Sampling scheme for pyrethroids on multiple surfaces on commercial aircrafts

Usefulness and applicability of infectious disease control measures in air travel: a review

BACKGROUND

Air travel has opened up opportunities for world transportation, but has also increased infectious disease transmission and public health risks. To control disease spread, airlines and governments are able to implement control measures in air travel. This study inventories experiences and applicability of infectious disease control measures.

METHODS

A literature search was performed in PubMed, including studies between 1990 and 2013. Search terms included air travel terms and intervention terms. Interventions were scored according outcome, required resources, preparation, passenger inconvenience and passenger compliance.

RESULTS

Provision of information to travelers, isolation, health monitoring, hygiene measures and vector control reportedly prevent disease spread and are well applicable. Contact tracing can be supportive in controlling disease spread but depend on disease characteristics. Exit and entry screening, quarantine and travel restrictions are unlikely to be very effective in preventing disease spread, while implementation requires extensive resources or travel implications.

CONCLUSIONS

Control measures should focus on providing information towards travelers, isolation, health monitoring and hygiene measures. Appropriateness of measures depends on disease characteristics, and the required resources. As most studies analyze one type of measure in a particular situation, further research comparing the effectiveness of measures is recommended.

Modeling flight attendants' exposures to pesticide in disinsected aircraft cabins

Aircraft cabin disinsection is required by some countries to kill insects that may pose risks to public health and native ecological systems. A probabilistic model has been developed by considering the microenvironmental dynamics of the pesticide in conjunction with the activity patterns of flight attendants, to assess their exposures and risks to pesticide in disinsected aircraft cabins under three scenarios of pesticide application. Main processes considered in the model are microenvironmental transport and deposition, volatilization, and transfer of pesticide when passengers and flight attendants come in contact with the cabin surfaces. The simulated pesticide airborne mass concentration and surface mass loadings captured measured ranges reported in the literature. The medians (means ± standard devitions) of daily total exposure intakes were 0.24 (3.8 ± 10.0), 1.4 (4.2 ± 5.7), and 0.15 (2.1 ± 3.2) μg day(-1) kg(-1) of body weight for scenarios of residual application, preflight, and top-of-descent spraying, respectively. Exposure estimates were sensitive to parameters corresponding to pesticide deposition, body surface area and weight, surface-to-body transfer efficiencies, and efficiency of adherence to skin. Preflight spray posed 2.0 and 3.1 times higher pesticide exposure risk levels for flight attendants in disinsected aircraft cabins than top-of-descent spray and residual application, respectively.

Computational fluid dynamics modeling of transport and deposition of pesticides in an aircraft cabin

Spraying of pesticides in aircraft cabins is required by some countries as part of a disinsection process to kill insects that pose a public health threat. However, public health concerns remain regarding exposures of cabin crew and passengers to pesticides in aircraft cabins. While large scale field measurements of pesticide residues and air concentrations in aircraft cabins scenarios are expensive and time consuming, Computational Fluid Dynamics (CFD) models provide an effective alternative for characterizing concentration distributions and exposures. This study involved CFD modeling of a twin-aisle 11 row cabin mockup with heated manikins, mimicking a part of a fully occupied Boeing 767 cabin. The model was applied to study the flow and deposition of pesticides under representative scenarios with different spraying patterns (sideways and overhead) and cabin air exchange rates (low and high). Corresponding spraying experiments were conducted in the cabin mockup, and pesticide deposition samples were collected at the manikin's lap and seat top for a limited set of five seats. The CFD model performed well for scenarios corresponding to high air exchange rates, captured the concentration profiles for middle seats under low air exchange rates, and underestimated the concentrations at window seats under low air exchange rates. Additionally, both the CFD and experimental measurements showed no major variation in deposition characteristics between sideways and overhead spraying. The CFD model can estimate concentration fields and deposition profiles at very high resolutions, which can be used for characterizing the overall variability in air concentrations and surface loadings. Additionally, these model results can also provide a realistic range of surface and air concentrations of pesticides in the cabin that can be used to estimate potential exposures of cabin crew and passengers to these pesticides.

Exposure of flight attendants to pyrethroid insecticides on commercial flights: urinary metabolite levels and implications

Pyrethroid insecticides have been used for disinsection of commercial aircrafts. However, little is known about the pyrethroids exposure of flight attendants. The objective of the study was to assess pyrethroids exposure of flight attendants working on commercial aircrafts through monitoring the urinary pyrethroids metabolite levels. Eighty four urine samples were collected from 28 flight attendants, 18-65 years of age, with seventeen working on planes that were non-disinsected, and eleven working on planes that had been disinsected. Five urinary metabolites of pyrethroids were measured using gas chromatographic-mass spectrometric method: 3-phenoxybenzoic acid (3-PBA), cis-/trans-3-(2,2-Dichlorovinyl)-2,2-dimethylcyclo-propane carboxylic acid (cis-/trans-Cl2CA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclo-propane-1-carboxylic acid (cis-Br2CA) and 4-fluoro-3-phenoxybenzoic acid (4F-3-PBA). Flight attendants working on disinsected planes had significantly higher urinary levels of 3-PBA, cis- and trans-Cl2CA in pre, post- and 24-h-post flight samples than those on planes which did not report having been disinsected. Urinary levels of cis-Br2CA and 4F-3-PBA did not show significant differences between the two groups. Flight attendants working on international flights connected to Australia had higher urinary levels of 3-PBA, cis- and trans-Cl2CA than those on either domestic and other international flights flying among Asia, Europe and North America. Post-disinsection duration (number of days from disinsection date to flight date) was the most significant factor affecting the urinary pyrethroid metabolites levels of 3-PBA, cis- and trans-Cl2CA of the group flying on disinsected aircraft. It was concluded that working on commercial aircraft disinsected by pyrethroids resulted in elevated body burdens of 3-PBA, cis- and trans-Cl2CA.

Comparison of wipe materials and wetting agents for pesticide residue collection from hard surfaces

Different wipe materials and wetting agents have been used to collect pesticide residues from surfaces, but little is known about their comparability. To inform the selection of a wipe for the National Children's Study, the analytical feasibility, collection efficiency, and precision of Twillwipes wetted with isopropanol (TI), Ghost Wipes (GW), and Twillwipes wetted with water (TW), were evaluated. Wipe samples were collected from stainless steel surfaces spiked with high and low concentrations of 27 insecticides, including organochlorines, organophosphates, and pyrethroids. Samples were analyzed by GC/MS/SIM. No analytical interferences were observed for any of the wipes. The mean percent collection efficiencies across all pesticides for the TI, GW, and TW were 69.3%, 31.1%, and 10.3% at the high concentration, respectively, and 55.6%, 22.5%, and 6.9% at the low concentration, respectively. The collection efficiencies of the TI were significantly greater than that of GW or TW (p<0.0001). Collection efficiency also differed significantly by pesticide (p<0.0001) and spike concentration (p<0.0001). The pooled coefficients of variation (CVs) of the collection efficiencies for the TI, GW, and TW at high concentration were 0.08, 0.17, and 0.24, respectively. The pooled CV of the collection efficiencies for the TI, GW, and TW at low concentration were 0.15, 0.19, and 0.36, respectively. The TI had significantly lower CVs than either of the other two wipes (p=0.0008). Though the TI was superior in terms of both accuracy and precision, it requires multiple preparation steps, which could lead to operational challenges in a large-scale study.