Risk Of Human Exposure Research Articles

Key active mercury methylating microorganisms and their synergistic effects on methylmercury production in paddy soils

Rice contamination with neurotoxic methylmercury (MeHg) from paddy soils is an escalating global concern. Identifying the microorganisms responsible for mercury (Hg) methylation in these soils is essential for controlling Hg contamination in the food chain and mitigating health impacts. Current research often focuses on total Hg-methylating microorganisms, overlooking the contributions of active ones, which can lead to either overestimating or neglecting the specific roles of microorganisms in Hg methylation within paddy soils. In this study, active Hg-methylating microorganisms in paddy soils were identified using a combination of DNA-SIP, Hg isotope labelling, and Hg methylation gene sequencing techniques. Our findings revealed that Geobacter and Anaerolinea are pivotal active Hg-methylating microorganisms across a contamination gradient in paddy soils. Transcriptomic analysis of soils from major rice-producing provinces in China confirmed the widespread and synergistic involvement of these microorganisms. Microbial incubation further validated their interaction significantly enhances Hg methylation, with Me198Hg concentrations increasing 2.8-fold compared to Geobacter alone and 5.2-fold compared to Anaerolinea alone. These findings enhance our understanding of microbial Hg methylation in paddy soils, providing critical insights for accurately predicting soil MeHg load, rice grain MeHg contamination, and human MeHg exposure risks.

Polycyclic Aromatic Compounds in Ambient PM2.5 in the Central Region of Ghana: Molecular Distribution, Origin and Cancer Risk Assessment

The distribution, sources and the cancer risk of human exposure to PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) were investigated in this work. Airborne particulate samples were obtained at the Winneba highway junction (WHJ) and Apam fish-smoking community (AFC) in the Central Region of Ghana from July 2022 to June 2023. PM2.5 particulates were collected using a Gent sampler equipped with a Gast pump and a stacked filter unit. 24-hour sampling was done two times a month using Teflon filters. Dichloromethane and gas chromatography with a mass spectrometer (GC-MS) were used to extract and analyse the samples, respectively, to identify 14 PAH compounds. The study discovered average PAH concentrations of 67.38 ng/m3 at WHJ and 41.59 ng/m3 at AFC. PAH profile was predominated with Phenanthrene, accounting for 25-27 % of total PAHs. The distribution pattern of PAHs was LMW>HMW>MMW at the two research sites. A strong correlation was found among BaA, BkF, BbF and BeP. The diagnostic ratio model revealed that PAHs stemmed from pyrogenic sources. The carcinogenic PAHs (BaP, BaA, Chr, BbF, BkF, BghiP) contributed approximately 90 % to the carcinogenic activity of total PAHs, denoting a high cancer potential of PAHs. The mean levels of BaP were about 8-10 times higher than the permissible limit of 1 ng/m3. The overall cancer risk values for exposure to PAHs via inhalation were more than 10-4, signifying high cancer risks: 11.61×10-4-21.14×10-4 for children and 19.91×10-4-36.24×10-4 for adults. Reducing PM2.5 and its health effects requires the use of clean fuel and the adoption of eco-friendly transportation.

Phthalate esters in dusts from different indoor and outdoor microenvironment and potential human health risk: A case study in Beijing

Phthalate esters (PAEs) are widely used plasticizers that can easily migrate from plastic products, thereby presenting potential health risks through exposure. While PAE concentrations in dust have received increasing attention, there is still a lack of comprehensive understanding regarding their environmental distribution, composition profiles, and associated human exposure risks in Beijing. This study investigated the presence of seven PAEs in 124 dust samples collected from eight indoor and four outdoor microenvironment types across the Beijing metropolitan area. The PAEs were detected universally in all samples, with di(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP) and di-iso-butyl phthalate (DIBP) as the predominant compounds, accounting for 91.78%-99.91% and 91.22%-99.76% of total PAE concentrations (Σ7PAEs) in indoor and outdoor dust, respectively. Indoor dust exhibited significantly higher Σ7PAEs (range: 45.33-1212.41 μg/g, mean: 130.61 μg/g) compared to outdoor dust (range: 2.10-5.41 μg/g, mean: 3.38 μg/g). Among indoor microenvironments, taxis had the highest Σ7PAEs (mean: 1250.59 μg/g), followed by private cars, print shops, residences, furniture shops, shopping malls, dormitories and offices. Outdoor Σ7PAEs levels decreased in the order of roads, residential areas, green belts, and parks. Estimated daily exposure doses through dust ingestion were significantly higher than those from dermal absorption and inhalation for five occupational groups (taxi drivers, print shop workers, road workers, office workers, jobless people), indicating dust ingestion as the primary exposure route, with DEHP and DBP as the main contributors. While current exposure levels may not present significant non-cancer risks based on hazard quotient and hazard index estimations, it’s noteworthy that DEHP may pose a carcinogenic risk to taxi drivers. Potential risks cannot be overlooked considering the absence of toxicity thresholds, additional exposure pathways, and possible cocktail effects from coexisting pollutants.

