to the extent that the

same would apply to any new regulations developed by PPQ for the

authorization of other treatments. However, additional clarity and

completeness are necessary to address the range of commodity, pest,

treatment, and operational issues potentially involved with the

approval of irradiation treatments for phytosanitary problems. In

addition, new information needs to be considered in adjusting existing

policies, and program designs must be adapted to address the unique

situations created by authorizing treatments conducted outside the

United States. Therefore, in addition to the five policy precedents

established by the existing regulations, APHIS has identified 28

additional policies, for a total of 33 policies relevant to

irradiation.

The following are summary statements of the 28 additional policies

and positions:

6. PPQ does not endorse the position that irradiation treatment

should be the only replacement for methyl bromide. PPQ believes that

there is adequate scientific evidence to show that irradiation provides

an alternative treatment to be explored and developed, and PPQ

recognizes that irradiation has potentially broad applications in the

treatment of quarantine plant pests.

7. The highest priority for treatment approval is generally given

to treatments deemed by PPQ to have the greatest potential immediate

need, use, and benefit.

8. Treatment schedules approved by PPQ must have been demonstrated

experimentally to achieve the level of efficacy required for a defined

level of quarantine security.

9. To the extent possible, PPQ will ensure consistent requirements

for both import and export authorizations, and align domestic

requirements with foreign requirements as fairly as possible.

10. Specific authorizations for the use of irradiation as a

phytosanitary treatment will initially be provided by PPQ on a case by

case basis following a pest risk analysis, the evaluation of efficacy

data, and the approval of operational protocols.

11. Irradiation may be used as a single treatment achieving

quarantine security, or as part of a multiple treatment, or as a

component in a pest mitigation system (systems approach).

12. Measures aimed at reducing pest presence prior to treatment are

encouraged but will not be required for treatments achieving quarantine

security. However, a very low initial infestation rate is important for

enhancing the acceptance and use of irradiation as a treatment and for

alleviating regulatory concerns arising from the detection of living

pests in the irradiated product.

13. In those instances where pest organisms survive treatment, it

is essential for quarantine purposes that the organism is unable to

reproduce, and it is desirable for the organism to be unable to emerge

from the commodity unless it can be easily distinguished from a non-

irradiated pest of the same species.

14. Live stages of pest organisms, or their signs or symptoms,

found in a commodity following a PPQ prescribed and approved

irradiation treatment will be presumed by PPQ to have been effectively

treated unless evidence exists to indicate that the integrity of the

treatment was inadequate. PPQ may perform or require laboratory or

other analyses on surviving pest organisms, or employ any available

technology to verify efficacy. Authorizations may be suspended or

modified and the requirements for system integrity may be adjusted

based upon the results of such studies.

15. Ionizing energy (radiation) may be provided by radionuclides

(gamma rays from cobalt-60 or cesium-137), electrons generated from

machine sources, or by x-rays. PPQ is not concerned with specifically

describing the requirements for equipment except to the extent that

equipment used for plant quarantine treatments is capable of

irradiating commodities to the specifications required for approved

treatments.

16. Irradiation treatment must be carried out to ensure that the

minimum absorbed dose (Dmin) required to assure quarantine security is

fully attained throughout the commodity. The schedule process for Dmin

must account for uncertainty associated with the dosimetry system

employed.

17. Definition of the lower dose limit is essential to the approval

of irradiation treatments for quarantine purposes. Definition of the

upper dose limit is not critical to determining quarantine security,

but is important from a quality standpoint and to identify potential

problems with the FDA limit for the maximum dose for food (currently 1

kilogray - see 21 CFR 179.26). PPQ will not be concerned with defining

the upper dose limit except to the extent that it is necessary to

determine the feasibility of a particular treatment.

18. Treatments must be proven with adequate dosimetry in accordance

with relevant internationally accepted standards, such as those

published by the American Society for Testing and Materials (ASTM) or

similar organizations. The dosimetry systems must be completely

described, including records related to identifying specific suppliers,

batches, processing dates, locations, and procedures as well as the

means of calibration (reference dosimetry) used.

19. PPQ will confer with the Agricultural Research Service (ARS),

United States Department of Agriculture (USDA) concerning the adequacy

of treatment data, research protocols, and treatment design. ARS will

identify or concur with the minimum dose for efficacy at the level

defined by PPQ as providing quarantine security for a pest or complex

of pests. Other experts may also be asked to provide input.

