Risk assessment of sensory irritants in indoor air--a case study in a French school

Exposure to airborne pollutants can result in adverse health effects. Acute symptoms can for instance comprise of irritation of the eyes or of the respiratory tract (called sensory irritation). In a recent case, health problems were reported in a French school and supposedly attributed to the presence of airborne irritant pollutants. Based on measured concentrations, the risk of developing the described health effects was assessed.Numerous airborne sensory irritants (aldehydes, organic acids, volatile organic compounds (VOCs), SO(2), NH(3)) were identified and quantified in the indoor air by using active and passive sampling and online monitoring techniques. Reference values based on toxicological properties of compounds (sensory irritants) were taken from the literature. If not available, tentative values were specially developed for this purpose. Concentrations of all sensory irritants remain below their corresponding guideline values and are comparable to literature data. It was concluded that the risk of developing sensory irritation due to the presence of the studied compounds is negligible. This holds both for individual compounds and for the mixture of studied compounds. Limitations of the employed sampling strategy, and of existing sampling and analytical techniques, which do not allow for analysing more reactive compounds-which are strong sensory irritants-may play a role. New sampling techniques need to be developed. Psychosocial factors (group behaviour, increased attention to sensory irritation) should also be taken into account when dealing with health complaints on sensory irritation.     

Determination of organic micropollutants in rain water for laboratory screening of air quality in urban environment

Rain water may collect organic air pollutants, such as polycyclic aromatic hydrocarbons (PAHs), phthalate ester (PEs), pesticides, and polychrorinated biphenyls (PCBs), that could be present in air in consequence of different factors. The determination of these compounds in rain water samples consequently may be interesting for a first screening of air quality in urban and/or industrial areas. For this purpose, 3 areas of the city of Rieti (central Italy) were selected for rain water sampling: a) the city center, densely populated and with high road traffic; b) a suburban residential area; c) the industrial area, about 3 km out of the city center and along the state road. Wet-only precipitation collectors were used for sampling; solid-phase microextraction or liquid-liquid microextraction techniques followed by GC/MS determinations were applied for sample analysis. PCBs and pesticides were never found in the samples collected. On the contrary, some polycyclic aromatic hydrocarbons and phthalates were always found. Significant and seasonal differences in PAH levels were observed in the 3 different sampling areas, with higher values always found in the city center and during the winter period; on the contrary, PEs levels remained unchanged.     

Evaluation of genotoxic and non-genotoxic effects of organic air pollution using in vitro bioassays

In this study, organic extracts of total suspended particles (TSP) and the particulate matter (PM) with the size below 2.5 microm (PM(2.5)) combined with organic extracts of the gas phase (GP) collected at two urban and two background localities were analyzed with a bacterial genotoxicity test, SOS chromotest, and an in vitro test for the dioxin toxicity determination, using a modified cell-line of rat hepatoma H4IIE.luc. In addition, the samples of TSP and GP were analyzed for PAHs contents. The PAHs concentrations and both of the toxic activities at the urban localities were much higher than ones at the background localities. Predominantly, traffic was a source of the urban air pollution there which was also confirmed by the evaluation of portions of certain PAHs (BaP/BPE, PYR/BaP) at the localities. On the other hand, the background localities were apparently affected by a long-distance transport of the pollutants from urban and industrial centers. The results of the bioassays indicated potential health risks for the population exposed to the organic air pollutants, especially at the urban localities. Based on the collected samples, distribution of the organic pollutants with the toxic effects in the air was evaluated. The significant portion of the direct genotoxins was bound to the particles larger than 2.5 microm. On the contrary, the indirect genotoxins were bound predominantly to the particles with the size below 2.5 microm. However, in the urban air they may be also bound to the larger particles, as well. While the direct genotoxicity may be related with the presence of PAH-derivatives as well as some polar organic pollutants, the indirect genotoxicity is related with the detected carcinogenic PAHs. But besides the above specified pollutants it is also necessary to consider the presence of other toxic components of the complex organic air pollution mixture that may also show potential health risks. This study demonstrates application of the combination of the screening bioassays for the evaluation of organic air pollution and identification of its health risks.     

