EPA Limit Research Articles

Impact of COVID-19 Lockdown on Inhaled Toxic Elements in PM2.5 in Beijing: Composition Characterization and Source-Specific Health Risks Assessment

In early 2020, China experienced a mass outbreak of a novel coronavirus disease (COVID-19). With an aim to evaluate the impact of emission variations on toxic element species in PM2.5 and the health risks associated with inhalation exposure during COVID-19, we collected PM2.5 filter samples in Beijing from January 1 to February 28, 2020. Positive matrix factorization (PMF) and a health risk (HR) assessment model were used to assess the health risks of the toxic elements and critical risk sources. The total concentration of eight toxic elements (Se, Cd, Pb, Zn, As, Cu, Ni, and Cr) in Beijing showed a trend of first increasing and then decreasing: full lockdown (322.9 ng m−3) > pre-lockdown (264.2 ng m−3) > partial lockdown (245.3 ng m−3). During the lockdown period, stringent control measures resulted in significant reductions (6−20%) in Zn, Pb, Cd, and Ni levels, while concentrations of Se, As, Cu, and Cr were unexpectedly elevated (14−348%). A total of five sources was identified: traffic emission, coal combustion, dust emission, industrial emission and mixed source of biomass burning and firework combustion. Total carcinogenic risk (TCR) of the selected toxic elements exceeded the US EPA limits for children and adults. As and Cr (IV) were the main contributors to non-carcinogenic and carcinogenic risks, respectively. For source-resolved risks, coal combustion was the main contributor to HI (43%), while industrial emissions were the main cause of TCR (45%). Additionally, increased contributions from coal combustion, biomass burning, and firework combustion during the full lockdown elevated the HI and TCR values.

Distribution, Levels, Potential Sources and Human Health Risk Assessment of Trace Metals in Atmospheric Particulate Matter in Ogbia communities of Bayelsa State, Niger Delta, Nigeria

The occurrence of toxic metals in atmospheric particulate matter is of high risk to human health. Hence, the objective of this paper was to evaluate the distribution, concentrations, potential sources and human health risk assessment of trace metals in atmospheric particulate matter in Ogbia communities of Bayelsa State, Niger Delta, Nigeria. Samples of atmospheric particulate matter were digested using a mixture of acids, and quantification of trace metals was achieved using atomic absorption spectrophotometry (Model: Buck 230 ATS). The concentration (µg m-3) of trace metals in atmospheric particulate matter ranged as follows: Pb (<0.010 - 0.060), Cd (<0.010 - 0.880), Ni (<0.010 - 0.028), Cu (<0.010 - 0.046), Zn (<0.010 - 0.028), and Co (<0.010 - 0.021). Except nickel (Ni) and cadmium (Cd), other metal concentrations were below the US EPA limits. Principal component analysis indicated a common source of the studied metals and two major factors (gas flaring and uncontrollable fossil fuel combustion) were identified; while non-carcinogenic risk due to inhalation indicated negligible health risk. Therefore, hazardous effects due to inhalation of trace metals in atmospheric particulate matter in the study area is minimal.

Evaluation of environmental radioactive contamination of radon gas in Karrada homes in Baghdad Governorate, Iraq

The analysis addressed the study of radon contamination collection in dwellings located at Karada, Baghdad. The outcomes revealed that the concentration of radon varied from 17.324 to 45.00 Bq/m3 with an average value of 26.8432 ± 2.216 Bq/m3. AED results were observed to vary from 0.001 mSv/year to 0.847 mSv/year having an average value of 0.2352 ± 0.0647 mSv/year, where potential alpha energy concentrations ranged from 0.26 mWL to 0.93 mWL with a mean value of 0.4179 ±0.057 mWL and radon daughter exposure ranged from 0.13 mWLM/Y to 0.44 mWLM/Y having a mean value of 0.4943 ± 0.111 mWLM/Y.Based on our findings we can conclude that, as anticipated, most indoor values are well below the US EPA limit of 148 Bq/m3

