Factors affecting the survival of genetically engineered Escherichia coli bearing a plasmid in a paddy field microcosm

In order to clarify some of the factors affecting the survival of a genetically engineered Escherichia coli (g‐E. coli) bearing a plasmid in a paddy field microcosm and its parent E. coli (p‐E. coli), we focused on protozoa and the metabolites of indigenous bacteria.

It was found that both g‐E. coli and p‐E. coli decreased remarkably in a microcosm with protozoa but not so in that without protozoa. The populations of both g‐E. coli and p‐E. coli decreased much more in the metabolites of indigenous bacteria than in those of their respective metabolites. Therefore, the metabolites of indigenous bacteria as well as protozoa are factors affecting the decreases of both g‐E. coli and p‐E. coli in a paddy field microcosm.     

Recombinant plasmid gene transfer in amended soil

Genetically engineered E. coli amended into a non-sterile soil microcosm were able to mobilize their recombinant plasmid DNA into a plasmidless E. coli recipient. This transfer required participation of a mobilizer bacterium containing a self-transmissible (conjugative) plasmid. Mobilization also depended on mob sequences present on the non-conjugative recombinant plasmid. Sequences from the non-conjugative plasmid pHSV106, which contains the herpes simplex virus thymidine kinase gene, were identified by DNA hybridization in recipient cells isolated from the soil.     

Land recovery: “brownfields” — a viewpoint

A laboratory‐based microcosm study was conducted to assess the survival of Enterococci faecalis in the estuarine sediments of Lake Pontchartrain, Louisiana, USA. The survival curves of E. faecalis were characterized by a growth phase followed by a stationary phase, a logarithmic decay period, and/or finally by a tailing region. The usual exponential decay model could not be applied to E. faecalis survival in the estuarine sediments. The estuarine sediments appeared to stimulate E. faecalis reproduction within 10 days of incubation. Furthermore, the estuarine sediments prolonged the survival of E. faecalis for a period of at least a month under the study conditions. Based on research results, the amount of organic matter and nutrients did not significantly affect the survival of E. faecalis in the estuarine sediments. This outcome may have occurred due to the small sample size. Throughout the duration of the 45 day experiment, relatively the same proportion of E. faecalis remained culturable. Therefore, the estuarine sediments appear to provide a favorable environment for E. faecalis.     

Protozoan predation ofEscherichia coli in estuarine waters

The role of the indigenous microbial population in the decline ofEscherichia coli in marine estuarine water was investigated.The survival ofE. coli was mainly dependent on the presence of protozoan predators and not on the presence of predacious bacteria. The removal of indigenous protozoa by filtration or the use of antibiotics resulted in a reduced destruction of theE. coli population. Increasing the protozoan concentration caused an increased reduction inE. coli numbers.     

n‐Alkane distributions in soil and water samples collected near Agbabu bitumen field of southwestern Nigeria

Soil and water samples from the vicinity of Agbabu bitumen field of Southwestern Nigeria were analysed by GC‐FID for n‐alkanes, in order to characterize their distributions and to gather information on the degree of contamination by bitumen exploration and processing and other biogenic contributions. Total concentrations of n‐alkanes in water and soil samples analysed ranged from 61.5 to 472.7 µg L^?1 and 422.8 to 2289.4 ng g^?1 dw, respectively. On the basis of the total n‐alkane concentrations, carbon preference index (CPI) values and the odd‐even carbon predominance, it is suggested that both natural (e.g. aquatic input) and anthropogenic (e.g. bitumen and synthetics) sources contribute to the n‐alkanes load in soil and water samples of the area studied.     

DECAY OF ESCHERICHIA COLI IN SOIL FOLLOWING THE APPLICATION OF BIOSOLIDS TO AGRICULTURAL LAND

The decay of Escherichia coli in a sandy loam soil, amended with enhanced and conventionally treated biosolids, was investigated in a field experiment following spring and autumn applications of sewage sludge. Control soils, without the application of biosolids, were also examined to determine the background indigenous populations of E. coli which are present in the environment. The survival of indigenous E coli and populations of E coli applied to soil in biosolids, is assessed in relation to environmental factors influencing pathogen-decay processes in soil.     