Estrogen-, androgen- and aryl hydrocarbon receptor mediated activities in passive and composite samples from municipal waste and surface waters

Passive and composite sampling in combination with in vitro bioassays and identification and quantification of individual chemicals were applied to characterize pollution by compounds with several specific modes of action in urban area in the basin of two rivers, with 400,000 inhabitants and a variety of industrial activities. Two types of passive samplers, semipermeable membrane devices (SPMD) for hydrophobic contaminants and polar organic chemical integrative samplers (POCIS) for polar compounds such as pesticides and pharmaceuticals, were used to sample wastewater treatment plant (WWTP) influent and effluent as well as rivers upstream and downstream of the urban complex and the WWTP. Compounds with endocrine disruptive potency were detected in river water and WWTP influent and effluent. Year-round, monthly assessment of waste waters by bioassays documented estrogenic, androgenic and dioxin-like potency as well as cytotoxicity in influent waters of the WWTP and allowed characterization of seasonal variability of these biological potentials in waste waters. The WWTP effectively removed cytotoxic compounds, xenoestrogens and xenoandrogens. There was significant variability in treatment efficiency of dioxin-like potency. The study indicates that the WWTP, despite its up-to-date technology, can contribute endocrine disrupting compounds to the river. Riverine samples exhibited dioxin-like, antiestrogenic and antiandrogenic potencies. The study design enabled characterization of effects of the urban complex and the WWTP on the river. Concentrations of PAHs and contaminants and specific biological potencies sampled by POCIS decreased as a function of distance from the city.     

A survey of pollutant emission levels in wastewaters and residuals from the petroleum refining industry

This paper summarizes the data made available during the last decade on the subject of emission levels of wastewaters and solid residuals from the petroleum refininf industry. The data for both traditional and priority pollutants from a number of studies are considered. Specific organic compounds which are not traditional pollutants and are not on the priority pollutant list are presented for some cases. A discussion of accuracy, precision, variance, and some causes of variance is presented. Types of wastewater and residual samples for which data are presented include raw waste loadings from Class A through E refineries, loadings of various pollutants across several process units such as dissolved air flotation, activated sludge processes, carbon columns (powdered and granular), and clarifiers, and oily solids (tank bottoms, crude oil, bunker C, and waxy product).     

The mutagenic activity of thirty polycyclic aromatic hydrocarbons (PAH) and oxides in urban airborne particulates

Data are presented on the mutagenicity of an organic extract of a composite sample of urban air particulates and of thirty PAH compounds in such samples, including four quinone derivatives, isolated quantitatively by thin-layer chromatography and identified by fluorescence or other spectral techniques. Mutagenic activity was determined by the Ames assay, using histidine auxotrophs of Salmonella typhimurium strains TA98, TA100, TA1537 and TA1538. All compounds were dissolved in dimethyl sulfoxide (DMSO) which was the least toxic of eight organic solvents tested.The mutagenic activity of a benzene extract of suspended particulates from the air of Hamilton, Ontario was significantly greater with strain TA98 than with strain TA100, suggesting the presence of more frame-shift acting mutagens. The mutagenic response of this extract was similar with and without S-9 activation.Mutagenic tests on the 30 PAH compounds indicated that only the benzo(a)pyrene quinones were direct acting mutagens. All of the chemical compounds were tested with and without S-9 activation. The following PAH showed unequivocal mutagenic activity, with S-9 activation: benz(a)anthracene, benzo-(a)pyrene, benzo(ghi)perylene, benzo(rst)pentaphene, benzophenanthrene, chrysene, 1, 2, 3, 4-dibenzanthracene, 2, 3, 6, 7-dibenzanthracene, and 3-methyl cholanthrene. The quinones of 1, 6-; 3, 6-; and 6, 12-benzo(a)pyrenes showed weak mutagenic activity but 3, 6-benzo(a)pyrene elicited also a photodynamic response.     