Annual effective dose estimation of radon in drinking water sources of Nizampur basin, North Western Pakistan

ABSTRACT This study assessed radon (222Rn) levels in drinking water sources in the Nizampur basin and their potential health risks for the local community. We analyzed 48 water samples on-site using RAD7. Additionally, we measured pH, temperature (T), total dissolved solids (TDS), redox potential (ORP), and electrical conductivity (EC) with a multiparameter analyzer. Results showed pH, T, TDS, ORP, and EC ranging from 7.2 to 8, 17 to 26 °C, 333 to 1130 mg/l, –56 to 284 mV, and 469 to 2370 µS/cm. 222Rn levels varied significantly (0.7–107 Bq/l, mean 23 ± 21, median = 17 Bq/l), with about 65 % exceeding the EPA's limit of 11.1 Bq/l, indicating health risks likely due to local geological conditions. The annual effective doses for ingestion (EwIng) were 0.87 ± 0.01, 0.35 ± 0.006, and 0.13 ± 0.002 µSv/a for adults, infants, and children, respectively. Exposure risk via the inhalation (EwInh) route ranged from 1.75 to 270 µSv/a, with the highest risk in infants, followed by children and adults. Inhalation was the primary exposure route for all age groups. Further, spatial distribution maps and hotspot analysis suggested that the central region characterized by high structural deformation and favorable geology for radon emanation was the area of concern in terms of health risks.

Statistical Analysis and Health Risk Assessment: Vegetables Irrigated with Wastewater in Kirri Shamozai, Pakistan.

One of the primary environmental routes through which humans are exposed to metals and may be exposed to health risks is the food chain's contamination with heavy metals. The study observed the risks posed by contaminants in vegetables produced in soil that received wastewater irrigation, as well as their origins and the human health impacts. Eight harmful metals (Cu, Fe, Zn, Mn, Pb, Cd, Ni, and Cr) were tested for concentration levels in water, soil, and vegetable samples using analytical techniques and an atomic absorption spectrophotometer. The present study investigated the potential health implications associated with the consumption of vegetables irrigated using wastewater containing heavy metals. The results indicated a notable accumulation of heavy metals in plant and soil samples obtained from Kirri Shamozai, Pakistan. In comparison to vegetables cultivated in soil irrigated with fresh water, the concentration levels of heavy metals in vegetables grown on soil irrigated with untreated wastewater were considerably higher at (P ≤ 0.001) and above the World Health Organization (WHO) recommended limits. The results showed that heavy metals had significantly accumulated in the soil and had permeated into the crops. Heavy metal concentrations in vegetables cultivated on land irrigated with wastewater were more significant than those grown on land irrigated with freshwater. They exceeded US EPA and World Health Organization (WHO) limits. PCA results for Pb, Cu, and Cr are the main issues impacting water quality and health hazards. The PCA results show that the soil has an extensive loading of heavy metals Cd, Ni, and Mn.

Air Quality Implications of Using Ammonia as a Renewable Fuel: How Low Can NOx Emissions Go?

In addition to their lifecycle carbon emissions, another important issue with decarbonized energy pathways is their air quality, water, or land use implications. This paper considers the air quality issue for ammonia combustion. When directly combusting ammonia, reactions of its N atom with atmospheric oxygen lead to NOx emissions that are O(103) ppm, 2 orders of magnitude higher than EPA limits or the amount emitted by current natural-gas-fired technologies. In order to provide guidance to policymakers and technologists on what is fundamentally possible, this Perspective analyzes the fundamental minimum NOx emissions that can be produced from ammonia combustion. The analysis shows that it is possible to achieve quite low NOx emission levels of O(10) ppm, but these designs differ markedly from those used in today's lean, premixed combustion systems.

Fate and Exposure Assessment of Pb Leachate from Hypothetical Breakage Events of Perovskite Photovoltaic Modules.

