Risk assessment of chemical release accident triggered by landslide using Bayesian network.

This study evaluated the risk of 461,260,800 scenarios of chemical release accidents triggered by landslides. Several industrial accidents triggered by landslides have recently occurred in Japan; however, only a few studies have analyzed the impact of landslide-triggered chemical release accidents on the surrounding areas. Bayesian networks (BNs) have recently been used in the risk assessment of natural hazardtriggered technological accidents (Natech) to quantify uncertainties and develop methods applicable to multiple scenarios. However, the scope of BN-based quantitative risk assessment is limited to the risk assessment of explosions triggered by earthquakes and lightning. We aimed to extend the BN-based risk analysis methodology and evaluate the risk and the effectiveness of the countermeasures for specific facility. A methodology was developed to assess human health risk in the surrounding areas when n-hexane was released and dispersed into the atmosphere due to a landslide. Risk assessment results showed that the societal risk (representing the relationship between frequency and number of people suffering from a particular harm) of the storage tank closest to the slope exceeded the Netherlands' criteria, which are the safest among the criteria in the United Kingdom, Hong Kong, Denmark, and the Netherlands. Limiting the storage rate reduced the probability of one or more fatalities by up to about 40% compared with the no countermeasure case and was a more effective countermeasure than using oil fences and absorbents. Diagnostic analyses quantitatively showed that the distance between the tank and slope was the main contributing factor. The catch basin parameter contributed to the reduction in the variance of the results compared to the storage rate. This finding indicated that physical measures, such as strengthening or deepening the catch basin, are essential for risk reduction. Our methods can be applied to other natural disasters for multiple scenarios by combining it with other models.

Reducing waste management scenario space for developing countries: A hierarchical clustering on principal components approach.

The complexity of waste management (WM) problems resulted in the explosion of scenarios that challenge focused discussion among stakeholders and hinder the integrity of policy responses in developing countries. Hence, drawing similarities is essential to reduce the number of scenarios to simplify the WM efforts. To extract similarities, measuring WM performance is not enough, but the background factors related to this performance should be incorporated. These factors form a unique system characteristic that facilitates or hinders WM functions. Thus, this study applied multivariate statistical analysis to clarify underlying characteristics that facilitate efficient WM scenario developments for developing countries. The study first analysed drivers associated with improved WM system performance using bivariate correlation analysis. As a result, twelve significant drivers associated with controlled solid waste were identified. Then, it mapped the countries based on their WM system characteristics using the combined principal component analysis and hierarchical clustering approach. Thirteen variables were examined to extract similarities between the countries. The results identified three homogenous clusters. The clusters were found considerably parallel to the global classifications based on income and human development index. Hence, the presented approach is efficient in explaining similarities that reduce WM scenarios and favours cooperation among countries.

Health risk assessment and cost-benefit analysis of agricultural soil remediation for tailing dam failure in Jinding mining area, SW China.

The impact of the tailing dams and the economic feasibility of the remediation process is significant for future risk management for tailing dams. In this research, we develop a hypothetical failure scenario for a tailing dam in the Jinding mining area, Southwest China. We assess the exposure with the Geo-Environmental Risk Assessment System, tier-1 model, and health impact with Disability-Adjusted Life Years (DALY). Cost and benefit are also analyzed for the following clean-up process. The result shows that the exposure dose (mg/kg-BW/d) of As, Cd, and Pb right after the dam failure is 1.07 × 10-2 for As, 1.76 × 10-4 for Cd, and 5.68 × 10-3 for Pb, respectively. The DALY caused by heavy metal exposure is 2.63 × 10-2 DALY per year, which significantly exceeds the tolerable level. This indicates that the tailing dam failure will pose a high health risk to the residents, and remediation is necessary. After remediation, the DALY is 1.24 × 10-8 DALY per year, indicating the clean-up process effectively reduces the resident's health impact. From the financial point of view, the net present value of the clean-up is $- 1.02 × 107. This indicates that the clean-up process is not economically feasible. Sensitivity analysis shows that the amount of released tailing influences the output result. The time span for benefit estimation is also an important issue. This research shows that the impact of a tailing dam failure will be severe, and remediation may be effective but economically infeasible. Therefore, preventing tailing dam failure is the most crucial task for the local government.

