Quantitative Microbial Risk Assessment (QMRA) of Workers Exposure to Bioaerosols at MSW Open Dumpsites.

The bioaerosol exposure data from the study by Akpeimeh, Fletcher, and Evans (2019) was used to compute the risk of infection from the exposure of dumpsite workers to Aspergillus fumigatus and Escherichia coli O157:H7. A stochastic (Markov Chain) model was used to model the transport of the inhaled dose though the human respiratory system and then integrated into the beta-Poisson dose-response model to estimate workers risks of respiratory and gastrointestinal (GI) infection. The infection risk was computed based on workers exposure to E. coli O157:H7 at 10-50% pathogen ingestion rate and pathogen-indicator ratio (P:I) of 1:103 and 1:104 , while exposure to A. fumigatus was based solely on the average initial exposure dose. The results showed that after 11 hours of exposure, workers engaged in scavenging, waste sorting, and site monitoring were at risk of respiratory and GI infection in the magnitude of 10-1 . However, the risk estimates associated with specific areas of the dumpsite showed that, the risk of GI infection at the active area ranged between 3.23 × 10-3 -1.56 × 10-2 and 3.25 × 10-4 -1.62 × 10-3 ; dormant area 2.06 × 10-3 -1.01 × 10-2 and 2.09 × 10-4 -1.04 × 10-3 ; entrance 1.85 × 10-3 -9.09 × 10-3 and 1.87 × 10-4 -9.27 × 10-4 ; boundary 1.82 × 10-3 -8.82 × 10-3 and 2.09 × 10-4 -8.94 × 10-4 for P:I = 1:103 and 1:104 respectively, while the risk of respiratory infection risks were in the magnitude of 10-1 for all four locations. The estimated risk of workers developing respiratory and gastrointestinal infections were high for all activities assessed at the dumpsite.

Rapid propidium monoazide cPCR assay for exclusive quantification of viable Salmonella spp. cells.

Combination of pretreatment with propidium monoazide by competitive polymerase chain reaction (cPCR) was evaluated to enumerate the viability of Salmonella spp. The results showed that PMA treatment was effective in preventing the cPCR detection of target sequences from non- viable cells. In less than 5 hrs, this method generated a signal from viable but nonculturable (VBNC) Salmonella spp. The standard culture method gave approximately 1-2 log(10)cfu ml(-1) less as compared to the PMA-cPCR results. These results provided evidence to support the VBNC state, whereas, the viable cells failed to be cultured by SCM. The proposed method did not detect DNA from dead Salmonella spp. but recognizes the infectious potential of the VBNC state and is thereby, able to assess the effect of control strategies and provide trustworthy data for risk assessment.

CFD simulation of airborne pathogen transport due to human activities.

Computational Fluid Dynamics (CFD) is an increasingly popular tool for studying the impact of design interventions on the transport of infectious microorganisms. While much of the focus is on respiratory infections, there is substantial evidence that certain pathogens, such as those which colonise the skin, can be released into, and transported through the air through routine activities. In these situations the bacteria is released over a volume of space, with different intensities and locations varying in time rather than being released at a single point. This paper considers the application of CFD modelling to the evaluation of risk from this type of bioaerosol generation. An experimental validation study provides a direct comparison between CFD simulations and bioaerosol distribution, showing that passive scalar and particle tracking approaches are both appropriate for small particle bioaerosols. The study introduces a zonal source, which aims to represent the time averaged release of bacteria from an activity within a zone around the entire location the release takes place. This approach is shown to perform well when validated numerically though comparison with the time averaged dispersion patterns from a transient source. However, the ability of a point source to represent such dispersion is dependent on airflow regime. The applicability of the model is demonstrated using a simulation of an isolation room representing the release of bacteria from bedmaking.

Fruit, fiber, bark, and resin: social organization of a maya urban center.