Emerging lead halide perovskite (LHP) photovoltaics are undergoing intense research and development due to their outstanding efficiency and potential for low manufacturing costs that render them competitive with existing photovoltaic (PV) technologies. While today's efforts are focused on stability and scalability of LHPs, the toxicity of lead (Pb) remains a major challenge to their large-scale commercialization. Here, we present a screening-level, EPA-compliant model of fate and transport of Pb leachate in groundwater, soil, and air, following hypothetical catastrophic breakage of LHP PV modules in conceptual utility-scale sites. We estimated exposure point concentrations of Pb in each medium and found that most of the Pb is sequestered in soil. Exposure point concentrations of Pb from the perovskite film fell well below EPA maximum permissible limits in groundwater and air even upon catastrophic release from PV modules at large scales. Background Pb levels in soil can influence soil regulatory compliance, but the highest observed concentrations of perovskite-derived Pb would not exceed EPA limits under our assumptions. Nonetheless, regulatory limits are not definitive thresholds of safety, and the potential for increased bioavailability of perovskite-derived Pb may warrant additional toxicity assessment to further characterize public health risks.

Sustainable assessment of air quality in school buildings in Saudi Arabia

The aim is to study the influence of outdoor air on the indoor air quality (IAQ) of an elementary school located near the roadside in Riyadh, Kingdom of Saudi Arabia (KSA). The air quality was asses at two locations of the school (inside and outside). The concentrations of particulate matter (PM) 1.0, 2.5, and 10, carbon monoxide (CO), and nitrogen dioxide (NO2) were determined with the help of Air Quality Egg (Kickstarter Company, USA). The factors that can influence the air quality (working and non-working hours, arriving/leaving hours, weekends, and dust storms) were also considered during observations. The methodology followed in this study was according to the standard of "ISO 12103-1 AI Test Dust; ASHRAE". The findings of this study clearly show that traffic-related air pollution (TRAP) affected the IAQ of the school near the roadside. During the working and arrival/leaving hours, PM (1.0 2.5, 10.0) inside the classroom remains below the ambient air quality standards of WHO, EPA, and Saudi limits. Likewise, CO and NO2 levels were lower than the reported limit with the maximum value of 0.176, 0.078 ppb, and 48.69, 46.22 ppb at working and arrival/leaving hours. However, indoor/outdoor ratios were found to be > 1.0 at working hours of CO and all parameters of NO2, indicating strong relation between occupants and surrounding human activities. During dust storms, indoor and outdoor average values remain highest due to natural climatic conditions. The study's findings can be applied to epidemiological investigations of children's exposure to PM, CO, and NO2 due to TRAP, as well as the formation and implementation of remedial action to protect children's health.

Hybrid extractive scintillator resin for simultaneous concentration and detection of plutonium from aqueous solutions

A scoping study of a commercially available resin selective for aqueous plutonium (Pu), AnaLig® Pu-02, modified with scintillator was investigated as a scheme to simultaneously concentrate and detect Pu in aquatic matrices. The extractive scintillating resin was comprised of a silica base, functionalized for plutonium extraction, grafted with plastic scintillator of polyvinyl toluene (PVT) and 2-(1-naphthyl)-4-vinyl-5- phenyloxazole (vNPO) fluor. Scintillator was incorporated onto the AnaLig® Pu-02 resin in a two-step process of silanization followed by surface-polymerization. Successful modification was facilitated by grinding the resin beads prior to silanization to expose cleaved silica surface sites appropriate for scintillator grafting. The modified resin was subjected to initial characterization of batch uptake and radioluminosity measurements where a total detection efficiency of 32.5% was observed. The modified resin was then subjected to pH 1 simulants containing environmental relevant groundwater constituents of varying concentration. Concentrations of 0.001M Fe(III) interfered with Pu uptake, while concentrations of up to 0.01M Ca(II) and 0.001 mM concentration of natural uranium and thorium had minimal influence on plutonium uptake. A translucent column packed with the modified AnaLig® Pu-02 was placed in a commercial flow-cell radiation detector for real-time detection of plutonium; a total detection efficiency of 20.4% was achieved for on-line measurements. The modification of AnaLig® Pu-02 results in a minimum detection limit capable of meeting the EPA limit for gross alpha activity in drinking water given a sufficient counting time of 15 min and approximately 300 mL of solution volume.

