Environmental Protection Agency Method Research Articles

Nitrate Contamination in the Groundwater and Associated Human Health Risk Assessment for Gaya District, Bihar, India

The study pertains to nitrate concentration in groundwater resources of the Gaya district, Bihar, India and its related health risk to the local population. Groundwater serves as the principal source of drinking water in the area. 40 representative groundwater samples were collected and analyzed for nitrate and other water quality parameters. The concentration of Nitrate (NO3 -) in the groundwater of Gaya district varied from 1.62 to 155.6 mg/L and exceeded the Bureau of Indian Standards (BIS) permissible limits for drinking water in 30% of the samples. The elevated nitrate levels were predominantly attributed to agricultural activities. To evaluate the human health risks associated with groundwater, Hazard Quotient for nitrate (HQnitrate) were calculated using the United States Environmental Protection Agency method. The mean HQnitrate values were estimated to be 1.03, 0.89 and 1.65 for the male, female and child populace, respectively depicting considerable risk to male and child populace. In 67.5% of the samples, HQnitrate for children exceeded the safety threshold of 1. The study advocates significant health risks, especially to children in many parts of Gaya district due to high concentrations of nitrate in the groundwater. Judicial use of nitrogen-based fertilizers is suggested to prevent further contamination of groundwater.

Surveillance of PFAS in sludge and biosolids at 12 water resource recovery facilities.

Per- and polyfluoroalkyl substances (PFAS) are refractory anthropogenic chemicals and current treatment processes at municipal water resource recovery facilities (WRRFs) cannot efficiently degrade them, hence, these chemicals cycle through the environment. Certain PFAS can be concentrated in biosolids from WRRFs and are commonly land applied for beneficial reuse. Given recent advances in measurement of PFAS, documentation of the range of concentrations in pre-stabilized sludge and stabilized biosolids is critical to evaluating treatment best practices and assessing potential human health and ecological risks. In this study, pre-stabilized sludge and post-stabilized biosolids samples were collected from 12 major WRRFs across the United States. PFAS were analyzed using Environmental Protection Agency (EPA) Method SW846-3500C/537.1, and Draft EPA Method 1633, by one commercial laboratory and two university research laboratories, respectively. Results comparison among laboratories demonstrated statistical differences in PFAS concentrations among split samples. For example, 5:3 FTCA (fluorotelomer carboxylic acid) concentrations in post-stabilized sludge at Lab 1 were measured at 21ng/g (dry), while they were detected at 151ng/g (dry) in Lab 3. Further, higher PFAS concentrations were observed in post-stabilized biosolids compared to pre-stabilized sludges, regardless of the laboratory or analysis method, even when solids destruction through solids stabilization was considered. Further research is required to refine methods for analyses of PFAS in sludge and biosolids samples from WRRFs prior to being used for development of regulatory actions as well as understanding how various treatment protocols could impact concentrations of PFAS in land-applied biosolids.

Occurrence and potential ecological risks of PFAS in Pampulha Lake, Brazil, a UNESCO world heritage site

Per- and polyfluoroalkyl substances (PFAS) comprise >4000 synthetic substances used in industrial applications and consumer products. PFAS used daily in households and manufacturing plants end up in domestic sewage, and industrial effluents can be discharged to surface water. Urban watersheds located in low and middle-income countries (LMIC), which lack sanitation infrastructure, are potential recipients of waste containing PFAS. Yet, only a few studies report PFAS occurrence in urban reservoirs and lakes, especially those located in the Global South due to resource limitations. This is the first study aimed to assess PFAS occurrence and ecological risks in Pampulha Lake, Brazil, a site which represents the reality of many other urban watersheds in LMIC as it is surrounded by densely populated areas and manufacturing plants. Surface water samples were collected monthly for 1 year from four sampling points at Pampulha Lake. Sample analysis was based on US Environmental Protection Agency Method 1633, which employs solid phase extraction followed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Species sensitivity distribution (SSD) curves were built to identify potentially susceptible species based on detected water concentrations. Bioaccumulation was estimated for fish tissue. Short-chain (perfluorobutanesulfonic acid, PFBS and perfluorohexanoic acid, PFHxA) and long-chain PFAS (perfluorodecanoic acid, PFDA; perfluorooctanoic acid, PFOA; perfluorododecanoic acid, PFDoA; and perfluorooctanesulfonic acid, PFOS) were detected at the μg L−1 range. Total PFAS concentrations in the wet season were generally higher than in the dry season, likely due to limited capacity of the treatment plant processing water from tributaries which receive raw sewage. More than 5 % of aquatic species are potentially susceptible to chronic effects of PFOS at detected concentrations (0.2–2.2 μg L−1). Predicted bioaccumulation of PFOS in fish was above advisory diet intake levels for humans. Results emphasize the need for studies related to PFAS occurrence in watersheds located in LMIC.