Quantitative analysis of 3579 trees recorded in the Classic Maya city of Cobá, Quintana Roo, Mexico, indicates a strong relation between the location and quantity of certain trees producing fruit, fiber, bark, and resin, high-status vaulted architecture, and their distance from the center of the site out toward the fringes. The relationships suggest agreement between the residence pattern of Cobá and Diego de Landa's 16th-century class-oriented description of Maya towns during preconquest times.

Exposure to bioaerosols at open dumpsites: A case study of bioaerosols exposure from activities at Olusosun open dumpsite, Lagos Nigeria.

Activities associated with the open dumping of municipal solid waste has the potential for greater impact on the environment and public health compared to other forms of waste-to-land treatment of such wastes. However, there is a lack of quantitative data on the exposure to bioaerosols from open dumpsites, hence impeding the development of effective interventions that would reduce the risk of respiratory symptoms among scavengers and waste workers at such dumpsites. This study investigated exposure to bioaerosols at Olusosun open dumpsite, Lagos Nigeria using three methodologies; (1) Conducting a cross-sectional survey on the respiratory health of the population on the dumpsite, (2) Measuring bioaerosol concentrations in the ambient air by measuring four bioaerosols indicator groups (total bacteria, gram-negative bacteria, Aspergillus fumigatus and total fungi) using a Anderson six stage impactor sampler, (3) Measuring activity related exposures to bioaerosols using an SKC button personal sampler. After a cross sectional health survey of 149 participants (waste workers, scavengers, middlemen, food vendors and business owners), smokers reported higher symptoms of chronic cough (21%) and chronic phlegm (15%) compared to non-smokers (chronic cough 15%, chronic phlegm 13%). Years of work > 5 years showed no statistically significant association with chronic phlegm (OR 1.2, 95% CI 0.4-3.4; p > 0.05) or asthma (OR 1.8, 95% CI 0.6-5.2; p > 0.05). At the 95th percentile, the concentration of total bacteria was the highest (2189 CFU/m3), then gram negative bacteria (2188 CFU/m3), total fungi (843 CFU/m3) and Aspergillus fumigatus (441 CFU/m3) after ambient air sampling. A comparison of the data showed that the activity-based sampling (undertaken using body worn personal sampler) had higher bioaerosols concentrations (104 -106 CFU/m3), i.e. 2-3 logs higher than those recorded from static ambient air sampling. Bioaerosol exposure was highest during scavenging activities compared to waste sorting and site supervision. Particle size distributions showed that 41%, 46%, 76% and 63% of total bacteria, gram-negative bacteria, Aspergillus fumigatus and total fungi respectively were of respirable sizes and would therefore be capable of penetrating deep into the respiratory system, posing a greater human health risk. This study has shown that exposure to bioaerosols can be associated with activities undertaken at open dumpsites and may contribute to the high prevalence of the chronic respiratory symptoms among the workers in such environments.

Pilot-scale biofiltration at a materials recovery facility: The impact on bioaerosol control.

This study investigated the performance of four pilot-scale biofilters for the removal of bioaerosols from waste airstreams in a materials recovery facility (MRF) based in Leeds, UK. A six-stage Andersen sampler was used to measure the concentrations of four groups of bioaerosols (Aspergillus fumigatus, total fungi, total mesophilic bacteria and Gram negative bacteria) in the airstream before and after passing through the biofilters over a period of 11 months. The biofilters achieved average removal efficiency (RE) of 70% (35 to 97%) for A. fumigatus, 71% (35 to 94%) for total fungi, 68% (47 to 86%) for total mesophilic bacteria and 50% (-4 to 85%) for Gram negative bacteria, provided that the inlet concentration was high (103-105 cfu m-3), which is the case for most waste treatment facilities. The performance was highly variable at low inlet concentration with some cases showing an increase in outlet concentrations, suggesting that biofilters had the potential to be net emitters of bioaerosols. The gas phase residence time did not appear to have any statistically significant impact on bioaerosol removal efficiency. Particle size distribution varied between the inlet and outlet air, with the outlet having a greater proportion of smaller sized particles that represent a greater human health risk as they can penetrate deep into the respiratory system where gaseous exchange occurs. However, the outlet concentrations were low and would further be diluted by wind in full scale applications. In conclusion, this study shows that biofilters designed and operated for odour degradation can also achieve significant bioaerosol control in waste gas.

