Exposure Risk Analysis Research Articles

OCENA FUNKCJONOWANIA NOWYCH REGULACJI PRAWNYCH DOTYCZĄCYCH CHORÓB ZAWODOWYCH

On 3 July 2009, new law pertaining to occupational diseases (ODs) became effective in Poland. The article presents opinions of the representatives of the 1st degree ODs certification entities and sanitary inspectorates on the changes in OD) law and the problems that may cause difficulties and/or certification errors. A questionnaire study was performed covering representatives of 20 voivodeship occupational medicine centers and 40 national district sanitary inspectorates. We received 57 completed questionnaires which were analyzed. Positive opinions were expressed on changes in procedures on reporting suspected occupational diseases (50%), keeping time limits for diagnosing ODs (89.2%), and changes pertaining to entities responsible for certifying infectious ODs (92.9%). A large group of respondents (66.7%) was in favor of conducting jointly an occupational exposure risk analysis by occupational medicine physicians and occupational health and safety practitioners and/or sanitary inspectors. One-third of the respondents declared that changes in the list of ODs had no influence on the certification procedure. New law has improved the existing procedure of ODs certification. There is a need to elaborate detailed diagnostic guidelines on and criteria for ODs identification and recognition. A panel of experts should be established by the Ministry of Health to track the latest advancements in medicine and to update the list of OD)s. Conducting jointly an occupational exposure risk analysis by occupational medicine physicians and occupational health and safety practitioners and/or sanitary inspectors should become a standard.

Urban runoff impacts on receiving aquatic ecosystems assessed using periphyton community

Urban runoff is a major cause of stream degradation. For appropriate management action, there is a need to establish whether or not the runoff is degrading or potentially will degrade the receiving water. This work explored the use of local periphyton communities for assessing the ecological impacts of runoff of two urban catchments. Periphyton communities were colonized on glass substrate for 2 weeks in riverine waters receiving the urban runoff and in non-receiving waters at an upstream reference site. The receiving communities were evaluated against the reference community for photosynthetic efficiency and tolerance to copper, identified to be a significant runoff stressor. Photosynthesis efficiency was measured as a PSII quantum yield, and community tolerance was assessed using a laboratory ecotoxicological test. The hypothesis tested is that the runoff degrades by causing communities in receiving waters to become more sensitive to runoff stressors. The bioassessment indicated a much higher copper threshold than provided for in the generic water quality guidelines. The significance in the use of local community is that it allows for ecological risk analysis of exposure to runoff stressors, providing site-specific information relevant to management.

Transportation and Risk Analysis of Influenza Indoor and Outdoor Transportation and Exposure Risk Analysis of Influenza Aerosol

With the frequent outbreak of influenza virus in urban areas, the ecological security of high-density housing is becoming increasingly prominent. An Eulerian-Lagrangian pollutant diffusion model based on Large Eddy Simulation (LES) is established to simulate the transport of airborne virus. After the reliability of the numerical model is validated by the indoor experiment, the indoor and outdoor dispersion of microbial aerosol are simulated. The exposure risk is further studied based on the space-time concentration of pathogenic microorganisms of numerical simulation. The outcome can provide evidences for building plan optimization, environmental risk analysis and safety withdrawal planning.

Delta-9-tetrahydrocannabinol (THC) serum concentrations and pharmacological effects in males after smoking a combination of tobacco and cannabis containing up to 69 mg THC

Delta9-Tetrahydrocannabinol (THC) is the main active constituent of cannabis. In recent years, the average THC content of some cannabis cigarettes has increased up to approximately 60 mg per cigarette (20% THC cigarettes). The pharmacokinetics of THC after smoking cannabis cigarettes containing more than approximately 35 mg THC (3.55% THC cigarettes) is unknown. To be able to perform suitable exposure risk analysis, it is important to know if there is a linear relation at higher doses. The present study aimed to characterise the pharmacokinetics of THC, the active metabolite 11-OH-THC and the inactive metabolite THC-COOH after smoking a combination of tobacco and cannabis containing high THC doses. This double-blind, placebo-controlled, four-way, cross-over study included 24 male non-daily cannabis users (two to nine joints per month). Participants were randomly assigned to smoke cannabis cigarettes containing 29.3, 49.1 and 69.4 mg THC and a placebo. Serial serum samples collected over a period of 0-8 h were analysed by liquid chromatography electrospray tandem mass spectrometry. Effects on heart rate, blood pressure and 'high' feeling were also measured. Mean maximal concentrations (Cmax) were 135.1, 202.9 and 231.0 microg/L for THC and 9.2, 16.4 and 15.8 microg/L for 11-OH-THC after smoking a 29.3-, 49.1- and 69.4-mg THC cigarette, respectively. A large inter-individual variability in Cmax was observed. Heart rate and 'high' feeling significantly increased with increasing THC dose. This study demonstrates that the known linear association between THC dose and THC serum concentration also applies for high THC doses.

