Maximum Hazard Research Articles

Estimation of the maximum credible hazard in Kuala Lumpur and Singapore due to gigantic Sumatran megathrust earthquakes: based on a comparative study on attenuation laws

This paper has classified nine attenuation laws derived for subduction interface earthquakes through a comparative study based on the peak ground accelerations (PGAs) recorded in Peninsular Malaysia and Singapore. The goal of classification was to identify the attenuation laws that were the most compatible with the region. The PGAs predicted by the relations provided by Nabilah and Balendra (Earthq Eng 16:1076–1094, 2012) and Zhao et al. (Bull Seismol Soc Am 96:898–913, 2006) were found to correlate well with the recorded PGAs. The maximum credible hazard in Kuala Lumpur and Singapore was obtained by calculating the acceleration response spectra caused by three great Sumatran megathrust earthquakes (the worst possible earthquake scenarios) using Zhao et al. spectral attenuation law. Current building code in the region requires that buildings should be capable of resisting a notional ultimate lateral design load equals to 1.5 % of the characteristic dead weight, simultaneously applied at each floor (i.e., the minimum design level of buildings equals to ~0.15 m/s2). The results show that the risk level for structures of the two cities with natural period Tn = 1–1.5 s corresponding to 10- and 15-story buildings located on hard soil sites [National Earthquake Hazards Reduction Program (NEHRP) site class C] is high as the demand spectrum due to a worst possible earthquake scenario with moment magnitude (MW) 9.5 and an epicentral distance (Repi) of 600 km from Singapore was noticeably higher than their design level. The results of the present study are applicable in seismic hazard assessment projects in Peninsular Malaysia and Singapore. The most interesting conclusion from the earthquake engineering perspective, however, is that the design spectral shapes specified in IBC 2012 and Eurocode 8 (type 2) codes may not be particularly appropriate for sites that could be affected by large-magnitude, distant earthquakes.

Measurement of natural radioactivity in granites and its quartz-bearing gold at El-Fawakhir area (Central Eastern Desert), Egypt

The distribution of natural radionuclides (226Ra, 232Th and 40K) in Granites and its quartz-bearing gold at El-Fawakhir area (Central Eastern Desert, Egypt) were measured by using γ-ray spectroscopy [NaI (Tl) 3″ × 3″]. X-Ray Fluorescence technique was used for chemical analyses of the studied samples. The specific activity of 226Ra, 232Th and 40K values are in range (3 ± 0.5 to 43 ± 2 Bqkg−1), (5 ± 0.7 to 41 ± 2 Bqkg−1) and (128 ± 6 to 682 ± 35 Bqkg−1) respectively. The absorbed dose rates ranged from 13.8 to 58.4 nGy h−1, where the total effective dose rates were determined to be between 16.7 and 70.9 μSvy−1. The maximum external hazard index (Hex) is 0.3 nGyh−1. The calculated values of the excess lifetime cancer risks (ELCR) and annual effective dose rate values are in between (8.48 × 10−5 and 2.63 × 10−4) and (24.2 and 72.9 μSvy−1) respectively. Geochemically, the studied granites consist of major oxides, they are characterized by SiO2, K2O, Na2O, Al2O3, and depleted in CaO, MgO, TiO2, and P2O5. The average absorbed dose rate (Do) in air is 37.8 nGyh−1 for the whole studied samples, this value is about 3.78% of the 1.0 mSvy−1 recommended by (ICRP-60,1991) to the public, so there is no radiological risk for the workers in that area.

Ecological and Health Risk Assessment of Metal in Resuspended Particles of Urban Street Dust from an Industrial City in China

Concentrations and ecological and health risks of metals in the resuspended particles of urban street dust collected from an industrial city, Baotou, China were studied. The results show that the average concentrations of Ba, Co, Cr, Cu, Mn, Ni, Pb, V and Zn in the studied samples are 990.1, 56.2, 247.8, 31.5, 566.3, 26.1, 59.9, 82.2 and 77.5 mg kg -1 respectively, which are higher than the background values of Inner Mongolia soil, especially Co, Cr and Pb. The results of potential ecological risk analysis demonstrate that Ba, Mn, V, Zn and Ni in the samples are in low ecological risk levels whereas Cr, Cu and Pb are in low to moderate ecological risk levels. Co reveals moderate to considerable ecological risk. The aggregate ecological risk of metals in the resuspended particles of street dust from Baotou is in the moderate level. Human health risk assessment shows that ingestion is the main exposure pathway of metals in dust to the local habitants. The upper limit of the 95% confidence interval of hazard indices for non-cancer risks of all analysed metals in the resuspended particles of street dust is within the safe level, while the maximum hazard index of Cr for children exceeds the safe level. Thus, the health risk of Cr for children due to dust exposure is a matter of concern. The cancer risk of Co, Cr and Ni to local habitants, considering only inhalation, is within the currently acceptable range.