Year-round monitoring of three water sources in Québec, Canada, reveals site-specific differences in conditions for Cryptosporidium and Giardia contamination.

Cryptosporidium and Giardia are protozoan parasites responsible for gastrointestinal illnesses in humans and in animal species. The main way these parasites are transmitted is by ingestion of their (oo)cysts in drinking water. Monitoring (oo)cysts in water sources is beneficial to evaluate the quality of raw water supplying treatment plants. Currently, the only standardized protocol to enumerate these parasites from water samples is United States Environmental Protection Agency (USEPA) Method 1623.1. With this method, we monitored three major water sources in Quebec over a year to assess temporal and geographical variations of these parasite (oo)cysts. These three water sources have independent watersheds despite being in the same region. We found a general pattern for Giardia, with high concentrations of cysts during cold and transition periods, and significantly lower concentrations during the warm period. Cryptosporidium's concentration was more variable throughout the year. Statistical correlations (Pearson's correlation coefficients) were established between the concentration of each parasite and various environmental parameters. The three study sites each showed unique factors correlating with the presence of both protozoa, supporting the idea that each water source must be seen as a unique entity with its own particular characteristics and therefore, must be monitored independently. Although some environmental parameters could be interesting proxies to the parasitic load, no parameter was strongly correlated throughout the whole sampling year and none of the parameters could be used as a single proxy for all three studies sources.

3D numerical simulation of airflow structure and dust emissions from an open storage pile behind a dynamic solid fence-deflector

Open storage yards at industrial sites represent a significant fugitive dust emission source. Granular material subjected to wind erosion may emit significant dust into the atmosphere. Several windbreaks and fences with different shapes have been proposed to control and reduce those emissions. Solid fences are commonly erected around the open yard (i.e., open bays) to prevent and reduce those emissions, even though they have some limitations. The present study aims to enhance the effectiveness of solid fences by coupling them with dynamic wind deflectors. Computational fluid dynamics was employed to simulate the flow and shear stresses on storage pile surfaces using the numerical Reynolds-averaged Navier–Stokes equations and the k-ω SST turbulence model. At the same time, dust emission was estimated using an Environmental Protection Agency (EPA) method, which estimates the emission potential of a material based on the wind friction velocity and the material's threshold friction velocity. The numerical model was validated against experimental data from an EPA study. In addition, this study investigated the efficiency of various dynamic wind deflectors with different heights and inclination angles. The results showed that most of the investigated dynamic fence-deflector models reduced the velocity magnitude, vortices, and turbulence intensity, lessening the impact of shear stresses compared to single solid fences and consequently reducing the emission of dust from the exposed surfaces (i.e., a primary measure of impact reduction). More specifically, the deflector of width (Ydef) 2 m with an inclination of (∅def) 65° was the most effective, where the shear stress on the pile surface and the emission factor were reduced by 29.16% and 21.79%, respectively, compared to the single fence of the same height. Finally, adding dynamic wind deflectors enhances the performance of solid fences, and it is a more effective and less expensive solution than replacing single fences with other windbreak models.

Health risk assessment of exposure to benzene, toluene, ethyl benzene, and xylene in shoe industry-related workplaces.