20. Dosages may be generic relative to a pest group or to a

commodity.

21. PPQ may prescribe treatments with doses higher than what is

indicated as effective by available data. This will be done to expedite

the incorporation of new treatments while providing a measure of safety

when PPQ and ARS judge the data to be inconclusive to the extent

necessary for approving a less rigorous treatment. All treatments will

be subject to amendment as new information is evaluated. PPQ expects

that modifications to an existing treatment will be more easily and

quickly accomplished than approval of a new treatment.

22. An irradiation program protocol, describing the details of a

program surrounding a specific commodity treatment and facility

processes (import or export, domestic or foreign), will be developed

prior to the approval of a new facility or a new commodity for an

existing facility.

[[Page 24435]]

23. Treatment facilities must be licensed by relevant national

authorities. When not conflicting with national authority, compliance

with the criteria of the International Inventory of Authorized Food

Irradiation Facilities, established by the International Consultative

Group on Food Irradiation (ICGFI), is also recommended for facilities

treating food items.

24. Treatment facilities will be subject to the prior approval of

PPQ and will be subject to periodic unannounced monitoring.

Recertification by PPQ will be done on an annual basis or following

repairs, modifications, or adjustments in equipment affecting the

delivery of treatments. Source replenishment (in the case of

radionuclide facilities) will require additional dose mapping.

25. Dose mapping of the product in every geometric packing

configuration, arrangement, and product density that will be used

during routine treatments will be required prior to PPQ approval of a

facility. Dose mapping must be performed in accordance with relevant

internationally accepted standards such as those published by ASTM or

similar organizations.

26. The irradiation treatment can be applied as an integral part of

packing operations, or it may be done at a central location such as the

port of embarkation after packing or packaging. Treatment may also be

performed at the port of arrival or a designated location in the

destination country when safeguards are deemed by PPQ to be adequate

and operationally feasible.

27. The irradiation treatment may be applied to bulk or continuous

unpackaged commodities, or the commodities may be packaged at the time

of treatment. If unpackaged or exposed in packaging,1 commodities

will require safeguarding immediately following treatment to ensure

that they do not become reinfested or contaminated after treatment.

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\1\ Note: Packaging materials may require FDA approval.

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28. Treated and untreated commodities must be adequately segregated

and handled under conditions that will safeguard against cross-

infestation or mistaken identity. Appropriate procedures specific to

each facility and commodity treatment program must be approved by PPQ

in advance.

29. Direct PPQ supervision of treatment programs may not be

necessary for programs deemed by PPQ to provide adequate system

integrity. Minimum criteria include PPQ approval of the treatment

facility, National Plant Protection Organization (NPPO) certification

of treatments, and PPQ approval of a program protocol for system

integrity. PPQ will directly and routinely verify the adequacy of

treatment facilities. PPQ presence may also be necessary for the

monitoring of related program activities and system integrity.

30. Requirements for program protocols and system integrity will be

harmonized with FDA, the USDA Food Safety Inspection Service (FSIS),

and other regulatory authorities to the extent possible.

31. Phytosanitary certificates issued in accordance with the

International Plant Protection Convention (IPPC) may be used as

official documentation verifying the successful completion of a

treatment. Certificates must specifically identify the treated lot and

record the prescribed minimum dose and the verified minimum dose. The

maximum dose may also be required in order to comply with FDA

requirements for some commodities.

32. PPQ is committed to harmonizing with other U.S. agencies,

States, foreign counterparts, and regulatory bodies involved with the

development, approval, and application of irradiation treatments for

phytosanitary problems. PPQ will make every attempt to avoid overlap,

conflict, and ambiguity associated with the relationship of PPQ

regulations to those of other authorities.

33. PPQ is committed to increasing its own depth of understanding

concerning irradiation as a treatment for phytosanitary problems and

expanding its expertise for the approval of treatments and the

certification of facilities.

Research Protocols

General PPQ Requirements for the Acceptance of Irradiation as a

Quarantine Treatment

Irradiation as a single treatment, part of a multiple treatment, or

combined with other pest mitigation measures as a component of a

systems approach, must have a scientifically demonstrated level of

efficacy. The research necessary to demonstrate efficacy for PPQ begins

with laboratory scale tests designed to provide results that can be

analyzed statistically to hypothesize the parameters necessary to

attain a defined level of quarantine security.