Occurrence and health risk assessment of trace heavy metals via groundwater in Shizhuyuan Polymetallic Mine in Chenzhou City, China

The Shizhuyuan Polymetallic Mine in Chenzhou City is an important multi-metal deposit in China. After a dam accident in 1985, there are still a number of mining plants, smelters and tailing ponds in this area. These had the potential to pollute the surrounding groundwater. In this study, groundwater samples were collected from 20 residents’ wells in this area during both dry and wet seasons. In particular, this study focused on the exposure and the health risk assessment of trace heavy metal in groundwater. Multiple statistical analysis and fuzzy comprehensive method were employed to reveal the distribution characteristics of heavy metal and to assess the groundwater quality. Results indicated that Cr, Fe, Ni, Cu, Zn, As, Cd, Ba, Hg and Pb were widespread with low exposure levels. There were 19 wells with low level exposure and one well with a moderate level exposure in the dry season. All of the wells were in low level exposure during the wet season. As and Mn exhibited potential noncarcinogenic concern, because their maximum hazard quotient (HQ) was higher than 1.0. This may cause adverse health effect on adults in dry season or on children in both seasons. Only As, showed that the maximum carcinogenic risk was more than 10−4, suggesting a high cancer risk for children in both dry and wet seasons. Therefore, analysis and reduction the concentrations of As and Mn in groundwater are needed in order to protect the health of residents and especially children in the area.

A strong linear representation for the maximum conditional hazard rate estimator in survival analysis

Quintela-del-Río (2006) considered the estimation of the maximum hazard under dependence conditions and established strong convergence with rate and asymptotic normality of the estimate. The aim of this paper is to generalize this work to the case of right censored data with covariate. Via a consistently Nadaraya–Watson weighted type estimator of the conditional hazard function, we get a non-parametric estimator of its maximum value. We establish strong representation and strong uniform consistency results for our estimators.

Controls on macrotidal rip current circulation and hazard

Rip currents are strong, narrow seaward-flowing currents in the surf zone and are common on energetic sandy beaches. They are generally associated with distinct beach morphology, comprising nearshore sand bars and channels, and represent a real natural hazard to surf zone users. Rip current circulation is primarily driven by spatial gradients in wave breaking and water levels in the surf zone, which in turn are controlled by beach morphology, offshore wave conditions and tidal level. These factors, which are highly variable over hours (tides), days (waves) and weeks (morphology), also control the rip risk to bathers. However, the precise roles of these different environmental factors in controlling rip dynamics on meso- to macro-tidal beaches are not exactly known and thresholds separating different types of rip circulation and flow strengths, and hence rip risk, have not been quantified. Here, the analysis of 5-year lifeguard incident records from 20 beaches in southwest England showed that high-risk, high-exposure scenarios for bathers occur disproportionately around mean low water on days with low wave height (Hs<1m), long wave period (Tp>10s), shore-normal wave approach and light winds (>5ms−1). Detailed in-situ Lagrangian field measurements of rip currents collected on 23 different days from Perranporth beach, UK identified waves (characterised by HsTp) and active morphology (characterised by tidal elevation) as the key controlling factors determining the mode of rip behaviour. Maximum hazard was associated with the combination of maximum rip exits and rip flow speeds. These conditions occurred when HsTp was at or just below average values and when those waves were acting on the active morphological template, around mean low water. The thresholds in wave conditions and tidal elevation identified here were effective in discriminating between observed coast-wide high-risk incident events, illustrating that such mass rescue events have a considerable element of environmental control. Because many beaches along the west coast of southwest England are characterised by nearshore bar morphology just below the mean low water level, and are affected by similar wave and tide conditions, the results obtained from this beach are transferable to other locations. The findings of this study may also have implications for other beaches with nearshore bar–rip morphology at specific tidal levels.

