Varying Levels Of Contamination Research Articles

Study on fungal contaminants in aborted calves of cattle herds in Iran.

Abortions in livestock herds are a major contributor to economic losses. The incidence of fungal aetiology has been reported thus far. The purpose of this study is to investigate the prevalence of abortions due to fungi in referred cases to the Center of Excellence in Ruminant Abortion and Neonatal Mortality, Veterinary Hospital of Ferdowsi University of Mashhad, Mashhad, Iran, from different provinces of Iran. A total of 200 calves were referred between 2018 and 2022. Samples were taken from the lungs, liver, spleen and abomasum. The fungi present in the cultures were analysed microscopically and morphologically. There were varying contamination levels in the liver, spleen and lungs, with prevalence ranging from 15% to 17%. Abdomasum had a 1% prevalence rate. Different fungal species, including Cryptococcus neoformans (C. neoformans), Aspergillus spp., Rhodotorula spp., Trichosporon spp., Candida spp., Geotrichum spp., Penicillium spp. and Mucor spp., were identified, indicating a diverse range of pathogens affecting calves. The specificity of fungal contaminants in certain organs, such as C. neoformans, Rhodotorula spp. and Trichosporon spp., highlighted the organ's microenvironment as a potential factor influencing fungal growth. As fungi are emerging as a significant cause of morbidity and mortality in animals, the growing role of fungi in livestock abortions should be investigated. As clinical signs are not pathognomonic, laboratory help is imperative to confirm fungal abortion diagnosis.

Field evaluation of oil crop rotations for cadmium remediation and safe vegetable oil production across five sites with varying contamination levels

Oil crops have the potential to remediate cadmium (Cd)-contaminated farmland while producing safe vegetable oil. However, it is currently unknown whether different oil crops can remediate varying levels of Cd contamination in farmland. This study assessed agricultural fields in southern China contaminated with Cd levels ranging from 0.42 to 10.3 mg/kg. Three representative oilseed crops winter rape, oil sunflower, and peanut were selected for field experiments under two rotation systems. The effects of different rotation systems on remediating various Cd contamination levels were compared to evaluate the feasibility and potential of a two oil crop rotation system. All three crops showed good tolerance to Cd without signs of biomass deficiency. The biomass produced by the rape-oil sunflower and rape-peanut rotation systems was 33.44–459.00 g/ha and 30.64–281.40 g/ha, respectively. The Cd concentration in the oil products obtained complied with existing national and international standards (0.05 mg/kg). The remediation efficiency of the rape-oil sunflower and rape-peanut rotation systems was 1.98–7.37 % and 1.21–4.94 %, respectively. However, the remediation efficiencies and enrichment capacities of both rotation systems were somewhat inhibited by heavy Cd contamination (10.3 mg/kg). Therefore, the agricultural model of rotating two oilseed crops can be implemented in Cd-contaminated farmland at all levels but is more suitable for light to moderate Cd contamination.

Assessment of heavy metal contamination risk in dry fish from India: A comprehensive study

The widespread presence of heavy metal contaminants in aquatic ecosystems, and consequently in fish, has emerged as a paramount concern owing to the staple role of fish in the Indian diet. The present study addresses heavy metal contamination in dried fish consumed across India and its associated health risks. The objectives of this study were to determine the heavy metal concentrations in dried fish from different regions of India, assess daily heavy metal intake through dried fish consumption, and evaluate the carcinogenic and non-carcinogenic health risks associated with heavy metal exposure. Subsequently, 111 dried fish samples from Guwahati-Assam, Mumbai, Karad-Maharashtra, and Goa were analyzed for eight selected heavy metals using a validated inductively coupled plasma mass spectrometry method results indicated varying contamination levels across locations, with As being the most abundant heavy metal. In Maharashtra and Assam, the heavy metal load in dried fish was as follows: As > Cr > Ni > V > Cd > Pb > Co > Hg. For Goa, the order was As > Cr > Ni > V > Cd > Co > Pb > Hg. Dietary exposure assessments revealed varying levels of exposure between adults and children, with As and Cd posing higher risks to children. The Target Hazard Quotient (THQ) and Hazard Index (HI) values for all metals were within acceptable limit of one. Health risk assessments revealed generally low hazard levels for adults, but higher risks for children, particularly at higher percentiles. Furthermore, As was identified as posing a medium risk of cancer. In essence, this research emphasizes the necessity for strict monitoring and regulations with the aim of controlling health hazards related to heavy metal pollution in food sources.

