Modelling the Spatio-Temporal Concentration of Diesel Particulate Matter in an Underground Mine

Diesel Particulate Matter (DPM) is an important pollutant, both in industrial areas and cities, and also in underground mines. DPM is essentially the carbonaceous aerosol emitted by diesel engines, with a primary particle size of 10-30 nm, though which rapidly agglomerates to form 100-300 nm aerosols. Most guidelines limit occupational exposure to DPM (measured as elemental carbon) to 100 μg/m3, on an 8-hr averaged basis. However directly assessing worker exposure is both time consuming and expensive. Apart from sampling the exposure of each individual worker, or conducting continuous (and expensive) monitoring, it is difficult to determine if the DPM levels in a workplace will be sufficient to cause DPM exposures above guideline levels. This work has developed a combined particle dynamics and Bayesian regression model, which allows the DPM levels in an underground mine to be predicted both spatially and temporally. The model incorporates known physical effects, (airflow conditions, dispersion, agglomeration), vehicle movement and vehicle emission rates. This enables the model to account for changing (increased) levels of productivity in the mine, a change in the vehicle fleet, or other such factors. The model has been validated against a monitoring study performed in the mine

Pathogens and Public Swimming Pools

Swimming pools are increasingly recognised as an important transmission route of cryptosporidiosis. Swimmers are infected through ingestion of waterborne faecal matter. The infective oocycts resulting from one Accidental Faecal Release (AFR) may be prolific. A swimmer swallowing just 10 ml of water would ingest an average of 200 oocysts, which is well above the dose capable of causing infection.

Cardiovascular disease risk score prediction models for women and its applicability to Asians

Purpose: Although elevated cardiovascular disease (CVD) risk factors are associated with a higher risk of developing heart conditions across all ethnic groups, variations exist between groups in the distribution and association of risk factors, and also risk levels. This study assessed the 10-year predicted risk in a multiethnic cohort of women and compared the differences in risk between Asian and Caucasian women. Methods: Information on demographics, medical conditions and treatment, smoking behavior, dietary behavior, and exercise patterns were collected. Physical measurements were also taken. The 10-year risk was calculated using the Framingham model, SCORE (Systematic COronary Risk Evaluation) risk chart for low risk and high risk regions, the general CVD, and simplified general CVD risk score models in 4,354 females aged 20–69 years with no heart disease, diabetes, or stroke at baseline from the third Australian Risk Factor Prevalence Study. Country of birth was used as a surrogate for ethnicity. Nonparametric statistics were used to compare risk levels between ethnic groups. Results: Asian women generally had lower risk of CVD when compared to Caucasian women. The 10-year predicted risk was, however, similar between Asian and Australian women, for some models. These findings were consistent with Australian CVD prevalence. Conclusion: In summary, ethnicity needs to be incorporated into CVD risk assessment. Australian standards used to quantify risk and treat women could be applied to Asians in the interim. The SCORE risk chart for low-risk regions and Framingham risk score model for incidence are recommended. The inclusion of other relevant risk variables such as obesity, poor diet/nutrition, and low levels of physical activity may improve risk estimation

Antimicrobial resistance in gram-positive cocci isolated from poultry in Western Australia : an assessment of poultry meat as a vehicle for the transmission of resistant strains via the food chain.