Spatial distribution and risk assessment of metals in dust based on samples from nursery and primary schools of Xi'an, China

The spatial distribution of metal (Cu, Pb, Zn, As, Ba, Co, Cr, Mn, Ni and V) concentrations in urban dust of Xi'an, China was determined using the geographical information system method on dust from nursery and primary schools. The health risk of these metals in campus dust to children was assessed based on the EPA heath risk model. The results indicate elevated metal concentrations, especially of Cu, Pb, Zn, Co, Cr and Ba, which are 1.5–10.2, 2.6–73.0, 2.1–26.5, 2.0–10.9, 1.2–10.2 and 1.1–10.4 times the background values of Shaanxi soil, respectively. Pb, Cr, Cu and Ba have similar distribution patterns. The hot-spot areas of Pb, Zn, Cu, Co, Cr and Ba are mainly associated with industrial activities and heavy traffic. Their spatial distributions in the Xi'an urban dust indicated that these metals mainly originate from vehicles and industrial activities. For As, Mn, Ni and V, natural factors are important in controlling their distributions. Health risk assessment shows that ingestion is the largest exposure route of metals in dust from nursery and primary schools to children. The mean hazard indices for non-cancer risk of all analyzed metals due to campus dust are within the safe range, while the maximum hazard indices of Pb, Cr and As are close to, or slightly higher than, safe levels. The cancer risks of As, Co, Cr and Ni to nursery and primary school children, considering only inhalation, are within the acceptable range.

Undersampling power-law size distributions: effect on the assessment of extreme natural hazards

The effect of undersampling on estimating the size of extreme natural hazards from historical data is examined. Tests using synthetic catalogs indicate that the tail of an empirical size distribution sampled from a pure Pareto probability distribution can range from having one-to-several unusually large events to appearing depleted, relative to the parent distribution. Both of these effects are artifacts caused by limited catalog length. It is more difficult to diagnose the artificially depleted empirical distributions, since one expects that a pure Pareto distribution is physically limited in some way. Using maximum-likelihood methods and the method of moments, we estimate the power-law exponent and the corner size parameter of tapered Pareto distributions for several natural hazard examples: tsunamis, floods, and earthquakes. Each of these examples has varying catalog lengths and measurement thresholds, relative to the largest event sizes. In many cases where there are only several orders of magnitude between the measurement threshold and the largest events, joint two-parameter estimation techniques are necessary to account for estimation dependence between the power-law scaling exponent and the corner size parameter. Results indicate that whereas the corner size parameter of a tapered Pareto distribution can be estimated, its upper confidence bound cannot be determined and the estimate itself is often unstable with time. Correspondingly, one cannot statistically reject a pure Pareto null hypothesis using natural hazard catalog data. Although physical limits to the hazard source size and attenuation mechanisms from source to site constrain the maximum hazard size, historical data alone often cannot reliably determine the corner size parameter. Probabilistic assessments incorporating theoretical constraints on source size and propagation effects are preferred over deterministic assessments of extreme natural hazards based on historical data.

Optimized breast MRI functional tumor volume as a biomarker of recurrence‐free survival following neoadjuvant chemotherapy

To evaluate optimal contrast kinetics thresholds for measuring functional tumor volume (FTV) by breast magnetic resonance imaging (MRI) for assessment of recurrence-free survival (RFS). In this Institutional Review Board (IRB)-approved retrospective study of 64 patients (ages 29-72, median age of 48.6) undergoing neoadjuvant chemotherapy (NACT) for breast cancer, all patients underwent pre-MRI1 and postchemotherapy MRI4 of the breast. Tumor was defined as voxels meeting thresholds for early percent enhancement (PEthresh) and early-to-late signal enhancement ratio (SERthresh); and FTV (PEthresh, SERthresh) by summing all voxels meeting threshold criteria and minimum connectivity requirements. Ranges of PEthresh from 50% to 220% and SERthresh from 0.0 to 2.0 were evaluated. A Cox proportional hazard model determined associations between change in FTV over treatment and RFS at different PE and SER thresholds. The plot of hazard ratios for change in FTV from MRI1 to MRI4 showed a broad peak with the maximum hazard ratio and highest significance occurring at PE threshold of 70% and SER threshold of 1.0 (hazard ratio = 8.71, 95% confidence interval 2.86-25.5, P < 0.00015), indicating optimal model fit. Enhancement thresholds affect the ability of MRI tumor volume to predict RFS. The value is robust over a wide range of thresholds, supporting the use of FTV as a biomarker.

