Disinfection byproducts in Canadian provinces: associated cancer risks and medical expenses

Chlorination for drinking water forms various disinfection byproducts (DBPs). Some DBPs are probably linked to human cancer (e.g., bladder, colorectal cancers) and other chronic and sub-chronic effects. This emphasizes the need to understand and characterize DBPs in drinking water and possible risks to human health. In this study, occurrences of DBPs throughout Canada were investigated. Trihalomethanes (THMs) were observed to be highest in Manitoba followed by Nova Scotia and Saskatchewan, while haloacetic acids were highest in Nova Scotia followed by Newfoundland and Labrador. Based on the characterization of DBPs, risk of cancer from exposure to THMs was predicted using ingestion, inhalation and dermal contact pathways of exposure. In Canada, approximately 700 cancer cases may be caused by exposure to THMs in drinking water. Medical expenses associated with these cancer incidents are estimated at some $140 million/year. Expense may be highest in Ontario (～$47 million/year) followed by Quebec (～$25 million/year) due to a greater population base. This paper suggests improvements in water treatment, source protection and disinfection processes, and caution in the use of alternative disinfectants to reduce DBPs. Finally, elements are provided to mitigate risks and reduce cost estimates in future studies.     

Pollution level, phase distribution and source analysis of polycyclic aromatic hydrocarbons in residential air in Hangzhou, China

A survey of polycyclic aromatic hydrocarbons (PAHs) in residential air in Hangzhou, China, was carried out. Air samples were collected from indoor and outdoor environments during both summer and winter and analyzed for the level of 16 PAHs. The results showed total PAH contents ranging from 0.425 to 36.2 microg/m(3) with highest concentrations in the kitchen areas generally. Particulate PAHs were predominantly absorbed on PM(2.5) with proportion of 59-97% to total particulate phase, followed by PM(2.5-10) (3-24%) and PM(>10) (0-17%). PAH concentrations in indoor air of smoking residences tended to be higher than those of nonsmoking residences. Outdoor environment, Chinese conventional cooking practice, mothball emission and unknown source accounted for -10.5%, 32.8%, 71.5% and 6.2% of total PAHs in indoor air of nonsmoking residences, respectively. Outdoor environment was the fate for indoor PAHs in general, and consumed 10.5% of total PAHs. Finally, health risks associated with the inhalation of PAHs were assessed, and the results indicated that health-based guideline levels for lung cancer risk were exceeded. The largest contribution to total health risks in summer and winter was NA (72.9%) and BaP (45.2%), respectively.     

A GIS-based evaluation of risks due to trihalomethane exposure during showering in coastal Texas

Disinfection of water supplies with chlorine is essential to water treatment, but can lead to the formation of trihalomethanes (THMs) in the presence of natural organic matter. Exposure to THMs via inhalation during daily activities such as showering can significantly increase cancer risks. An innovative decision support system was developed for evaluating THM exposure and risks in water supplies in the Gulf Coast region of Texas by combining a shower THM volatilization model, geospatial analysis techniques, and risk assessment methodologies. Based on THM data from fourteen locations in the region, a power-law equation was developed to predict the formation of THMs in groundwater wells. Health risks associated with THMs in the water supplies of the Gulf Coast of Texas were evaluated. Cancer risks were found to vary from 7.14?×?10^?7 to 7.75?×?10^?6. While two-thirds of the geographical area was below the threshold risk of 1?×?10^?6, it accounted for only a tenth of the total population. Metropolitan areas such as Corpus Christi and McAllen, which currently use surface water sources, and Houston, which is seeking alternate water sources due to subsidence issues, were found to have significant cancer risks (in excess of one in a million). A third of the population of Texas is housed in the Gulf Coast region, and with more population migration toward the metropolitan areas, it is recommended that water resource management decisions be made taking into consideration both the quantity and quality of water available.     

Atmospheric monitoring and its impact on air shower observables at the Pierre Auger Observatory

The Pierre Auger Observatory, completed in September 2008, detects cosmic rays by observing and studying the development of extensive air showers in atmosphere. The atmosphere itself, with its unpredictable changes of conditions, directly influences the estimation of the air shower characteristics. In this paper, all the instruments and techniques adopted by the Auger Observatory are explained, and the impact of their results on the most important shower parameters are shown.     

