APHIS BRS Weed Risk Assessment System for Genetically Engineered Plants

APHIS BRS Weed Risk Assessment System for Genetically Engineered Plants

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The APHIS Weed Risk Assessment System (WRA) is a system being developed by APHIS for the purpose of assessing noxious weed risk of GE organisms. The WRA has several potential uses, including the review of petitions for listing GE plants as Federal Noxious Weeds (7 CFR part 360); our current petition process for nonregulated status; “Am I regulated?” inquiries; and our noxious weed authority if incorporated under new regulations (7 CFR part 340).  

The WRA is a valuable tool for gathering, integrating, and assessing evidence to inform regulatory decision-making. It was created because APHIS needed a more systematic and standardized approach under our current petition process. It helps an assessor identify critical weediness and impact characteristics for a given species; identifies characteristics of GE plants that could plausibly increase weed risk (comparative assessment); and helps identify important knowledge gaps.  

Weed Risk Assessment System  

APHIS evaluated existing weed risk assessment models and found that they can identify potentially invasive plant species prior to their introduction to a country or region. However, crop plants present a particular challenge because most are already present in the United States, typically for decades or centuries.  Many possess some characteristics of weeds, such as high reproductive potential and tolerance to pests, yet do not persist in the environment.  Additionally, existing WRA models are not designed to compare varieties within a species (e.g., the weediness of a GE corn variety compared with a conventional corn) assess plants at the variety level (plants with distinct, consistent differences from other members of the species) relevant to GE plants, and GE traits often have no historical record and are not well studied for weed risk, which can contribute uncertainty to the assessment.  

After evaluating WRA models worldwide, APHIS` Biotechnology Regulatory Services (BRS) found the one closest to home–APHIS’ Plant Protection and Quarantine (PPQ) Plant Epidemiology and Risk Analysis Laboratory (PERAL) model–to be the best fit as a starting point to assess GE plants in agriculture. We adapted the weed risk assessment model developed by PERAL to best meet our specific needs; that is, the need to assess plants that are bred to fulfill a role in agriculture. 

APHIS BRS Weed Risk Assessment

For the BRS WRA system, a non-GE (baseline) WRA of a plant taxon is prepared first, to serve as a basis for comparative assessment of weed risk between a GE plant and its non-GE counterpart. Risk assessors collect, document, and analyze objective, evidence-based information about the biology of the baseline and GE plants, as well as their impacts, if any, to agricultural plants and agriculturally important natural resources.  The WRA includes 25 background questions on the taxonomy, biology, cultivation, and distribution of the plant as well as 25 weed risk questions (16 biology and 9 impact questions). These questions cover a wide range of topics such as whether the plant could establish, persist, and spread without intentional human assistance; whether the plant is reported as native, escaped, naturalized, weedy, or invasive; the reproductive ability of the plant; the plant’s stress tolerance; and whether the plant could reduce agricultural yield or quality. The risk assessor answers each question, assigns a certainty rating for his or her findings and conclusions, and provides a written explanation using supporting evidence.  

The assessor’s findings are based on a close examination of current scientific literature, including resources such as peer-reviewed journals and archives; reports and databases from academia, scientific societies, government meeting and conference papers; applicant-provided reports of internal research; information from developers; and theses reporting original research. The completed GE WRA presents an overall qualitative characterization of weed risk of the GE plant and indicates any changes in risk compared to the baseline, including risks supported by documented evidence and plausible risk hypotheses. Plausible risk hypotheses are based on knowledge of the mechanism of action of the introduced gene(s) and/or the intended phenotype. For each assessment, the risk assessor develops a comprehensive summary that includes biological and impact information of the GE plant and information regarding the baseline, non-GE crop and sexually compatible wild relatives, if any, to further inform risk management decisions.  This information will also be made available to the public to support and increase understanding of how risk management decisions are made.  

Revised Regulatory Framework

The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) is proposing revisions to its regulations at 7 CFR part 340 that will balance oversight and risk, based on the best available science. Under the proposed revisions, APHIS would only regulate genetically engineered (GE) plants if they pose weed or plant pest risks, consistent with our authority under the Plant Protection Act.  

For noxious weed risks, the following five focus areas support our mission to protect plant health. Would the GE plant or GE relative be expected to…  

  1. Displace native/established organisms that are agriculturally important?

  2. Including plant products derived from them, degrade community structure in agriculture and agriculturally-important environments or degrade agricultural ecosystem function?

  3. Negatively affect the production or quality of an agriculturally important plant?

  4. Including plant products derived from them, contain a new end product (or increased levels of an end-product) that causes toxicity, resulting in decreases in agriculturally beneficial organisms?

  5. Cause damage to other plants or plant products when there is mixing of the GE plant, GE relative, or plant products with other plants or plant products?

Upfront Risk Analysis

In concert with the proposed revised regulations, APHIS is developing an upfront risk analysis process that includes an evidenced-based, standardized approach to analyzing risk prior to making the decision whether to regulate.  For plants, this process includes a Weed Risk Assessment (WRA) to characterize the weed risks, if any, of genetically engineered (GE) plants. For other organisms, it includes a Plant Pest Risk Assessment (PPRA) to characterize the plant pest risk, if any. This upfront risk analysis emphasizes our risk assessment experience with GE organisms and places oversight on those organisms that represent an identified risk to plant health.

Example Weed Risk Assessments

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