武汉月湖和莲花湖表层沉积物中持久性有机物的污染状况

采用气－质联用技术分析了武汉汉阳月湖和莲花湖的4个表层沉积物样品中的有机污染物,探讨了两湖沉积物受持久性有机物污染的程度。月湖中共检测出124种有机物,其中属环境优先控制污染物和美国EPA筛选的内分泌干扰物19种;莲花湖中共检测出186种有机物,环境优先控制污染物和美国EPA筛选的内分泌干扰物34种。主要污染物包括：酞酸酯、酯类、酚类、杂环和苯及其衍生物等。污染物浓度顺序为L1＞L2＞Y2＞Y1,莲花湖中有机物浓度明显高于月湖。两湖邻苯二甲酸酯的含量最高,占了污染物总量的96%~98%,邻苯二甲酸乙基己基酯（平均值 17 59903 ng/g 干重）和邻苯二甲酸二丁酯（平均值 2 515.76 ng/g 干重）是两湖沉积物中的主要酞酸酯类污染物。     

Analysis of priority pollutants at a primary aluminum production facility

This paper investigated the source of priority pollutants, assessment of the wastewater treatment plant, and priority pollutant removal efficiency for a single Soderberg-type primary aluminum plant.Forty-eight hour composite samples were collected from the following streams: (1) plant intake water; (2) wastewater from the primary air pollution control system (gas stream cooling water and wet ESPs); (3) secondary air pollution control system (room ventilation wet scrubber liquor); (4) paste plant briquette cooling water; and (5) final effluent after the wastewater treatment plant.Wastewater from the primary air pollution control system entered a conventional chemical coagulation (using slacked lime) — clarification plant. Clarified water from the clarifier was combined with the other three wastewater streams and flowed into a settling lagoon with a 20-h hydraulic retention time. Clarified lagoon water was finally discharged to the river.The principal source of organic compounds in the wastewater was from the primary and secondary air pollution control systems and results from the volatilization of petroleum coke and pitch in the Soderberg anode. Wastewater treatment plant removal efficiencies of greater than 85% were achieved for the majority of the organic priority pollutant species detected.     

Basic characterization of Norwegian NOM samples — Similarities and differences

NOM (natural organic matter) samples, isolated by reverse osmosis (RO), and nine NOM samples, concentrated by low-pressure, low-temperature evaporation (EVA) from various origin in Norway, were characterized by different methods. The methods included elemental content of the freeze-dried samples (C, H, N, and O), elemental content of the redissolved samples (DOC, Na, Ca, Cu, Fe, and Mn), specific spectral absorbance at λ = 254 nm (A(254 nm)/DOC) and at λ = 436 nm (A(436 nm)/DOC), UV/Vis-spectra, specific fluorescence (excitation and emission spectra), proton capacity, Cu-complexation capacity, and content of hydrolysable amino acids and carbohydrates. In addition, chromatographic characterization by gel chromatography and reversed-phase chromatography was done. Studies on adsorption and flocculation abilities and the formation of trihalomethanes (THM) and organic halogens adsorbable on activated carbon (AOX) upon chlorination were also investigated. Comparison of the results showed that the samples were different according to the origin of the sample, isolation procedure, and time of sampling. The differences are not the same for all parameters used. Standardized procedures have to be applied to redissolve the organic material in water in order to compare data. For the samples investigated, it was shown that parameters like elemental analysis (H/C ratio), the specific spectral absorption in the UV range, proton capacity, complexation capacity and anionic particle charge, amount of hydrolysable amino acids and carbohydrates, adsorption behaviour on activated carbon, and the THM-FP are sensitive parameters to show differences concerning origin and isolation procedure.     

A review of traffic-related air pollution exposure assessment studies in the developing world

Exposure assessment studies in the developing world are important. Although recent years have seen an increasing number of traffic-related pollution exposure studies, exposure assessment data on this topic are still limited. Differences among measuring methods and a lack of strict quality control in carrying out exposure assessment make it difficult to generalize and compare findings between studies. In this article, exposure assessment studies carried out in the developing world on several traffic-related air pollutants are reviewed. These pollutants include particulate matter (PM), carbon monoxide (CO), nitrogen dioxide (NO(2)), volatile organic compounds (VOCs), and polycyclic aromatic hydrocarbons (PAHs). In addition, it discusses advantages and disadvantages of various monitoring methods (ambient fixed-site monitoring, microenvironment monitoring, and personal exposure assessment using portable samplers) for these pollutants in exposure assessment studies. Also included in this paper is a brief introduction of standards for these pollutants in ambient air or in occupational settings established by the United States Environmental Protection Agency (USEPA), the United States Occupational Safety and Health Administration (OSHA) and the World Health Organization (WHO). The review ends with a summary of the limitations and gaps in recent studies and suggestions for future research in the developing world.     