Introduction of Chlamydia psittaci into a hospital area by feral pigeons

Pigeons are associated with zoonotic pathogens such as Chlamydia psittaci, the main causative agent of avian chlamydiosis, and related to psittacosis cases in humans worldwide. The aim of the present study was to investigate the occurrence of C. psittaci in feral pigeons (Columba livia) and environmental samples from places frequented by pigeons in a Brazilian hospital area. A cross-sectional study was carried out sampling feral pigeons, their droppings and nest material in a hospital area. Squares in a nearby region with a high density of pigeons were also sampled. Pigeon cloacal swabs (n=123) were collected from each bird, as well as pigeon droppings from the environment (n=77) and material from pigeon's nests (n=28). Chlamydiaceae-PCR targeting the 23S rRNA gene was used as screening. Positive samples were submitted to another PCR targeting the ompA gene of C. psittaci, followed by sequencing and phylogenetic analysis. C. psittaci was detected in 7.5% (17/228) of the samples, 7.3% (12/164) from the hospital area and 7.8% (5/64) from the squares. By sample type, 9.8% (12/123) of the pigeon cloacal swabs, 5.2% of droppings (4/77) and 3.6% of nest material (1/28) were positive for C. psittaci. All sequenced samples corresponded to C. psittaci genotype B. These results demonstrate the occurrence of C. psittaci in urban areas, with emphasis on a hospital area where immunocompromised individuals are present. Adopting a One health approach to prevent the proliferation of the pigeons, health education campaigns and specific recommendations for the hospital administration are essential. Guidance on practices such as not feeding the pigeons, avoiding contact or proximity and removing available areas for roosting and nesting, are measures that will reduce environmental contamination and risk of human exposure to C. psittaci.

Fluralaner treatment of chickens kills the southern house mosquito, Culex quinquefasciatus.

The control of zoonotic and vector-borne pathogens is challenging due to the limited availability of intervention tools. West Nile virus (WNV) is an example of a globally distributed zoonotic arbovirus that circulates between Culex species (Diptera: Culicidae) mosquitoes and avian hosts, with spillover transmission to humans, resulting in disease cases. Interventions delivering systemic insecticides to vertebrate hosts used by vector species, known as xenointoxication, are potential tools for managing vector populations by creating toxic bloodmeals. In this study, we evaluated the impact of two systemic pesticides (ivermectin; Ivomec® Pour-On and fluralaner; Bravecto®), and one anthelmintic (fenbendazole; Safe-Guard® Aquasol) on the mortality of Cx. quinquefasciatus Say (Diptera: Culicidae). We found no significant difference in the feeding rates of mosquitoes that fed on treated chickens compared with those fed on untreated chickens, suggesting that the treatment did not repel mosquitoes. The mortality of Cx. quinquefasciatus mosquitoes feeding on fluralaner-treated chickens was significantly higher (p < 0.01) than those fed on control chickens at 3 and 7 days post-treatment, but this effect was not observed in mosquitoes fed on chickens treated with fenbendazole or ivermectin. No differences in mortality were observed among the groups at 14, 26 or 56 days post-treatment. These data support fluralaner as a xenointoxication tool to control Cx. quinquefasciatus populations and decrease the risk of human exposure to their associated pathogens.

Comprehensive evaluation of Toxoplasma gondii in sheep intended for human consumption in Brazil: seroprevalence, isolation, and genotyping.