Heavy Metal Risk Assessment from Agriculture in Shallow Tropical Karst Lake, Gunungsewu Karst Area, Java Island, Indonesia

This research investigates the heavy metal pollution in karst lakes, crucial for fisheries, agriculture, and domestic activities. Target metals include Pb, Cd, Cr, Fe, Zn, and Cu. Objectives comprise assessing pollution levels via the Heavy Metal Pollution Index (HPI) and conducting an ecological risk assessment, incorporating the Enrichment Factor, Geoaccumulation Index, and Ecological Risk Index. The Pearson’s correlation and cluster analysis were performed to analyze the connection between samples. Results reveal strong correlations between metals in soil and sediment, such as Pb in soil correlating with Cu in sediment (r = 0.88), Zn in soil with Cu in sediment (r = 0.75), and Zn in soil with Pb in sediment (r = 0.81). Kedokan Lake emerges as the most representative observation (distance 13.1), while Kepleng Lake is the least representative (distance 535). Cluster analysis identifies two distinct clusters: Cluster 1 encompasses Ngrejek Lake, Kedokan Lake, Sodong Lake, Kanigoro Lake, and Ngampelombo Lake. HPI calculations reveal varying contamination levels in lake water and underground river samples within the Bribin Underground River Catchment Area. Notably, one location in Kedokan Lake is categorized as contaminated (HPI value of 188.05). Mean Enrichment Factor values range from no enrichment factor (<1) to low enrichment factor (1–3). Geoaccumulation Index (Igeo) indicates an overall unpolluted classification (Igeo<0) across all sampling sites. These findings underscore the nuanced pollution status in the studied area, emphasizing the importance of continued monitoring and intervention to ensure the sustainability of karst lakes in the face of heavy metal contamination.

ScCDC: a computational method for gene-specific contamination detection and correction in single-cell and single-nucleus RNA-seq data

In droplet-based single-cell and single-nucleus RNA-seq assays, systematic contamination of ambient RNA molecules biases the quantification of gene expression levels. Existing methods correct the contamination for all genes globally. However, there lacks specific evaluation of correction efficacy for varying contamination levels. Here, we show that DecontX and CellBender under-correct highly contaminating genes, while SoupX and scAR over-correct lowly/non-contaminating genes. Here, we develop scCDC as the first method to detect the contamination-causing genes and only correct expression levels of these genes, some of which are cell-type markers. Compared with existing decontamination methods, scCDC excels in decontaminating highly contaminating genes while avoiding over-correction of other genes.

Unveiling the molecular mechanisms of arsenic tolerance and resilience in the primitive bryophyte Marchantia polymorpha L.