Volatile organic compounds in indoor environment and photocatalytic oxidation: state of the art

Volatile organic compounds (VOCs) are the major pollutants in indoor air, which significantly impact indoor air quality and thus influencing human health. A long-term exposure to VOCs will be detrimental to human health causing sick building syndrome (SBS). Photocatalytic oxidation of VOCs is a cost-effective technology for VOCs removal compared with adsorption, biofiltration, or thermal catalysis. In this paper, we review the current exposure level of VOCs in various indoor environment and state of the art technology for photocatalytic oxidation of VOCs from indoor air. The concentrations and emission rates of commonly occurring VOCs in indoor air are presented. The effective catalyst systems, under UV and visible light, are discussed and the kinetics of photocatalytic oxidation is also presented.     

Characterizing multi-pollutant air pollution in China: Comparison of three air quality indices

Multi-pollutant air pollution (i.e., several pollutants reaching very high concentrations simultaneously) frequently occurs in many regions across China. Air quality index (AQI) is used worldwide to inform the public about levels of air pollution and associated health risks. The current AQI approach used in China is based on the maximum value of individual pollutants, and does not consider the combined health effects of exposure to multiple pollutants. In this study, two novel alternative indices – aggregate air quality index (AAQI) and health-risk based air quality index (HAQI) – were calculated based on data collected in six megacities of China (Beijing, Shanghai, Guangzhou, Shjiazhuang, Xi'an, and Wuhan) during 2013 to 2014. Both AAQI and HAQI take into account the combined health effects of various pollutants, and the HAQI considers the exposure (or concentration)-response relationships of pollutants. AAQI and HAQI were compared to AQI to examine the effectiveness of the current AQI in characterizing multi-pollutant air pollution in China. The AAQI and HAQI values are higher than the AQI on days when two or more pollutants simultaneously exceed the Chinese Ambient Air Quality Standards (CAAQS) 24-hour Grade II standards. The results of the comparison of the classification of risk categories based on the three indices indicate that the current AQI approach underestimates the severity of health risk associated with exposure to multi-pollutant air pollution. For the AQI-based risk category of ‘unhealthy’, 96% and 80% of the days would be ‘very unhealthy’ or ‘hazardous’ if based on AAQI and HAQI, respectively; and for the AQI-based risk category of ‘very unhealthy’, 67% and 75% of the days would be ‘hazardous’ if based on AAQI and HAQI, respectively. The results suggest that the general public, especially sensitive population groups such as children and the elderly, should take more stringent actions than those currently suggested based on the AQI approach during high air pollution events. Sensitivity studies were conducted to examine the assumptions used in the AAQI and HAQI approaches. Results show that AAQI is sensitive to the choice of pollutant irrelevant constant. HAQI is sensitive to the choice of both threshold values and pollutants included in total risk calculation.     

Immunotoxic effects of environmental pollutants in marine mammals

Due to their marine ecology and life-history, marine mammals accumulate some of the highest levels of environmental contaminants of all wildlife. Given the increasing prevalence and severity of diseases in marine wildlife, it is imperative to understand how pollutants affect the immune system and consequently disease susceptibility. Advancements and adaptations of analytical techniques have facilitated marine mammal immunotoxicology research. Field studies, captive-feeding experiments and in vitro laboratory studies with marine mammals have associated exposure to environmental pollutants, most notable polychlorinated biphenyls (PCBs), organochlorine pesticides and heavy metals, to alterations of both the innate and adaptive arms of immune systems, which include aspects of cellular and humoral immunity. For marine mammals, reported immunotoxicology endpoints fell into several major categories: immune tissue histopathology, haematology/circulating immune cell populations, functional immune assays (lymphocyte proliferation, phagocytosis, respiratory burst, and natural killer cell activity), immunoglobulin production, and cytokine gene expression. Lymphocyte proliferation is by far the most commonly used immune assay, with studies using different organic pollutants and metals predominantly reporting immunosuppressive effects despite the many differences in study design and animal life history. Using combined field and laboratory data, we determined effect threshold levels for suppression of lymphocyte proliferation to be between < 0.001–10 ppm for PCBs, 0.002–1.3 ppm for Hg, 0.009–0.06 for MeHg, and 0.1–2.4 for cadmium in polar bears and several pinniped and cetacean species. Similarly, thresholds for suppression of phagocytosis were 0.6–1.4 and 0.08–1.9 ppm for PCBs and mercury, respectively. Although data are lacking for many important immune endpoints and mechanisms of specific immune alterations are not well understood, this review revealed a systemic suppression of immune function in marine mammals exposed to environmental contaminants. Exposure to immunotoxic contaminants may have significant population level consequences as a contributing factor to increasing anthropogenic stress in wildlife and infectious disease outbreaks.     