Ovine toxoplasmosis caused by Toxoplasma gondii is a zoonotic disease responsible for triggering reproductive problems in sheep with great public health impact. The zoonotic risk for humans occurs through the ingestion of meat contaminated with bradyzoites, water and vegetables contaminated with oocysts, or by ingesting unprocessed sheep milk contaminated with tachyzoites. The study aimed to determine the seroprevalence, isolate, and genetically characterize T. gondii from sheep in northeastern Brazil. Blood and tissue samples, including the liver, heart, brain, lung, and diaphragm, were collected from 256 sheep in slaughterhouses. The presence of anti-T. gondii IgG antibodies was assessed by the indirect fluorescent antibody test (IFAT), and sera with titers ≥ 1: 64 were considered positive. Tissue samples from seropositive sheep were digested in acidic pepsin solution and inoculated into two Swiss mice for T. gondii isolation and further characterized by molecular methods. The prevalence of anti-T. gondii antibodies in sheep was 31.64% and the isolation rate was 40.7%. Sixteen out of 33 isolates were submitted to mnRFLP-PCR using ten genetic markers. Four isolates were fully genotyped, and four isolates were amplified at least in one marker. All isolates were characterized as atypical genotypes, and ToxoDB #57 (n = 3) and #143 (n = 1) were identified. The detection of viable T. gondii in sheep from slaughterhouses in Brazil highlights the risk of human exposure. There is the need for proactive control and prevention measures to mitigate the risk of human exposure, considering the importance of sheep meat as a source of protein to humans.

High Gradient Magnetic Fields Generated in Events on the 230 kV Electric Power Transmission Infrastructure: Human Exposure Analysis and Risk

This work presents a process for analyzing human exposure to high-gradient magnetic fields based on protection models for patients undergoing magnetic resonance examinations developed by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). A series of events presented in the electrical energy transmission infrastructure is taken, with typical currents and front times, a case of extreme failure is added, and results are presented. Subsequently, with a classic lightning signal, compliance with the exposure to this type of field in the right-of-way strip of a transmission line is verified and validated in the event of a hypothetical atmospheric discharge impact event. Finally, a simulation is implemented with space discretization techniques, establishing the signal resulting from the magnetic field generated as a function of time. The exposure is evaluated using the presented model. Only in one of the analysis cases was it found that the perception threshold is exceeded at distances less than 0.6 cm, virtually a situation in which the worker has contact with the down conductor. With the results obtained and the cases analyzed, it is concluded that failures of this type do not generate significant exposure to high-gradient magnetic fields and do not exceed the determined perception thresholds.

Ventilation strategy for particulate matter control in subway stations

Particulate matter severely affects human health, and its migration is closely related to human walking and ventilation. It is essential to select an appropriate ventilation strategy to control the particulate matter caused by cluster passengers walking. In this study, cluster passengers walk in the narrow passage of a subway station. Large eddy simulation (LES) was used to study the influence of cluster passengers walking on the transmission of particulate matter under ventilation conditions involving upper exhaust and lower exhaust. The risk of passengers exposure was analyzed by comparing the exposure levels of particulate matter at different heights under the effect of human disturbance. The results show that the amount of particulate matter near the legs is greatest during human walking. Clustered passengers disturbance airflow induces particulate matter to rise to the breathing zone, which increases the risk of human exposure. Lower-side exhaust conditions are more conducive to the discharge and control of particulate matter. The disturbance of cluster passengers enhances the continuous transmission of particulate matter in the wake flow. This study is applicable to traffic hubs and other public places where passengers gather, the ventilation of the upper side exhaust has better control effect on particulate matter caused by passengers wake flow.