Unlike most other PPQ treatment approvals, irradiation treatments

may not always require a second level of confirmatory testing to

demonstrate that the treatment is efficacious under the conditions

associated with the commercial treatment of the commodity. However, the

equipment, processes, and dosimetry for any specific treatment facility

must be approved and monitored by PPQ to ensure that commercial

treatments comply with the parameters for approved treatments.

Judging the feasibility of treatments for commercial applications

is outside the scope of PPQ's authority and responsibility. Likewise,

concerns related to phytotoxicity and issues of quality are not the

responsibility of PPQ. Therefore, primary responsibility falls upon the

research and commercial sectors to ensure that treatments demonstrated

to be efficacious against pests of quarantine concern are also

practical for commercial use.

The efficacy of the treatment as demonstrated against naked pests

in vitro is the primary criterion for approval in most cases,2 but

concurrent phytotoxicity studies are important and appropriate in order

to determine the commercial feasibility of proposed treatments even

though data of this nature will not normally be required by PPQ to

demonstrate efficacy.

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\2\ The FDA establishes the maximum absorbed ionizing radiation

dose for food (currently established at 1 kilogray for the

disinfestation of food for arthropods--21 CFR 179.26). Irradiation

treatments designed for the treatment of other than arthropods in

food must receive FDA approval as well.

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General Research Protocol

If Unknown, Determine the Pest or Pests That Are of Quarantine

Significance and Would be Expected to be Found on or Within the

Commodity at the Time of Export

Submit this information to PPQ for concurrence. PPQ will assess the

risks associated with any quarantine significant pest or pests.

Irradiation may serve as the means of mitigating the risks identified

in the risk analysis process.

Determine the Most Tolerant Life-stage of the Pest(s) of Concern That

Would be Encountered at the Time of Treatment

If not documented in the literature, this must be determined

through research. Research to determine the most tolerant life-stage

may be done with naked organisms outside the commodity. Submit this

information to PPQ for concurrence.

Determine the Minimum Absorbed Dosage (Dmin) and the Type of Radiation

Required to Maintain Quarantine Security

Experimental design must utilize sampling methods and sample sizes

appropriate for statistical tests to be used. In some instances,

efficacy may be

[[Page 24436]]

inferred from the literature for related species and commodities when

complete laboratory investigations are not possible.3 The means of

calibration (reference dosimetry) must be described in detail and

should be developed in accordance with relevant accepted standards,

such as those published by ASTM or similar organizations. Submit the

proposed experimental design to PPQ for concurrence.

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\3\ Quarantine security may be defined in terms of mortality or

in terms of other criteria that would ensure that survivors are not

able to reproduce and are not confused with untreated pests

encountered inside and outside the commodity. In the case of fruit

flies, PPQ has established the criterion as ``the non-emergence of

adults,'' referring to interruption of the developmental sequence

leading to an adult that can emerge from the commodity.

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Confirm That the Proposed Irradiation Dosage Will Provide Quarantine

Security by Testing Large Numbers of Organisms

Submit the proposed experimental design to PPQ for concurrence.

Analyze data statistically.

Analyze data statistically

Submit the proposed statistical methodology to PPQ for concurrence.

Describe Specific Conditions Necessary for Commercial Application of

the Proposed Treatment Methodology. Specify Maximum and Minimum

Absorbed Dose

Submit proposed treatment regime and conditions necessary for

commercial-scale treatment to PPQ for review. This does not mean that

commercial-scale testing is necessary, only that the conditions for

commercial-scale treatments be described to PPQ prior to building a

facility or configuring existing facilities for quarantine treatments.

This provides PPQ the opportunity to address components of design,

monitoring, safeguarding, and commodity handling that will be essential

for the ultimate approval of a specific facility.

Specific Research Protocol: Quarantine Significant Fruit Flies

Quarantine security for a single treatment protocol will be defined

as the prevention of adult emergence at the 99.9968 percent level with

95 percent confidence as demonstrated by a valid statistical method.

Specific Research Protocol: Quarantine Significant External Feeders,

Hitchhikers, and Surface Contaminants

Quarantine security for a single treatment protocol will be defined

as achieving 99.9968 percent sterility or mortality at the 95 percent

confidence level, depending on the pest. Large scale or commercial

confirmatory testing may be waived if satisfactory evidence can be

presented showing that conditions in small scale testing are

representative of commercial practices.