Benzene, toluene, ethyl benzene, and xylene (BTEX) are prevalent pollutants in shoe industry-related workplaces. The aim of this study was to assess exposure to BTEX and their carcinogenic and non-carcinogenic risks in shoe-industry-related workplaces. This study was carried out at different shoe manufactures, small shoe workshop units, shoe markets, and shoe stores in Tabriz, Iran in 2021. Personal inhalation exposure to BTEX was measured using the National Institute for Occupational Safety and Health (NIOSH) 1501 method. Carcinogenic and non-carcinogenic risks due to inhalation exposure to BTEX were estimated by United States Environmental Protection Agency (U.S. EPA) method based on Mont Carlo simulation. Results showed that the concentrations of benzene and toluene were higher than the threshold limit value (TLV) in both gluing and non-gluing units of shoe manufactures. The total carcinogenic risk (TCR) due to exposure to benzene and ethyl benzene was considerable in all shoe industry-related workplaces. Also, the hazard index (HI) as a non-carcinogenic index was higher than standard levels in all shoe industry-related workplaces. Therefore, shoe industry-related workers are at cancer and non-cancer risks due to exposure to BTEX. Prevention measures need to be implemented to reduce the concentration of BTEX in shoe industry-related workplaces.

Evaluation of Selected Heavy Metals in Indoor Dust and Interior Painted Walls of Nursery Schools in Nairobi County, Kenya

School playgrounds found in painted environments have become death chambers for millions of innocent children who unknowingly ingest toxic metals. The objective of this study is to determine the levels of the heavy metals in paint chips from painted interior walls and indoor dust samples from 14 selected nursery schools in Nairobi County. The paint chips and indoor dust samples collected were digested using the Environmental Protection Agency method SW846 3050B then analyzed using Flame Atomic Absorption Spectrometry. Iron (Fe) had the highest concentrations in both the paint chip from interior walls and the indoor dust while Cadmium (Cd) had the lowest concentration followed by Chromium (Cr), Lead (Pb) and Zinc (Zn) respectively. 50% of the nursery schools had Lead (Pb) concentrations that exceeded the 90 µg/g limit set by KEBS. For Cadmium (Cd) and Chromium (Cr), the concentration in the nursery schools and the indoor dust was below the 200 µg/g used in Germany. Generally, the correlation between the various metal pairs for the samples analyzed showed a non-significant correlation with exception of Lead - Iron (Pb-Fe) and Chromium - Cadmium (Cr-Cd) for the indoor dust samples from pre-schools. The t-tests carried out show that levels of the heavy metals in the paint chip did not differ significantly with the levels in the indoor dust for nursery schools at 95% confidence level.

Antibiotic, Heavy Metal, and Biocide Concentrations in a Wastewater Treatment Plant and Its Receiving Water Body Exceed PNEC Limits: Potential for Antimicrobial Resistance Selective Pressure.

Although the rise in antimicrobial resistance has been attributed mainly to the extensive and indiscriminate use of antimicrobials such as antibiotics and biocides in humans, animals and on plants, studies investigating the impact of this use on water environments in Africa are minimal. This study quantified selected antibiotics, heavy metals, and biocides in an urban wastewater treatment plant (WWTP) and its receiving water body in Kwazulu-Natal, South Africa, in the context of the predicted no-effect concentrations (PNEC) for the selection of antimicrobial resistance (AMR). Water samples were collected from the WWTP effluent discharge point and upstream and downstream from this point. Heavy metals were identified and quantified using the United States Environmental Protection Agency (US EPA) method 200.7. Biocides and antibiotic residues were determined using validated ultra-high-performance liquid chromatography with tandem mass spectrometry-based methods. The overall highest mean antibiotic, metal and biocide concentrations were observed for sulfamethoxazole (286.180 µg/L), neodymium (Nd; 27.734 mg/L), and benzalkonium chloride (BAC 12) (7.805 µg/L), respectively. In decreasing order per sampling site, the pollutant concentrations were effluent > downstream > upstream. This implies that the WWTP significantly contributed to the observed pollution in the receiving water. Furthermore, most of the pollutants measured recorded values exceeding the recommended predicted no-effect concentration (PNEC) values, suggesting that the microbes in such water environments were at risk of developing resistance due to the selection pressure exerted by these antimicrobials. Further studies are required to establish such a relationship.

