A field investigation into the characteristics and formation mechanisms of particles during the operation of laser printers and photocopiers.

Indoor particle release from toner printing equipment (TPE) is a major health concern and has received wide attention. In this study, nine printing centers were randomly selected and three working phases were simulated, namely, non-working, normal printing/copying, and heavy printing/copying. The dynamics of the ozone (O3), volatile organic compound (VOC), and particle emissions from TPE were determined by portable detectors. Results showed that particles, VOCs, and O3 were indeed discharged, and particles and VOCs concentrations remained at high levels. Among them, 44% of the rooms represented high-level particle releases. Submicrometer-sized particles, especially nanoparticles, were positively correlated with VOCs, but were inversely proportional to the O3 concentration. Four elements, Ca, Al, Mg and Ni, were usually present in nanoparticles because of the discharge of paper. Si, Al, K, Ni and Pb were found in the submicrometer-sized particles and were consistent with the toner composition. The potential particle precursors were identified, which suggested that styrene was the most likely secondary organic aerosol (SOA) precursor. Overall, the use of the toner formulation and the discharge of paper attribute to the TPE-emitted particles, in which styrene is a specific monitoring indicator for the formation of SOA.

Spatio-temporal analysis of malaria incidence at the village level in a malaria-endemic area in Hainan, China.

BACKGROUND: Malaria incidence in China's Hainan province has dropped significantly, since Malaria Programme of China Global Fund Round 1 was launched. To lay a foundation for further studies to evaluate the efficacy of Malaria Programme and to help with public health planning and resource allocation in the future, the temporal and spatial variations of malaria epidemic are analysed and areas and seasons with a higher risk are identified at a fine geographic scale within a malaria endemic county in Hainan. METHODS: Malaria cases among the residents in each of 37 villages within hyper-endemic areas of Wanning county in southeast Hainan from 2005 to 2009 were geo-coded at village level based on residence once the patients were diagnosed. Based on data so obtained, purely temporal, purely spatial and space-time scan statistics and geographic information systems (GIS) were employed to identify clusters of time, space and space-time with elevated proportions of malaria cases. RESULTS: Purely temporal scan statistics suggested clusters in 2005,2006 and 2007 and no cluster in 2008 and 2009. Purely spatial clustering analyses pinpointed the most likely cluster as including three villages in 2005 and 2006 respectively, sixteen villages in 2007, nine villages in 2008, and five villages in 2009, and the south area of Nanqiao town as the most likely to have a significantly high occurrence of malaria. The space-time clustering analysis found the most likely cluster as including three villages in the south of Nanqiao town with a time frame from January 2005 to May 2007. CONCLUSIONS: Even in a small traditional malaria endemic area, malaria incidence has a significant spatial and temporal heterogeneity on the finer spatial and temporal scales. The scan statistics enable the description of this spatiotemporal heterogeneity, helping with clarifying the epidemiology of malaria and prioritizing the resource assignment and investigation of malaria on a finer geographical scale in endemic areas.

Sensitive and rapid detection of cytolethal distending toxin encoding genes in Providencia alcalifaciens.

Cytolethal distending toxins (CDTs) produced by P. alcalifaciens are considered as potential virulence factors. A loop-mediated isothermal amplification (LAMP) method for the detection of cdtA, cdtB, and cdtC genes was established which showed high specificity and strong sensitivity. The LAMP assay showed a detection threshold was 3.13 pg/µl within 40 min.

Assessment of the inhalation risks associated with working in printing rooms: a study on the staff of eight printing rooms in Beijing, China.

The concentration of pollution directly determines the occupational health risk, and the exposure time is an important influencing factor. We evaluated the inhalation risks of working in a printing room. Eight units with centralized printing rooms were randomly selected. Formaldehyde, ozone, benzene, toluene, xylene, and fine particulate matter were detected by spectrophotometry, gas chromatography, and direct reading instruments, respectively. The U.S. EPA inhalation risk assessment model was used to assess cancer and non-cancer risks. The formaldehyde inhalation cancer risk value was 1.35-3.45 × 10-6, which is greater than the limit of 1 × 10-6, suggesting a risk of squamous cell carcinoma. The benzene inhalation cancer risk in five of the rooms was 1.09-4.65 × 10-6, which is greater than the limit of 1 × 10-6, suggesting a risk of leukemia. In terms of non-cancer risk, in five of the rooms, the hazard quotient (HQ) was > 1 (range 1.99-4.69) due to benzene pollution, suggesting a risk of reduced lymphocyte count. In one room, due to benzene and xylene pollution, the HQ was > 1, suggesting a risk of lymphocyte count drop and motor coordination impairment. Collectively, the study concludes that staff members of printing rooms are exposed to both cancer and non-cancer occupational health risks.

Detection and identification of intestinal pathogenic bacteria by hybridization to oligonucleotide microarrays.

AIM: To detect the common intestinal pathogenic bacteria quickly and accurately. METHODS: A rapid (<3 h) experimental procedure was set up based upon the gene chip technology. Target genes were amplified and hybridized by oligonucleotide microarrays. RESULTS: One hundred and seventy strains of bacteria in pure culture belonging to 11 genera were successfully discriminated under comparatively same conditions, and a series of specific hybridization maps corresponding to each kind of bacteria were obtained. When this method was applied to 26 divided cultures, 25 (96.2%) were identified. CONCLUSION: Salmonella sp., Escherichia coli, Shigella sp., Listeria monocytogenes, Vibrio parahaemolyticus, Staphylococcus aureus, Proteus sp., Bacillus cereus, Vibrio cholerae, Enterococcus faecalis, Yersinia enterocolitica, and Campylobacter jejuni can be detected and identified by our microarrays. The accuracy, range, and discrimination power of this assay can be continually improved by adding further oligonucleotides to the arrays without any significant increase of complexity or cost.