Influence of pH on hydrothermal treatment of swine manure: Impact on extraction of nitrogen and phosphorus in process water.

This study investigates the influence of pH on extraction of nitrogen and phosphorus from swine manure following hydrothermal treatment. Conditions include thermal hydrolysis (TH) at 120°C and 170°C, and hydrothermal carbonisation (HTC) at 200°C and 250°C in either water alone or in the presence of 0.1M NaOH, H2SO4, CH3COOH or HCOOH. Phosphorus extraction is pH and temperature dependent and is enhanced under acidic conditions. The highest level of phosphorus is extracted using H2SO4 reaching 94% at 170°C. The phosphorus is largely retained in the residue for all other conditions. The extraction of nitrogen is not as significantly influenced by pH, although the maximum N extraction is achieved using H2SO4. A significant level of organic-N is extracted into the process waters following hydrothermal treatment. The results indicate that operating hydrothermal treatment in the presence of acidic additives has benefits in terms of improving the extraction of phosphorus and nitrogen.

Phosphate and ammonium sorption capacity of biochar and hydrochar from different wastes.

The potential for biochar and hydrochar to adsorb phosphate and ammonium is important for understanding the influence of these materials when added to soils, compost or other high nutrient containing environments. The influence of physicochemical properties such as mineral content, surface functionality, pH and cation exchange capacity has been investigated for a range of biochars and hydrochars produced from waste-derived biomass feedstocks. Hydrochars produced from hydrothermal carbonisation at 250 °C have been compared to low and high temperature pyrolysis chars produced at 400-450 °C and 600-650 °C respectively for oak wood, presscake from anaerobic digestate (AD), treated municipal waste and greenhouse waste. In spite of differences in char physicochemical properties and processing conditions, PO4-P and NH4-N sorption capacities ranged from about 0 to 30 mg g(-1) and 105.8-146.4 mg g(-1) respectively. Chars with high surface areas did not possess better ammonium adsorption capacities than low surface area chars, which suggests that surface area is not the most important factor influencing char ammonium adsorption capacity, while char calcium and magnesium contents may influence phosphate adsorption. Desorption experiments only released a small fraction of adsorbed ammonium or phosphate (<5 mg g(-1) and a maximum of 8.5 mg g(-1) respectively).

Acute exposure to cyclosporine does not increase plasma homocysteine in rats.

There is interest in the postulate that cyclosporine a (CsA) contributes to the elevated homocysteine levels seen in organ transplant recipients, as hyperhomocysteinemia is now considered an independent risk factor for cardiovascular disease (CVD) and may partially explain the increased prevalence of CVD in this population. The main purpose of this investigation was to determine the effect of CsA administration on plasma homocysteine. Eighteen female Sprague Dawley rats (4 months old) were randomly assigned to either a treatment or a control group. For 18 days the treatment group received of CsA (25 mg/kg/d) while the control group received the same volume of the vehicle. Blood samples obtained following sacrifice to measure CsA, total homocysteine, and plasma creatinine. There were no significant differences in plasma homocysteine (mean values +/- SD: treatment = 4.79 +/- 0.63 micromol/L, control = 4.46 +/- 0.75 micromol/L; P = .37). Homocysteine was not significantly correlated with final CsA concentrations (r = .17; P = .69). There was a significant difference in plasma creatinine values between the two groups (treatment = 60.44 +/- 7.68 micromol/L, control = 46.33 +/- 1.66 micromol/L; P < .001). Furthermore, plasma homocysteine and creatinine were positively correlated with the treatment group (r = .73; P < .05) but not the controls (r = -.10; P = .81). In conclusion, CsA does not influence plasma homocysteine concentrations in rats.

The transmission of tuberculosis in confined spaces: an analytical review of alternative epidemiological models.

