Emission rates and the personal cloud effect associated with particle release from the perihuman environment

Inhalation exposure to elevated particulate matter levels is correlated with deleterious health and well‐being outcomes. Despite growing evidence that identifies humans as sources of coarse airborne particles, the extent to which personal exposures are influenced by particle releases near occupants is unknown. In a controlled chamber, we monitored airborne total particle levels with high temporal and particle‐size resolution for a range of simulated occupant activities. We also sampled directly from the subject's breathing zone to characterize exposures. A material‐balance model showed that a sitting occupant released 8 million particles/h in the diameter range 1‐10 μm. Elevated emissions were associated with increased intensity of upper body movements and with walking. Emissions were correlated with exposure, but not linearly. The personal PM₁₀ exposure increment above the room‐average levels was 1.6‐13 μg/m³ during sitting, owing to spatial heterogeneity of particulate matter concentrations, a feature that was absent during walking. The personal cloud was more discernible among larger particles, as would be expected for shedding from skin and clothing. Manipulating papers and clothing fabric was a strong source of airborne particles. An increase in personal exposure was observed owing to particle mass exchange associated with a second room occupant.     

Asbestos: world concern,involvement and culpability

The general population is exposed to asbestos fibers stemming from a massive number of consumer products and from environmental pollution. Asbestos bodies are present in the lungs of many urban dwellers who do not work with the mineral. Heavy occupational exposure to asbestos is known to cause asbestosis, pleural calcification, pleural plaques, lung cancer, and pleural and peritoneal mesotheliomas. The ingestion of asbestos fibers may increase the risk of gastrointestinal tract cancer. At the present time, little is known about the hazards of chronic low‐level exposure to asbestos. However, the use of asbestos fibers should be curtailed whenever possible, more pathogenicity data should be collected and evaluated, and the health risk to the general public should be reassessed and updated with progressing research.     

Disgust as a disease-avoidance mechanism.

Many researchers have claimed that the emotion of disgust functions to protect us from disease. Although there have been several discussions of this hypothesis, none have yet reviewed the evidence in its entirety. The authors derive 14 hypotheses from a disease-avoidance account and evaluate the evidence for each, drawing upon research on pathogen avoidance in animals and empirical research on disgust. In all but 1 case, the evidence favors a disease-avoidance account. It is suggested that disgust is evoked by objects/people that possess particular types of prepared features that connote disease. Such simple disgusts are directly disease related, are acquired during childhood, and are able to contaminate other objects/people. The complex disgusts, which emerge later in development, may be mediated by several emotions. In these cases, violations of societal norms that may subserve a disease-avoidance function, notably relating to food and sex, act as reminders of simple disgust elicitors and thus generate disgust and motivate compliance. The authors find strong support for a disease-avoidance account and suggest that it offers a way to bridge the divide between concrete and ideational accounts of disgust. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Desorption kinetics of trichloroethylene and perchloroethylene from aged dense nonaqueous phase liquid-contaminated soil

Batch experiments were conducted to investigate the desorption kinetics of a contaminated soil collected from a field site at Hill Air Force Base (AFB), Utah. The site has been contaminated with many dense nonaqueous phase liquids (DNAPLs), primarily trichloroethylene (TCE) and perchloroethylene (PCE), for more than 60 years. Similar desorptive behaviour of both TCE and PCE was observed: a stage of fast release of the contaminant at the start followed by a very slow stage. Moreover, it is suggested that not all the contaminant in the solid phase may be released to the aqueous phase, apparently due to the age factor. Local variations were observed in the effective diffusivity and other sorption-related parameters across the site due to aquifer heterogeneity. Experimental results were then simulated using a numerical code based on the intraparticle diffusion model. Good agreement was found between both results.     

顾及基准点稳定性的高崩溃污染率坐标转换模型

针对矿区基准点布设时间较早,容易发生位移的特点,为确保高精度GPS控制网坐标系统转换后的质量,克服基准点位移对转换成果的影响,提出顾及基准点位移的高崩溃污染率抗差估计理论,建立坐标转换参数的估计模型和转换后GPS网的质量评价体系。对兖州某矿区进行应用,结果表明,该模型可以选择分布合理且稳定的基准点,很好地保留了GPS技术高精度的特点,并为矿区建立了高精度的坐标基准。     

The effect of changes in nitrate concentration in drinking water on methemoglobin levels in infants

For a five‐day period infants consuming powdered milk formula made up with tap water were exposed to water of controlled nitrate content. There was a significant rise in MetHb levels above normal in most children after the first day of exposure to high nitrate water (108 mg/1 NO3). This was followed by some indication of a drop in MetHb levels despite the continued exposure and finally a return to normal levels when the exposure to nitrates stopped. No clinical signs of methemoglobinemia developed. The possible existence of an adaption mechanism is suggested but requires further elucidation.     