Angular resolution of the Ohya air shower detector

Accurate measurements of the total number of muons in an air shower are important for the discrimination of showers produced by astronomical gamma rays from those produced by protons. In order to perform this discrimination, muon detectors with a total area of about 400 m² have been constructed in the Ohya stone mine. At ground level, scintillation detectors have been distributed for determining the total number of electrons in the air shower. The arrival direction of the air shower determined by usual timing information was examined using independent data on the arrival direction determined by muons in the shower. The angular resolution thus obtained at the shower maximum is 1.7° in the south-north plane and 2° in the east-west plane. The difference of the resolution is due to the asymmetric arrangement of scintillation detectors.     

The sensitive area of cosmic ray air shower arrays

Some closed expressions are derived for the collecting area of cosmic ray air shower arrays, taking into account the varying geometry such arrays present to showers arriving from different directions.     

Measurement of radio emission from extensive air showers with LOPES

A new method is explored to detect extensive air showers: the measurement of radio waves emitted during the propagation of the electromagnetic shower component in the magnetic field of the Earth. Recent results of the pioneering experiment LOPES are discussed. It registers radio signals in the frequency range between 40 and 80 MHz. The intensity of the measured radio emission is investigated as a function of different shower parameters, such as shower energy, angle of incidence, and distance to shower axis. In addition, new antenna types are developed in the framework of LOPES^star and new methods are explored to realize a radio self-trigger algorithm in real time.     

Chlorination byproducts, their toxicodynamics and removal from drinking water

No doubt that chlorination has been successfully used for the control of water borne infections diseases for more than a century. However identification of chlorination byproducts (CBPs) and incidences of potential health hazards created a major issue on the balancing of the toxicodynamics of the chemical species and risk from pathogenic microbes in the supply of drinking water. There have been epidemiological evidences of close relationship between its exposure and adverse outcomes particularly the cancers of vital organs in human beings. Halogenated trihalomethanes (THMs) and haloacetic acids (HAAs) are two major classes of disinfection byproducts (DBPs) commonly found in waters disinfected with chlorine. The total concentration of trihalomethanes and the formation of individual THM species in chlorinated water strongly depend on the composition of the raw water, on operational parameters and on the occurrence of residual chlorine in the distribution system. Attempts have been made to develop predictive models to establish the production and kinetics of THM formations. These models may be useful for operational purposes during water treatment and water quality management. It is also suggested to explore some biomarkers for determination of DBP production. Various methods have been suggested which include adsorption on activated carbons, coagulation with polymer, alum, lime or iron, sulfates, ion exchange and membrane process for the removal of DBPs. Thus in order to reduce the public health risk from these toxic compounds regulation must be inforced for the implementation of guideline values to lower the allowable concentrations or exposure.     

The track imaging Cherenkov experiment

We describe a dedicated cosmic-ray telescope that explores a new method for detecting Cherenkov radiation from high-energy primary cosmic rays and the large particle air shower they induce upon entering the atmosphere. Using a camera comprising 16 multi-anode photomultiplier tubes for a total of 256 pixels, the Track Imaging Cherenkov Experiment (TrICE) resolves substructures in particle air showers with 0.086° resolution. Cherenkov radiation is imaged using a novel two-part optical system in which a Fresnel lens provides a wide-field optical trigger and a mirror system collects delayed light with four times the magnification. TrICE records well-resolved cosmic-ray air showers at rates ranging between 0.01 Hz and 0.1 Hz.     

A method for energy estimation and mass composition determination of primary cosmic rays at the Chacaltaya observation level based on the atmospheric Cherenkov light technique

A new method for energy and mass composition estimation of primary cosmic rays based on the atmospheric Cherenkov light flux in extensive air showers (EAS) is proposed. The Cherenkov light flux in EAS initiated by primary protons and iron nuclei is simulated with the CORSIKA 5.62 code for the Chacaltaya observation level (536 g/cm²) in the energy range 10 TeV–10 PeV. An adequate model for the lateral distribution of Cherenkov light in showers is obtained. Using the model and a solution for the overdetermined system of nonlinear equations based on the Gauss–Newton method with autoregularization, two different detector arrangements are compared. The accuracies in energy and shower axis determination are studied and the corresponding selection criteria are proposed. An approximation with a nonlinear fit is obtained and the energy dependence of the proposed model parameters is studied. A detailed study of the model parameters as a function of the primary energy is made. This permits, taking into account the properties of the proposed method and the strong nonlinearity of the model, a distinction to be made between proton and iron primaries. The detector response for the detector sets is simulated and the accuracies in energy determination are calculated. In addition, the accuracies in shower axis determination are studied and criteria for shower axis position estimation are proposed.     