Contamination and Ecological Risk Assessment of Metal(loid)s in Sediments of Two Major Seaports along Bay of Bengal Coast

Pollution from shipping, industrial, and municipal wastewater discharges is a major source of heavy-metal contamination at seaports located near estuaries or along the coast. In this study, for the first time, nine metal(loid)s (Pb, Cd, Cr, Cu, Mn, Zn, Ni, Fe, and As) were analyzed from the surface sediment of two major seaports on the Bay of Bengal coast to evaluate the degree of pollution and ecological risk. The average concentrations of metal(loid)s followed the decreasing order of Fe (53,800 ± 4002 mg/kg) > Mn (590 ± 116.8 mg/kg) > Zn (67.59 ± 13.5 mg/kg) > Ni (62.8 ± 22.5 mg/kg) > Cr (36.59 ± 7.22 mg/kg) > Cu (32.63 ± 6.78 mg/kg) > Pb (16.78 ± 3.93 mg/kg) > As (6.33 ± 1.9 mg/kg) > Cd (0.71 ± 0.16 mg/kg). Both sites had much greater Fe concentrations (compared to other metals) than the levels that had been previously recorded at nearby localities. Furthermore, elements such as Fe and Ni surpassed the recommended NOAA and EPA limits for maximum samples from both ports. However, with the exception of one sampling point in Chattogram Port, the pollution-load-index (PLI) values were <1, indicating no heavy-metal contamination. For all metals except Cd, the enrichment factor (EF) values were also <1, indicating that the metals came from natural sources. Besides, the contamination factor (CF) was 1 < CF < 3 for Cd and <1 for other metals, therefore, the study area was under moderate risk for Cd contamination. The geo-accumulation index (Igeo) values indicated that the study area is moderately polluted with Cd (Igeo > 0). In addition, the potential ecological-risk index (PERI) revealed that the both areas are under considerable (PERI > 80) to moderate (PERI > 40) risk due to Cd pollution. Correlation and Principal Component Analyses (PCA), demonstrated the anthropogenic sources of some metals, especially Fe, Ni, and Cd. As a result, it is suggested that the study area should be followed up on, to track changes and design a pollution-control strategy to reduce future pollution hazards.

Mineral and heavy metal concentration of nutritionally and therapeutically valued wild plants: Insights into health effects

Background and Aims: The purpose of the study was to determine the concentrations of minerals and heavy metals in nutritive and therapeutically valued wild plants Allium orientale Boiss., Eremurus spectabilis M. Bieb., Anchusa officinalis L. and Arum elongatum Steven. Methods: The presence and quantity of 23 minerals and heavy metals were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Results: The most common minerals were P, Mg, K, Ca, Fe and Al. Moderately abundant elements were Na, Sr, Zn, Cu, Mn, B and Ni. Toxic heavy metals such as Sn, Li, Co, Se, Sb, Hg, Cd, As and Pb were present at very low concentrations or were not detected. A. officinalis was observed to be rich in K (7496.435 mg/kg) and Ca (2947.378 mg/kg). On the other hand, Fe concentrations were high in A. orientale (1022.068 mg/kg) and A. elongatum (699.932 mg/kg). The Mg concentration in A. orientale (731.012 mg/kg) was almost double that in the other three plants. Al was found in high concentrations in A. orientale (889.368 mg/kg) and A. elongatum (651.570 mg/kg). Cr concentration of A. orientale, A. officinalis and A. elongatum exceeded both EPA limits and standard concentrations in plants. Conclusion: The study reveals the elemental profile, heavy metal content and possible effects on human health of four wild plants that are frequently used in alternative medicine and nutrition. Most of the elements are not at detrimental levels. Additionally, the results can be useful for the food and pharmaceutical industries and to guide nutritional and comparative studies.