Unexpected increase in indoor pollutants after the introduction of a smoke‐free policy in a correctional center

Correctional centers (prisons) are one of the few non‐residential indoor environments where smoking is still permitted. However, few studies have investigated indoor air quality (IAQ) in these locations. We quantified the level of inmate and staff exposure to secondhand smoke, including particle number (PN) count, and we assessed the impact of the smoking ban on IAQ. We performed measurements of indoor and outdoor PM_2.5 and PN concentrations, personal PN exposure levels, volatile organic compounds (VOCs), and nicotine both before and after a complete indoor smoking ban in an Australian maximum security prison. Results show that the indoor 24‐h average PM_2.5 concentrations ranged from 6 (±1) μg/m³ to 17 (±3) μg/m³ pre‐ban. The post‐ban levels ranged from 7 (±2) μg/m³ to 71 (±43) μg/m³. While PM_2.5 concentrations decreased in one unit post‐ban, they increased in the other two units. Similar post‐ban increases were also observed in levels of PN and VOCs. We describe an unexpected increase of indoor pollutants following a total indoor smoking ban in a prison that was reflected across multiple pollutants that are markers of smoking. We hypothesise that clandestine post‐ban smoking among inmates may have been the predominant cause.     

Determinants of house dust,endotoxin, and β‐(1→3)‐D‐glucan in homes of Danish children

Little is known about the geographic variation and determinants of bacterial endotoxin and β ‐(1,3)‐d ‐glucan in Danish house dust. In a population of 317 children, we: (i) described loads and concentrations of floor dust, endotoxin, and β‐(1→3)‐d ‐glucan and (ii) their correlations and (iii) assessed their determinants; (iv) Finally, we compared our findings with previous European studies. Bedroom floor dust was analyzed for endotoxin content by the kinetic limulus amoebocyte lysate assay and for β‐(1→3)‐d ‐glucan by the inhibition enzyme immunoassay. The parents answered questions regarding potential determinants. We found: geometric means (geometric standard deviations) 186 mg/m² (4.3) for dust; 5.46 × 10³EU/m² (8.0) and 31.1 × 10³EU/g (2.6) for endotoxin; and 142 μg/m² (14.3) and 0.71 × 10³ μg/g (7.3) for β‐(1→3)‐d ‐glucan. High correlations (r > 0.75) were found between floor dust and endotoxin and β‐(1→3)‐d ‐glucan loads, while endotoxin and β‐(1→3)‐d ‐glucan concentrations were moderately correlated (r = 0.36–0.41) with the dust load. Having a carpet was positively associated with dust load and with endotoxin and β‐(1→3)‐d ‐glucan concentrations. Pet keeping, dwelling type, and dwelling location were determinants of endotoxin concentrations. No other determinants were associated with β‐(1→3)‐d ‐glucan concentrations. Compared with other European studies, we found lower β‐(1→3)‐d ‐glucan loads and concentrations but higher endotoxin loads and concentrations suggesting a geographically determined different composition of Danish floor dust compared with other European regions.     

Air quality,mortality, and economic benefits of a smoke – free workplace law for non‐smoking Ontario bar workers

We estimated the impact of a smoke‐free workplace bylaw on non‐smoking bar workers' health in Ontario, Canada. We measured bar workers' urine cotinine before (n = 99) and after (n = 91) a 2004 smoke‐free workplace bylaw. Using pharmacokinetic and epidemiological models, we estimated workers' fine‐particle (PM_2.5) air pollution exposure and mortality risks from workplace secondhand smoke (SHS). workers' pre‐law geometric mean cotinine was 10.3 ng/ml; post‐law dose declined 70% to 3.10 ng/ml and reported work hours of exposure by 90%. Pre‐law, 97% of workers' doses exceeded the 90th percentile for Canadians of working age. Pre‐law‐estimated 8‐h average workplace PM_2.5 exposure from SHS was 419 μg/m³ or ‘Very Poor’ air quality, while outdoor PM_2.5 levels averaged 7 μg/m³, ‘Very Good’ air quality by Canadian Air Quality Standards. We estimated that the bar workers' annual mortality rate from workplace SHS exposure was 102 deaths per 100 000 persons. This was 2.4 times the occupational disease fatality rate for all Ontario workers. We estimated that half to two‐thirds of the 10 620 Ontario bar workers were non‐smokers. Accordingly, Ontario's smoke‐free law saved an estimated 5–7 non‐smoking bar workers' lives annually, valued at CA $50 million to $68 million (US $49 million to $66 million).     