Measurement of the time development of particle showers in a uranium scintillator calorimeter

We report on the time evolution of particle showers, as measured in modules of the uranium-scintillator barrel calorimeter of the ZEUS detector. The time development of hadronic showers differs significantly from that of electromagnetic showers, with about 40% of the response to hadronic showers arising from energy depositions which occur late in the shower development. The degree of compensation and the hadronic energy resolution were measured as a function of integration time, giving a value of for a gate width of 100 ns. The possibilities for electron-hadron separation based on the time structure of the shower were studied, with pion rejection factors in excess of 100 being achieved for electron efficiencies greater than 60%. The custom electronics used to perform these measurements samples the calorimeter signal at close to 60 MHz, stores all samples for a period of over 4 μs using analog switched capacitor pipelines, and digitizes the samples for triggered events with 12-bit ADCs.     

Does exposure to residential radon increase the risk of lung cancer?

In assessing the risks of exposure to ionising radiation, it is important to neither overstate nor understate the effects of the hazard. These requirements are often difficult to satisfy, especially since much of our knowledge about the effects of low levels of radiation is subject to rather large uncertainties. Our participants have given their opinions about the risk of lung cancer induction resulting from exposure to radon in residences. Each agrees that exposures to high concentrations of radon are hazardous. However, as with low level exposures to other types of ionising radiation, quantifying relatively small risks is quite difficult. The national and international standards setting bodies have recommended a fairly conservative approach that may overestimate the 'true' magnitude of deleterious effects and their dependence upon exposure, but this is to be expected given the uncertainties in the data and the need to avoid underestimates. A conservative approach can have both positive and negative consequences, and it is also important to neither overstate nor understate these consequences.     

Development of a multi-pathway probabilistic health risk assessment model for swimmers exposed to chloroform in indoor swimming pools

For swimmers, exposure to chloroform, a probable carcinogen, in indoor swimming pools can be through different pathways such as ingestion, dermal absorption, inhalation during swimming, and inhalation during resting. In order to evaluate health risk results from excessive exposure to chloroform, concentrations of chloroform in pool water were first collected and analyzed. Then, a two-layer model is used, which is capable of estimating the concentrations of chloroform in the boundary layer adjacent to the water surface and the concentrations of chloroform in indoor swimming pool air. The use of stratification model is important for estimating the risks for swimmers since they are exposed to these kinds of situations while performing swimming and resting in indoor swimming pools environment. The incremental lifetime cancer risk (ILCR) was then estimated using the multi-pathway exposure model. The results showed that the 95th percentile of ILCRs calculated for male and female swimmers were 2.80 × 10(-4) and 2.47 × 10(-4), respectively. The major exposure routes were found to be inhalation during swimming which contributes to more than 99% of the total health risk. Our study suggested that to protect swimmers from excessive exposure to chloroform, alternative methods or processes of disinfection should be considered for swimming pool managers.     

Extensive air shower experiment at Kolar Gold Fields

An experiment to determine the nature of primary cosmic rays of energy > 10¹⁴ eV by studying high energy (> 220 GeV) muons and their correlations with other parameters of extensive air showers generated by them, was carried out at Kolar Gold Fields, India (atmospheric depth of 920 g cm⁻²). An accurate estimate of shower parameters in showers as small as 10⁴ particles was achieved by means of a closely packed array of large area detectors and by employing special methods of analysis. In this paper, the details of the array, the data recording system, the procedure of data analysis and error estimates are described.     

Chemical agent identification by field-based attenuated total reflectance infrared detection and solid-phase microextraction

Attenuated total reflectance Fourier transform infrared (ATR-FT-IR) spectroscopy is used to identify liquid and solid-phase chemicals. This research examines the feasibility of identifying vapor-phase chemicals using a field-portable ATR-FT-IR spectrometer (TravelIR) combined with solid-phase microextraction (SPME). Two nerve agent simulants, diisopropyl methylphosphonate (DIMP) and di-methyl methylphosphonate (DMMP), and three sorbent polymers were evaluated. Each polymer was deposited as a thin film on the instrument's sampling interface to partition and concentrate the simulants from air samples prepared in Tedlar bags. The lowest vapor concentrations identified were 50 ppb (v/v) (DIMP) and 250 ppb (v/v) (DMMP). The ATR-FT-IR instrument demonstrated a linear response at concentrations of 1 ppm (v/v) and below. Increasing the sample exposure time, the sample air velocity, and the film thickness was demonstrated to increase the amount of analyte extracted from the air sample. This research demonstrates that it is feasible to use a portable ATR-FT-IR spectrometer with SPME sampling to detect and identify vapor-phase chemicals.     