Characterizing potential risk triggered by road traffic noise in comparison with typical air pollutants NO2 and PM2.5.

Characterizing multiple risk stemming from automobiles are required from the viewpoint of priority setting for future risk management. However, little is known about such issues given the inadequacy of indicators. In this research, with the illustration of the metropolitan city of Osaka, Japan, using disability-adjusted life years (DALYs), impacts of road traffic noise and exhausts gas (nitrogen dioxide (NO2) and particulate matter (PM2.5)) were quantified and compared with the risks of ischemic heart disease and high sleep disturbance; and respiratory disease as endpoints, respectively. Health risks due to automobile noise were 3102.1 and 97.8 DALYs under the condition of open and closed windows, respectively. The health risks were reduced by 96.8% under closed-window condition. On the other hand, the health risks caused by NO2 and PM2.5 from automobiles were 137.6 DALYs, which was lower than the health risks due to automobile noise. These results indicate the effectiveness of DALYs as an indicator to characterize different kinds of burden of health and environmental impacts from automobiles, and they were successfully used to evaluate the effectiveness of risk reduction options such as the difference between open and closed windows. Furthermore, most people were found to have been exposed to 55-60 dB noise level. Although they easily get used to and can tolerate this level, it is also the stage at which health risks begin to occur. Therefore, with continuous exposure, qualitative estimation showed that open windows under this noise level subsequently leads to high potential health risks.

Flows, stocks, and emissions of DEHP products in Japan.

The usage of products containing Bis (2­ethylhexyl) Phthalate (DEHP) is widespread, mainly through the great variety of PVC products. However, DEHP has become a worldwide concern, due to the potential health and environmental risks it presents. In this study, material flow analysis and emission estimations for DEHP products in Japan, from 1948 to 2030, were performed. Moreover, an evaluation of the potentially damaging impacts on human health and the environment was completed through a lifecycle impact assessment approach. The analysis focused on three representative lifecycle phases - Production, Use and Treatment and Disposal. The peak flows of DEHP from Production to the Use phase were in 1996 with 285,300 tons for shipment and the stocks peaked in 2001 with 1,981,908 tons. Accordingly, in 2006 the peak of DEHP waste to the Treatment and disposal phase was 190,792 tons. The primary emissions were observed in the Use phase, due to the large stocks, with DEHP mostly being released to the pedosphere. The total emissions from the Use phase reached the maximum of 48,960 tons in 2000, whereas in the Production and Treatment and disposal phase it was 248 tons and 15 tons, respectively. Subsequently, concerning the evaluation of impacts, the damage to the human health was the most widespread impact, totaling 13,782 disability-adjusted life years (DALYs), compared with the damage to the ecosystems, with 0.12 species·year. Furthermore, the risk-risk tradeoffs between the lifecycle phases were clarified throughout the years.

Application of fuzzy c-means clustering to PRTR chemicals uncovering their release and toxicity characteristics.

Increasing manufacture and usage of chemicals have not been matched by the increase in our understanding of their risks. Pollutant release and transfer register (PRTR) is becoming a popular measure for collecting chemical data and enhancing the public right to know. However, these data are usually in high dimensionality which restricts their wider use. The present study partitions Japanese PRTR chemicals into five fuzzy clusters by fuzzy c-mean clustering (FCM) to explore the implicit information. Each chemical with membership degrees belongs to each cluster. Cluster I features high releases from non-listed industries and the household sector and high environmental toxicity. Cluster II is characterized by high reported releases and transfers from 24 listed industries above the threshold, mutagenicity, and high environmental toxicity. Chemicals in cluster III have characteristics of high releases from non-listed industries and low toxicity. Cluster IV is characterized by high reported releases and transfers from 24 listed industries above the threshold and extremely high environmental toxicity. Cluster V is characterized by low releases yet mutagenicity and high carcinogenicity. Chemicals with the highest membership degree were identified as representatives for each cluster. For the highest membership degree, half of the chemicals have a value higher than 0.74. If we look at both the highest and the second highest membership degrees simultaneously, about 94% of the chemicals have a value higher than 0.5. FCM can serve as an approach to uncover the implicit information of highly complex chemical dataset, which subsequently supports the strategy development for efficient and effective chemical management.