The great asymmetric divide: An empirical investigation of the link between indigenous and non‐indigenous economic systems in Northern Australia

This empirical study explores financial links between indigenous and non‐indigenous economic systems in a remote river catchment in Northern Australia (the Mitchell). It finds evidence of a profound and asymmetric ‘disconnect’ between these economies: an exogenous increase in indigenous incomes raises the incomes of non‐indigenous people, but the reverse is not true. Evidently, those seeking to improve the incomes of indigenous people in Northern Australia cannot simply seek to (i) increase payments to indigenous people, or (ii) expand the non‐indigenous sector hoping that some benefits will ‘trickle down’. Instead, structural change is required.     

Optimization of PMA‐qPCR for Staphylococcus aureus and determination of viable bacteria in indoor air

Staphylococcus aureus may cause infections in humans from mild skin disorders to lethal pneumonia. Rapid and accurate monitoring of viable S. aureus is essential to characterize human exposure. This study evaluated quantitative PCR (qPCR) with propidium monoazide (PMA) to quantify S. aureus. The results showed comparable S. aureus counts between exclusively live cells and mixtures of live/dead cells by qPCR with 1.5 or 2.3 μg/mL PMA (P>.05), illustrating the ability of PMA‐qPCR to detect DNA exclusively from viable cells. Moreover, qPCR with 1.5 or 2.3 μg/mL PMA performed optimally with linearity over 10³‐10⁸ CFU/mL (R²≥0.9), whereas qPCR with 10, 23 or 46 μg/mL PMA significantly underestimated viable counts. Staphylococcus aureus and total viable bacteria were further determined with PMA‐qPCR (1.5 μg/mL) from 48 samples from a public library and two university dormitories and four from outside. Viable bacteria averaged 1.9×10⁴ cells/m³, and S. aureus were detected in 22 (42%) samples with a mean of 4.4×10³ cells/m³. The number of S. aureus and viable bacteria were positively correlated (r=.61, P<.005), and percentages of S. aureus relative to viable bacteria averaged 12‐44%. The results of field samples suggest that PMA‐qPCR can be used to quantify viable S. aureus cells.     

Isothiazolone emissions from building products

Adding biocides to dispersion products is a well‐known practice to control microbial deterioration. Isothiazolones are among the most commonly used preservatives, in particular a mixture of 2‐methyl‐2H‐isothiazol‐3‐one (MIT) and 5‐chloro‐2‐methyl‐2H‐isothiazol‐3‐one (CIT). In recent years, for health reasons, due to its strong sensitizing effect, CIT has been replaced by 1,2‐benzisothiazol‐3‐one (BIT). Furthermore, numerous products are now available for interiors containing the fungicidal active substance 2‐octyl‐2H‐isothiazol‐3‐one (OIT). So far nearly nothing is known of the emission behavior of BIT and OIT. An analytical method was developed for these two isothiazolones and interior products containing BIT respectively OIT have been investigated in an emission chamber and in test rooms. The chamber tests revealed maximum concentrations of 6.7 μg OIT/m³, 1.9 μg BIT/m³, and 187 μg MIT/m³. Concentrations obtained in the test rooms were at levels up to 1.4 μg OIT/m³ and 29 μg MIT/m³. A noticeable finding was the very slight subsidence of OIT and BIT levels over several weeks. While MIT outgassed quickly, OIT in particular showed low concentrations, but prolonged evaporation.     

