Biosafety reviewers often face uncertainty when certain data needed for a complete evaluation are missing. Risk-assessment research is designed to provide information and generate data that fill in knowledge gaps and expand basic understanding of crop biology, agricultural ecosystems, and the ecological interactions of crop plants and their environment.
High-priority topics for risk-assessment research are often identified in the course of biosafety reviews. They may take the form of questions such as:
• What characteristics of the crop limit its ability to become established, persist, or spread in the environment where it grows?
• How will the genetic modification change this?
• In cases where crops and their wild relatives are known to hybridize naturally:
- Are there genetic mechanisms that favor or hinder gene introgression?
- What is the relative fitness of hybrid progeny?
- Will they have ecological characteristics that are more problematic than either parent?
• Where the engineered trait confers pest resistance:
- What are the potential secondary effects? (e.g., changes in local/field-level ecology)
- What new problems may develop as a result? (e.g., emergence of alternative pests as a consequence of changes in pesticide applications)
• Where the engineered trait confers virus resistance:
- What viruses other than the target virus infect the crop?
- What is the incidence of multiple virus infection?
- What are the similarities and differences in the replication mechanisms of infecting viruses?
• Regarding the new gene product:
- What parts of the engineered plant will contain the new protein?
- What nontarget species will be exposed to it?
- What is its toxicity to those species?
- What is their expected level of exposure?
- What are the likely biological effects of exposure?
These questions, and others like them, reflect sharpened awareness of (1) the ecological complexities of cultivated fields and adjacent areas;
(2) the potential for long-term effects whose nature and probability can only be guessed; and
(3) the knowledge gaps that hamper science-based decision making. These same types of questions, modified to fit a particular interaction among crop, introduced trait, location, and scale and expanded to cover any other applicable environmental or ecological considerations, constitute the basis of risk assessment for a proposed GMO field test or commercial use. It must be emphasized, however, that lack of complete knowledge should not prevent biosafety decision making. An element of uncertainty will always be present.
The primary human health concern with foods produced from transgenic crops is that new proteins expressed in the GM plant may be hazardous - they may be toxic or cause an allergic reaction. Other hazards may include reduced levels of certain nutrients, or elevated levels of certain antinutri-ents. Genes themselves are made of DNA and are present in all foods. DNA ingestion is not associated with any negative health effects.
In general, health ministries are responsible for the safety of foods including those derived through biotechnology. Biosafety risk assessors review data on the nature and expression of newly inserted genes, detailed characterization of new proteins, changes in composition or nutritional qualities of food, intended new uses of the product, and a comparison of the new food with conventional counterparts.
Countries that are signatories to Codex Alimentarius, the international commission that sets food safety standards, usually have reactive rather than proactive food-safety regulations in place - that is, regulatory supervision begins only when products are commercialized. Codex requires that any new food that varies from its conventional counterpart in composition, nutrition, or intended use must be labeled as such. Thus, according to Codex rules, foods produced using oil from GM canola having a modified fatty acid profile are routinely labeled. Note that labeling is required because of the altered composition of the oil, not because it came from a GM crop.
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