New approaches for seismic hazard studies in the Indian subcontinent

Earthquakes constitute among the most feared natural hazards and these occur with no warning which can result in great destruction and loss of lives, particularly in developing countries. One way to mitigate the destructive impact of such earthquakes is to conduct a seismic hazard assessment and take remedial measures. This article aims at demonstrating significant contributions in the field of seismic zonation and microzonation studies in the Indian subcontinent. The contributions in the field of earthquake hazard have been very valuable and beneficial not only for science but also for society. The historical seismicity and seismic zonation studies as well as the present scenario of seismic hazard assessment in the Indian subcontinent, whether through probabilistic or deterministic approaches, are discussed. It has been found that many parts of the Himalayan region have peak acceleration values exceeding 0.6g. The epicentral areas of the great Assam earthquakes of 1897 and 1950 in northeast India represent the maximum hazard with acceleration values reaching 1.2–1.3g. The peak velocity and displacement in the same region is estimated as 120–177 cm s−1 and 60–90 cm, respectively. To mitigate seismic risk, it is necessary to define a correct response in terms of both peak ground acceleration and spectral amplification. These factors are highly dependent on local soil conditions and on the source characteristics of the expected earthquakes. This article will also present the findings of site-specific hazard assessment in megacities.

The geography of extreme heat hazards for American football players

American Football players are among the most susceptible athletes to heat-related illnesses. Environmental conditions are an important factor when considering risk rates for these illnesses. Thus, we examine the spatio-temporal variations in the wet bulb globe temperature (WBGT), a commonly used metric for heat exposure, and quantify the hazard for extreme heat using safety thresholds specifically derived for athletes from the American College of Sports Medicine (ACSM). The objective is to provide better information on heat-related hazards to help mitigate the risk of exertional heat illnesses (EHI) among football players. We created a unique 15-year climatology (1991–2005) of August WBGTs for 217 locations across the contiguous United States using weather station observations and a WBGT model. Thirteen 3-h overlapping training session times ranging from 6–9 a.m. to 6–9 p.m. were examined to identify how the WBGT varies with the time of day the practice session was held and how frequently the WBGT during those sessions posed a hazard for extreme heat by exceeding two ACSM safety thresholds (30.1 °C and 32.3 °C). Maximum hazards for extreme heat are located in an arc across the Southern tier of the country, stretching from eastern Texas through to South Carolina as well as across southern Arizona and southeastern California. Climatologically, practice sessions early in the morning and later in the evening were best for minimizing heat exposure while those held from late morning through afternoon, particularly the noon-3 p.m. and 1–4 p.m. periods, had the highest WBGT values and were the practice periods that most frequently exceeded safety thresholds. Delaying the start of afternoon practices a few hours, however, may substantially reduce the likelihood of oppressive conditions and reduce the risk for heat illnesses.

Demarcation of potential avalanche sites using remote sensing and ground observations: a case study of Gangotri glacier

This study demonstrates the effectiveness of remote sensing and analytical hierarchy process for avalanche hazard mapping. The layers incorporated in this study were of slope, aspect, profile curvature, ground cover and elevation. The accuracy of output was determined using the registered avalanche sites based on ground observations and field-based modelling techniques. 93.35% of avalanche-affected areas came under maximum and moderate hazard zones, thus proving the effectiveness of this technique for Gangotri glacier basin. A parallel study was done to observe the change in the results, if any, by using high-resolution DEM and Cartosat-1 imagery. Similar methodology was adopted and the outcome was having significant improvement over the previous result as 98.8% of the preregistered avalanche area falling within maximum and moderate hazard zones.

Development of an inverse method for coastal risk management

Abstract. Recent flooding events, like Katrina (USA, 2005) or Xynthia (France, 2010), illustrate the complexity of coastal systems and the limits of traditional flood risk analysis. Among other questions, these events raised issues such as: "how to choose flooding scenarios for risk management purposes?", "how to make a society more aware and prepared for such events?" and "which level of risk is acceptable to a population?". The present paper aims at developing an inverse approach that could seek to address these three issues. The main idea of the proposed method is the inversion of the usual risk assessment steps: starting from the maximum acceptable hazard level (defined by stakeholders as the one leading to the maximum tolerable consequences) to finally obtain the return period of this threshold. Such an "inverse" approach would allow for the identification of all the offshore forcing conditions (and their occurrence probability) inducing a threat for critical assets of the territory, such information being of great importance for coastal risk management. This paper presents the first stage in developing such a procedure. It focuses on estimation (through inversion of the flooding model) of the offshore conditions leading to the acceptable hazard level, estimation of the return period of the associated combinations, and thus of the maximum acceptable hazard level. A first application for a simplified case study (based on real data), located on the French Mediterranean coast, is presented, assuming a maximum acceptable hazard level. Even if only one part of the full inverse method has been developed, we demonstrate how the inverse method can be useful in (1) estimating the probability of exceeding the maximum inundation height for identified critical assets, (2) providing critical offshore conditions for flooding in early warning systems, and (3) raising awareness of stakeholders and eventually enhance preparedness for future flooding events by allowing them to assess risk to their territory. The next challenge is to develop a framework to properly identify the acceptable hazard level, as an input to the present inverse approach.