Survival and viability of Escherichia coli in a thermally altered reservoir

Escherichia coli survived and grew in a warm, monomictic reservoir receiving thermal effluent from a nuclear production reactor, which suggests that the presence of E. coli in these aquatic systems is not an indication of recent fecal contamination. Known populations of E. coli were placed in sterile diffusion chambers and suspended at various depths throughout the water column. Experiments were conducted during both ambient water conditions (reactor not operating) and thermally altered water conditions (reactor operating). E. coli populations were observed for changes in density by using optical density and direct and indirect counting methods. During both ambient water and thermally altered water conditions, E. coli survived and grew 2–3 weeks at each depth and at all stations. During thermal alteration, cell populations attained higher optical densities and maintained those densities for longer time periods than those during ambient water conditions. In addition, populations suspended in the hypolimnion generally maintained higher optical densities than those in the epilimnion. Data show that E. coli survives and grows for extended periods of time while it is in diffusion chambers in both aerobic and anaerobic portions of the water column.     

Fate of N-nitrosodimethylamine in recycled water after recharge into anaerobic aquifer

Laboratory and field experiments were undertaken to assess the fate of N-nitrosodimethylamine (NDMA) in aerobic recycled water that was recharged into a deep anaerobic pyritic aquifer, as part of a managed aquifer recharge (MAR) strategy. Laboratory studies demonstrated a high mobility of NDMA in the Leederville aquifer system with a retardation coefficient of 1.1. Anaerobic degradation column and ¹⁴C-NDMA microcosm studies showed that anaerobic conditions of the aquifer provided a suitable environment for the biodegradation of NDMA with first-order kinetics. At microgram per litre concentrations, inhibition of biodegradation was observed with degradation half-lives (260 ± 20 days) up to an order of magnitude greater than at nanogram per litre concentrations (25-150 days), which are more typical of environmental concentrations. No threshold effects were observed at the lower ng L⁻¹ concentrations with NDMA concentrations reduced from 560 ng L⁻¹ to <6 ng L⁻¹ over a 42 day ¹⁴C-NDMA aerobic microcosm experiment.Aerobic ¹⁴C-NDMA microcosm studies were also undertaken to assess potential aerobic degradation, likely to occur close to the recharge bore. These microcosm experiments showed a faster degradation rate than anaerobic microcosms, with a degradation half-life of 8 ± 2 days, after a lag period of approximately 10 days.Results from a MAR field trial recharging the Leederville aquifer with aerobic recycled water showed that NDMA concentrations reduced from 2.5 ± 1.0 ng L⁻¹ to 1.3 ± 0.4 ng L⁻¹ between the recharge bore and a monitoring location 20 m down gradient (an estimated aquifer residence time of 10 days), consistent with data from the aerobic microcosm experiment. Further down gradient, in the anaerobic zone of the aquifer, NDMA degradation could not be assessed, as NDMA concentrations were too close to their analytical detection limit (<1 ng L⁻¹).     

Chimney stoves modestly improved Indoor Air Quality measurements compared with traditional open fire stoves: results from a small‐scale intervention study in rural Peru

Nearly half of the world's population depends on biomass fuels to meet domestic energy needs, producing high levels of pollutants responsible for substantial morbidity and mortality. We compare carbon monoxide (CO) and particulate matter (PM_2.5) exposures and kitchen concentrations in households with study‐promoted intervention (OPTIMA‐improved stoves and control stoves) in San Marcos Province, Cajamarca Region, Peru. We determined 48‐h indoor air concentration levels of CO and PM_2.5 in 93 kitchen environments and personal exposure, after OPTIMA‐improved stoves had been installed for an average of 7 months. PM_2.5 and CO measurements did not differ significantly between OPTIMA‐improved stoves and control stoves. Although not statistically significant, a post hoc stratification of OPTIMA‐improved stoves by level of performance revealed mean PM_2.5 and CO levels of fully functional OPTIMA‐improved stoves were 28% lower (n = 20, PM_2.5, 136 μg/m³ 95% CI 54–217) and 45% lower (n = 25, CO, 3.2 ppm, 95% CI 1.5–4.9) in the kitchen environment compared with the control stoves (n = 34, PM_2.5, 189 μg/m³, 95% CI 116–261; n = 44, CO, 5.8 ppm, 95% CI 3.3–8.2). Likewise, although not statistically significant, personal exposures for OPTIMA‐improved stoves were 43% and 17% lower for PM_2.5 (n = 23) and CO (n = 25), respectively. Stove maintenance and functionality level are factors worthy of consideration for future evaluations of stove interventions.     