Decabromodiphenyl Ether (DecaBDE) in Electrical and Electronic Equipment in Japan: Stock, Emission, and Substitution Evaluation.

DecaBDE has been widely used as flame retardant in electrical and electronic equipment (EEE). It has recently been listed in Annex A of the Stockholm Convention. The time series flow, stock, and emission of DecaBDE in EEE in Japan were quantified. On this basis, a risk/risk trade-off analysis of substituting DecaBDE with triphenyl phosphate (TPhP) that is one possible phosphorus-based alternative was conducted. The stock of DecaBDE reached a maximum of ∼42 000 t in 1995. Even though the demand flow was negligible in 2030, the stock was modeled to be still ∼470 t. The outflow of DecaBDE, from the use phase to the disposal phase, peaked at ∼4500 t/yr. in 2001. The DecaBDE emission to atmosphere was mainly derived from the production phase before 1990. The use phase became the largest contributor to the total emission from 1995 to 2000. Whereas the disposal phase dominated the total emission from 2000 onward. In the substitution analysis, a trade-off between human and ecological health effect was revealed in case of replacing DecaBDE with TPhP. This study attempted to give an overall picture of DecaBDE application at national level providing insights into relevant environmental policy making.

Flow, stock, and impact assessment of refrigerants in the Japanese household air conditioner sector.

Refrigerants provide society with great benefits while have the potential to cause adverse effects on the environment and human health. The present study estimated time-dependent flows and stocks and assessed the effects of refrigerants (R-22, R-410a, and R-32) in household air conditioners in Japan. It was found that stock of R-22 and R-410a peaked at 49,147t in 2000 and 55,994t in 2017, respectively. The largest flow of R-22 and R-410a to waste phase occurred at 3417t/yr. in 2005 and 4011t/yr. in 2023, respectively. The total global warming potential (GWP) due to refrigerant emissions increased from 3.6kt CO2 eq. in 1952 to 6999kt CO2 eq. in 2019, and then decreased to 5314kt CO2 eq. in 2030. The ozone depletion potential (ODP) peaked at 141t CFC-11 eq. in 2002. When substituting R-410a for R-22, the ODP decreased 50% while the GDP increased 8%. When substituting R-32 for R-410a, there was no effect on the ODP while the GDP decreased 6%. The human health damage due to the global warming effect of refrigerant emission was much higher than that due to the ozone depleting effect. The refrigerant emission in use and waste management phases dominated the human health damage. The dynamic estimation not only allows us to evaluate the performance of past policies but also supports the future sustainable management associated with the health effects of refrigerants.

Estimating the probability of exceeding the maximum residue limit for Japanese tea using a crop residue model.

Maximum residue limits (MRLs) for pesticides in export countries from Japan often become a trade barrier for Japanese tea. The purpose of this study is to develop a probabilistic risk estimation method for pesticide residues in green tea. First, we developed a model to estimate the pesticide residue level in green tea. Second, we introduced a regression model for pesticide half-lives on plants, one of the most critical parameters in the model. Finally, we estimated the time-course change of the distribution of the residue level by setting the probability distribution to the half-lives on tea leaves. Applying the model to three pesticides, acetamiprid, dinotefuran, and thiamethoxam, we suggested that the pre-harvest interval of thiamethoxam should be increased by three weeks for export to Taiwan. For EU nations, the MRL excess probabilities of acetamiprid and dinotefuran were measured as 99.6% and 99.5%, respectively, even 28 days after spraying.

Data uncertainties in material flow analysis: Municipal solid waste management system in Maputo City, Mozambique.