Specific Research Protocol: Quarantine Significant Systemic Organisms

Quarantine security for a single treatment protocol will be defined

as achieving 99.9968 percent sterility or mortality 4 at the 95

percent confidence level, depending on the pest. Efficacy must be

demonstrated with lab scale testing of organisms in host material.

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\4\Note: In general, sterility is more acceptable for organisms

that remain in (or on) the host. Demonstrating the efficacy of

treating organisms for sterility may be difficult to accomplish

without full information on the factors favoring successful

reproduction.

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System Integrity (Quality Assurance/Quality Control)

Post-treatment safeguard methods are critical for irradiation

treatments, as they are for many other commodity treatments, because

the pest may continue to live and develop following treatment. As a

result, confidence in the adequacy of irradiation treatment rests with

the assurance that the treatment:

(a) Is efficacious against the pest under specific conditions, and

(b) Has been properly conducted and the commodity safeguarded.

To ensure condition (a) is met, strict research protocols and

dosimetry requirements prevent lack of efficacy that would lead to

treatment failure. Condition (b) is assured by well designed and

closely monitored systems for treatment delivery and safeguards that

assure system integrity.

This section addresses the policies being considered by PPQ for

ensuring system integrity in the application of irradiation to

phytosanitary problems. The focus of these policies is the achievement

of quarantine security. Product quality is a commercial responsibility

that must also be considered.

A. Pretreatment Conditions

Packers and treatment facility operators must keep complete records

concerning sources (growers) supplying commodities for treatment. These

records must be available for PPQ review in the event a trace-back is

necessary. Trace-back capability is important when pests other than the

target pests have been detected.

Untreated commodities and other agricultural products must be

stored separately from treated commodities and appropriately marked. A

fail-safe means of moving the commodity from receiving areas to

treatment areas in a timely fashion and without mistaken identity or

risk of cross-contamination is essential.

Packaging prior to irradiation is desirable to prevent

reinfestation if irradiation is done at the export source, and to

prevent the accidental escape of target pests at the destination if the

treatment is applied at the destination.

B. Treatment Conditions

An accurate measure of absorbed dose is critical to determining and

monitoring adequacy. The required number and frequency of these

measurements will be prescribed by PPQ based on the specific equipment,

processes, configurations, and commodities.

Approved, standardized dosimetry must demonstrate that the absorbed

dose range, including areas of the minimum and maximum dose is well

mapped, controlled, and recorded for specific pests, commodities, and

equipment.

Dosimetry must consider variations due to density and composition

of the material treated, variations in shape and size, variations in

orientation of the product, stacking, volume, and packaging.

Absorbed dose must be measured using calibrated dosimeters approved

in advance by PPQ. Dosimeters must be calibrated to a recognized

national or international standard.

The number of dosimeters used shall be in accordance with relevant

internationally accepted standards, such as those published by ASTM.

Complete dosimetry records must be kept by the treatment facility

for at least 1 year after treatment. These records must be available to

PPQ for review at any time.

Facilities and control procedures must have approval and licensing

in conformance with local, national, and, where applicable,

international regulatory bodies having authority over the particular

situation or location. For non-U.S. locations, PPQ must judge these to

be adequate and equivalent to U.S. standards.

Facilities must be certified by PPQ for use initially and at least

annually. An increase or decrease in radioisotope or major modification

to equipment that impacts the delivered dose must be reviewed by PPQ

prior to recertification. Approval will be based on a common set of

criteria plus those specific to the site and commodity programs.

Significant variance in dose delivery (based on PPQ monitoring of

dosimetry

[[Page 24437]]

records) may provide the basis for requiring recertification.

Products not treated according to required schedules must be

removed and discarded or otherwise eliminated from shipments for

export. Retreatment is not allowed unless it can be demonstrated that

there is a high degree of confidence that retreatment will not result

in misidentification or cross-contamination, or conflict with other

restrictions.

C. Post-treatment Conditions

Treated commodities must be protected from reinfestation by pest-

proof packaging or other safeguards if treated outside the U.S.

Packages must be marked and labeled with treatment lot numbers and

other identifying features allowing the identification of treatment

lots and trace-back (packing and treatment facility identification and

locations, dates of packing and treatment).

D. Documentation and Monitoring

A phytosanitary certificate will be accepted as certification of

treatment. Minimum information to provide includes identification of

the shipment by treatment lot and certification of the target minimum

dose and the verified minimum absorbed dose.