Historical ferrous slag induces modern environmental problems in the Moravian Karst (Czech Republic)

Ferrous slag produced by a historic smelter is washed from a slagheap and transported by a creek through a cave system. Slag filling cave spaces, abrasion of cave walls / calcite speleothems, and contamination of the aquatic environment with heavy metals and other toxic components are concerns. We characterize the slag in its deposition site, map its transport through the cave system, characterize the effect of slag transport, and evaluate the risks to both cave and aqueous environments. The study was based on chemical and phase analysis supported laboratory experiments and geochemical modeling. The slag in the slagheap was dominated by amorphous glass phase (66 to 99 wt%) with mean composition of 49.8 ± 2.8 wt% SiO2, 29.9 ± 1.6 wt% CaO, 13.4 ± 1.2 wt% Al2O3, 2.7 ± 0.3 wt% K2O, and 1.2 ± 0.1 wt% MgO. Minerals such as melilite, plagioclase, anorthite, and wollastonite / pseudowollastonite with lower amounts of quartz, cristobalite, and calcite were detected. Slag enriches the cave environment with Se, As, W, Y, U, Be, Cs, Sc, Cd, Hf, Ba, Th, Cr, Zr, Zn, and V. However, only Zr, V, Co, and As exceed the specified limits for soils (US EPA and EU limits). The dissolution lifetime of a 1 mm3 volume of slag was estimated to be 27,000 years, whereas the mean residence time of the slag in the cave is much shorter, defined by a flood frequency of ca. 47 years. Consequently, the extent of slag weathering and contamination of cave environment by slag weathering products is small under given conditions. However, slag enriched in U and Th can increase radon production as a result of alpha decay. The slag has an abrasive effect on surrounding rocks and disintegrated slag can contaminate calcite speleothems.

Geochemical Evidence of Potential Groundwater Contamination with Human Health Risks Where Hydraulic Fracturing Overlaps with Extensive Legacy Hydrocarbon Extraction.

Unconventional oil and gas development (UOGD) sometimes impacts water resources, including incidents of methane (CH4) migration from compromised wells and spills that degrade water with salts, organics, and metals. We hypothesized that contamination may be more common where UOGD overlaps with legacy coal, oil, and gas extraction. We tested this hypothesis on ∼7000 groundwater analyses from the largest U.S. shale gas play (Marcellus), using data mining techniques to explore UOGD contamination frequency. Corroborating the hypothesis, we discovered small, statistically significant regional correlations between groundwater chloride concentrations ([Cl]) and UOGD proximity and density where legacy extraction was extremely dense (southwestern Pennsylvania (SWPA)) but no such correlations where it was minimal (northeastern Pennsylvania). On the other hand, legacy extraction of shallow gas in SWPA may have lessened today's gas leakage, as no regional correlation was detected for [CH4] in SWPA. We identify hotspots where [Cl] and [CH4] increase by 3.6 and 3.0 mg/L, respectively, per UOG well drilled in SWPA. If the [Cl] correlations document contamination via brines leaked from wellbores, impoundments, or spills, we calculate that thallium concentrations could exceed EPA limits in the most densely developed hotspots, thus posing a potential human health risk.

Potential cancer risk estimates from trihalomethanes in peri-urban settings of Kawama East of Mufulira, Zambia.

