Evaluating screening test protocols to assess methamphetamine contamination in buildings

Area of Science:

• Environmental Science
• Forensic Science
• Public Health

Background:

• Methamphetamine (meth) contamination in buildings necessitates regulatory sampling, which can be expensive.
• Current screening tests use fewer samples and biased collection to reduce costs and minimize false negatives (FN), but their accuracy is unproven.

Purpose of the Study:

• To evaluate the accuracy of two less costly meth screening protocols compared to the comprehensive Colorado regulatory protocol.
• To determine the frequency of false positive (FP) and false negative (FN) results for the screening tests.
• To identify potential thresholds for screening tests to trigger further comprehensive testing.

Main Methods:

• Compared results from two Colorado screening protocols against the comprehensive regulatory protocol as the benchmark.
• Evaluated screening tests for FP and FN results, with a focus on FN occurrences.
• Utilized logistic regression to determine FN rates across various threshold concentrations.
• Calculated location-specific and whole-house average meth concentrations to identify contamination hotspots.

Main Results:

• Few false negatives (FN) were observed, and in those cases, contamination levels above regulatory standards were minimal.
• Both screening tests demonstrated FN rates approaching 0% when a threshold lower than the regulatory standard was applied.
• Identified specific hotspots for meth contamination, including kitchen fan/stove areas (41-fold increase), bathroom exhaust fans (47-fold increase), and furnace/ductwork systems (17-fold increase) compared to average house concentrations.

Conclusions:

• Simplified, less costly meth sampling protocols can serve as a valid screening approach for building contamination.
• Establishing appropriate thresholds for screening tests can effectively trigger additional, more comprehensive testing when necessary.
• A validated sampling protocol, including aliquots from identified hotspots, is proposed for effective meth screening.