Tuberculosis (TB) is a disease that is closely associated with poverty, with transmission occurring in situations where infected persons are in close contact with others in confined spaces. While it is well recognised that overcrowding increases the risk of transmission, this increased risk has not been quantified and the relationship between overcrowding and duration of exposure is not well understood. This paper analyses three epidemiological models that have been used to predict the transmission of airborne disease in confined spaces: the Mass Action model, Riley, Murphy and Riley's model and Gammaitoni and Nucci's model. A study is presented to demonstrate the range of applicability of each model and show how they can be applied to the transmission of both TB and diseases with short incubation periods such as measles. Gammiatoni and Nucci's generalised formulation is shown to be the most suitable for modelling airborne transmission in ventilated spaces, and it is subsequently used in a parametric study to evaluate the effect of physical and environmental factors on the rate of disease transmission. The paper also presents reported quanta production data for several TB outbreaks and demonstrates that the greatest risk of TB infection is during clinical procedures that produce large quantities of aerosol, such as bronchoscopy or intubation.

Exercise training reduces myocardial lipid peroxidation following short-term ischemia-reperfusion.

PURPOSE: The purpose of these experiments was to test the hypothesis that endurance exercise training will reduce myocardial lipid peroxidation following short-term ischemia and reperfusion (I-R). METHODS: Female Sprague-Dawley rats (4 months old) were randomly assigned to either a sedentary control group (N = 13) or to an exercise training group (N = 13). The exercise trained animals ran 4 d.wk-1 (90 min.d-1) at approximately 75% V02max. Following a 10-wk training program, animals were anesthetized, mechanically ventilated, and the chest was opened by thoracotomy. Coronary occlusion was achieved by a ligature around the left coronary artery; occlusion was maintained for 5 min followed by a 10-min period of reperfusion. RESULTS: Although training did not alter (P > 0.05) myocardial activities of antioxidant enzymes (superoxide dismutase and glutathione peroxidase), training was associated with significant increase (P > 0.05) in heat shock protein (HSP72) in the left ventricle. Compared with controls, trained animals exhibited significantly lower levels (P < 0.05) of myocardial lipid peroxidation following I-R. CONCLUSION: These data support the hypothesis that exercise training provides protection against myocardial lipid peroxidation induced by short-term I-R in vivo.

A clinical tool for rating response to civil commitment for substance abuse treatment.

OBJECTIVE: The objectives of this study were to develop a measure to assess patients' response to civil commitment, to test this measure on two groups of dually diagnosed patients (medically ill alcoholics and patients with dual mental and substance use disorders), and to identify patient characteristics associated with a positive response to commitment. METHODS: The outcome of 38 male veterans civilly committed to inpatient substance abuse treatment for an average of six months was rated by their treating clinicians. Raters used the Commitment Response Form (CRF), a scale anchored to behavioral descriptions that was developed for the study and that measures outcome in five areas: patients' attitude toward recovery, substance use, medical condition, engagement in substance abuse treatment, and independence of functioning. Each patient's medical records were reviewed by two clinical staff members who made independent retrospective ratings and a joint rating using the CRF. They also made independent and joint dichotomous ratings of whether the patient was a positive responder or a nonresponder to civil commitment. RESULTS: The CRF showed superior reliability when compared with the dichotomous rating of outcome. The scale demonstrated reasonable psychometric properties. Mean scale scores did not differ significantly by patient group; slightly more than half were rated as having a good to excellent overall response. Better outcome was associated with longer periods of previous abstinence from alcohol and a higher level of education. CONCLUSIONS: Use of a scale anchored to behavioral descriptions improved reliability of outcome determinations by clinical staff. Civil commitment resulted in good to excellent outcome in many but not all committed patients.

Alcohol home delivery services: a source of alcohol for underage drinkers.