Soil metal concentrations and toxicity: Associations with distances to industrial facilities and implications for human health

Urban and rural areas may have different levels of environmental contamination and different potential sources of exposure. Many metals, i.e., arsenic (As), lead (Pb), and mercury (Hg), have well-documented negative neurological effects, and the developing fetus and young children are particularly at risk. Using a database of mother and child pairs, three areas were identified: a rural area with no increased prevalence of mental retardation and developmental delay (MR/DD) (Area A), and a rural area (Area B) and an urban area (Area C) with significantly higher prevalence of MR/DD in children as compared to the state-wide average. Areas were mapped and surface soil samples were collected from nodes of a uniform grid. Samples were analyzed for As, barium (Ba), beryllium (Be), chromium (Cr), copper (Cu), Pb, manganese (Mn), nickel (Ni), and Hg concentrations and for soil toxicity, and correlated to identify potential common sources. ArcGIS^® was used to determine distances between sample locations and industrial facilities, which were correlated with both metal concentrations and soil toxicity. Results indicated that all metal concentrations (except Be and Hg) in Area C were significantly greater than those in Areas A and B (p ≤ 0.0001) and that Area C had fewer correlations between metals suggesting more varied sources of metals than in rural areas. Area C also had a large number of facilities whose distances were significantly correlated with metals, particularly Cr (maximum r = 0.33; p = 0.0002), and with soil toxicity (maximum r = 0.25; p = 0.007) over a large spatial scale. Arsenic was not associated with distance to any facility and may have a different anthropogenic, or natural source. In contrast to Area C, both rural areas had lower concentrations of metals, lower soil toxicity, and a small number of facilities with significant associations between distance and soil metals.     

Effective sampling strategy to detect food and feed contamination: Herbs and spices case

Sampling plans for food safety hazards are aimed to be used to determine whether a lot of food is contaminated (with microbiological or chemical hazards) or not. One of the components of sampling plans is the sampling strategy. The aim of this study was to compare the performance of three different sampling strategies, being simple random sampling (SRS), stratified random sampling (STRS), and systematic sampling (SS), with each other for their probability of detecting a heterogeneously distributed contamination in a lot of herbs or spices (i.e., a dry food product). To this end, a simulation model was developed, and applied to different scenarios for contamination level and numbers of samples collected. In addition, as a case study, the sampling plan of a company processing herbs and spices was evaluated using the simulation model. Results showed that the effectiveness of the sampling plan is influenced by the sampling strategy. With expected low contamination levels the SS strategy performs better than the two other strategies. At higher expected contaminated levels, the STRS strategy is preferred.     

Aflatoxin contamination and exposure in processed cereal-based complementary foods for infants and young children in greater Accra,Ghana

In the study, aflatoxin levels were assessed in thirty five (35) cereal-based food products intended for infants and young children. Additionally, the results showed that 71% of the processed foods intended for infants contained AFB₁ (0.18 ± 0.01 to 36.10 ± 0.32 μgkg⁻¹) levels higher than the European Union permissible limits of 0.1 μg kg⁻¹. Aflatoxin intake was estimated using aflatoxin levels in the food products and the estimated individual consumption rates. The study also revealed mixed cereals as having the highest intake of aflatoxin B₁ contaminants (0.005–0.852 μgkg⁻¹bw d⁻¹; 0.004–0.657 μgkg⁻¹bwd⁻¹) with mean estimated daily intake (EDI) of 0.23 ± 0.16 μgkg⁻¹bwd⁻¹ and 0.153 ± 0.13 μgkg⁻¹bwd⁻¹ for infants and young children respectively. The estimated AFT intake recorded for infants and young children for all the cereal-based food ranged from 0.005 to 1.054 μgkg⁻¹bwd⁻¹ and 0.004–0.838 μgkg⁻¹bwd⁻¹ respectively.     

Monitoring generic Escherichia coli in reclaimed and surface water used in hydroponically cultivated greenhouse peppers and the influence of fertilizer solutions

Systematic monitoring of indicator microorganisms, such as Escherichia coli, can help to identify potential risk factors for faecal contamination in the agricultural environment. In this study, levels of E. coli in irrigation water (both reclaimed and surface water), water sprayed in humidifiers to regulate ambient humidity, and pepper fruits were assessed in a commercial greenhouse of hydroponically cultivated crops. Additionally, the role of fertilizer solutions as a potential vector of contamination was investigated. Lab-scale studies were also performed to evaluate the influence of fertilizer solutions on the growth/survival of E. coli in irrigation water. As expected, higher levels of E. coli were detected in reclaimed water compared with surface water. No link between E. coli prevalence in irrigation water and presence in fruit could be established. Regarding the fertilizer solutions, E. coli was detected more frequently and in higher levels in the fertilizer solution richer in micronutrients. Low concentrations of E. coli were also present in pulverized water sprayed inside the greenhouse to control humidity. In lab-scale experiments, E. coli showed potential for surviving but not for growing in most fertilizer solutions and irrigation water. Fertilizer solution of HNO₃, was the only solution in which no E. coli were able to survive in the irrigation head and a rapid inactivation was observed in lab-scale tests. These results suggest that there is a low risk of contamination in this agricultural system despite the combination of higher risk irrigation water sources (reclaimed and surface water) and the hydroponic growing system. Nevertheless, special care should be taken regarding the microbiological quality of the agricultural solutions in direct contact with the edible parts of the crop.