A 24-hour study to investigate persistent chemical exposures associated with clandestine methamphetamine laboratories.

The clandestine manufacture of methamphetamine continues to be a concern across the United States. Although the exposures associated with the actual production process have been evaluated, the persistence of those exposures in a residential setting have not been investigated. This study was designed to document the contamination associated with two red phosphorous methamphetamine "cooks" conducted in a residence and the associated exposures up to 24 hours after the cook. The two cooks were conducted on the first day of the study, and exposures associated with different occupant activity levels were measured the following day. Airborne methamphetamine levels during the cook ranged from 520 microg/m(3) to 760 microg/m(3). On Day 2, airborne levels of methamphetamine ranged from 70 microg/m(3) to 210 microg/m(3) and increased with moderate to high activity levels within the residence. The majority of the methamphetamine measured during both days had a particle size of less than 1 mum, suggesting that the methamphetamine is formed as a condensation aerosol and is readily resuspended from contaminated surfaces. Significant methamphetamine contamination was found in the carpeting and likely was associated with the elevated levels of methamphetamine during activity. Levels of hydrogen chloride and iodine were also detected on Day 2 of the project although at very low levels. The study concluded that exposures may still present a significant inhalation exposure well after the actual cook.