Oxidative stress risk analysis for exposure to diesel exhaust particle-induced reactive oxygen species

We constructed a probabilistic risk-based framework to assess the human oxidative stress (OS) risk from diesel exhaust particle (DEP)-induced reactive oxygen species. A human respiratory tract model was used to estimate DEP concentration and cumulative doses in lung regions for three occupational groupings (driver, homeworker and student) in northern, central, and southern Taiwan. Dose-response profiles were reconstructed in terms of the specific ratio of the reduced and oxidized forms of glutathione (GSH/GSSG ratio) for the human macrophage cell (THP-1) and human bronchial epithelial cell (BEAS-2B). The highest estimated median daily cumulative dose of DEP with 95% CI was for driver in northern Taiwan (DEP(2.5): 0.716 (0.443-1.197) mg and DEP(0.18): 0.584 (0.417-0.822) mg), significantly higher than that of the other settings. The driver in northern Taiwan setting had the highest cumulative dose-response calculated over a 2-year exposure period: 0.57 (0.41-0.76) and 0.70 (0.53-0.87) for DEP(2.5) and 0.40 (0.25-0.70) and 0.47 (0.34-0.80) for DEP(0.18), respectively, in THP-1 and BEAS-2B cells. Our results implicate that potential risks of OS from above-critical exposure to DEP(2.5) in all settings are found, whereas from DEP(0.18) in the driver in northern Taiwan setting is also alarming.

Studying atmospheric exposure risks during oil spills using a localized computational model

This paper has investigated the risk of atmospheric exposure during oil spills. Air levels of volatile components (VCs) arising from oil spills under some hypothetical scenarios have been studied using a computational model. The computational results indicate that overexposure to benzene may exist under general conditions. A table summarizing the exposure risks under various conditions is presented which may be useful in exposure risk analysis during oil spill response. The exposure to other volatile hydrocarbon components is negligible. Exposure to sulphur components occurs, but the duration is very short.

Pesticides and nitrate in groundwater and rainwater in the Province of Limburg in The Netherlands.

The purpose of this study was to investigate the occurrence of high levels of pesticides in groundwater and rainwater in The Province of Limburg in The Netherlands. In groundwater samples in particular the presence of triazines--atrazine, simazine and propazine--was observed; besides these pesticides, dieldrin has also been observed. Atrazine and simazine were found to exceed the groundwater standard of 100 ng L(-1). In the rainwater samples, the presence of 13 of 23 different analyzed pesticides was observed. A number of pesticides were found in high concentrations; e.g. atrazine (>200 ng L(-1)). Two pesticides detected in rainwater (beta+gamma-HCH and atrazine) were found to exceed the groundwater standard. Seven pesticides in rainwater were found to exceed the target value and three pesticides the maximum tolerable risk value (DDT, heptachlor and heptachlorepoxide A), which are used as ecotoxicological standards in The Netherlands. Nitrate in 15 of 16 analyzed natural springs was found to exceed the guideline value for nitrate in drinking water of 50 mg L(-1), up to levels of about 200 mg L(-1). Nitrate concentrations in rainwater samples were observed up to 4.5 mg L(-1). A risk analysis of exposure to high pesticide levels in groundwater or rainwater has been performed using the model HESP. For atrazine levels due to deposition of rainwater in two different locations, exceedance of the T.D.I. level of 0.5 microg kg(-1) day(-1) based on WHO criteria was observed for children using both an urban and a rural scenario and use of groundwater as drinking water.

Considerations in probabilistic evaluation of seismic inputs

Two aspects pertinent to the probabilistic treatment of seismic inputs are covered in this discussion. The first aspect concerns the occurrence of great earthquakes taking into account spatial and temporal dependencies. A semi-Markov model is used for this purpose. This model takes into account the probability distribution of holding times between earthquakes, transition probabilities, and magnitude of the most recent great earthquake and the time since its occurrence. The use of this model is illustrated for an area in the circum-Pacific belt, and is shown to provide notable differences compared to the use of a Poisson's model. Accordingly, the use of a semi-Markov model can significantly influence the selection of the magnitude of the OBE, because the OBE represents a risk function that is time-dependent. The longer the elapsed time since the last great earthquake, the larger is the magnitude of the earthquake having a reasonable probability of occuring in the next forty years. The second aspect is related to limiting values of ground motion parameters pertinent to very low probability of exceedance. Three possible approaches to modifying the tail of a probability distribution are proposed; these are: truncated, censored, or a constrained distribution. Without such modifications, the usual exposure risk analysis may suggest extremely high values of ground motion parameters which the site is not physically capable of transmitting.