OBJECTIVE: This study describes the use of alcohol home delivery services by underage drinkers, and characteristics of grocery and liquor stores that deliver alcohol. The availability of alcohol home delivery services across the United States is also described. METHOD: Individuals surveyed were from 15 small- and medium-sized midwestern communities. Of all enrolled 12th graders, 83.5% (N = 4,487) responded, and of a randomly selected cohort of 18- to 20-year-olds, 93.9% (N = 1,721) responded. All grocery stores that sold alcohol and liquor stores in the corresponding communities were invited to participate in the study and 124 (92.5%) of those businesses completed surveys regarding outlet characteristics and practices. Data for the surveys were based on a nested cross-sectional design with individual respondents nested within the 15 communities. RESULTS: Purchases of delivered alcohol were made by 10% of 12th graders and 7.3% of 18- to 20-year-olds within the past year; 20.2% of outlets delivered alcohol. Using bivariate analyses, purchasing delivered alcohol was associated with male gender, high-risk drinking (drinking five or more drinks on an occasion), more recent and more frequent drinking. Providing delivery services was more common among outlets selling keg beer and/or single servings. Multivariate analyses revealed positive associations between purchasing delivered alcohol and male gender for the 12th graders, and high risk and more recent drinking for both the 12th graders and 18- to 20-year-olds. For outlets, selling keg beer was positively associated with providing delivery services. A separate survey indicated that home delivery services appear to be available in many areas of the country. CONCLUSIONS: Home delivery is a previously unidentified source of alcohol for underage drinkers that could be curtailed with effective alcohol policies.

Minimal velocities necessary for perforation of skin by air gun pellets and bullets.

A series of tests were conducted to determine the velocities necessary for lead air gun pellets (calibers .177 and .22) and caliber .38 lead bullets to perforate skin. Human lower extremities were used. Caliber .177 air gun pellets weighing 8.25 grains required a minimum velocity of 101 m/s (331 ft/s) to perforate skin. The energy per area of presentation ratio E/a was 1:86 m X kg/cm2. Caliber .22 air gun pellets weighing 16.5 grains needed a minimum velocity of 75 m/s (245 ft/s). The E/a was 1:3 m X kg/cm2. A round nose, caliber .38 lead bullet weighing 113 grains perforated skin at 58 m/s (191 ft/s). The E/a was 1.95 m X kg/cm2. These studies appear to indicate that lightweight projectiles need greater velocity to perforate skin than do larger caliber, heavier bullets.

An aerobiological model of aerosol survival of different strains of Pseudomonas aeruginosa isolated from people with cystic fibrosis.

Pseudomonas aeruginosa is a common and important pathogen in people with cystic fibrosis (CF). Recently epidemic strains of P. aeruginosa associated with increased morbidity, have been identified. The method of transmission is not clear, but there is evidence of a potential airborne route. The aim of this study was to determine whether different strains of P. aeruginosa isolated from people with CF were able to survive within artificially generated aerosols in an aerobiological chamber. Viable P. aeruginosa could still be detected up to 45min after halting generation of the aerosols. All of the strains of P. aeruginosa expressing a non-mucoid phenotype isolated from people with CF had a reduced ability to survive within aerosols compared to an environmental strain. Expression of a mucoid phenotype by the strains of P. aeruginosa isolated from people with CF promoted survival in the aerosol model compared to strains expressing a non-mucoid phenotype.

The use of alcohol home delivery services by male problem drinkers: a preliminary report.

Alcohol home delivery services (AHDS) provide convenient and confidential access to alcohol, yet little is known about their use. The purpose of this report is to present preliminary data describing the use of AHDS by problem drinkers. We surveyed 174 males regarding social and demographic characteristics, alcohol use history, and use of AHDS. Use of AHDS was most common among problem drinkers. When statistically controlling for the effects of demographic and social characteristics, regular drinkers without a history of alcohol problems were significantly less likely to have had alcohol delivered than problem drinkers, p = .0036. Contrary to expectation, medically ill alcoholics with advanced and disabling medical complications of heavy drinking were not more likely than other problem drinkers to have alcohol delivered. Living in an urban area and not having a vehicle available were associated with the use of AHDS. The public health and safety considerations of alcohol availability via home delivery are discussed.