This study addresses the pressing issue of high arsenic (As) contaminations, which poses a severe threat to various life forms in our ecosystem. Despite this prevailing concern, all organisms have developed some techniques to mitigate the toxic effects of As. Certain plants, such as bryophytes, the earliest land plants, exhibit remarkable tolerance to wide range of harsh environmental conditions, due to their inherent competence. In this study, bryophytes collected from West Bengal, India, across varying contamination levels were investigated for their As tolerance capabilities. Assessment of As accumulation potential and antioxidant defense efficiency, including SOD, CAT, APX, GPX etc. revealed Marchantia polymorpha as the most tolerant species. It exhibited highest As accumulation, antioxidative proficiency, and minimal damage. Transcriptomic analysis of M. polymorpha exposed to 40 μM As(III) for 24 and 48 h identified several early responsive differentially expressing genes (DEGs) associated with As tolerance. These includes GSTs, GRXs, Hsp20s, SULTR1;2, ABCC2 etc., indicating a mechanism involving vacuolar sequestration. Interestingly, one As(III) efflux-transporter ACR3, an extrusion pump, known to combat As toxicity was found to be differentially expressed compared to control. The SEM-EDX analysis, further elucidated the operation of As extrusion mechanism, which contributes added As resilience in M. polymorpha. Yeast complementation assay using Δacr3 yeast cells, showed increased tolerance towards As(III), compared to the mutant cells, indicating As tolerant phenotype. Overall, these findings significantly enhance our understanding of As tolerance mechanisms in bryophytes. This can pave the way for the development of genetically engineered plants with heightened As tolerance and the creation of improved plant varieties.

Spatial Distribution, Risk Index, and Correlation of Heavy Metals in the Chuhe River (Yangtze Tributary): Preliminary Research Analysis of Surface Water and Sediment Contamination

This comprehensive study aimed to evaluate the water quality and sediment contamination in the Chuhe River in Nanjing. The spatial assessment of 10 samples collected in September highlighted that, in surface water, Copper (Cu) > Nickel (Ni) > Zinc (Zn) > Chromium (Cr) > Lead (Pb) > Arsenic (As) > Cadmium (Cd) > Mercury (Hg), whereas in sediments, Zn > Cr > Cu > Pb > Ni > As > Cd > Hg. The coefficient of variation (CV) for Ni and Zn in surface water was >15, whereas As, Cu, Pb, and Ni had a CV that was higher than 15 in sediments, indicating variability in contamination sources. The Pollution Load Index values ranged between 2.16 and 3.05, reflecting varying contamination levels across samples. The Geoaccumulation Index data also showed moderate-to-considerable contamination, especially for elements such as Cd and Cu. Correlation analyses in water and sediments unearthed significant relationships, with notable links between Cu and Pb in the water and strong correlations between As and Cu and between Cr and Ni in sediments. In sediments, Total Nitrogen and Phosphorus were significantly correlated with As, Cu, Pb, and Ni. The Potential Ecological Response Index for sediments indicated that they are at medium to high risk (307.47 ± 33.17) and could be potentially detrimental to aquatic life in the tributary. The tributary, influenced by agricultural runoff, residential areas, and other anthropogenic activities, showed that despite Nemerow pollution index values for water samples being below 1, sediment analysis indicated areas of concern. Principal Component Analysis (PCA) was conducted to identify the potential sources of heavy metal contamination. In surface water, shared negative loadings on PC 1 (60.11%) indicated a unified influence, likely from agricultural runoff, while PC 2 (14.26%) revealed additional complexities. Sediments exhibited a unique signature on PC 1 (67.05%), associated with cumulative agricultural impacts, with PC 2 (18.08%) providing insights into nuanced factors, such as sediment composition and dynamic interactions. These findings offer a complete insight into the Chuhe River tributary’s condition, underlining the urgency for ongoing monitoring and potential remediation measures.

Reviewing the interdecadal dynamics of micropollutants in the Tanzanian coastal zone from 2002 to 2022.