Material flow analysis can effectively trace and quantify the flows and stocks of materials such as solid wastes in urban environments. However, the integrity of material flow analysis results is compromised by data uncertainties, an occurrence that is particularly acute in low-and-middle-income study contexts. This article investigates the uncertainties in the input data and their effects in a material flow analysis study of municipal solid waste management in Maputo City, the capital of Mozambique. The analysis is based on data collected in 2007 and 2014. Initially, the uncertainties and their ranges were identified by the data classification model of Hedbrant and Sörme, followed by the application of sensitivity analysis. The average lower and upper bounds were 29% and 71%, respectively, in 2007, increasing to 41% and 96%, respectively, in 2014. This indicates higher data quality in 2007 than in 2014. Results also show that not only data are partially missing from the established flows such as waste generation to final disposal, but also that they are limited and inconsistent in emerging flows and processes such as waste generation to material recovery (hence the wider variation in the 2014 parameters). The sensitivity analysis further clarified the most influencing parameter and the degree of influence of each parameter on the waste flows and the interrelations among the parameters. The findings highlight the need for an integrated municipal solid waste management approach to avoid transferring or worsening the negative impacts among the parameters and flows.

Application of material flow analysis to municipal solid waste in Maputo City, Mozambique.

Understanding waste flows within an urban area is important for identifying the main problems and improvement opportunities for efficient waste management. Assessment tools such as material flow analysis (MFA), an extensively applied method in waste management studies, provide a structured and objective evaluating process to characterize the waste management system best, to identify its shortcomings and to propose suitable strategies. This paper presents the application of MFA to municipal solid waste management (MSWM) in Maputo City, the capital of Mozambique. The results included the identification and quantification of the main input and output flows of the MSWM system in 2007 and 2014, from the generation, material recovery and collection, to final disposal and the unaccounted flow of municipal solid waste (MSW). We estimated that the waste generation increased from 397×103 tonnes in 2007 to 437×103 tonnes in 2014, whereas the total material recovery was insignificant in both years - 3×103 and 7×103 tonnes, respectively. As for collection and final disposal, the official collection of waste to the local dumpsite in the inner city increased about threefold, from 76×103 to 253×106 tonnes. For waste unaccounted for, the estimates indicated a reduction during the study period from 300×103 to 158×103 tonnes, due to the increase of collection services. The emphasized aspects include the need for practical waste reduction strategies, the opportunity to explore the potential for material recovery, careful consideration regarding the growing trend of illegal dumping and the urgency in phasing-out from the harmful practice of open dumping.

Approaches for establishing predicted-no-effect concentrations for population-level ecological risk assessment in the context of chemical substances management.

The establishment of rational frameworks for population-level ecological risk assessment (PLERA) in the context of chemical substances management is an important issue. We illustrate two feasible approaches for establishing predicted-no-effect concentrations (PNECs)for PLERA through a case study of 4-nonylphenol (4-NP) using life-cycle toxicity data for medaka (Oryzias latipes). We first quantified the potential impacts of 4-NP on medaka in terms of reduction of population growth rate (i). An age-classified population matrix model (daily time-step) was developed and used to combine life-cycle survivorship and fecundity data obtained from individual-level responses of medaka expDsed to 4-NP into population-level responses defined by the parameter lambda. Thereafter, from the resulting lambdas, two approaches for establishing population-level PNEC values were proposed and examined. We then derived the PNEC values for population-level impacts, based on (a) the threshold concentration, defined as the chemical concentration at which lambda = 1 as a value with a 95% confidence interval, and (b) the no-observed-effect concentration (NOEC) and the maximum-acceptable-toxic concentration (MATC). The results suggest that PNEC values of 4-NP ranging between 0.82 and 2.10 microg/L affect medaka population growth. Although these approaches have their limitations, current knowledge indicates that they are reasonable and practical for evaluating population-level impacts of chemicals, thereby serving as a case study for establishing PNEC values for PLERA in the context of chemical substances management and decision-making.