Characterization of hydrocarbon pollutant burdens in petrochemical and refinery process streams

This paper describes techniques which provide for both qualitative and quantitative identification of major components in a process stream. The techniques and instrumentation have been deliberately chosen so as to be within the technical and financial reach of all but the smallecompany laboratory. The sample preparation steps consist of an initial series of extractions which isolate compounds into organic acid, base, and neutral compounds and a totally water soluble phase. Each fraction is then concentrated and subjected to thin-layer chromatography, gas chromatography, infrared spectroscopy or ultraviolet spectroscopy as appropriate. Results are given for laboratory samples, one a mixture of aniline, phenol, benzoic acid, m-nitrobenzaldehyde, 1-butanol, 2-hexanone, nonane, and cyclohexane, and the other a mixture of benzene, ethylbenzene, and styrene. Also, a qualitative analysis of a petroleum refinery desalter water is presented.     

Measuring environmental stress in East Greenland polar bears, 1892–1927 and 1988–2009: What does hair cortisol tell us?

Hair sampled from 96 East Greenland polar bears (Ursus maritimus) over the periods 1892–1927 and 1988–2009 was analyzed for cortisol as a proxy to investigate temporal patterns of environmental stress. Cortisol concentration was independent of sex and age, and was found at significantly higher (p < 0.001) concentrations in historical hair samples (1892–1927; n = 8) relative to recent ones (1988–2009; n = 88). In addition, there was a linear time trend in cortisol concentration of the recent samples (p < 0.01), with an annual decrease of 2.7%. The recent hair samples were also analyzed for major bioaccumulative, persistent organic pollutants (POPs). There were no obvious POP related time trends or correlations between hair cortisol and hair POP concentrations. Thus, polar bear hair appears to be a relatively poor indicator of the animal's general POP load in adipose tissue. However, further investigations are warranted to explore the reasons for the temporal decrease found in the bears' hair cortisol levels.     

Evaluation of some air pollution indicators in Turkey

This article intends to shed a light on air quality in Turkey and compare air pollutant emissions on a national scale with that of the European countries. In order to estimate the quantities of Turkish emissions in the past and their future predictions, a national emission inventory was prepared with respect to five major pollutants consisting of particulate matter(PM), SOx, NOx, non-methane volatile organic compounds, and CO with 5-year intervals between 1985 and 2005. The results suggest that Turkey is a rather large emission source at the European scale, although emission indicators on unit area and per capita were shown to be somewhat smaller in magnitude. Levels of air pollution in some of the big cities in Turkey were also evaluated from available national monitoring data. These evaluations for the urban air qualities covered SO2 and PM parameters between 1986 and 1996, and results were compared with the present Turkish air quality limits, their probable revisions, WHO (Europe) guidelines and related EC directives. Results showed that the air quality limits were not met, especially during the winter periods in Turkish cities. Urban air pollutants characterizing the air in Turkish cities other than SO2 and PM, however, could not have been evaluated as these pollutants were not systematically monitored in these cities.     

Is external contamination with organic pollutants important for concentrations measured in bird feathers?