The treatment operator must have reliable and probative evidence of

correct treatment for each lot certified.

Regulatory Framework

Existing Regulations

Few PPQ treatments are specifically described within the Code of

Federal Regulations (CFR). Most approved treatments are included in the

PPQ Treatment Manual, which is incorporated into the CFR by reference.

An irradiation treatment for papayas from Hawaii is the only

irradiation treatment currently approved by PPQ. This authorization is

specific for a commodity, origin, and program but is designed for a

complex of fruit flies rather than a single pest. The authorization has

proven useful from the standpoint of beginning to establish policies

for irradiation as a phytosanitary treatment in the United States.

Proposed Processes and Structure for New Regulations

The degree of sophisticated work and testing needed to develop and

prove an irradiation treatment program make it essential that the

criteria for approval be clearly understood in advance. A specific and

comprehensive statement of policies combined with a pre-defined

strategy for regulatory incorporation are essential to ensuring that

the development and implementation of new treatments is not unduly

stifled by regulatory requirements nor too liberal as to allow

failures.

PPQ assumes that many additional requests for treatment approvals

will be specific for pest-commodity-origin combinations and will

include unique provisions for particular program parameters. Single

pest treatments as well as broader targets, such as entire groups of

pests, are likely to be explored. A number of individual authorizations

corresponding to items within regulated commodity groups (such as

fruits and vegetables or logs and lumber) will be necessary. There is

also the potential for broad spectrum uses resulting in authorizations

that cross the lines of existing regulated commodity groups. There is a

need to provide general statements of policy and background

requirements that pertain to all irradiation treatments. Any

requirements concerning irradiation that APHIS develops will be

promulgated through rulemaking published in the Federal Register.

The following is offered as a regulatory framework and policy

communication strategy for irradiation treatment:

Use draft position documents to solicit input in the

development of policies and the collection of pertinent information.

Use Federal Register publication and other methods to

widely circulate policy statements.

Use notice and comment rulemaking to propose and

ultimately codify new treatments approved by PPQ.

Commodity specific treatments may be incorporated through

additions to the regulations specific to the commodity group (i.e.,

fruits and vegetables).

Treatments with broader applications (either crossing the

lines of regulated groups, or having broad spectrum pest effectiveness)

may be incorporated into the CFR without being associated with an

existing regulated group.

Needs and Unresolved Issues

There is a need to develop standards for conducting and reporting

the findings of irradiation efficacy research for quarantine decision

making, including:

--Confirmatory testing requirements with sufficient numbers to

demonstrate quarantine security

--Standardized dosimetry and details concerning the methods used

--Information concerning the condition or viability of test organisms

and survivors

--Information concerning the condition of the commodity before and

after treatment

--Appropriate number of replications

--Appropriate methods of statistical analysis

--Criteria for combining data for different organisms or species

--Criteria for the substitution of organisms

There is a need for additional research on product tolerance, in

order to:

--Establish tolerance ranges for more commodities

--Characterize treatment variables that affect phytotoxicity

There is a need for additional research on the efficacy of

irradiation for other pests and diseases, including:

--Data supporting generic doses for commodity and pest groups

--Treatments for other arthropods, diseases, nematodes, noxious weeds

--Coordination with other quarantine and food safety concerns, i.e.,

animal products

Research is needed to develop methods to verify the adequacy of

treatments, particularly a means for verifying that a live pest that

has survived treatment has been adequately irradiated. This also

requires development of dosimeters appropriate to the relatively low

levels of irradiation used for quarantine treatments.

Research is needed to determine the conditions under which in vitro

efficacy data can be considered acceptable in lieu of in vivo or in

situ data.

There is a need to increase the number of facilities available for

treatment research.

A coordinated system is needed for storing and accessing data

associated with irradiation treatments for quarantine purposes.

There is a need for integration and coordination with food safety

and other authorities involved in regulatory aspects of applying

irradiation to agricultural commodities.

There is a need to identify critical control points for purposes of

avoiding hazards (process failures) associated with treatment.

There is a need to determine the load required to have

statistically meaningful results.

Finally, there is a need to develop estimates of the influence of

climate or other environmental effects on the pest's susceptibility to

irradiation treatment.