The Tanzanian coast is a vastly diversified ecosystem offering ecological, cultural, and economic services. However, anthropogenic and environmental stressors threaten its productivity and sustainability, prompting extensive research to understand the contamination extent, sources, and impacts. This review covers 77 original field research studies published between 2002 and 2022, focusing on the Tanzanian coastal area. A summary of information on the occurrences, levels, distributions, sources, and impacts of organic and inorganic micropollutants in environmental and biological compartments is provided. The studies were further discussed based on their research focus, where seven key areas were identified, which included the types of micropollutants analyzed, the parameters sampled, the locations investigated, and the crucial conclusions reached. The aim was to evaluate the research trends and identify gaps for future investigations. The studies reveal varying contamination levels, from low to severe, encompassing metals, persistent organic pollutants, pesticide residues, nutrients, and microbial contaminants. However, data gaps exist for micropollutant concentrations in ambient air, microplastics, pharmaceuticals, and emerging contaminants of concern. With increasing urbanization and socio-economic activities, the review emphasizes the necessity for solution-based research to remove and control micropollutants in the area. Addressing these challenges is crucial for sustaining the diverse ecological nature of this vital coastal system.

Towards a clean environment: To what extent can trees serve as phytoremediators for chemically polluted soils?

The study investigated the potential of five common tree species in West Africa to bioaccumulate heavy metals in their various plant components over the course of different growth phases and at varying contamination levels (control, double the permissible level and triple the permissible limit). Heavy metals in plant tissues were extracted and analyzed using standard wet chemistry procedures. The results showed metal concentrations in tree tissues to positively and significantly correlate with contamination level, growth stage, and plant component. Metal mobility and availability in the tree tissues were in descending order of Mn >Zn>Cu=Pb>Cd. We found heavy metals to be principally accumulated in the stem tissues following a metal exclusion theory, independent of tree species. Tree roots demonstrated a significant accumulation of heavy metals second only to the stem. The results revealed that heavy metal mobility and bioavailability in plant tissue was tree-specific, growth stage-dependent, and metal-specific; showing that trees have a preferential affinity to accumulate a specific metal or pollutant. The study established Shorea roxborghi to be a mono-accumulator of manganese while Tectona grandis and Terminalia ivorensis were multi-accumulators of metals such as Mn, Cu, Zn and Pb. The interactive effects of contamination levels and tree species showed Tectona grandis and Terminalia ivorensis grown in chemically polluted soils at triple the permissible level to have the highest heavy metal uptake with the highest phytoextraction potential. We conclude that all the tree species considered in this study could potentially be effective phytoremediators of chemically polluted soils through their ability in phytoextraction of metals such as lead, zinc, copper, and manganese as well as through phytostabilization of cadmium in contaminated soils.

Evaluation of soil arsenic pollution and phytoaccumulation capabilities of 24 indigenous plant species in Barak Valley, South Assam, India

AbstractThis study investigated the concentrations of arsenic (As) in soil and plant biomass from the Barak Valley in South Assam, India. Soil samples showed concentrations ranging from 6.06 ± 0.84 mg/kg to 18.61 ± 1.52 mg/kg, with an average of 10.60 ± 3.15 mg/kg, 41.67% of the sample exceeding uncontaminated ranges (0.1–10 mg/kg). Ecological risk assessments such as contamination factors, pollutant load index, geo‐accumulation index, and anthropogenicity identified varying contamination levels across sampling points. A total of 24 plant species were collected, ferns (two species), shrubs (five species), grass (six species), and herb (11 species). The concentration of As in different plants types decreased in the order of fern (393.45 ± 159.63 mg/kg) > shrub (20.48 ± 7.25 mg/kg) > herb (17.92 ± 13.75 mg/kg) > grass (14.98 ± 13.80 mg/kg). Plant species, namely Pityrogramma calomelanos, Christella dentata, Mimosa pudica, Chromolaena odorata, Leucas aspera, Persicaria decipiens, Melastoma malabathricum, and Clerodendrum infortunatum, accumulated higher concentrations of As in their above‐ground parts compared to roots and were categorized as tolerant accumulators (TF > 1). By incorporating these plant species into phytoextraction strategies, the region can benefit from their unique properties and abilities to effectively remediate arsenic‐contaminated sites, ultimately improving the affected areas' environmental and human health conditions.

Phage-Host Prediction Using a Computational Tool Coupled with 16S rRNA Gene Amplicon Sequencing.

