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Why is the term "field screening" discouraged under Triad?
 
Answer

Although Triad practitioners may use the term "screening analytical method" to refer to methods with certain characteristics (such as more imprecise, not analyte-specific, higher detection limits, and more biased than available fixed lab methods), they avoid the term "field screening" because this term fosters a number of misconceptions in the environmental community. The term "field screening" is rooted in the first-generation data quality model where the rigor of the method was considered the only determinant of data quality. Issues associated with using this term include the following:

  • "Field screening" implies that analytical data are of screening quality simply by virtue of having been produced in the field. The linkage of "field" with "screening" causes regulators to consider any field-generated data to be unreliable. Perhaps this was justified ten years ago. However, this no longer need be true. With proper QC and planning, modern field analytical technologies can produce data of known quality that are invaluable to CSM development and regulatory decision-making (i.e., decision quality data).


  • "Field screening" implies that there is no expectation that qualified personnel will be involved in planning and operating field technologies. This is not acceptable under the Triad. Historically, poorly trained junior staff performed field testing with little oversight and inadequate or non-existent quality control (QC). Such testing should not be considered "screening," but should be considered "data of unknown quality" and rejected.


  • The term suggests that all methods used in the field qualify as screening analytical methods. Recent advances in the capabilities of analytical technologies, such as field-portable GC-MS, render such assumptions out-of-date.


  • The term implies that traditional fixed laboratories do not produce screening quality data. But previous FAQs in this section have explained why that assumption is incorrect.


  • The term implies that fixed laboratories would never use screening analytical methods. There is tremendous benefit to using screening techniques in fixed laboratories. For example, knowing how heavily contaminated a sample is allows the lab to make better choices for follow-up analysis by more rigorous methods. If rapid turn-around of results is not important to the work plan, the less expensive per-sample costs should allow for more samples to be analyzed in the fixed lab. Finally, sometimes a laboratory is just down the road from the site, and running the samples in the controlled environment of the facility is more cost-effective than setting up an analysis area on-site, and using trained laboratory staff is easier than locating a provider of field analytical services.


  • The term was sometimes used to convey the idea of "screening the site" for hotspots and detecting different contaminant populations. This concept remains the same under the Triad, but is less ambiguous if expressed in terms of "building and refining the conceptual site model."