[[Page 24438]]

Current Initiatives

1. Generic Doses for Fruit Flies

An exhaustive review of the scientific literature concerning the

efficacy of irradiation treatments for fruit flies in fresh fruits and

vegetables has been conducted by ARS with the goal of determining

whether generic dosages could be recommended. An evaluation of the

results by ARS and PPQ provided the basis for the commodity-generic

dosages listed below.

----------------------------------------------------------------------------------------------------------------

Min.

Tephritid species Common name absorbed

dose (Gy)

----------------------------------------------------------------------------------------------------------------

Bactrocera dorsalis 5................. Oriental fruit fly......................................... 250

Ceratitis capitata.................... Mediterranean fruit fly.................................... 225

Bactrocera cucurbitae................. Melon fly.................................................. 210

Anastrepha suspensa................... Caribbean fruit fly........................................ 150

Anastrepha ludens..................... Mexican fruit fly.......................................... 150

Anastrepha obliqua.................... West Indian fruit fly...................................... 150

Anastrepha serpentina................. Sapote fruit fly........................................... 150

Bactrocera tryoni..................... Queensland fruit fly....................................... 150

Bactrocera jarvisi.................... (No common name)........................................... 150

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5 Unless noted as Bactrocera dorsalis complex, B. dorsalis refers specifically to the species as described by

R.A.I. Drew and D.L. Hancock (1994) ``The Bactrocera dorsalis complex of fruit flies (Diptera: Tephritidae:

Dacinae) in Asia.'' Bulletin of Entomological Research: Supplemental Series Number 2 in Supplement 2. CAB

International, pp 68.

These dosages are generic in the sense that the prescribed dose is

deemed appropriate regardless of the commodity. In cases where more

than one of the listed species is of concern, the prescribed dose would

be the dose for the most tolerant species. All doses are subject to

adjustment based on the scientific evidence supporting a different

dose.

2. Modification of 7 CFR 318.13-4f (Papaya From Hawaii)

The regulations at 7 CFR 318.13-4f have not been used for routine

commercial shipments due to the lack of a treatment facility in Hawaii.

Recently however, PPQ has been approached concerning the potential for

modifying the existing regulations to allow for shipping to northern

areas of the mainland U.S. for treatment, and to include tropical

fruits such as lychee, rambutan, carambola, and cherimoya under a

modification of the existing authorization for papaya.

Pest risk analyses have been done or are underway to determine if

quarantine significant pests other than fruit flies are associated with

other tropical fruits of interest. At the same time, PPQ has authorized

a few experimental shipments from Hawaii to Chicago for treatment at

the dose prescribed in the existing regulations.

Test shipments were authorized under strict safeguards and

supervision. Each shipment was designed to provide PPQ with information

and experience required to determine whether suitable program protocols

could be developed and what conditions would be most appropriate. The

results may provide sufficient basis for proposing modifications to the

existing regulation.

3. Universal Treatment for Logs, Lumber and Unmanufactured Wood

Products

Interest is high in exploring the potential to use irradiation as a

means to address phytosanitary problems in raw wood products. Logs from

Russia are the primary commercial focus at this time.

Russian researchers have conducted research and provided data in

support of adopting a generic dose for treating raw logs. PPQ has

formed a science panel consisting of scientists from APHIS, ARS, and

the Forest Service to establish a research protocol, review data, and

oversee the research effort toward a generic dose providing probit 9

mortality for all organisms of concern in logs from Russia. If

approved, the treatment will be included among the universal treatment

options in 7 CFR 319.40.

Definitions

Absorbed Dose

Quantity of radiation energy imparted per unit of mass of a

specified material (D=de/dm). The mathematical relationship is the

quotient of de by dm, where de is the mean energy imparted by ionizing

radiation to matter of mass dm. The unit of absorbed dose is the gray

(Gy) where 1 gray is equivalent to the absorption of 1 joule per

kilogram (=100 rad).

Absorbed-Dose Mapping

Measurement of the absorbed-dose distribution within a process load

through the use of dosimeters placed at specified locations.

Absorbed-Dose Rate

The absorbed dose in a material per incremental time interval, ie.

the quotient of dD by dt (D=dD/dt). The unit for absorbed-dose rate is

gray per second (Gy/s)

Dmax

The maximum absorbed dose within the process load.

Dmin

The minimum absorbed dose within the process load.

Dose Uniformity Ratio

Ratio of the maximum to the minimum absorbed dose within the

process load. The concept is also referred to as the max/min dose

ratio.