On the nature of an anomalous RF electromagnetic pulse caused by an extensive air shower

Theoretical estimates validating a hypothesis concerning the origin of anomalously intense RF pulses generated in extensive air showers are obtained. It is shown that these pulses are due to a quasi-coherent radiation of the transverse current of ionization electrons flowing in the shower in a 10⁴–10⁵ V/m field of the thunderstorm cloud. For particles with an energy of W ₀=10¹⁷ eV, the amplitude of the field generated by the anomalous RF pulse is on the order of 10⁻¹ V/m at ∼ 500 m from the shower axis.     

Risk analysis of hazardous materials in oil shale

A future oil shale industry will be a massive solids-handling industry generating large amounts of hazardous materials. A risk analysis was performed on a hypothetical oil shale industry to aid in the formulation and management of research. The analysis considered occupational, public, and ecosystem risks for a steady-state one million barrels per day (160 cubic dekameters per day) industry. The risks for designated groups of the occupational workforce were statistically described by accident and injury rates for fatalities, accidents with days lost from work, and accidents with no days lost from work. Workforce diseases analyzed were cancers, silicosis, pneumoconiosis, chronic bronchitis, chronic airway obstruction, and high-frequency hearing loss. The miners represented the group with the largest fatality and the most serious accident rate. Lung disease from inhalation exposure to dust about the nuisance dust threshold limit value presented the most significant risk for future concerns. Public health inhalation risks were estimated for life-time cancer risks from As, Cd, Cr, Ni, polycyclic aromatic hydrocarbons, and radiation to be less than 10⁻⁷ occurrences per person per year. An air pollution surrogate, sulfate, as a measure of all air pollution exposure, yielded a result of 10⁻⁵ deaths per person per year with large uncertainties. Public health risks associated with oil shale solid waste were considered for leachates. Ecosystem risks considered impact on designator species, plant damage from sulfates, and disturbance in plant communities. The simple analysis approach indicated that the potential impact on the semi-arid, high-altitude ecosystem was minimal from air pollutants and land disturbances, but of potential concern for aquatic systems under extreme conditions. The methodology and treatment of uncertainties are oriented towards establishing research implications.     

Measurement of cascade showers in lead with thermoluminescent sheets

A new type of detector, thermoluminescent (TL) sheets (BaSO₄:Eu), and a readout system for the TL sheets have been developed to study electromagnetic cascade showers in ultrahigh energy interactions. To perform a measurement of showers recorded in TL sheets, the longitudinal and radial development of an electromagnetic cascade shower in lead produced by accelerator electrons has been studied for comparison. Simulations of the longitudinal and radial development of cascade showers were also performed using the EGS code system.

This study is useful for the design of a thermoluminescent calorimeter (TLC) for the measurement of electromagnetic cascade showers originating from ultrahigh energy (above 10¹⁵ eV) interactions.     

Hadron showers in a low-density fine-grained flash chamber calorimeter

Hadronic showers at six incident particle energies from 33.8 to 415.4 GeV have been studied using the low-density fine-grained flash chamber calorimeter of the Lab C neutrino detector at Fermilab. Transverse distributions of unprecedented fine granularity have been obtained for a range of depths in the shower. Longitudinal energy distributions have been compared with those from iron-scintillator detectors. Some differences are observed which may be attributable to the different relative sensitivity of the two detector types to electromagnetic and hadronic shower components. Both longitudinal and transverse distributions have been parametrized. Fluctuations in energy deposition have been studied. The relative size of the fluctuations is largest near the starting vertex and in the tail of the shower, and falls slowly with increasing beam energy. Correlations between energy deposition in neighboring parts of the shower are observed, and anticorrelation is seen between energy deposition in the peak and in the tail of the shower. Containment lengths and widths have also been measured and parametrized.     

GEANT4 physics evaluation with testbeam data of the ATLAS hadronic end-cap calorimeter

We evaluate the validity of the GEANT4 electromagnetic and hadronic physics models by comparing experimental data from beam tests of modules of the ATLAS hadronic end-cap calorimeter with GEANT4-based simulations. Two physics lists (LHEP and QGSP) for the simulation of hadronic showers are evaluated. Calorimeter performance parameters like the energy resolution and shapes of showers are studied both for electrons and charged pions. Furthermore, throughout the paper we compare GEANT4 and the corresponding predictions of GEANT3 used with the G-CALOR code for hadronic shower development.