Adult Aedes aegypti (Linnaeus) (Diptera: Culicidae) were previously recovered from emergence traps on septic tanks in southeastern Puerto Rico. In this study we quantified immature mosquito abundance and its relationship with structural variables of the septic tanks and chemical properties of the water containing raw sewage. A miniaturized floating funnel trap was used to sample 89 septic tanks for larvae in the Puerto Rican community of Playa-Playita. Aedes aegypti larvae were recovered from 18% of the sampled tanks (10.3 larvae per septic tank per day). Larval presence was positively associated with cracking of the septic tank walls and uncovered access ports. Larval abundance was positively associated with cracking of the septic tank walls and larger tank surface areas, and inversely associated with the total dissolved solids (TDS). Culex quinquefasciatus (Say) larvae were also recovered from 74% of the septic tanks (129.6 larvae per septic tank per day). Larval presence was negatively associated with TDS in the water and larval abundance was positively associated with cracking of the septic tank walls. A screened, plastic emergence trap was used to sample 93 septic tanks within the community for Ae. aegypti and Cx. quinquefasciatus adults. Aedes aegypti adults were recovered from 49% of the sampled tanks (8.7 adults per septic tank per day) and Cx. quinquefasciatus adults were recovered from 97% of the sampled tanks (155.5 adults per septic tank per day). Aedes aegypti adult presence was positively associated with cracking, uncapped openings and septic water pH. The Ae. aegypti adult counts were positively associated with cracking and inversely associated with TDS and conductivity. This study marks the first published record of the recovery of Ae. aegypti larvae from holding tanks containing raw sewage in the Caribbean region. Our study indicates that Ae. aegypti larvae are present in sewage water and that septic tanks have at least the potential to maintain dengue transmission during the dry season.

Solid phase microextraction with analysis by gas chromatography to determine short term hydrogen cyanide concentrations in a field settingOccupational air concentration ceiling standards should not be exceeded during any part of a working exposure. Air sampling with pumps, and filters or sorbent tubes may be coupled to methods such as gas chromatography for definitive identification of occupational air contaminants. With such methods, 15-minute sample durations are common for ceiling standard comparisons (to trap sufficient analyte for detection) giving a 15-minute time-weighted average, and not an instantaneous concentration. We used 2-minute duration solid phase microextraction (SPME) field sampling, followed later by gas chromatography with a nitrogen-phosphorous detector (GC/ NPD) to detect, identify, and quantify airborne hydrogen cyanide (HCN) concentrations encountered in a field setting. The presence of HCN was confirmed in the atmosphere sampled by SPME field sampling followed by gas chromatography with mass spectrometric detection. The HCN-contaminated atmosphere was from two CS riot control canisters actuated in an enclosed building. With four simultaneous SPME field samples and GC/NPD analysis, the coefficient of variation associated with the HCN peak areas for the samples was 17%, and the HCN concentrations measured ranged from about 12 to 19 ppm. Acetonitrile and acrylonitrile were also detected as volatile nitrogen-containing air contaminants dispersed along with the CS, although their concentrations were not determined.

The opinions or assertions contained herein are the private ones of the authors and are not to be construed as official or reflecting the views of the United States Department of Defense or the Uniformed Services University of the Health Sciences. Rapid on-site detection and identification of environmental contaminants to which personnel may be exposed is often needed during military deployment situations. The availability of military industrial hygienists with capabilities for "complete" on-site exposure assessment of chemical species should allow detection and identification of a number of important stressors almost immediately following sample collection. Portable gas chromatography/mass spectrometry (GC/MS) provides a rapid and efficient separation of volatile and semivolatile organic analytes, accompanied by sensitive electron impact ionization-mass spectrometry (EI-MS) detection. The use of GC/MS in the field is limited, however, by equipment cost, complexity of the equipment, and the analytical process. Additionally, a skilled operator is needed to obtain useful separations and to interpret mass spectral data. To demonstrate benefits and limitations of "complete" exposure assessment capabilities, a previously unidentified complex mixture, produced by thermal dispersion of riot control agents, was examined. Established active sampling methods were used with laboratory analyses. Solid phase microextraction, a passive sampling method that simplifies preparation for GC/MS analysis, also was used with a field-portable GC/MS system. Both sampling/analysis methods were used to detect CS riot control agent-derived air contaminants dispersed from riot control type canisters through oxidizer-supported combustion of a chemical fuel.

High temperature dispersion (greater than 700 degrees C) of the riot control agent orthochlorobenzylidenemalononitrile (CS) has previously been shown to produce a number of organic thermal degradation products through rearrangements and loss of cyano and chlorine substituents present on the parent CS compound. Until now the possibility that HCN and HCl might also be air contaminants produced during high temperature CS dispersion has not been examined. Air samples were collected to detect HCN and HCl as air contaminants released during high-temperature CS dispersion indoors. Sampling and analysis based on National Institute of Occupational Safety and Health methods 7904 and 6010 for HCN, and 7903 for HCl, showed evidence that both compounds were present in air samples collected. A reassessment of human health risks associated with exposure to CS riot control agent dispersed at high temperature should be conducted, and should consider the full range of contaminants produced during the dispersion process.