Potential health risk of human exposure to tobacco-specific nitrosamines in second-hand and third-hand smoke

Environmental tobacco smoke (ETS), including both second-hand (SHS) and third-hand smoke (THS), seriously impacts human health. However, the potential health risk of non-smokers’ exposure to ETS (especially THS) has not been fully characterized. The present study conducted smoking events in a 100 m³ room. Gaseous and size-fractioned particulate samples from SHS and THS along with wipe samples on desk and floor surfaces were collected and analyzed for tobacco-specific nitrosamines (TSNAs). The concentration, composition, and size distribution of indoor TSNAs varied between SHS and THS due to variability in particle deposition, air exchange, chemical reaction, and partitioning. Children had higher per body weight daily intake of TSNAs and nicotine through all exposure pathways than other population groups. The contributions of different exposure pathways to the intake of pollutants were influenced by their octanol-air partition coefficients. Incremental lifetime cancer risk (ILCR) for different population groups from exposure to residential TSNAs in ETS exceeded 1.0 × 10−6, even with exposure to THS only. The ILCR from e-cigarettes was lower than that from cigarettes, but it still posed potential carcinogenic risk, particularly through air-to-skin transdermal exposure to THS. Reducing health risk for exposure to both SHS and THS requires rigorous enforcement of smoking-free policies.

Electromagnetic compatibility study of trackside antenna array miniaturization in the subway tunnel

Abstract To improve the compatibility of the subway tunnel’s electromagnetic environment and reduce the radiation impact of trackside antennas on subway workers. This paper proposes a miniaturized dual-band trackside antenna array by using metamaterial units. Its operation bandwidth is 2.33 ∼ 2.56 GHz and 3.24 ∼ 3.45 GHz, which could simultaneously satisfy the signal cover demands of the communications-based train control (CBTC) and the civil 5G wireless communication system. The proposed miniaturized antenna array has a maximum gain of 14.4 dBi and a maximum channel capacity of 13.9 bps Hz−1 at a signal-to-noise ratio (SNR) of 20 dB, which can effectively improve the quality of wireless communication systems. The number of trackside antennas with a single operation frequency band is reduced, and the distance between the antennas is enlarged at the same time. Besides that, we analyze the radiation impact on the tunnel electromagnetic environment of the proposed trackside antenna array. In particular, the electromagnetic dose absorbed by the human model of a tunnel worker is quantized. The results show that the electric field strength in the tunnel reduces by 4.11% at least after antenna array miniaturization, and the specific absorption rate (SAR) absorbed by the worker model’s trunk, skull, brain, heart, and liver is reduced by a maximum of 19.02%, 33.16%, 28.27%, 41.75%, and 74.54%, respectively, further lowering the human electromagnetic exposure risk. Therefore, a miniaturized trackside antenna array could reduce the interference from other radiation sources in the tunnel while providing a new idea for electromagnetic protection for subway workers.

Modeling traffic pollutants in a street canyon by CFD: Idealized line sources versus multiple realistic car sources

Idealized sources are commonly used to reproduce the traffic emission in street canyons in experimental and numerical investigations. However, it remains unclear whether idealized sources can accurately reproduce the pollutant dispersion compared to more realistic sources. The goal of this paper is to investigate the impact of idealized and realistic sources on traffic-induced pollutant concentration in a street canyon by numerical simulation with Computational Fluid Dynamics (CFD). First, the scale-adaptive simulation (SAS) results of mean velocity and concentration are compared with wind-tunnel (WT) data for idealized line sources (ILS) and a satisfactory agreement is found between the SAS and WT results. Next, SAS are performed to investigate the impact on mean velocity and mean pollutant concentration of ILS versus multiple realistic car sources (MRCS) cases, designed to mimic a configuration of traffic jam-like conditions (i.e. rows of idling cars) in a street canyon. Different levels of geometrical simplifications of sources and total emission rates are considered. Although this research study focuses on these aforementioned specific set of conditions and conclusions relate solely to these circumstances, the SAS results show that the overall-averaged concentration associated with MRCS and the simplified source-geometry cases is about 1.18–6.22 times larger than that by ILS. Thus, ILS may be inadequate to reproduce the pollutant concentration in real scenarios. This study can contribute to enhancing the pollution prediction accuracy and reduce the potential risk of human exposure.

7Method for Detection of Naturally Occurring Toxins in Human Urine Using Liquid Chromatography High Resolution Mass Spectrometry.