Quantitative risk assessment of respiratory exposure to acrylonitrile vapor in petrochemical industry by U.S. Environmental Protection Agency method: a cross-sectional study.

Acrylonitrile is a potential carcinogen for humans, and exposure to this substance can cause adverse effects for workers. This study aimed to carcinogenic and health risk assessment of acrylonitrile vapor exposure in exposed personnel of a petrochemical complex. This crosssectional study was performed in 2019 in a petrochemical complex. In this study, to sample and determine acrylonitrile's respiratory exposure, the method provided by the National Institute of Occupational Safety and Health (NIOSH 1601) was used, and a total of 45 inhaled air samples were sampled from men workers, aged 39.43 ± 9.37 years. All subjects' mean exposure to acrylonitrile vapors was 71.1 ± 122.8 μg/m3. Also, the mean exposure index among all subjects was 0.02 ± 0.034. The non-carcinogenic risk assessment results showed that the mean Hazard quotient index was 4.04 ± 6.93. The mean lifetime cancer risk index was also 2.1 × 10-3 ± 3.5 × 10-3 and was in the definite risk range. Considering that both carcinogenicity and health indicators of exposure to acrylonitrile in the studied petrochemical complex are more than the recommended limits, the necessary engineering and management measures to control and manage the risk to an acceptable level are essential to improving the worker's health.

Effect of feed trace elements on eggs of five strains of laying hens and their health risk assessment.

Trace elements are essential for human nutrition, and their deficiencies or excesses are strongly associated with several diseases, such as cardiovascular ones. The current cross-sectional study investigated the concentration of essential trace elements (copper, non-metal selenium, iron, zinc, cobalt and manganese) in eggs and diets of five strains of laying hens. The yolk and albumen were analysed separately, and wet preparation was carried out following inductively coupled plasma-optical emission spectrometry detection. The target hazard quotients (THQs) for the non-carcinogenic disease were calculated by the United States environmental protection agency (USEPA) method. The highest concentrations of selenium, zinc and manganese were found in egg yolks of native hens (0.76, 44.22 and 6.52mg/kg, respectively). The highest amounts of copper and cobalt were recorded in the egg yolk of Lohman (2.07 and 0.023mg/kg, respectively). On the other hand, the egg yolk of Bovans contained the highest amount of iron (57.46mg/kg). Overall, the potential health risks were minimal, and the consumption of eggs was generally safe.

Risk Assessment and Source Apportionment of Metals on Atmospheric Particulate Matter in a Suburban Background Area of Gran Canaria (Spain).

Concentration levels of 11 heavy metals were analyzed in PM10 and PM2.5 samples from a suburban area frequently affected by Saharan dust in which is located a school. The heavy metals risk assessment was carried out by the 2011 U.S. Environmental Protection Agency method, estimating the chronic and carcinogenic hazard levels both in adults and children. The highest level of chronic hazard was reached for Cr, with values of approximately 8 (PM10, adulthood), 2 (PM10, childhood) and 1.5 (PM2.5, adult age), significantly exceeding the limit value (equal to 1). Regarding the carcinogenic risk level, it was also high for Cr, with values between 10-3 and 10-1 for both study populations and particle size. For the rest of the studied metals, no health risk levels of concern were obtained. The positive matrix factorization method was used for the estimation of heavy metal emission sources apportionment. Non-exhaust vehicle emissions were the main source of Cr emissions under PM2.5, while industrial processes were the main source for PM10. Mineral dust and marine aerosol were common emission sources for both particles sizes-with different contributions. Vehicle emissions, construction and agricultural activities were the main emission sources for PM10, and fossil fuel combustion, road dust re-suspension and ammonium sulfate were for PM2.5. The results obtained in this study support the need to continue applying mitigation measures in suburban areas which are affected by nearby anthropogenic emissions, causing the consequent emission of materials hazardous to human health.