In this study, we report the formation and cancer risk estimation of trihalomethanes (THMs) emanating from 'ex-situ' chlorination of shallow hand-dug well water obtained from a peri-urban area of Mufulira District, Zambia. The aim of the study was to evaluate the potential cancer risks for people in this area where chlorine water disinfection at the household level is commonly practiced. Water samples from 13 randomly selected hand-dug wells (4-8 m deep) were collected and analyzed for pH, turbidity, and dissolved organic carbon before chlorination. Then another set of water samples from the same 13 wells was chlorinated using the methods commonly practiced in this area, consistent with WHO recommended doses. The chlorination degradation products, THMs, trichloromethane, bromodichloromethane (CHCl2Br), dibromochloromethane (CHClBr2), and tribromomethane, were determined at three different times of 60, 180, and 300 min after chlorination, while residual chlorine was determined immediately after chlorination and at 60 and 1,440 min after chlorination. THMs were determined using gas chromatography (GC), while residual chlorine was determined colorimetrically. Then cancer risk estimation from ingestion, inhalation, and dermal routes was carried out. All water samples from the 13 wells showed elevated amounts of THMs, which also increased with increasing contact time. For instance, the concentrations of THMs at 60 min after chlorination ranged from 24.3 ± 2.0 to 61.3 ± 1.0 μg/L, while at 180 and 300 min, ranged between 85.6 ± 4.3-146.9 ± 2.5 μg/L and 188.1 ± 7.1-250.1 ± 7.1 μg/L, respectively. It was observed that tribromomethane was not detected at all in all samples, while CHCl2Br and CHClBr2 were only detected at 180 and 300 min post chlorination. The lifetime cancer risk estimation results showed negligible risk at 60 min post chlorination. However, at 180 and 300 min post chlorination, the results were far above negligible, but within the regulatory US EPA limits. The overall risk, however, could not be ignored, given a multiplicity of exposure to various other contaminants, raising concerns over additivity and synergistic interactive effects, particularly for non-cancer hazard indices.

Distribution, exposure, and human health risk analysis of heavy metals in drinking groundwater of Ghayen County, Iran

The concentrations of arsenic (As), chromium (Cr), lead (Pb) and zinc (Zn) and the human health risk of the metals were estimated through drinking water consumption. Totally, 48 samples of groundwater were collected and analyzed during 2019. Health risk indices were estimated using chronic daily intake (CDI), hazard quotient (HQ) and, hazard index (HI), as well as cancer risk (CR). Except for As (66.6% of the areas were above permissible limits), the concentrations of other three heavy metals were within the US EPA and WHO permissible limits. values in 100% and 75% of the areas were above 1 for children and adults, implying non-carcinogenic risk from sum of heavy metals. Children total cancer risk (CRt) in all areas (except one area with acceptable risk) fell within unacceptable risk. Adults CRt in all areas (except one area with unacceptable risk) were in acceptable risk category. As was the highest contributor to non-carcinogenic and carcinogenic risks both for children and adults. Our results showed that children were more exposed to health risks, due to intake of drinking water containing As, Cr, and Pb in the study areas. The study can provide a basis for local governments to properly manage drinking water quality and provide a reference for water quality management in neighborhood areas.

Reduction, mineralization, and magnetic removal of chromium from soil by using a natural mineral composite

Reductive immobilization has been a commonly used technique to detoxify Cr(VI) from soil; however, it's challenging to remove the reduced Cr from soil to prevent its re-oxidation. This work explored a natural magnetic composite for the remediation, mineralization, and magnetic removal of Cr(VI) from the soil. It consists of 77% magnetite and 23% pyrrhotite with strong magnetic properties. A series of characterization tests show that composites of magnetite and pyrrhotite are interlaced and closely bonded, and contain no other heavy metals. The Cr(VI) removal rate increases with the decrease in composite particle size. A kinetics study shows that removing Cr(VI) by the composite is likely through both adsorption and reduction. Acidic conditions are more favorable for the immobilization of Cr(VI), at 45.8 mg Cr(VI) removal per g of composite at pH 2. After 100 days of in-situ treatment by the composite, the leaching concentration (TCLP) of Cr(VI)-contaminated soil was 1.95 mg L−1, which was below the EPA limit (5 mg L−1) for hazardous waste. After reduction, the composite was separated from soil by magnetic characteristics, and 58.2% of Cr was found mineralized. The post-treatment Cr-containing composite was analyzed by SEM-EDS, Raman spectra, and XPS. It was found that Cr was mineralized on the surface of the composite in the form of Cr(OH)3, Cr2O3, and FeCr2O4. This indicates that reduction and mineralization of Cr(VI) in the soil can be accomplished through natural magnetic mineral composites and easily separated and removed from the soil, achieving a complete soil cleanup.