Natural toxins present an ongoing risk for human exposure that requires a rapid, accurate diagnosis for proper response. In this study, a qualitative liquid chromatography high resolution mass spectrometry (LC-HRMS) method was developed and validated for the detection of a large, diverse selection of natural toxins. Data-dependent acquisition was performed to identify compounds with an in-house mass spectral library of 129 hazardous toxins that originate from plants, animals, and fungi. All 129 compounds were spiked into human urine, extracted, and evaluated for spectral library matching. Of these, 92 toxins met the quality criteria and underwent validation in urine matrix based on American National Standards Institute (ANSI) guidelines. A generalized workflow for method expansion was developed and enables the rapid addition of relevant compounds to the established method. This LC-HRMS method achieves efficient detection of natural toxins in urine, and the created workflow can rapidly increase compound coverage via method expansion.

Human health risk of exposure to potentially toxic metals (PTMS) in indoor settled dusts from selected worship centres (WCS)

The study aimed to determine the concentration of potentially toxic metals (PTMs) and the health risk of exposure to indoor dust from worship centres in Abeokuta, Nigeria. Twenty-four (24) dust samples were collected from various corners of selected worship centres. One (1) gram of the sieved dust was digested using aqua regia. PTM analyses were done using an Atomic Absorption Spectrometer (AAS). The result revealed the presence of Iron (Fe)&gt; Zinc (Zn)&gt;Manganese (Mn)&gt; Lead (Pb) &gt; Copper (Cu) &gt;Nickel (Ni) &gt; Cadmium (Cd) (1050; 81.6; 72.5; 3.304; 2.43; 0.516; 0.076 mg/kg) respectively. The PTMs were within the permissible limit for PTMs in dust stated by UK and Dutch Intervention. Pollution indices revealed Zn as the primary pollutant in the dust. A significant association between Zn, Cu, Ni and Cd while that of Mn and Fe suggest a common origin of anthropogenic and lithogenic sources respectively (p&lt;0.01). Health risk assessment revealed inhalation as the major pathway of PTM exposure with the children population being the most susceptible. Hazard index (HI) values were &lt;1, showing a non-significant non-cancer effect on exposure while the cancer risk estimate shows no carcinogenic risk. Conclusively, the selected worship centres have no PTM concentration of health concern at the time of the investigation. However, regular wet cleaning and close monitoring of the worship centres should be considered.

Little disease but lots of bites: social, urbanistic, and entomological risk factors of human exposure to Aedes aegypti in South Texas, U.S.

Aedes aegypti presence, human-vector contact rates, and Aedes-borne virus transmission are highly variable through time and space. The Lower Rio Grande Valley (LRGV), Texas, is one of the few regions in the U.S. where local transmission of Aedes-borne viruses occurs, presenting an opportunity to evaluate social, urbanistic, entomological, and mobility-based factors that modulate human exposure to Ae. aegypti. Mosquitoes were collected using BG-Sentinel 2 traps during November 2021 as part of an intervention trial, with knowledge, attitudes, and practices (KAP) and housing quality surveys to gather environmental and demographic data. Human blood samples were taken from individuals and a Bitemark Assay (ELISA) was conducted to quantify human antibodies to the Ae. aegypti Nterm-34kDa salivary peptide as a measure of human exposure to bites. In total, 64 houses were surveyed with 142 blood samples collected. More than 80% of participants had knowledge of mosquito-borne diseases and believed mosquitoes to be a health risk in their community. Our best fit generalized linear mixed effects model found four fixed effects contributed significantly to explaining the variation in exposure to Ae. aegypti bites: higher annual household income, younger age, larger lot area, and higher female Ae. aegypti abundance per trap night averaged over 5 weeks prior to human blood sampling. Most surveyed residents recognized mosquitoes and the threat they pose to individual and public health. Urbanistic (i.e., lot size), social (i.e., income within a low-income community and age), and entomological (i.e., adult female Ae. aegypti abundance) factors modulate the risk of human exposure to Ae. aegypti bites. The use of serological biomarker assays, such as the Bitemark Assay, are valuable tools for surveillance and risk assessment of mosquito-borne disease, especially in areas like the LRGV where the transmission of target pathogens is low or intermittent.