Proposed Drinking Water Standards for PFAS

Proposed Drinking Water Standards for PFAS

Do high soil geochemical backgrounds of selenium and associated heavy metals affect human hepatic and renal health? Evidence from Enshi County, China

It is unclear whether the United States Environmental Protection Agency (US EPA) method can accurately assess heavy metal risks in high-Se areas. Herein, a black shale outcropping in Enshi County, China, was taken as the study area, and a carbonate outcropping in Lichuan County was the control area. Selenium and associated heavy metal concentrations in rock, soil, rice, human blood and urine samples and human sensitive hepatic and renal biomarkers were measured. The results showed that the contents of selenium, cadmium, molybdenum and copper in the study area were 3.68 ± 2.72 μg/g, 2.65 ± 1.42 μg/g, 16.3 ± 15.5 μg/g, and 57.3 ± 17.6 μg/g, respectively, in soil (n = 47) and 1.072 ± 0.924 μg/g, 0.252 ± 0.310 μg/g, 2.800 ± 2.167 μg/g, and 10.91 ± 27.42 μg/g, respectively, in rice (n = 47). The daily adult intake levels of selenium, cadmium and molybdenum from rice consumption in the study area (exposure group) exceed the recommended tolerance values in China. According to the US EPA method, these environmental media pose a significant risk to human health. However, in the exposure group (n = 111), the median levels of the sensitive hepatic biomarkers alanine aminotransferase (18 U/L), aspartate aminotransferase (28 U/L) and total bilirubin (10.9 μmol/L) and the sensitive renal biomarkers serum creatinine (70.1 μmol/L), urinary nitrogen (5.73 mmol/L) and uric acid (303.80 μmol/L) were within reference ranges and had values equivalent to those of the control group (P > 0.05). The elements tended to differentiate during migration from one medium to another. Due to the complex interaction between selenium and heavy metals, a survey of human health indicators is indispensable when the US EPA method is used to assess the heavy metal risks in high-Se areas. The recommended molybdenum tolerable intake in the U.S. (2000 μg/d) is reasonable based on a comparison.

Cancer risk assessment of exposure to asbestos during old building demolition.

Years ago, the use of asbestos in construction materials was common. Although asbestos has been recently banned in many countries, exposure to asbestos during old building demolition is not unexpected. The aim of this study is to assess the concentration of exposure to asbestos and estimate its cancer risk among old building demolition workers. In this study, personal air samples were collected during building demolition. The number of asbestos fibers in collected samples were determined according to the NIOSH-7400 standard method. Chemical compositions of fibers were assessed using scanning electron microscopy (SEM). The carcinogenic risk of exposure to asbestos was determined based on the recommended United State Environmental Protection Agency (USEPA) method and Monte-Carlo simulation used to estimate the probability of cancer. Chemical analysis confirmed the presence of asbestos in collected air samples, and 67% of counted fibers were asbestos. In a number of buildings, workers had exposed to asbestos that was higher than occupational exposure limit (0.10 f/ml). Results of cancer risk estimation showed that cancer risk were considerable among workers. Implementation of asbestos risk management program such as separation of asbestos containing material, personal protective equipment's and use of wet method in demolition could minimize asbestos exposure during old building demolition.

Characterization of Escherichia coli Isolates from Agricultural Water on Kansas and Missouri Fresh Produce Farms by Whole-Genome Sequencing

Contaminated agricultural water has been a source of pathogenic Escherichia coli in recent produce-related outbreaks. The purpose of this study was to characterize E. coli isolates from agricultural water sources by using whole-genome sequencing (WGS) to better understand contamination routes. Groundwater and surface water samples were collected quarterly from five farms in Missouri and Kansas over a 1-year period. Samples were tested for generic E. coli by using U.S. Environmental Protection Agency Method 1603, and presumptive E. coli colonies were isolated. In total, 570 isolates were analyzed by PCR, with 191 of these isolates confirmed as E. coli. WGS was completed using an Illumina MiSeq system. The de novo genome assemblies were obtained with Shovill pipeline version 0.9. The NCBI Pathogen Detection system was used to identify antimicrobial resistance (AMR) genes. The prevalence of E. coli was higher during spring and summer than winter. A diverse serotype pool was observed where more than 53% of isolates could be linked to a bovine source as the potential animal host. An AMR analysis showed that 100% of isolates carried at least two antimicrobial resistance genes. Recognizing the diversity of E. coli may help guide agricultural water assessments as proposed in the new agricultural water rule Food Safety Modernization Act Produce Safety Rule.