A comparative study of human exposures to household air pollution from commonly used cookstoves in Sri Lanka

Solid fuel burning cookstoves are a major source of household air pollution (HAP) and a significant environmental health risk in Sri Lanka. We report results of the first field study in Sri Lanka to include direct measurements of both real‐time indoor concentrations and personal exposures of fine particulate matter (PM_2.5) in households using the two most common stove types in Sri Lanka. A purposive sample of 53 households was selected in the rural community of Kopiwatta in central Sri Lanka, roughly balanced for stove type (traditional or improved ‘Anagi’) and ventilation (chimney present or absent). At each household, 48‐h continuous real‐time measurements of indoor kitchen PM_2.5 and personal (primary cook) PM_2.5 concentrations were measured using the RTI MicroPEM^? personal exposure monitor. Questionnaires were used to collect data related to household demographics, characteristics, and self‐reported health symptoms. All primary cooks were female and of an average age of 47 years, with 66% having completed primary education. Median income was slightly over half the national median monthly income. Use of Anagi stoves was positively associated with a higher education level of the primary cook (P = 0.026), although not associated with household income (P = 0.18). The MicroPEM monitors were well‐received by participants, and this study's valid data capture rate exceeded 97%. Participant wearing compliance during waking hours was on average 87.2% on Day 1 and 83.3% on Day 2. Periods of non‐compliance occurred solely during non‐cooking times. The measured median 48‐h average indoor PM_2.5 concentration for households with Anagi stoves was 64 μg/m³ if a chimney was present and 181 μg/m³ if not. For households using traditional stoves, these values were 70 μg/m³ if a chimney was present and 371 μg/m³ if not. Overall, measured indoor PM_2.5 concentrations ranged from a minimum of 33 μg/m³ to a maximum of 940 μg/m³, while personal exposure concentrations ranged from 34 to 522 μg/m³. Linear mixed effects modeling of the dependence of indoor concentrations on stove type and presence or absence of chimney showed a significant chimney effect (65% reduction; P < 0.001) and an almost significant stove effect (24% reduction; P = 0.054). Primary cooks in households without chimneys were exposed to substantially higher levels of HAP than those in households with chimneys, while exposures in households with traditional stoves were moderately higher than those with improved Anagi stoves. As expected, simultaneously measuring both indoor concentrations and personal exposure levels indicate significant exposure misclassification bias will likely result from the use of a stationary monitor as a proxy for personal exposure. While personal exposure monitoring is more complex and expensive than deploying simple stationary devices, the value an active personal PM monitor like the MicroPEM adds to an exposure study should be considered in future study designs.     

Assessing exposure to secondhand smoke in restaurants and bars 2 years after the smoking regulations in Beijing,China

Field observation of patron smoking behaviors and multiple sampling approaches were conducted in 79 restaurants and bars in Beijing, 2010, 2 years after implementing the governmental smoking regulations. Smoking was observed in 30 visits to 22 of the 37 nominal non‐smoking venues during peak patronage times and six visits to four of the 14 nominal non‐smoking sections. The median area secondhand smoke (SHS) concentrations during peak patronage time were 27, 15, 43, and 40 μg/m³ in nominal non‐smoking venues, non‐smoking sections, smoking sections, and smoking venues, respectively, as indicated by the difference between indoor and outdoor PM_2.5 levels; and 1.4, 0.6, 1.7, and 2.7 μg/m³, respectively, as indicated by airborne nicotine. In the 27 venues with sampling of different approaches and over different time periods, the median nicotine concentration was 1.8 μg/m³ by one‐hour peak patronage‐time sampling, 1.1 μg/m³ by 1‐day active area sampling, 2.5 μg/m³ by 1‐day personal sampling, and 2.3 μg/m³ by week‐long passive sampling. No significant differences in nicotine levels were observed among venues/sections with different nominal smoking policies by all sampling approaches except during peak patronage time. This study showed that the 2008 Beijing governmental smoking restriction has been poorly implemented, and SHS exposures in Beijing restaurants and bars remain high.     