Multivariate Metal-Organic Framework/Single-Walled Carbon Nanotube Buckypaper for Selective Lead Decontamination.

The search for efficient technologies empowering the selective capture of environmentally harmful heavy metals from wastewater treatment plants, at affordable prices, attracts wide interest but constitutes an important technological challenge. We report here an eco-friendly single-walled carbon nanotube buckypaper (SWCNT-BP) enriched with a multivariate amino acid-based metal–organic framework (MTV-MOF) for the efficient and selective removal of Pb2+ in multicomponent water systems. Pristine MTV-MOF was easily immobilized within the porous network of entangled SWCNTs, thus obtaining a stable self-standing adsorbing membrane filter (MTV-MOF/SWCNT-BP). SWCNT-BP alone shows a moderately good removal performance with a maximum adsorption capacity of 180 mg·g–1 and a considerable selectivity for Pb(II) ions in highly concentrated multi-ion solutions over a wide range of lead concentration (from 200 to 10000 ppb). Remarkably, these features were outperformed with the hybrid membrane filter MTV-MOF/SWCNT-BP, exhibiting enhanced selectivity and adsorption capacity (310 mg·g–1, which is up to 42% higher than that of the neat SWCNT-BP) and consequently enabling a more efficient and selective removal of Pb2+ from aqueous media. MTV-MOF/SWCNT-BP was able to reduce [Pb2+] from the dangerous 1000 ppb level to acceptable limits for drinking water, below 10 ppb, as established by the current EPA and WHO limits. Thus, the eco-friendly composite MTV-MOF/SWCNT-BP shows the potential to be effectively used several times as a reliable adsorbent for Pb2+ removal for household drinking water or in industrial treatment plants for water and wastewater lead decontamination.

Recycling of chromium sludge to promote aggregation and growth of metal during self-reduction of nickel laterite ore

Addition of stainless steel pickling sludge, which contains hazardous hexavalent chromium, to low-grade nickel laterite ore has the potential to eliminate the hexavalent chromium and promote the aggregation and growth of iron-nickel particles during reduction with anthracite. The effect of chromium sludge on the aggregation and growth of metal particles during a self-reduction process of nickel laterite ore has been studied. The detoxification effect of hexavalent chromium in the sludge was evaluated using the standard TRGS 613 leaching test. Results showed that with increasing chromium sludge addition, the size of metal particles increased. With the addition of 13.94% by mass chromium sludge the average metal particle size in the reduce ore increased from 0.42 µm to 1.38 µm while the recovery of Fe, Ni and Cr increased from 53.73%, 19.39% and 33.36% to 78.33%, 69.22% and 58.26%, respectively. It is proposed that a low melting point eutectic phase of FeS formed in the reduced products, significantly promoted the migration and aggregation of metal particles. Leaching tests indicated that the original chromium sludge released > 600 mg/kg Cr(VI) while the slag from the combined laterite and chromium sludge released less than the EPA limit of 2 mg/kg Cr(VI).

Urban mosquitoes and filamentous green algae: their biomonitoring role in heavy metal pollution in open drainage channels in Nairobi industrial area, Kenya