Mobility and bioaccessibility of arsenic (As) bound to titanium dioxide (TiO2) water treatment residuals (WTRs)

This work systematically describes arsenic mobility and potential bioaccessibility of arsenic-enriched titanium dioxide water treatment residuals (TiO2 WTRs) by employing a suite of wet chemical experiments and spectroscopic measurements. Specifically, Environmental Protection Agency (EPA) digestion method 3051a indicated <3% of total arsenic in the solid phase was released, and arsenic assessed by EPA method 1340 for bioaccessibility was below detection limits. A novel finding is while the arsenic appeared to be stable under highly acidic digestion conditions, it is in fact highly mobile when exposed to simple phosphate solutions. On average, 55% of arsenic was extracted from all samples during a 50-day replenishment study. This was equivalent to 169 mg kg−1 arsenic released from the solid phase. Macroscopic desorption experiments indicated arsenic likely formed inner-sphere bonds with the TiO2 particles present in the samples. This was confirmed with X-ray absorption spectroscopy (XAS), where an interatomic distance of 3.32 Å and a coordination number (CN) of 1.79 titanium atoms were determined. This translates to a configuration of arsenic on TiO2 surfaces as a bidentate binuclear inner-sphere complex. Thus, both macroscopic and spectroscopic data are in agreement. During incubation experiments, arsenic(V) was actively reduced to arsenic(III); the amount of arsenic(III) in solution varied from 8 to 38% of total dissolved arsenic. Lastly, elevated concentrations and mobility of vanadium in these systems merit further investigation. The high mobility of arsenic and its potential for reduction when reintroduced into the environment, particularly in agriculturally important areas, presents an important risk when waste products are not properly managed.

Liquid Chromatographic Separation of MM 302 Da Polycyclic Aromatic Hydrocarbons in Synthetic Mixtures Using Chiral Stationary Phase Material

High molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) are an example of a family of compounds that exist with isomeric mixtures. While multi-instrument techniques may isolate many isomeric PAHs at qualitative and quantitative levels, complete separation of this class of environmental pollutant has not yet been attained, leaving ample room for method improvement. In this research, the separation of 21 commercially available isomers of MM 302 Da was studied using polysaccharide-based chiral immobilized materials as stationary phase. Isocratic, normal phase runs were performed using mixed concentrations and combinations of 302 Da PAH isomers. Retention times and calibration data were determined using a chiral chromatographic setup. Selectivity values are given for all the evaluated HMW-PAH isomers, retention and intensity factors were also calculated based on the directions outlined in Environmental Protection Agency Method 550.1, along with chromatographic peak resolution values. With the use of chiral separation, a total of 16 HMW-PAH peaks are visible on the chromatogram of the 21 MM 302 Da PAH synthetic mixture. This group of molecules does not possess chiral centers in the classical sense; however, larger molecules such as these may possess pseudochiral characteristics, providing a little-researched opportunity for separation strategy of formerly considered achiral molecules to be separated using chiral stationary phases. The resolution of this method makes it suitable for the identification and quantitation of MM 302 Da PAH isomers fractionated from a larger complex sample. The potential for this approach with other classes of high molecular weight achiral molecules is yet to be explored.

Particulate matter exposure in construction sites is associated with health effects in workers.

Exposure to suspended particulate matters (PMs) at high concentrations, mainly observed in the construction workplace, is found to be a risk factor for major health outcomes. The present study was conducted to investigate the degree of exposure to suspended PMs in different stages of construction of the buildings and the health risk associated with the exposure in Lar, Fars, Iran. In this cross-sectional study, two construction sites were selected in Lar. Cancer and non-cancer health risks of exposure to PM2.5 and PM10 were assessed using the US Environmental Protection Agency method in three-dimensions: inhalation, digestion, and dermal absorption. The hazard quotient (HQ) and total cancer risk (TCR) were considered as parameters for risk analysis. The highest level of non-cancer risk for workers in the concentrations of PM2.5 and PM10 particles in the drilling process were determined to be 2.97 × 10-1 and 8.52 × 10-2, respectively. In the cancer risk analysis, PM10 concentrations were estimated to be at the highest level (1.7 × 10-7) in the drilling process and the lowest level (4.29 × 10-8) in the facilities process. For suspended PM2.5, it was an unacceptable risk level in all processes, except for the implementation of facilities. These results show that the construction industry, especially in developing countries such as Iran, needs better management to maintain the health of construction workers.