The aim of this study was to examine whether Gram-positive cocci isolated from processed poultry in Western Australia provided a potential risk for the transfer of antimicrobial-resistant organisms to humans via commercially prepared ready-to-eat chicken. Research in this study was conducted in three phases: the characterisation of Gram-positive cocci isolated from poultry, an assessment of the isolates' thermal tolerance and the development of a Hazard Analysis Critical Control Points (HACCP) based food-safety program. In the first phase of the study, three specific objectives were investigated. The first determined the presence of Gram-positive cocci on poultry and on processing equipment from poultry-processing plants. The findings confirm the presence of staphylococci and enterococci on incoming live and slaughtered birds and processed carcasses. The data also indicate that carcasses probably become cross-contaminated during processing, when these bacteria are present on the incoming live birds and equipment. The second objective was to characterise staphylococcal isolates by antimicrobial susceptibility testing, and chromosomal and plasmid DNA analysis. The susceptibility of isolates to antimicrobial agents was tested by the disk diffusion method according to the NCCLS (National Committee for Clinical Laboratory Standards) guidelines. Isolates were typed by contour-clamped homogeneous electric field (CHEF) gel electrophoresis of SmaI digested chromosomal DNA, and plasmids were isolated by the cetyltrimethylammonium bromide (CTAB) method. Approximately 37% of Staphylococcus aureus and 16% of coagulase-negative staphylococcal (CNS) isolates were resistant to six or more of the antimicrobial agents tested. Many isolates exhibited resistance to antibiotics that are commonly used in human medicine and registered for veterinary use in Australia.Among the S. aureus isolates there were twenty-four epidemiologically unrelated SmaI CHEF groups. All staphylococcal isolates, except three CNS, were found to harbour from one to seven plasmids. Some staphylococcal isolates with epidemiologically related CHEF patterns had similar plasmid profiles and resistance patterns. The third objective was to determine the antimicrobial susceptibility of enterococci isolates to the glycopeptide antibiotics. The isolation of two vancomycin-resistant E. faecalis isolates is the first report of VRE outside the health-care setting in Western Australia. Additionally the detection of the vanA gene in an E. gallinarum isolate, a motile enterococcus, has potentially important implications for infection control practices in hospitals. In the second phase of the study, three specific objectives were established to investigate the practical implications of these findings for the chicken industry. The first objective of this phase of the study was to determine the thermal tolerance (D and Z-values) of antimicrobial-resistant, Gram-positive cocci in ground chicken meat. The results indicate that these isolates do not exhibit enhanced thermal-resistance characteristics compared to antimicrobial-susceptible bacteria. The second objective established the internal time-temperature profiles for cooking commercially prepared chicken and estimated the process lethality (F-values).From three cooking trials, it was confirmed that the internal temperature of at least 70°C was achieved for at least thirty-eight minutes. The third objective of this phase assessed the effectiveness of the thermal process in reducing the risk of the transfer of antimicrobial-resistant cocci via the food chain. The data confirm that the lethal effect (F-values) of the thermal process destroyed these antimicrobial-resistant cocci in commercially prepared ready-to-eat chicken. In the third phase of the study, the data obtained in the earlier parts of the study was incorporated into a model food-safety program for a fast-food chicken chain. The model was based upon the internationally accepted HACCP system, adopted by the Codex Alimentarius Commission. Mindful that the thermal-process step represents only one critical control point in the safe preparation of chicken, this preventative approach ensures that all hazards are controlled at every other step of the process. The data suggest that antimicrobial-resistant, Gram-positive cocci will be present on some ready-to-cook poultry meat processed in Western Australia. This creates opportunities for the potential spread of resistant strains or resistance genes to humans via the food chain. The information from this study will be useful in providing background data and direction for future planning in preventing antimicrobial-resistant bacteria from poultry meat being transmitted through the food chain. The full implementation of the HACCP program would offer substantial benefits and protection to consumers

Food Safety and Risk Analysis

Food safety is defined by the World Health Organization as the assurance that food will not cause harm to the consumer when it is prepared and eaten according to its intended use. It is estimated that, annually, one-third of the populations of developed countries are affected by foodborne disease and, globally, food and waterborne diseases kill an estimated 1.8 million people, mostly in developing countries, with the majority of victims being children.Environmental health professionals have an important role in the challenging task of protecting the community from foodborne disease. To manage resources effectively, they need to understand current and emerging food safety challenges, the causes and consequences of foodborne disease, and the food safety tools available to identify and control food safety hazards.By applying the three risk analysis principles of risk assessment, risk management, and risk communication, environmental health professionals are able to develop food safety policies based on sound scientific evidence that are effectively communicated and implemented by all stakeholders including industry, governments, and consumers at all stages of the food chain. The resultant integrated food safety systems can operate at an international, national, local, or business level to improve public health and facilitate trade

Indoor air pollution and its health impacts on woman and children in rural China

Indoor air pollution (IAP) from solid fuel combustion is a prominent risk factor in women and children in rural China. About two-thirds of China’s population lives in rural areas where solid fuels are the primary sources of energy. Burning solid fuel on open fires and in poorly ventilated stoves produces toxic substances that can exceed recommended exposure levels in homes that are inadequately ventilated. Despite programs to improve stoves, China’s at risk population, principally women and children, continue to suffer from high exposure to health-damaging pollutants. This paper reviews IAP sources in rural China and the health impact on occupants, in particular women and children, exposed to harmful pollutants from burning solid fuels for domestic energy purposes