Although there is increasing evidence that bird feathers can be used as a non-destructive biomonitoring tool for organic pollutants [such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and p,p'-dichlorodiphenyl-trichloroethane and metabolites (DDTs)], the importance of external contamination of these organic pollutants onto the feathers has not been considered. Here we examine to which extent external contamination of organic pollutants occurs onto the feathers of a predatory bird. We have analysed primary wing feathers of 16 common buzzards (Buteo buteo) collected in Belgium. In order to study differences in external contamination within and among wing feathers, the vane and the shaft of each feather were separated and were analysed in parallel, pooled for the three inner and the three outer primary wing feathers. Most organic pollutants could be measured in these pooled samples of both the vane and the shaft. Concentrations of hexachlorobenzene (HCB), DDTs, PCBs and PBDEs were significantly higher in the vane compared to the shaft. The profiles of PCBs and PBDEs in the shaft closely resembled the profiles in liver and muscle tissue, in contrast with the profile of the vane. The PBDE congeners 47, 99 and 153 had a similar contribution in shafts of primary feathers of common buzzards. Although these results suggest that external contamination could be important on the vane, no differences in the profile of PBDEs or PCBs were found between the inner and outer (more exposed) primary feathers. Furthermore, correlation coefficients with internal tissues were not univocally distinct between the shaft and the vane. Therefore our results indicate that the higher concentrations found in the vane in comparison to the shaft do not originate from external contamination via the air, but that other factors such as structure and chemical properties of the feathers may be of importance. The lack of significant external contamination onto the feather surface is an additional asset for the use of feathers as a non-destructive biomonitor for organic pollutants.     

Confidence interval estimation for pooled-sample biomonitoring from a complex survey design

The National Centers for Disease Control and Prevention (CDC) is using a weighted pooled-sample design to characterize concentrations of persistent organic pollutants (POPs) in the U.S. population. Historically, this characterization has been based on individual measurements of these compounds in body fluid or tissue from representative samples of the population using stratified multistage selection. Pooling samples before making analytical measurements reduces the costs of biomonitoring by reducing the number of analyses. Pooling samples also allows for larger sample volumes which can result in fewer left censored results. But because samples are pooled across the sampling design cells of the original survey, direct calculation of the design effects needed for accurate standard error and confidence interval (CI) estimation is not possible. So in this paper I describe a multiple imputation (MI) method for calculating design effects associated with pooled-sample estimates. I also evaluate the method presented, by simulating NHANES individual sample data from which artificial pools are created for use in a comparison of pooled-sample estimates with estimates based on individual samples. To further illustrate and evaluate the method proposed in this paper I present geometric mean and various percentile estimates along with their 95% CIs for two chemical compounds from NHANES 2005–2006 pooled samples and compare them to individual-sample based estimates from NHANES 1999–2004.     

Indoor air pollution due to organic gases and vapours of solvents in building materials

The emission of organic gases and vapours of solvent type from 42 commonly used building materials was measured under standard atmospheric conditions. An average of 22 compounds was found in the air around each building material, and the total concentration of gases and vapours was from 0.01 to 1410 mg/m³. The average arithmetic emission rate was 9.5 mg/m² h, and 52 different compounds were identified. A mathematical model was established for the indoor air concentrations of pollutants originating from building materials. The model was tested on three model rooms constructed from the materials investigated. The calculated total air concentrations of gases and vapours in the three rooms ranged from 1.6 to 23.6 mg/m³, and the number of compounds in the air from 23 to 32. These concentrations and number of compounds did not differ from those found in actual rooms similar in size and construction to the model rooms. The risks of health effects due to the compounds identified from the building materials were investigated, and criteria for future air quality standards are discussed. It is concluded that the possibility of negative health effects cannot be neglected, especially not for the more sensitive minority of the general population.     

Determination of potentially bioaccumulating complex mixtures of organochlorine compounds in wastewater: a review

Organic chlorine compounds can be persistent environmental contaminants and may be accumulated through the food chain to the aquatic organisms, to fish and humans, depending basically on their hydrophobic properties. Consequently, there is an interest to measure these organic compounds from both the scientific and regulatory communities. The analytical essays have been improved for measuring specific organic chlorine compounds that present the most toxicological potential (polychlorinated biphenyls [PCBs], certain pesticides and dioxins), although they are tedious and time-consuming procedures. The existing tests to measure adsorbable organic halogens (AOX) or extractable organic halogens (EOX) do not distinguish the more hydrophobic organic chlorine matter. The intention of this paper is to make a review of the existing methods to measure the potentially bioaccumulating organochlorine compounds (OCs) from wastewater and propose a methodology to a standardisation procedure for complex mixtures of OCs in wastewater, such as pulp mill effluents. A new method has been proposed for determining the most hydrophobic part of the extractable organic halogens (EOX(fob)), the lowest reported value is 0.6 microg/l, expressed as chloride, and the relative standard deviation at 20 microg/l is 7% on laboratory samples and 30% on real effluents. This new procedure could be a valuable tool to complement environmental risk assessment studies of wastewater discharges.