Assessing drinking water quality and health risks of contaminants in the coastal areas of Cambodia

Abstract The present study aimed to assess the health risks of chemical contaminants of residents in the coastal areas of Cambodia through their drinking water pathways. Water was sampled from tube wells (n= 22), dug wells (n= 31), ponds (n= 11), canals (n= 12) and lakes (n= 4) across the Cambodian coastal areas, and measured for the contaminants of health concern (As, Cu, Cr, Cd, F−, NO2-, NO3-, Pb, Escherichia coli and total coliform) and aesthetic quality following the United States Environmental Protection Agency (USEPA) and standard methods. Analytical results reveal that 9.1% of tube wells and 9.7% of dug wells contained As &amp;gt; 0.01 mg/L. Appropriately, 22.7% of tube wells and 32.3% of dug wells contained Fe &amp;gt; 0.3 mg/L while 100% of tube wells and 80.6% of dug wells contained Mn &amp;gt; 0.1 mg/L. Health risk assessment found that the hazard quotient (HQ) &amp;gt; 1 for children and women. Additionally, the lifetime cancer risk (LCR) was found &amp;gt;1 × 10−4 for As in Cambodian coastal areas. Therefore, a monitoring programme and appropriate treatment to remove contaminants like arsenic, cadmium and fluoride would be required to ensure a safe drinking water supply to Cambodian coastal residents.

Measurement of visible dust emissions during almond nut-picking operations at various harvester settings

ABSTRACT Peak ambient dusts levels in the San Joaquin Valley (SJV) are often coincident with peak agricultural harvest seasons, particularly for nut orchards. Federal reference methods (FRMs), consist of mass-based sampling techniques, are designated to measure and analyze ambient dust concentrations. However, FRMs generally require meticulous attention to sampling details, tedious labor and logistics, and time-consuming dispersion calculations. This study used opacity-based techniques - the U.S. Environmental Protection Agency (EPA) Method 9 and the Digital Compliance Opacity Technique (DCOT) - to quickly measure relative dust intensity at different harvester settings, and to evaluate visible dust emission reductions using a new/low-dust nut harvester. Results indicate that old/conventional harvester at standard settings (3 mph ground speed and 900 rpm blower speed) produced visible dusts with opacities ranging from 23.3% - 29.0%. The dust plume generated from new/low-dust harvesters at similar settings registered lower opacity readings, with an average of 13.94%. The lowest average dust opacity (7.8%) was achieved when the separation fan was turned off. The present results validated the previous FRM emission findings that an old/conventional harvester has the highest PM emissions, but with a potential to achieve 50% reduction by adopting new/low-dust harvesters. Compared to an old harvester, the relative intensity of dusts was reduced by 40% - 51% for low-dust harvesters operated at lower ground speeds. Further dust reductions could be achieved by lowering the fan speed (58%) and operating at no fan/blower setting (66.4%). Both visible emission evaluation (VEE) techniques were able to provide rapid quantitative feedback on the effects of operational changes on emitted harvest dusts. At this stage, opacity-based techniques can potentially be adapted as a screening tool for identifying best management practices (BMP) in reducing harvest dusts, rather than to solely rely on FRM mass-based techniques. Implication: U.S. EPA VEE techniques are established, robust methods of dust measurement systems that can be adopted to evaluate visible dust mitigation strategies in the SJV, alongside the existing FRM protocols. The use of Method 9 and DCOT, as both non-disruptive and rapid dust measurement tools, can bring immediate impact concerning the goal of the almond industry to significantly reduce its PM emissions in the next coming years.