Metagenomics studies have revealed tremendous viral diversity in aquatic environments. Yet, while the genomic data they have provided is extensive, it is unannotated. For example, most phage sequences lack accurate information about their bacterial host, which prevents reliable phage identification and the investigation of phage-host interactions. This study aimed to take this knowledge further, using a viral metagenomic framework to decipher the composition and diversity of phage communities and to predict their bacterial hosts. To this end, we used water and sediment samples collected from seven sites with varying contamination levels in the Ebrié Lagoon in Abidjan, Ivory Coast. The bacterial communities were characterized using the 16S rRNA metabarcoding approach, and a framework was developed to investigate the virome datasets that: (1) identified phage contigs with VirSorter and VIBRANT; (2) classified these contigs with MetaPhinder using the phage database (taxonomic annotation); and (3) predicted the phages' bacterial hosts with a machine learning-based tool: the Prokaryotic Virus-Host Predictor. The findings showed that the taxonomic profiles of phages and bacteria were specific to sediment or water samples. Phage sequences assigned to the Microviridae family were widespread in sediment samples, whereas phage sequences assigned to the Siphoviridae, Myoviridae and Podoviridae families were predominant in water samples. In terms of bacterial communities, the phyla Latescibacteria, Zixibacteria, Bacteroidetes, Acidobacteria, Calditrichaeota, Gemmatimonadetes, Cyanobacteria and Patescibacteria were most widespread in sediment samples, while the phyla Epsilonbacteraeota, Tenericutes, Margulisbacteria, Proteobacteria, Actinobacteria, Planctomycetes and Marinimicrobia were most prevalent in water samples. Significantly, the relative abundance of bacterial communities (at major phylum level) estimated by 16S rRNA metabarcoding and phage-host prediction were significantly similar. These results demonstrate the reliability of this novel approach for predicting the bacterial hosts of phages from shotgun metagenomic sequencing data.

Zearalenone and Its Masked Forms in Cereals and Cereal-Derived Products: A Review of the Characteristics, Incidence, and Fate in Food Processing.

Zearalenone (ZEA) is known as a Fusarium-produced mycotoxin, representing a risk to cereal food safety with repercussions for economies and worldwide trade. Recent studies have reported the co-occurrence of ZEA and masked ZEA in a variety of cereals and cereal-based products, which may exert adverse effects on public health due to additive/synergistic interactions. However, the co-contamination of ZEA and masked ZEA has received little attention. In order to minimize the threats of co-contamination by ZEA and masked ZEA, it is necessary to recognize the occurrence and formation of ZEA and masked ZEA. This review focuses on the characteristics, incidence, and detection of ZEA and its masked forms. Additionally, the fate of ZEA and masked ZEA during the processing of bread, cake, biscuits, pasta, and beer, as well as the ZEA limit, are discussed. The incidence of masked ZEA is lower than that of ZEA, and the mean level of masked ZEA varies greatly between cereal samples. Published data showed a considerable degree of heterogeneity in the destiny of ZEA during cereal-based food processing, mostly as a result of the varying contamination levels and complicated food processing methods. Knowledge of the fate of ZEA and masked ZEA throughout cereal-based food processing may reduce the likelihood of severe detrimental market and trade ramifications. The revision of legislative limits of masked ZEA may become a challenge in the future.

Agent‐based simulation of cross‐contamination of Escherichia coli O157:H7 on lettuce during processing and temperature fluctuations during storage in a produce facility. Part 2: Model implementation

