The importance of outlier detection and training set selection for reliable environmental QSAR predictions

Empirical QSAR models are only valid in the domain they were trained and validated. Application of the model to substances outside the domain of the model can lead to grossly erroneous predictions. Partial least squares (PLS) regression provides tools for prediction diagnostics that can be used to decide whether or not a substance is within the model domain, i.e. if the model prediction can be trusted. QSAR models for four different environmental end-points are used to demonstrate the importance of appropriate training set selection and how the reliability of QSAR predictions can be increased by outlier diagnostics. All models showed consistent results; test set prediction errors were very similar in magnitude to training set estimation errors when prediction outlier diagnostics were used to detect and remove outliers in the prediction data. Test set prediction errors for substances classified as outliers were much larger. The difference in the number of outliers between models with a randomly and systematically selected training illustrates well the need of representative training data.     

Toxicology of benzyl alcohols: a QSAR analysis

There is an evidence that benzyl alcohols may exhibit toxicity via a radical mechanism. To test this possibility, we studied the toxicity of para substituted benzyl alcohols on rapidly dividing cancer cells (L1210 leukemia). This system has previously found utility in studying the apparent radical toxicity of a variety of phenols. However, no evidence could be found for an electronic effect and the cellular toxicity was associated primarily with hydrophobicity. Comparison of this quantitative structure-activity relationships (QSAR) with others for the reactions of benzyl alcohols in diverse systems provides insight into mechanisms of action. A QSAR for the interaction of benzyl alcohols with protozoa yields an equation that is dependent on both hydrophobicity and acidity of the OH group versus a mixture of bacteria and fungi, the critical dependence on hydrophobicity prevails with a small dependence on a resonance-stabilized, radical mediated electronic effect. The chloramphenicols provide an instructive example, where the radical mediated electronic effect overshadows the hydrophobic contribution to bacterial toxicity. These various QSAR for benzyl alcohols indicate that mechanisms of growth inhibition in vitro vary depending on cell/organism type, the strength of the bond and lability of the hydrogen, and the strength of the initiating radical reagent.     

The Kitchen Factory: a training tool for Cleaner Production

Successful integration of Cleaner Production concepts and technologies into businesses and industries requires effective education and training of the professionals. Cleaner Production, in spite of its conceptual simplicity, implies a new way of thinking about processes and products and a more sustainable approach to problem solving. Teaching university students about Cleaner Production is particularly challenging because many concepts depend on tools and experiences that are difficult to recreate in the typical classroom. Full understanding of the methodology and concepts of a Cleaner Production assessment can be achieved only by engaging students in practical application. To overcome the difficulties of providing a high number of students with a practical application, a very simple and useful exercise, based on the activities performed in the average kitchen, has been developed. The kitchen at home has all the elements of a factory, is available to everybody and can be used to supplement the theory provided in the classroom     

Identifying problems for choosing suitable areas for installation of a new landfill through GIS technology: A case study

Selecting a suitable place to install a new landfill is a hard work. Bauru is a Brazilian municipality where the local landfill currently in use has a life span that is almost over, and the selection of a new area for a future landfill is crucial and urgent. Here we use a geographic information system (GIS) approach to indicate possible suitable areas for installing the landfill. The considered criteria were: river network and the respective buffer zone, relief, urban areas and their respective buffer zone, existence of Areas for Environmental Protection (AEPs), occurrence of wells and their respective buffer zones, existence of airports and their buffer zones, wind direction, and the road network and its respective buffer zone. Due the facts that (1) Bauru has an urban area relatively large in relation to whole municipal area, (2) Bauru has two airports, and (3) this area encompasses parts of three AEPs, the model showed that there are few areas suitable and moderately suitable in Bauru, and the greater part of the municipality is unsuitable to install a new landfill. Due to this important finding reported here, the local policymakers should consider the suitable or even moderately suitable areas for analysis in situ or look for other creative solutions for destination of the solid waste. We highly encourage the use of GIS in studies that seek suitable areas for future landfills, having found that SIG was a tool that allowed fast and precise work and generated an outcome sufficiently clear of interpretation.

Implications:?Solid waste (SW) management is one of the main environmental concerns nowadays. Landfilling SW is still the main practice to disposal of such material. However, for many regions, suitable places for landfilling are getting scarce. This study proved this situation for a populous place in a southeastern Brazilian region. This study also showed how the decision makers should manage the problem in order to minimize the amount of SW generated and delivered for the landfill. Massive investment in education is a critical issue to reach the proposed aim.     

Reliable QSAR for estimating Koc for persistent organic pollutants: correlation with molecular connectivity indices

Several recent studies have shown that n-octanol/water partition coefficients may not be a good predictor for estimating soil sorption coefficients of persistent organic pollutants (POPs), defined here as chemicals with log Kow greater than 5. Thus, an alternative QSAR model was developed that seems to provide reliable estimates for the soil sorption coefficients of persistent organic pollutants. This model is based on a set of calculated molecular connectivity indices and evaluated soil sorption data for 18 POPs. The chemical's size and shape, quantified by 1chi, 3chiC and 4chiC(v) indices, have a dominant effect on the soil sorption process of POPs. The developed QSAR model was rationalized in terms of potential hydrophobic interactions between persistent organic pollutants and soil organic matrix. Its high predictive power has been verified by an extensive internal and external validation procedure.     