Risk of human exposure to Brucella species through the consumption of milk among traditional cattle farmers in the western province of Zambia

MARY MUBIANA1,2⁎, CHISONI MUMBA1, DOREEN SITALI1, MULENGA MALATA1,3, ISABEL NAMFUKWE LUAMBIA4, JOHN BWALYA MUMA1

Structure-Dependent uptake and metabolism of Tire additives Benzothiazoles in carrot plant

Tire additives, such as benzothiazole and its derivatives (collectively called BTs), are large-volume chemicals that are constantly emitted into agricultural environment via tire-road wearing and other actions. The potential accumulation of BTs in food crops depends largely on their metabolism in plants, which is poorly understood. Herein, we evaluated uptake and metabolism of six BTs in carrot callus and intact carrot plants to understand their structure-specific metabolism. All BTs were readily taken up by carrot roots, with their root concentration factors (RCF) ranging from 1.66 ± 0.01 to 2.95 ± 0.05. Although the tested BTs exhibited poor upward translocation from root to leaves (translocation factors < 1), the translocation factors of 2-methylbenzothiazole (0.79) and 2-aminobenzothiazole (0.65) were significantly higher than that of 2-methylbenzothiazole (0.18) and 2-(methylthio)benzothiazole (0.22). These results indicated the structure-dependent uptake and translocation of BTs in carrot. Correlation analysis between log Kow and log RCF or TF revealed that the hydrophobicity of BTs predominantly affected their root uptake and acropetal translocation in carrots. With the aid of high-resolution mass spectrometry, a total of 18 novel metabolites of BTs were tentatively identified, suggesting that BT compounds can be metabolized by carrot callus. The proposed metabolites of BTs include four hydroxylated products, one demethylated product, five glycosylated products and eight amino acid conjugated products, revealing that glycosylation and amino acid conjugation were the dominant transformation pathways for BT metabolism in carrot. However, the detected species of metabolites for six BTs varied distinctly, indicating structure-specific metabolism of BTs in plants. The findings of this study improve our understanding of structure-dependent fate and transformation of BTs in plants. Since BTs metabolites in food crops could present an unintended exposure route to consumers, the structure-specific differences of BTs uptake, metabolism and accumulation in plants must be considered when addressing human dietary exposure risks.

Evaluation of the relationships between physico-chemical parameters and the abundance of Vibrio spp. in blue crabs (Callinectes sapidus) and seawater from the Maryland Coastal Bays.

Fluctuations in water quality characteristics influence the productivity of blue crabs (Callinectes sapidus), and the risk of human exposure to pathogenic Vibrio species. Thus, this study assessed the prevalence of total and pathogenic/clinical markers of Vibrio parahaemolyticus and Vibrio vulnificus in blue crabs and seawater from the Maryland Coastal Bays (MCBs) and the correlation between Vibrio levels and physicochemical parameters. Three to five crabs and 1 L of seawater were collected monthly for 3 years (May 2018 to December 2020) from six sites within the MCBs. Hemolymph and crab tissue were extracted and pooled for each site. Extracted hemolymph, crab tissue, and seawater were analyzed for V. parahaemolyticus and V. vulnificus using the Most Probable Number (MPN) and real-time PCR methods. A one-way Analysis of Variance (ANOVA), correlations, and linear models were used to analyze the data. Akaike Information Criterion (AICc) was evaluated to determine the model that provides the best fit to the data relating to Vibrio concentrations and environmental factors. Results suggested that environmental factors could influence the growth of Vibrio spp. Both V. parahaemolyticus and V. vulnificus were more prevalent during the warmer months than colder months. Vibrio was more prevalent in crab samples compared to seawater. Vibrio vulnificus concentrations in seawater and hemolymph were positively correlated with temperature (p = 0.0143 seawater) and pH (p = 0.006 hemolymph). A negative correlation was observed between the concentration of V. vulnificus in whole crab (tissue) and dissolved oxygen level (p = 0.0256). The concentration of V. parahaemolyticus in seawater was positively correlated with temperature (p = 0.009) and negatively correlated with dissolved oxygen (p = 0.012). These results provide current information on the spatial and temporal distributions of Vibrio spp. in the MCBs that are useful for implementing more efficient processing and handling procedures of seafood products.