AbstractAn agent‐based simulation was developed to represent the spatial and temporal Escherichia coli O157:H7 cross‐contamination dynamics in a processing facility for fresh‐cut romaine lettuces using NetLogo. An extension was added to the model to predict E. coli O157:H7 growth due to temperature abuses in a cold storage facility. A user‐friendly interface was created to follow variations in model outputs. The number of contaminated bags and lettuce contamination levels were computed and visualized. Experimental data of cross‐contamination from literature was used to describe the facility and validate the model. The key factor affecting cross‐contamination in the process is the free chlorine (FC) concentration dose rate. The number of contaminated bags per batch decreases nonlinearly as FC is added to the flume tank. The contamination level in the shredded lettuces increases linearly with initial microbial load or the initial contamination probability on lettuce heads. Both the level and probability of contamination in the facility's environment alter the number of contaminated bags. Batch size influences the number of contaminated bags when the first incoming lettuce batch is contaminated. The smaller the batch size the smaller number of contaminated bags. Storage room temperature fluctuations (13 and 19°C and 8 and 12°C) show the importance of real‐time monitoring to avoid pathogen growth and number of contaminated bags. This work provides insight on applications of agent‐based modeling approach using NetLogo to visualize cross‐contamination in fresh‐cut leafy green processing operations. It analyzes cross‐contamination and its impact on processing performance by studying the effect of mitigation strategies.Practical applicationsTo support ready‐to‐eat leafy greens postharvest operations, this work investigated the benefits of using visualization to develop strategies to prevent produce cross‐contamination along processing and the effect of temperature abuse during storage. Output from the model can be used in Quantitative Management Risk Assessment (QMRA) applications. By developing a simulation‐based decision support system, the safety of processing and storage steps of fresh‐cut leafy greens are investigated. Pathogen cross‐contamination and growth models are integrated to observe impacts of varying contamination levels in incoming produce and equipment surfaces, concentrations of free chlorine in the wash water, and storage temperatures on the number of contamination bags over time. Computational experiments study a pilot plant of Romaine lettuces contaminated with E. coli O157:H7. Results indicate that the key factor affecting cross‐contamination is the chlorination concentration dose rate in the wash water. Other factors include the level of contamination on the incoming lettuce heads or in the facility environment (equipment). Storage room temperature fluctuations showed the importance of real‐time monitoring to avoid microorganism growth and thus prevent an increase in the number of contaminated bags.

Evaluating Permeable Clay Brick Pavement for Pollutant Removal from Varying Strength Stormwaters in Arid Regions

Permeable pavement is a low impact development technology for stormwater (SW) runoff control and pollutant removal. The strength of SW depends on land use of the catchment, e.g., semi-urban vs. industrial. The performance (in terms of pollutants removal) of permeable clay bricks (PCB) has not been adequately assessed for SW of varying strengths. For using the permeable clay bricks as a pavement surface layer, the present research investigates its pollutant removal capacity through SW infiltration using a laboratory setup. SW samples of two different strengths, i.e., high polluted stormwater (HPSW) and less polluted stormwater (LPSW), were tested for a pavement system consisting of the clay brick layer on top of a coarse gravel support layer. The tests were performed at a rainfall intensity of 12.5 mm/h (for a 10-year return period in Buraidah, Qassim) to evaluate the suitability of PCB for the arid and semi-arid regions. The experiments revealed that PCB became fully saturated and achieved a steady-state outflow condition after 10 min of rainfall. Irrespective of contamination level, the pollutant removal efficiency was found to be similar for both HPSW and LPSW. High TSS (>98%) and turbidity (>99%) removals were achieved for both strengths, while BOD5 (78.4%) and COD (76.1%) removals were moderate. Poor to moderate nutrient removal, 30.5% and 39.1% for total nitrogen (TN) and 34.7% and 31.3% for total phosphorus (TP), respectively for HPSW and LPSW, indicates an adsorptive removal of nutrients in the system. Heavy metal removal efficiency ranged from 6.7% to 94%, with higher removals archived for Fe, Mn, Se, and Pb. The study provides insights into the role of PCB as a surface layer in the permeable pavement for pollutant removal. The study also establishes the guidelines for the optimal permeable pavement design to deal with SW of varying contamination levels. Permeable clay bricks showed the potential to be used as a sustainable LID technology for arid regions.