Designing Treatability Studies for CERCLA Sites: Three Critical Issues

A great urgency has developed in the past few years within the U.S. EPA remediation program to perform treatability studies at Superfund (CERCLA) sites. The major reasons for this urgency is to ensure the selected treatment technology is applicable to the waste characteristics, and that Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) cleanup goals can be achieved. However, prior to conducting a treatability study, three critical issues must be resolved by the site manager. First, what scale and timing are appropriate? Second, should the treatability study be performed by a treatment technology vendor using proprietary equipment and processes, or can a generic study be performed? Third, should the study be performed in the field or should the waste be taken to the laboratory for testing? The objectives of the treatability study will have a major impact on how these issues are resolved. This paper discusses these major issues and provides information for the design and conduct of Superfund treatability programs.     

Designing hydro-energy led economic growth for pollution abatement: evidence from BRICS

Environmental Science and Pollution Research - Overutilized hydro-energy production through non-sustainable mode is detrimental for both the economy and the environment. Intermittent consumption of...     

On determining the statistical parameters for pollution concentration from a truncated data set

Concentrations of atmospheric pollutants do occasionally reach levels below detection and it is common to deal with pollution concentration data sets which are truncated at the detection limit of the analytical instrument employed. The problem addressed in this paper is how to correct for detection limits in determining the mean and standard deviation of pollution concentration. Two methods are described and evaluated. A comprehensive comparison is made using an analytical approach that incorporates the assumption of an infinite number of noise free measurements. Additional comparisons are made using actual pollution concentration data sets, in order to estimate the magnitude of truncation errors relative to those due to finite sample size and to inaccuracies in measurement for concentrations above the detection limit. Results show that if all data points corresponding to concentration levels below the detection limit are set equal to half the detection limit an error is introduced that would probably be acceptable for most applications. If required, greater accuracy in the determination of the geometric mean and standard deviation can be obtained using a method based on maximum likelihood estimation theory.     

Blind identification of active landslides in urban areas: a new set of comprehensive criteria

Environmental Science and Pollution Research - More than 70% of catastrophic landslides were previously unknown and brought tremendous losses to human life and property in urban regions; therefore,...     

小型磷化废水处理成套设备的开发与设计

考虑到机械行业磷化废水的特点 ,利用混凝沉淀与结晶除磷的原理 ,设计成 2t h的磷化废水处理成套设备     

Experimental studies on solar chimneys for natural ventilation in domestic applications: a comprehensive review

Environmental Science and Pollution Research - Solar chimneys are among relatively modern mechanisms in the field of renewable energy which can be employed for power generation or indoor...     

Bibliometric analysis of studies involving e-waste: a critical review

Environmental Science and Pollution Research - The correct destination of waste is an essential factor for sustainable development. Electronic waste, which is very toxic, is the type of waste with...     

Polar organic chemical integrative sampler (POCIS) uptake rates for 17 polar pesticides and degradation products: laboratory calibration

Polar organic chemical integrative samplers (POCIS) are useful for monitoring a wide range of chemicals, including polar pesticides, in water bodies. However, few calibration data are available, which limits the use of these samplers for time-weighted average concentration measurements in an aquatic medium. This work deals with the laboratory calibration of the pharmaceutical configuration of a polar organic chemical integrative sampler (pharm-POCIS) for calculating the sampling rates of 17 polar pesticides (1.15?≤?logK _ow?≤?3.71) commonly found in water. The experiment, conducted for 21 days in a continuous water flow-through exposure system, showed an integrative accumulation of all studied pesticides for 15 days. Three compounds (metalaxyl, azoxystrobine, and terbuthylazine) remained integrative for the 21-day experiment. The sampling rates measured ranged from 67.9 to 279 mL?day^?1 and increased with the hydrophobicity of the pesticides until reaching a plateau where no significant variation in sampling rate is observed when increasing the hydrophobicity.     

Designing cost efficient buffer zone programs: An application of the FyrisSKZ tool in a Swedish catchment

Riparian buffer zones are the only measure which has been used extensively in Sweden to reduce phosphorus losses from agricultural land. This paper describes how the FyrisSKZ web tool can be used to evaluate allocation scenarios using data from the Svärta River, an agricultural catchment located in central Sweden. Three scenarios are evaluated: a baseline, a uniform 6-m-wide buffer zone in each sub-catchment, and an allocation of areas of buffer zones to sub-catchments based on the average cost of reduction. The total P reduction increases by 30 % in the second scenario compared to the baseline scenario, and the average reduction per hectare increases by 90 % while total costs of the program fall by 32 %. In the third scenario, the average cost per unit of reduction (€163 kg P^?1) is the lowest of the three scenarios (58 % lower than the baseline) and has the lowest total program costs.     

Health effects of waste incineration: a review of epidemiologic studies

There is an increasing trend toward using incineration to solve the problem of waste management; thus, there are concerns about the potential health impact of waste incineration. A critical review of epidemiologic studies will enhance understanding of the potential health effects of waste incineration and will provide important information regarding what needs to be investigated further. This study reviews the epidemiologic research on the potential health impact of waste incineration. Previous studies are discussed and presented according to their study population, incinerator workers or community residents, and health end points. Several studies showed significant associations between waste incineration and lower male-to-female ratio, twinning, lung cancer, laryngeal cancer, ischemic heart disease, urinary mutagens and promutagens, or blood levels of certain organic compounds and heavy metals. Other studies found no significant effects on respiratory symptoms, pulmonary function, twinning, cleft lip and palate, lung cancer, laryngeal cancer, or esophageal cancer. In conclusion, these epidemiologic studies consistently observed higher body levels of some organic chemicals and heavy metals, and no effects on respiratory symptoms or pulmonary function. The findings for cancer and reproductive outcomes were inconsistent. More hypothesis-testing epidemiologic studies are needed to investigate the potential health effects of waste incineration on incinerator workers and community residents.