Unraveling the contribution of melamine tableware for human internal exposure to melamine and its derivatives: Insights from crossover and biomonitoring studies

Melamine tableware can release melamine in daily-use; however, currently there is insufficient evidence to support whether the amount released could pose human exposure risk. We therefore conducted two studies, one is 8-day randomized crossover trial involving 27 volunteers who used melamine and stainless-steel tableware in turn (n = 648) and the other is cross-sectional study including 113 college students and 200 residents (n = 313) to further provide population-based evidence. The crossover study results showed that using melamine tableware could promote urinary concentrations of melamine, cyanuric acid (CYA), and ammelide by 42.1 %, 66.9 %, and 36.2 %, respectively. In the biomonitoring survey, students who are more accessible to melamine tableware in the canteen had 1.47-fold higher median urinary concentrations of melamine-related compounds than that of common residents (393 vs 267 nmol/L, p < 0.01). Additionally, positive associations between exposure to melamine and an oxidative stress indicator, 8-oxo-7,8-dihydroguanine (β = 1.13, 95 % CI: 0.32, 1.94), and CYA and 8-hydroxy-2′-deoxyguanosine (β = 0.87, 95 % CI: 0.22, 1.53) were observed in students (p < 0.01), indicating long-term chronic exposure to these chemicals may induce molecular damage to nucleic acids. Our findings provide compelling evidence that frequent use of melamine tableware continues to be a potential threat to human health.

Prevalence and Genetic Diversity of Deer Tick Virus (Powassan Virus, Lineage II) in Ixodes scapularis Ticks in Five Habitats at a Nature Reserve in Southern Maine, United States.

Deer tick virus (DTV), also known as Powassan virus lineage II, is a rising health concern due to increased recognition as a cause of human encephalitis. Since European tick-borne encephalitis virus persists in nature in enzootic foci (i.e., higher prevalence rates in small pockets in nature), we sought to determine whether DTV is also focally maintained in relation to habitat type, to better understand factors leading to human risk of exposure. From 2018 to 2021, questing Ixodes scapularis ticks were collected from five habitats at the Wells National Estuarine Research Reserve (WNERR) in Wells, ME: forest with invasive vegetation in the understory, edge, shrub, forest with native vegetation in the understory, and open field. Deer tick virus prevalence was greater in adult ticks (2.0%) than in nymphs (0.5%). Deer tick virus prevalence in adult ticks collected from forest with invasive vegetation was 3.2% compared to 0 to 1.7% in other habitat types. A hot spot analysis revealed a higher number of infected adults collected per hour on one of the transects located in forest with invasive vegetation. Phylogenetic analysis of 37 full-length DTV genomes sequenced in this study revealed four major clades from the WNERR, and there was high genetic diversity within each transect, suggesting frequent, short-range dispersal between habitats. Analysis of DTV sequences from other New England counties and states also indicated long-distance dispersal to and/or from the WNERR. This study provides preliminary evidence that DTV is focal and that the risk of encountering DTV-infected ticks in forest with invasive vegetation may be greater than in other habitat types.

Simple fuzzy classification of metal qualities of Ona River, Ibadan, Nigeria, and its implication for fish production and other uses

Elevated concentrations of metals in rivers can pose significant risks to human health. Consequently, it is essential to monitor metal levels in river water to minimize human exposure, particularly through consumption of harvested fish and other uses. This study examined the water quality of the Ona River in Ibadan, Nigeria. Seven potentially toxic elements (PTEs), namely Fe, Cu, Mn, Zn, Pb, Cd, Cr and four macronutrients: Mg, Na, K, Ca were investigated. Surface and pore water samples were collected from six sampling points during the peak of the dry and the rainy seasons. These were analyzed according to standard procedures and processed using the Simple Fuzzy Classification (SFC) model with four classes. The results revealed that the PTEs: Fe, Pb, Cd, Cr, and Mn were detected above guideline limits in several sampling points, indicating possible contamination from anthropogenic sources. Simple fuzzy classification puts the quality of water in the investigated portion of the river in the range of 67.4–88.5% in the C1 (pristine) category during the dry season and 61.9–88.6% in C1 (pristine) during rainy season. However, there were membership functions of up to 58.7 and 63.2; 61.2 and 75.4 as well as 44.3 and 43.5% in C2, C3, and C4 categories (contaminated, polluted and extremely polluted, respectively) during the first and second sampling, respectively. Due to the high concentrations of toxic and bioaccumulative metals in the river, efforts should be made to control the discharge of pollutants into the river. These will prevent human health exposure risks tendencies for various uses, including fish production.