Harmonic Components Analysis of Emitted Ultraviolet Signals of Aged Transmission Line Insulators under Different Surface Discharge Intensities.

Flashover on transmission line insulators is one of the major causes of line outages due to contamination from the environment or ageing. Power utility companies practicing predictive maintenance are currently exploring novel non-contact methods to monitor insulator surface discharge activities to prevent flashover. This paper presents an investigation on the UV pulse signals detected using UV pulse sensor due to the discharges on the insulator surfaces under varying contamination levels and insulator ages. Unaged and naturally aged insulators (0 to >20 years) were artificially contaminated (none, light to heavy contamination). The electrical stresses on the insulator surfaces were varied to generate varying discharge intensity levels on the surfaces of the insulator. The DC and harmonic components of UV pulse signals detected during surface discharges were recorded and analysed. Results show a positive correlation between the discharge intensity level of contaminated and aged transmission insulators with the DC and harmonic components of the UV pulse signals. Furthermore, the study revealed that under dry insulator surface conditions, insulator ageing has a more profound effect during discharges than contamination level. The findings from this study suggest that the use of UV pulse sensors to monitor UV pulse signals emitted during insulator surface discharges can be another novel non-contact method of monitoring transmission line insulator surface conditions.

Determination of Characteristic vs Anomalous 135Cs/137Cs Isotopic Ratios in Radioactively Contaminated Environmental Samples.

A contamination with the ubiquitous radioactive fission product 137Cs cannot be assigned per se to its source. We used environmental samples with varying contamination levels from various parts of the world to establish their characteristic 135Cs/137Cs isotope ratios and thereby allow their distinction. The samples included biological materials from Chernobyl and Fukushima, historic ashed human lung tissue from the 1960s from Austria, and trinitite from the Trinity Test Site, USA. After chemical separation and gas reaction shifts inside a triple quadrupole ICP mass spectrometer, characteristic 135Cs/137Cs isotope signatures (all as per March 11, 2011) were obtained for Fukushima- (∼0.35) and Chernobyl-derived (∼0.50) contaminations, in agreement with the literature for these contamination sources. Both signatures clearly distinguish from the characteristic high ratio (1.9 ± 0.2) for nuclear-weapon-produced radiocesium found in human lung tissue. Trinitite samples exhibited an unexpected, anomalous pattern by displaying a low (<0.4) and nonuniform 135Cs/137Cs ratio. This exemplifies a 137Cs-rich fractionation of the plume in a nuclear explosion, where 137Cs is a predominant species in the fireball. The onset of 135Cs was delayed because of the longer half-life of its parent nuclide 135Xe, causing a spatial separation of gaseous 135Xe from condensed 137Cs, which is the reason for the atypical 135Cs/137Cs fractionation in the fallout at the test site.

Ingestion and Dermal Cancer Risk via Exposure to Polycyclic Aromatic Hydrocarbon-Contaminated Soils in an Oil-Producing Community, Niger Delta, Nigeria.

There is an intrinsic link between polycyclic aromatic hydrocarbons (PAHs) accumulated in soils and increased health risk to humans after exposure to contaminated soil via ingestion, inhalation of particulates carrying PAHs, and direct contact with polluted soils. However, the assessment of PAH contamination in most developing countries fails to consider health risk assessment. Therefore, a comprehensive study was conducted to determine the concentration, source, toxicity, and human health risks of 16 PAHs in an urban area in Warri, Delta State, in the Niger Delta region of Nigeria. The results showed varying contamination levels for PAH in soil samples from all sampling points, with benzo[a]anthracene (BaP; at 338.81 μg/kg) being the most abundant at all 9 sampling stations. The highest total concentration of PAH was observed at station 5 (1230.98 μg/kg), which was closest to a flow station. Further comparison with PAH contamination standards showed that soils from stations 1 and 2 were weakly contaminated (<600 μg/kg), and soil samples from stations 3, 4, 6, 7, and 9 were moderately contaminated (<1000 μg/kg). Soil samples from stations 5 and 8 were observed to be heavily contaminated (>1000 μg/kg). The BaP estimates for soil samples obtained for stations 3 to 9 were higher than the BaP soil screening value (15 μg/kg), indicating a carcinogenic potential of soil samples. The results also showed that the incremental lifetime cancer risk estimates for PAH in the soil for adults and children were above the recommended threshold (10-4 ) for ingestion and dermal contact, implying that exposure to contaminated soil could lead to cancers in adults and children. Currently, there are no regional or national standards for PAHs in soil that would indicate an increased likelihood for human exposure and subsequent health issues. Environ Toxicol Chem 2021;40:261-271. © 2020 SETAC.