BackgroundIndustrial wastewater is a human health hazard upon exposure. Aquatic organisms in contaminated wastewater may accumulate the toxic elements with time. Human population living in informal settlements in Nairobi industrial area risk exposure to such toxic elements. Biomonitoring using aquatic organisms in open drainage channels can be key in metal exposure assessment. Levels of Mercury (Hg), Lead (Pb), Chromium (Cr), Cadmium (Cd), Thallium (Tl), and Nickel (Ni) were established in samples of wastewater, filamentous green algae (Spirogyra) and mosquitoes obtained from open drainage channels in Nairobi industrial area, Kenya.ResultsPb, Cr, & Ni levels ranged from 3.08 to 15.31 µg/l while Tl, Hg, & Cd ranged from 0.05 to 0.12 µg/l in wastewater. The Pb, Cr, Ni, & Cd levels were above WHO, Kenya & US EPA limits for wastewater but Hg was not. Pb, Cr, Tl, & Ni levels in assorted field mosquitoes were 1.3–2.4 times higher than in assorted laboratory-reared mosquitoes. Hg & Cd concentrations in laboratory-reared mosquitoes (0.26 mg/kg & 1.8 mg/kg respectively) were higher than in field mosquitoes (0.048 mg/kg & 0.12 mg/kg respectively). The levels of Pb, Cr, & Ni were distinctively higher in field mosquito samples than in wastewater samples from the same site. Pb, Cr, Ni, Cd & Hg levels in green filamentous Spirogyra algae were 110.62, 29.75, 14.45, 0.44, & 0.057 mg/kg respectively. Correlation for Pb & Hg (r (2) = 0.957; P < 0.05); Cd & Cr (r (2) = 0.985; P < 0.05) in algae samples was noted. The metal concentrations in the samples analyzed were highest in filamentous green algae and least in wastewater.ConclusionWastewater, mosquitoes, and filamentous green algae from open drainage channels and immediate vicinity, in Nairobi industrial area (Kenya) contained Hg, Pb, Cr, Cd, Tl, and Ni. Mosquitoes in urban areas and filamentous green algae in open drainage channels can play a role of metal biomonitoring in wastewater. The potential of urban mosquitoes transferring heavy metals to human population from the contaminated wastewater should be investigated.

Assessing Personal PM2.5 Exposure and Respiratory Virus Infections among Farmworkers in the Southeastern United States

BACKGROUND AND AIM: Occupational studies have identified exposure to particulate matter (PM) air pollution as an emerging concern among crop farmworkers, with previous data suggesting that harvesting tasks contribute to the highest occupational PM exposures among this population. Particulates from agricultural dust may be composed of multi-pollutant mixtures of pesticides, heavy metals, mineral silicas, and microbes. Moreover, chronic respiratory conditions, as well as mortality attributable to acute respiratory infections, are notably elevated among crop farmworkers. In the United States, this workforce is comprised primarily of migrant and immigrant populations that face a multitude of social inequities. METHODS: Our pilot study uses personal air samplers to assess occupational exposure to respirable agricultural dust (PM2.5) among a hard-to-reach and vulnerable population of mostly Mexican-American farmworkers harvesting crops in the southeastern US. Participants worked in fernery harvesting, nursery greenhouses, and strawberry harvesting. We conduct prospective, weekly follow-up of participants during influenza season to determine the incidence of acute respiratory symptoms and viral respiratory infections. RESULTS:We collected nasal swab biospecimens from symptomatic participants and tested these samples for SARS-Cov-2 and 20 different respiratory pathogens using a panel array (Biofire). Thus far, we have collected n=30 occupational PM2.5 exposure samples. A majority of occupational PM2.5 exposure levels were above the US EPA limit for annual PM2.5 concentration, with four participants exposed above the OSHA PEL. Of the participants that enrolled in weekly follow-ups (n=20), four participants reported acute respiratory symptoms. Molecular analysis of collected biospecimen were positive for human rhinovirus (n=2), SARS-Cov-2 (n=1), and two samples are pending laboratory analysis. CONCLUSIONS:Follow-up of participants and chemical analysis of PM2.5 filters is ongoing. To our knowledge, this is the first study to assess occupational PM2.5 exposure and incidence of respiratory infections in Southeastern US-hired farmworkers, while characterizing the chemical composition of occupational dust exposures. KEYWORDS: COVID-19, Epidemiology, Exposure assessment, Infectious diseases, Particulate matter, Occupational exposures