DRAFT AGENDA

Meeting of the Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel (FIFRA SAP) 

to Consider and Review Scientific Issues Associated with

RNA Interference: Problem Formulation for Human Health and Ecological Risk Assessment

January 28, 2014

Docket Number: EPA-HQ-OPP-2013-0485 OPP Docket Tel: 703-305-5805

Please note that all times are approximate 

(See note at the end of the Agenda)

Tuesday, January 28, 2014

9:00 A.M. Opening of Meeting and Administrative Procedures – Sharlene Matten, Ph.D., Designated 

Federal Official, Office of Science Coordination and Policy, EPA

9:05 A.M. Introduction and Identification of Panel Members – Daniel Schlenk, Ph.D., Chair, FIFRA 

Scientific Advisory Panel

9:15 A.M. Opening Remarks – Steven Bradbury, Ph.D. Director, Office of Pesticide Programs (OPP), EPA

and Robert McNally, Director, Biopesticides and Pollution Prevention Division (BPPD), OPP, 

EPA

9:30 A.M. Background Information: Overview of RNAi and Proposed and/or Anticipated Pesticidal 

Formulations and Uses – Chris Wozniak, Ph.D., BPPD, OPP, EPA

9:45 A.M. Problem Formulation for Human Health Risk Assessment of Pesticidal Uses of dsRNA –

John Kough, Ph.D., BPPD, OPP, EPA

10:05 A.M. Problem Formulation for Ecological Risk Assessment of Pesticidal Uses of dsRNA –

Shannon Borges and Russell Jones, Ph.D., BPPD, OPP, EPA

10:25A.M. Break

10:35 A.M. Uncertainties Associated with Pesticidal Uses of dsRNA – Chris Wozniak, Ph.D., BPPD, OPP, 

EPA

10:50 A.M. Public Comments

12:00 A.M. Lunch

1:00 A. M. Panel Discussion of Charge Questions

Introduction

The intent of this meeting is to solicit scientific expertise for the problem formulation phase of risk assessment of 

pesticidal products based on RNA interference (RNAi). Problem formulation is the first step in the risk 

assessment process and guides the subsequent questions to pose about hazard and exposure (EPA, 1998b). The 

framework for the risk assessment of biopesticides is found in the RNAi issue paper in two sections. The current 

approach for mammalian safety assessment of PIPs and biochemical pesticides can be found at the start of section 

III. The framework for ecological safety assessment for PIPS and biochemical pesticides can be found in section 

IV A and B.
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EPA has found that the current approach utilizing reduced data sets and tiered approaches for more involved 

studies works well for the risk assessment of products based on biological materials. EPA recognizes that 

biopesticides tend to be more specific in their activity and present a lower risk profile than some alternative pest 

control measures. Biopesticide products are likely to be developed utilizing RNAi phenomena as both dsRNA 

PIPs expressed in plants and typical sprays and other products based on isolated dsRNA molecules. EPA is asking 

the following questions to ascertain the issues unique to RNAi and how they could fit under the existing risk 

assessment framework.

Human Health Considerations

Question 1. Please discuss the nature and extent of uncertainty in the specificity of long sequences of dsRNA 

targeted at pest species, if bioinformatic analysis shows no significant similarity to mammalian genes?

Question 2. Based on data indicating degradation of the majority of dsRNA in the digestive system, please 

discuss the strengths and limitations in concluding there will not be significant absorption of dsRNA with 

possible mammalian effects on oral exposure?

Question 3. To what extent does the specific structure of dsRNA, if it is super coiled or in a hairpin structure, 

make it more likely to survive degradation in the gut and lead to possible mammalian effects with oral 

exposure?

Environmental Considerations – Questions directed toward dsRNA expressed as part of a PIP and applied 

to the plant as a biochemical

Question 4. EPA needs a clear understanding of the environmental fate of dsRNAs in terrestrial and aquatic 

environments. In sections IV.A.1.and IV.B.3, respectively, EPA has presented potential scenarios for 

dsRNA movement within the environment that may result from their pesticidal uses as PIPs or as 

exogenously applied dsRNAs. Environmental fate of dsRNAs is not well understood; however, EPA has 

frameworks in place for PIPs and Biochemicals to obtain data related to degradation and movement of 

pesticides in the environment. These data can be used to refine environmental exposure estimates to 

dsRNAs. 

a. While nontarget exposure to dsRNA PIPs may result primarily from consumption of PIP crop plant 

tissue, EPA must also assess the exposure of nontarget organisms to dsRNA that may enter the 

environment through plant exudates and plant tissue breakdown. In section IV.A.2.a, EPA presented the 

current approach for testing to assess environmental fate for PIPs, which focuses on degradation within 

soil. 

i) To what extent will data on degradation in soil inform EPA on nontarget exposure to dsRNA PIPs?

ii) What additional information, if any, would EPA need to assess environmental fate of dsRNA PIPs? 

b. In section IV.B.4, EPA proposed environmental fate data needs for exogenously applied dsRNAs. To 

what extent is the proposed testing sufficiently robust to inform nontarget organism exposure for these 

dsRNAs? 

c. For both dsRNA PIPs that may be free in the environment and exogenously applied dsRNAs, knowledge 

of the initial residue burden, and the dissipation rate of residues, is essential for developing environmental 

exposure estimates, particularly if models of environmental fate are used to arrive at these estimates. 