Seismic hazard across Bulgaria and neighbouring areas: regional and site-specific maximum credible magnitudes and earthquake perceptibility

A probabilistic seismic hazard assessment is developed here using maximum credible earthquake magnitude statistics and earthquake perceptibility hazard. Earthquake perceptibility hazard is defined as the probability a site perceives ground shaking equal to or greater than a selected ground motion level X, resulting from an earthquake of magnitude M, and develops estimates for the most perceptible earthquake magnitude, MP(max). Realistic and usable maximum magnitude statistics are obtained from both whole process and part process statistical recurrence models. These approaches are extended to develop relationships between perceptible earthquake magnitude hazard and maximum magnitude recurrence models that are governed by asymptotic and finite return period properties, respectively. Integrated perceptibility curves illustrating the probability of a specific level of perceptible ground motion due to all earthquakes over the magnitude range extending from −∞ to a magnitude Mi are then developed from reviewing site-specific magnitude perceptibility. These lead on to achieving site-specific annual probability of exceedance hazard curves for the example cities of Sofia and Thessaloniki for both horizontal ground acceleration and ground velocity. Both the maximum credible earthquake magnitude M3 and the most perceptible earthquake magnitude MP(max) are of importance to the earthquake engineer when approaching anti-seismic building design. Both forms of hazard are illustrated using contoured hazard maps for the region bounded by 39°–45°N, 19°–29°E. Patterns are observed for these magnitude hazard estimates—especially MP(max) specific to horizontal ground acceleration and horizontal ground velocity—and compared to inferred patterns of crustal deformation across the region. The full geographic region considered is estimated to be subject to a maximum credible earthquake magnitude M3—estimated using cumulative seismic moment release statistics—of 7.53 Mw, calculated from the full content of the adopted earthquake catalogue, while Bulgaria’s capital, Sofia, is estimated a comparable value of 7.36 Mw. Sofia is also forecast most perceptible earthquake magnitudes for the lowest levels considered for horizontal ground acceleration of MPA(50) = 7.20 Mw and horizontal ground velocity of MPV(5) = 7.23 Mw for a specimen focal depth of 15 km.

Environmental and indoor study of Radon concentration in San Joaquin area, Queretaro, Mexico, first results

Abstract A highly contaminated zone with a maximum over 57,000 Bq/m 3 was discovered in a populated community “Agua de Venados” during the 2009–2011 soil Radon survey in San Joaquin, Queretaro State, Mexico. The indoor Radon monitoring accomplished in 2 different epoques in a nearby 4 dwellings has shown an increased Radon hazard in 1 of the 4 buildings (about 300 Bq/m 3 ) during a rainy season and highly elevated indoor Radon levels (over 400 Bq/m 3 ) already in 3 buildings during a dry season. The averaged diurnal indoor Radon variations are in a correlation with the atmospheric pressure and the air humidity and are independent on the air temperature. The maximum indoor Radon hazard for dwellings is estimated for the morning interval 5–10 a.m.

Estimation of Maximum Age Group Affected by StressProblems for the Teachers in Chennai by Using (RTDmatrix) (or) Fuzzy Matrix

Job stress in organization is widespread. About half of the youth feel the pressure of job-related stress. Extensive research shows that excessive job stress can have adverse effects on the emotional and physical health of workers. This paper analyze the health problem faced by Teacher in Chennai by using Refined Time Dependent Matrices (RTD matrices), from our interviews and field work undertaken we saw the people suffer by these six elements Management's use of authority, monetary, lack of opportunity for advancement, excessive loads, excessive noise, extreme temperatures. The data have been collected from local Chennai covering 100 people, the raw data, which is obtained, is transformed into time dependent matrices. After obtaining the time dependent matrices using the techniques of average and S.D. (Standard Deviation) we define the notin of ATD matrix, RTD matrix and CETD matrix. Using these concepts we identify the peakage group in which people suffer the maximum health hazard. The related graphic representation is also been given, we derive few conclusion from our study, the stress problems starts only at the age of 30 and the maximum age for getting stress problem is 37, which is unnatural and surprising.

