Monitoring Categories

EXPERIMENTATION

• Gather basic scientific information

• Test pre-release assumptions

• Improve experimental design

TRACKING

• Product development/marketing

• Regulatory compliance

• Incremental dissemination/dispersal

SURVEILLANCE

• Identified events

• Unanticipated impacts

When the first field tests of GMOs took place, it was not clear what should be monitored, why, or for how long. Monitoring objectives and methodologies were conceived and implemented with no precedent to follow and often resulted in unusable data or no data at all. Subsequently, methods and sampling designs have been refocused through experimentation to accommodate the large-scale releases of GM crops. For example, the issue of monitoring for the development of insect resistance to pesticides was raised as early as 1994 but did not become a major focus of risk-management programs until the commercialization of Bt crops. It is important to note, however, that the utility of monitoring programs is not restricted to answering biosafety concerns or indicating information gaps or the need for new assessments. Monitoring may also indicate a need for a different approach to regulatory or management decisions.

Biosafety Monitoring

Biosafety considerations are important in determining the need for monitoring, identifying appropriate target(s), and justifying the reasons for establishing specified levels of monitoring. Whether a GM crop or its DNA poses a safety concern if it should "move" into adjacent fields or to related plant species is an important environmental issue that raises the question of the extent to which transgene movement can or should be monitored. Furthermore, it necessitates the availability of efficient, accurate, and reliable methods of identifying transgenic material present in unintended locations.

Current methods include use of visual or selectable markers (e.g., P-glucuronidase, antibiotic resistance) or molecular analysis (e.g., PCR, Southern hybridization). Often the decision about what to monitor has depended as much on what is possible to monitor as on the identified concern. However, it is not possible to know what to monitor without knowing what potential problem might arise—the monitoring paradox.

Scales of Monitoring

Monitoring programs fall into three categories—experimentation, tracking, and surveillance. The categories correspond, respectively, to the progressive scale-up in field-test, pre-, and postmarketing stages of product development.

Each successive stage brings different monitoring objectives and the need to consider larger geographic sampling areas and longer term observation regimes. Further, care must be taken in extrapolating experimental field-test monitoring results to commercial applications. For example, significant variations in gene flow measurements have been associated with increasing population size. The increasing temporal and spatial scales of monitoring programs is paralleled by an increasing difficulty to control and implement them (Figure 3). Similarly, the magnitude of potential adverse effect and the degree of uncertainty in the monitored parameter is mirrored by a need to increase the intensity of the monitoring program (Figure 4).

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