Residual methamphetamine in decontaminated clandestine drug laboratories.

This pilot cross-sectional study examined three previously decontaminated residential clandestine drug laboratories (CDLs) in Washington State to determine the distribution and magnitude of residual methamphetamine concentrations relative to the state decontamination standard. A total of 159 discrete random methamphetamine wipe samples were collected from the three CDLs, focusing on the master bedroom, bathroom, living room, and kitchen at each site. Additional samples were collected from specific non-random locations likely to be contacted by future residents (e.g., door knobs and light switches). Samples were analyzed for methamphetamine by EPA method 8270 for semivolatile organic chemicals. Overall, 59% of random samples and 75% of contact point samples contained methamphetamine in excess of the state decontamination standard (0.1 micro g/100 cm(2)). At each site, methamphetamine concentrations were generally higher and more variable in rooms where methamphetamine was prepared and used. Even compared with the less stringent standard adopted in Colorado (0.5 micro g/100cm(2)), a substantial number of samples at each site still demonstrated excessive residual methamphetamine (random samples, 25%; contact samples, 44%). Independent oversight of CDL decontamination in residential structures is warranted to protect public health. Further research on the efficacy of CDL decontamination procedures and subsequent verification of methods is needed.