Whole-genome Sequencing for Tracing the Transmission Link between Two ARD Outbreaks Caused by a Novel HAdV Serotype 7 Variant, China.

From December 2012 to February 2013, two outbreaks of acute respiratory disease caused by HAdV-7 were reported in China. We investigated possible transmission links between these two seemingly unrelated outbreaks by integration of epidemiological and whole-genome sequencing (WGS) data. WGS analyses showed that the HAdV-7 isolates from the two outbreaks were genetically indistinguishable; however, a 12 bp deletion in the virus-associated RNA gene distinguished the outbreak isolates from other HAdV-7 isolates. Outbreak HAdV-7 isolates demonstrated increased viral replication compared to non-outbreak associated HAdV-7 isolate. Epidemiological data supported that the first outbreak was caused by introduction of the novel HAdV-7 virus by an infected recruit upon arrival at the training base. Nosocomial transmission by close contacts was the most likely source leading to onset of the second HAdV-7 outbreak, establishing the apparent transmission link between the outbreaks. Our findings imply that in-hospital contact investigations should be encouraged to reduce or interrupt further spread of infectious agents when treating outbreak cases, and WGS can provide useful information guiding infection-control interventions.

[Effect of low intensity and very high frequency electromagnetic radiation on occupationally exposed personnel].

OBJECTIVE: To investigate the effect of low intensity and very high frequency (VHF) electromagnetic radiation (170 MHz) on nervous system function and serum enzymes and immune function in human subjects with occupational exposure to VHF. METHODS: To measure the intensity of VHF and other environmental factors on the spot, to hold the questionnaire about chief complaints, to examine the rheoencephalography and the neurobehavior function, to analyze ALT, AST, ALP and LDH, and IgA, IgM and IgG in experimental group and control group. RESULTS: The intensity of VHF (direction of antenna: 0 degrees, 10 m and 135 degrees, 20 m) was higher than that of national standard on-the-spot. The incidences of symptoms such as headache, insomnia and amnesia etc. was significantly higher in experimental group (P < 0.01). Rheoencephalography indicated that the raising time of both left [(0.155 3 +/- 0.057 9) s] and right [(0.154 1 +/- 0.059 2) s] in the experimental group after exposure were significantly longer than before exposure [(0.104 4 +/- 0.030 2) s, (0.103 2 +/- 0.030 4) s respectively] or in the control [(0.118 5 +/- 0.056 8) s, (0.117 7 +/- 0.057 5) s respectively, (P < 0.01)]. Neurobehavior function test showed that digital symbol, digital span and pursuit aiming test were decreased after exposure in the experimental group (P < 0.01). Serum enzyme analysis showed that AST, ALP and LDH were significantly increased after exposure in the experimental group (P < 0.01). No marked change was found in IgA level, while the levels of IgM and IgG after exposure in the experimental group especially the latter were significantly increased (P < 0.01). CONCLUSIONS: Low-intensity VHF radiation can decrease the nervous system function in occupationally exposed personnel and induce increase in some kinds of enzymes and immunoglobulins.

Transmission characteristics of different students during a school outbreak of (H1N1) pdm09 influenza in China, 2009.

Many outbreaks of A(H1N1)pdm09 influenza have occurred in schools with a high population density. Containment of school outbreaks is predicted to help mitigate pandemic influenza. Understanding disease transmission characteristics within the school setting is critical to implementing effective control measures. Based on a school outbreak survey, we found almost all (93.7%) disease transmission occurred within a single grade, only 6.3% crossed grades. Transmissions originating from freshmen exhibited a star-shaped network; other grades exhibited branch- or line-shaped networks, indicating freshmen have higher activity and are more likely to cause infection. R0 for freshmen, calculated as 2.04, estimated as 2.76, was greater than for other grades (P < 0.01). Without intervention, the estimated number of cases was much greater when the outbreak was initiated by freshmen than by other grades. Furthermore, the estimated number of cases required to be under quarantine and isolation for freshmen was less than that of equivalent other grades. So we concluded that different grades have different transmission mode. Freshmen were the main facilitators of the spread of A(H1N1)pdm09 influenza during this school outbreak, so control measures (e.g. close contact isolation) priority used for freshmen would likely have effectively reduced spread of influenza in school settings.

[Spatial epidemiological study on malaria epidemics in Hainan province].

OBJECTIVE: To better understand the characteristics of spatial distribution of malaria epidemics in Hainan province and to explore the relationship between malaria epidemics and environmental factors, as well to develop prediction model on malaria epidemics. METHODS: Data on Malaria and meteorological factors were collected in all 19 counties in Hainan province from May to Oct., 2000, and the proportion of land use types of these counties in this period were extracted from digital map of land use in Hainan province. Land surface temperatures (LST) were extracted from MODIS images and elevations of these counties were extracted from DEM of Hainan province. The coefficients of correlation of malaria incidences and these environmental factors were then calculated with SPSS 13.0, and negative binomial regression analysis were done using SAS 9.0. RESULTS: The incidence of malaria showed (1) positive correlations to elevation, proportion of forest land area and grassland area; (2) negative correlations to the proportion of cultivated area, urban and rural residents and to industrial enterprise area, LST; (3) no correlations to meteorological factors, proportion of water area, and unemployed land area. The prediction model of malaria which came from negative binomial regression analysis was: I (monthly, unit: 1/1,000,000) = exp (-1.672-0.399xLST). CONCLUSION: Spatial distribution of malaria epidemics was associated with some environmental factors, and prediction model of malaria epidemic could be developed with indexes which extracted from satellite remote sensing images.