Probabilistic seismic hazard of Pakistan, Azad-Jammu and Kashmir

The seismic hazard study for Pakistan and Azad Jammu and Kashmir has been conducted by using probabilistic approach in terms of peak ground acceleration (PGA) in m/s2 and also seismic hazard response spectra for different cities. A new version of Ambraseys et al. (Bull Earthq Eng 3:1–53, 2005) ground acceleration model is used, and parameterization is based on most recent updated earthquake catalogs that consisted of 14,000 events. The threshold magnitude was fixed at Mw 4.8, but seismic zones like northern Pakistan–Tajikistan, Hindukush and northern Afghanistan–Tajikistan border had Mw 5.2. The average normalized ‘a’ and ‘b’ values for all zones are 6.15 and 0.95, respectively. Seismicity of study area was modeled, and ground motion was computed for eight frequencies (0.025, 0.1, 0.2, 0.5, 1.0, 1.5, 2.0, 2.5 s) for different annual exceedance rates of 0.02, 0.01, 0.005, 0.002 and 0.001 (return periods 50, 100, 200, 500 and 1,000 years) for stiff rocks at the gridding of 0.1° × 0.1°. Seismic hazard maps based on computed PGA for 0.02, 0.01 and 0.002 annual exceedance are prepared. These maps indicate the earthquake hazard of Pakistan and surrounding areas in the form of acceleration contour lines, which are in agreement with geological and seismotectonic characteristics of the study area. The maximum seismic hazard values are found at Muzaffarabad, Gilgit and Quetta areas.

Primary Health Risk Analysis of Metals in Surface Water of Taihu Lake, China

The status and health risks of eight metals, Pb, Cd, Cr, Cu, Zn, Fe, Ni and Mn, in surface water from Taihu Lake (Jiangsu Province, China) were evaluated. The results showed that the maximum hazard quotients (HQ) value through ingestion pathway and dermal adsorption pathway was 2.74E-01 (Ni) and 2.57E-02 (Cd), respectively. However, the individual hazard quotient and total hazard index of eight metals through ingestion and dermal adsorption pathway was all lower than 1, indicating that the pollution situation in the surface water of Taihu Lake concerning these metals has no or low adverse health effects.

Environmental Risks Caused by Pesticides at Forest Nurseries in Finland

ABSTRACT Previously, various persistent pesticides were used extensively in the production of seedlings at Finnish forest nurseries. The extent and magnitude of the risks arising from the consequent environmental contamination are largely unknown. Therefore, we selected two representative nurseries for which we conducted tiered health risk assessments (HRA) using risk-based benchmarks and two calculation tools (SSL and Risc-Human software). Ecological risk assessments (ERA) involved comparisons of environmental concentrations with ecotoxicological benchmarks. Site investigations revealed that the concentration of several pesticides exceeded the Finnish soil quality guidelines in some places. The compost pile for organic residues and the pond receiving runoffs contained traces of pesticides and the maximum concentration of atrazine and terbuthylazine in groundwater exceeded the corresponding guideline for household water. Hexachlorobenzene proved to pose the highest health risks, the maximum hazard quotient being around 10 (carcinogenity-based) in the residential land use scenario. Owing to the conservative assumptions, health risks are expected to remain insignificant, however. Risks to the local terrestrial ecosystem would also remain low, while only further studies will reveal the actual risks to the adjoining aquatic ecosystem. Both calculation tools showed shortcomings that generate uncertainty in the HRA, whereas the ERA was hampered particularly by the lack of benchmarks.

A Bootstrap Algorithm for Data from a Periodic Multiplicative Intensity Function

The periodic multiplicative intensity model is considered. A new bootstrap method for non stationary counting processes which intensity function has some periodicity properties is presented. Its main advantage is that it does not destroy the temporal order and the original periodicity of the underlying counting process. The proposed algorithm is used to construct a bootstrap version of the maximum likelihood hazard function estimator. The consistency of the bootstrap method is shown. A possible modification of the proposed bootstrap method is discussed. The bootstrap simultaneous confidence intervals for the hazard function are presented. The telecommunication network traffic real data example is discussed.