What analytical methods are available to accurately and precisely measure dsRNAs in diverse plant, soil, 

and water matrices?

3:00 P.M. Break

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3:15 P.M. Panel Discussion of Charge Questions, continued

Question 5. The primary route of exposure for nontarget organisms to dsRNA PIPs is assumed to be ingestion, 

either of dsRNAs contained in plant tissue or free in the environment. However, some evidence also 

indicates the potential for exposure by direct contact in nematodes and some arthropods. For dsRNAs 

that are applied to plants and/or the environment, the primary routes of exposure are expected to be both 

ingestion and direct contact. 

a. In section III.C. and IV.A.1.c. of the issue paper, EPA discusses potential barriers to uptake of dsRNA in 

the gut of mammals and arthropods; however, little information exists for other taxa. 

i) In addition to the conditions of the gut environment and enzymes influencing digestion, what other 

factors may play a role in uptake within the gut and potentially limit exposure to dsRNA? 

ii) Please comment on how these barriers can be generalized across all nontarget taxa that are 

considered in EPA’s risk assessments (e.g., birds, plants, fish, etc.) for both dsRNA PIPs and 

exogenously applied dsRNA. 

b. The degree of exposure by direct contact is likely to differ between nontarget risk assessments for dsRNA 

PIPs and nontarget risk assessments for exogenously applied dsRNAs. 

i) Please comment on the importance of the contact route of exposure for nontarget risk assessments 

for each of these types of dsRNAs

ii) What barriers are likely to exist for this route of exposure for both terrestrial and aquatic 

organisms, and how can these be generalized across nontarget taxa?

Question 6. In the issue paper, EPA discussed possible effects other than silencing of the target gene in the target 

organism that may occur as a result of exposure to dsRNA. These unintended effects of dsRNA include 

off-target effects, silencing the target gene in nontarget organisms, degradation of non-targeted mRNA by 

transitive RNA, and effects resulting from immune stimulation and saturation of the RNAi machinery. 

EPA has little information to estimate the range of unintended effects that may occur and their probability 

of occurrence as a result of exposure to dsRNA in the environment. 

a. Please comment on the unintended effects that EPA might reasonably anticipate in nontarget organisms 

exposed to dsRNAs, the likelihood of such unintended effects, and the biological significance of these 

effects in nontarget organisms, should they occur.

b. To the extent that additional information would reduce uncertainty in addressing these issues, please 

describe specifically the nature of additional information that EPA may need and the degree to which this 

information would reduce uncertainty in the ecological risk assessment. 

Question 7. In sections IV.A.2.a and IV.B.4 of the issue paper, EPA presents the current framework of testing for 

determining nontarget effects resulting from exposure to PIPs and biochemicals, respectively. In section 

IV.A.2.c, EPA also raised potential issues related to nontarget testing with dsRNAs that may arise given 

their unique mode of action, which included 1) the potential influence of latent effects on results of 

nontarget testing, 2) the appropriate life stage for testing, and 3) the possibility for chronic effects. 

a. Please comment on how each of EPA’s current PIP and biochemical frameworks for nontarget effects 

testing will inform risk assessment for dsRNA PIPs and exogenously applied dsRNAs. In providing a 

response, please address the potential for unintended effects as described in Question 7, as well as the 

three issues outlined as concerns for nontarget testing listed above.

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b. What additional nontarget effects testing, if any, should EPA consider to gain a full understanding of the 

potential for dsRNAs to cause effects to nontarget organisms? 

c. What other approaches, such as bioinformatics analysis, may be used to address concerns for effects on 

nontarget species and reduce the set of data requirements?

d. In providing answers to the above subquestions, please be specific in discussing the extent to which 

additional information would reduce the nature and magnitude of these specific areas of uncertainty.

6:00 P.M. Adjournment

Please be advised that agenda times are approximate; when the discussion for one topic is completed, discussions 

for the next topic will begin. For further information, please contact the Designated Federal Official for this 

meeting, Dr. Sharlene Matten, telephone: (202)-564-0130, fax: (202) 564-8382, or email: 

matten.sharlene@epa.gov.

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