U=Dmax/Dmin

Dosimeter

A device that, when irradiated, exhibits a quantifiable change in

some property of the device which can be related to absorbed dose in a

given material using appropriate analytical instrumentation and

techniques.

Dosimetry System

A system used for determining absorbed dose, consisting of

dosimeters, measurement instruments and their associated reference

standards, and procedures for the system's use.

Efficacy (Treatment)

Capability of a treatment to produce a defined, measurable, and

reproducible effect on pests.

Fruit Flies

Quarantine significant species of Tephritidae.

Gray (Gy)

Unit of absorbed dose where 1 Gy is equivalent to the absorption of

1 joule per kilogram.

1 Gy = 1 J/kg

[[Page 24439]]

Formerly, the special unit for absorbed dose was the rad 1 rad =

.01 J/kg = .01 GyIonizing radiation.

Any type of radiation consisting of charged particles or uncharged

particles, or both, that as a result of physical interaction, creates

ions by either primary or secondary processes. Charged particles could

be positive or negative electrons, protons, or other heavy ions, and

uncharged particles could be X-rays, gamma rays, or neutrons. (Note:

positive electrons, protons, heavy ions, or neutrons are not approved

for food irradiation.)

Irradiation

The purposeful application of ionizing radiation (gamma rays, x-

rays, or electrons) to a product (device or material) to achieve a

desired benefit. Gamma rays in commercial irradiation come from

radioactive cobalt-60 (60Co) or cesium-137 (137Cs). X-rays

(technically referred to as bremsstrahlung) are obtained using high

energy electrons from an electron accelerator striking a target.

Electrons from an accelerator can also be used to penetrate the product

directly.

Kilogray (kGy)

Measure of absorbed dose. 1kGy = 1,000 Gy

Label Dosimeter

A device that can be affixed to an article to be irradiated, and

which exhibits a quantifiable change in property which can be related

to absorbed dose. This change in property can be measured in situ.

(Note: as of 1994, no such devices that have the properties of a

dosimeter are commercially available for the levels appropriate to

quarantine treatments.)

Measurement Traceability

The ability to demonstrate and document on a continuing basis that

the measurement results from a particular measurement system are in

agreement with comparable measurement results obtained with a national

standard (or some identifiable and accepted standard) to a specified

uncertainty.

Pest (Plant)

Any biotic agent capable of causing damage to plants or plant

products.

Phytosanitary Treatment

Subjecting or exposing a plant or plant product to a process,

action, chemical or a physical influence proved to have a measurable

deleterious effect on pest organisms.

Probit 9 (Mortality)

A statistical estimation of 99.99683 percent mortality in a

population of live organisms, corresponding to a survival rate of 32

individuals per million.

Process Load

A volume of material with a specified loading configuration

irradiated as a single entity.

Quarantine Security

A management decision concerning the safety of a defined level of

pest risk. Additional mitigation is not required when quarantine

security is achieved.

Rad (rad or Radiation Absorbed Dose)

Special unit for absorbed dose that is being superseded by the gray

(Gy)

1 rad = 0.01 J/kg = 0.01 Gy

1 kilorad (krad) = 10 J/kg = 10 Gy

1 megarad (Mrad) = 1,000 J/kg = 1,000 Gy = 10 kGy

1Gy = 100 rads

1 kilogray = 100,000 rads

Radiation-Sensitive Indicators

Materials such as coated or impregnated adhesive-backed substrates,

inks, or coatings that may be affixed to, or printed on the irradiation

container and that undergo a visual change when exposed to ionizing

radiation. These indicators, sometimes referred to as go/no-go

indicators, are not dosimeters and are not a substitute for proper

dosimetry.

Systems Approach

A combination of multiple safeguards, treatments or other

mitigation measures. At least two mitigation measures must act

independently to reduce risk.

Validation

Establishing documented evidence that provides a high degree of

assurance that a specific process will consistently produce a product

(quarantine security) meeting its predetermined specifications and

quality characteristics.

Authority: 7 U.S.C. 150dd, 150ee, 150ff, 151-167, 450, 2803, and

2809; 21 U.S.C. 136 and 136a; 7 CFR 2.22, 2.80, 371.2(c).

Done in Washington, DC, this 8th day of May 1996.

Terry L. Medley,

Acting Administrator, Animal and Plant Health Inspection Service.

[FR Doc. 96-12185 Filed 5-14-96; 8:45 am]

BILLING CODE 3410-34-P