Dermal uptake directly from air under transient conditions: advances in modeling and comparisons with experimental results for human subjects

To better understand the dermal exposure pathway, we enhance an existing mechanistic model of transdermal uptake by including skin surface lipids (SSL) and consider the impact of clothing. Addition of SSL increases the overall resistance to uptake of SVOCs from air but also allows for rapid transfer of SVOCs to sinks like clothing or clean air. We test the model by simulating di‐ethyl phthalate (DEP) and di‐n‐butyl phthalate (DnBP) exposures of six bare‐skinned (Weschler et al. 2015, Environ. Health Perspect., 123 , 928) and one clothed participant (Morrison et al. 2016, J. Expo. Sci. Environ. Epidemiol., 26 , 113). The model predicts total uptake values that are consistent with the measured values. For bare‐skinned participants, the model predicts a normalized mass uptake of DEP of 3.1 (μg/m²)/(μg/m³), whereas the experimental results range from 1.0 to 4.3 (μg/m²)/(μg/m³); uptake of DnBP is somewhat overpredicted: 4.6 (μg/m²)/(μg/m³) vs. the experimental range of 0.5–3.2 (μg/m²)/(μg/m³). For the clothed participant, the model predicts higher than observed uptake for both species. Uncertainty in model inputs, including convective mass transfer coefficients, partition coefficients, and diffusion coefficients, could account for overpredictions. Simulations that include transfer of skin oil to clothing improve model predictions. A dynamic model that includes SSL is more sensitive to changes that impact external mass transfer such as putting on and removing clothes and bathing.     

Results of field investigations into the impact of intermittent sewage discharges on the microbiological quality of wild mussels (Mytilus edulis) in a tidal estuary

Field surveys were designed to examine the effects of sewage contamination from storm overflow effluent on faecal coliform and Escherichia coli concentrations in the flesh of wild mussels (Mytilus edulis). Bags containing 30 mussels each were fixed at known inter-tidal locations and retrieved at intervals following discharge from a nearby combined sewer overflow (CSO). Concentrations of faecal coliform bacteria and E. coli were measured in the shellfish flesh and in samples of overlying water prior to collection of the mussel samples. Faecal coliform and E. coli concentrations in shellfish increased rapidly after CSO discharge. E. coli concentrations exceeded the European shellfish hygiene class C limit of 46,000 100g(-1), and decayed during subsequent CSO discharge-free periods. The concentration and depuration response was independent of the magnitude of CSO spill volume. First-order exponential decay functions were fitted to the data. Decay rates were lower than those found in corresponding microcosm experiments. This relates to the repeated pattern of inundation and exposure associated with the tidal cycles in the estuary. Relationships between E. coli and faecal coliform concentrations in the shellfish and overlying water samples were relatively weak (r<0.60), a pattern often seen with data from uncontrolled environmental experiments.     

Air exchange rates and migration of VOCs in basements and residences

Basements can influence indoor air quality by affecting air exchange rates (AERs) and by the presence of emission sources of volatile organic compounds (VOCs) and other pollutants. We characterized VOC levels, AERs, and interzonal flows between basements and occupied spaces in 74 residences in Detroit, Michigan. Flows were measured using a steady‐state multitracer system, and 7‐day VOC measurements were collected using passive samplers in both living areas and basements. A walk‐through survey/inspection was conducted in each residence. AERs in residences and basements averaged 0.51 and 1.52/h, respectively, and had strong and opposite seasonal trends, for example, AERs were highest in residences during the summer, and highest in basements during the winter. Airflows from basements to occupied spaces also varied seasonally. VOC concentration distributions were right‐skewed, for example, 90th percentile benzene, toluene, naphthalene, and limonene concentrations were 4.0, 19.1, 20.3, and 51.0 μg/m³, respectively; maximum concentrations were 54, 888, 1117, and 134 μg/m³. Identified VOC sources in basements included solvents, household cleaners, air fresheners, smoking, and gasoline‐powered equipment. The number and type of potential VOC sources found in basements are significant and problematic, and may warrant advisories regarding the storage and use of potentially strong VOCs sources in basements.