Surface Discharge Analysis of High Voltage Glass Insulators Using Ultraviolet Pulse Voltage

Surface discharges are precursors to flashover. To pre-empt the occurrence of flashover incidents, utility companies need to regularly monitor the condition of line insulators. Recent studies have shown that monitoring of UV signals emitted by surface discharges of insulators is a promising technique. In this work, the UV signals’ time and frequency components of a set of contaminated and field-aged insulator under varying contamination levels and degrees of ageing were studied. Experimental result shows that a strong correlation exists between the discharge intensity levels under varying contamination levels and degree of ageing. As the contamination level increases, the discharge level of the insulator samples also intensifies, resulting in the increase of total harmonic distortion and fundamental frequencies. Total harmonic distortion and fundamental frequencies of the UV signals were employed to develop a technique based on artificial neural networks (ANNs) to classify the flashover prediction based on the discharge intensity levels of the insulator samples. The results of the ANN simulation showed 87% accuracy in the performance index. This study illustrates that the UV pulse detection method is a potential tool to monitor insulator surface conditions during service.

Reduction of isotopically enriched 50Ti-dioxide for the production of high-intensity heavy-ion beam

Titanium-50 (50Ti) is an important and often requested ion beam for nuclear physics’ experiments. While natural titanium of very high purity is available in different forms; enriched material can only be bought as the dioxide or the tetrachloride. These compounds cannot be processed from currently available ion sources with a sufficient beam quality and sufficient beam intensity for a long time. We describe here the process of converting titanium dioxide into the metal, the material analysis of the starting material as well as of the reduced material. Despite varying contamination levels of silicon, chlorine, and tin in the primary materials, we obtained high yields of metallic titanium with different contamination levels. The obtained metallic 50Ti was applied at the accelerator UNILAC for the production of a high intensity ion beam for several month of beam time.

Effects of decontamination at varying contamination levels of Campylobacter jejuni on broiler meat

When assessing effects of decontamination techniques on counts of Campylobacter spp. on broiler meat, it is essential that the results reflect the variations that may exist. Decontamination studies often use high inoculation levels (107 to 108 cfu) and one or few strains of Campylobacter jejuni, thereby restricting the results to reflect only a limited part of the true situation. This study presents results from physical and chemical decontamination of broiler meat medallions using different strains and different initial concentrations of C. jejuni. For 3 strains of C. jejuni, mean log reductions obtained by freezing at −20°C for 7 d was significantly higher for an initial concentration of 107 cfu/sample on the meat compared with an initial concentration of 103 cfu/sample. For freezing at −20°C for 24 h or application of 6% tartaric acid and subsequent storage for 24 h, no statistically significant difference in reductions was found for initial concentrations ranging from 103 to 107 cfu per sample. The mean log reductions obtained by all techniques were strongly dependent on the strain tested. The results reveal that reductions obtained with high inoculation levels of C. jejuni (107 cfu/sample) or single or few strains of the species (or both) should not be interpreted as a generic result for the species. If inoculation studies cannot be replaced by investigations of naturally contaminated meat, we advise using a mixture of strains found in the production environment at levels as close as possible to the natural contamination level.