Potential Sources Of Contamination Research Articles

A-327 Pre-analytical and Analytical Modifications to Improve the Quality of Pediatric Lead Tests

Abstract Background The recent decrease in the CDC Blood Lead Reference Value (BLRV) to 3.5 ug/dL has highlighted the need for systematic changes that some clinicians and laboratories need to implement to assure the quality of reported pediatric lead results. Building upon the recommendations of the Blood Lead Reference Value Workgroup, APHL has developed specific recommendations and resources designed to assist medical professionals and laboratory scientists in minimizing the likelihood of contamination when collecting and testing blood specimens. Also included are analytical practices that can improve precision, accuracy, and sensitivity of pediatric lead assays. Methods Evaluation of existing protocols and practices to identify potential sources of contamination and opportunities for process improvement. Results APHL will provide practical recommendations to systematically improve point of care and fixed laboratory testing to improve confidence in reported pediatric lead concentrations. These improved measurements will improve environmental health surveillance and inform public health intervention and patient care. Conclusion Rigorous pre-analytical practices including education, updated specimen collection guidance, pre-screening of collection materials, improvement of point of care technology and refinement of spectroscopic analytical methods result in less ambient contamination, improved sensitivity, precision and accuracy of pediatric lead testing. Clinician office practices, public health and commercial clinical laboratories will all benefit from implementing these strategies.

Identification of Contamination Sources and Assessment of Risk Factors Associated with the Occurrence of Escherichia coli O157:H7 on Small-scale Cow-calf Operations in Oklahoma and Louisiana

Escherichia coli O157:H7 is a human pathogen that exists as part of the commensal microflora of cattle and is shed in animal feces. Little is known about the effect of management practices on its occurrence and transmission on small-scale cow-calf operations. Identification of risk factors associated with farm practices could help implement effective measures to control E. coli O157:H7. This study quantified the risk of E. coli O157:H7 occurrence associated with cow-calf farm practices using risk modeling. Management practices of small-scale cow-calf operations in OK and LA were assessed through survey-based research. Fecal, water, sediments and water-trough-swab samples were collected to determine the incidence of E. coli O157:H7, and potential on-farm contamination sources and risk factors identified. Association between the occurrence of pathogen and farm practices was determined using two risk assessment models (I and II). Model I determined the association of E. coli O157:H7 occurrence with water source, water container, feed, cattle breed, and herd density, while Model II determined its association with farm cleanliness. For both models, logistic regression was followed using a two-step approach, univariable and multivariable analysis. In OK and LA, E. coli O157:H7 was present in 5.8% and 8.8% fecal, 4.4% and 9.4% water, 10.3% and 9.6% sediments, and 1.5% and 10.6% water-trough-swab samples, respectively. In Model I, univariable analysis identified water container and feed, whereas multivariable analysis identified feed as a significant risk factor. In Model II, the univariable analysis found cleanliness of cattle-contact areas, such as, alleyways, water-trough, chute and equipment, to be a significant risk factor. In multivariable analysis, only the cleanliness of water-trough was identified to be a significant risk factor. Results from the study could aid in the development of on-farm best management practices for the reduction of E. coli O157:H7.

Assessing groundwater quality: a case study in Ghana Talensi district

Abstract Because most life processes are directly or indirectly related to water, people are investigating on the various sources of drinking water supply. Surface water and groundwater are the most common sources of water for domestic and other uses. The availability of safe and sufficient drinking water in developing countries’ rural and many urban areas is critical. Groundwater has become the primary source of drinking water supply in northern Ghana, particularly in rural areas. Tongo, in northern Ghana, is entirely dependent on groundwater for its drinking water supply. The quality of groundwater from 15 boreholes and open well samples was assessed in this study. The primary goals of the research are to assess the quality of groundwater for drinking and to determine the distribution of major ions in groundwater and the factors that control them. Groundwater physicochemical parameters were within the WHO guidelines limit. However, coliform bacteria were found in some groundwater sources. Anthropogenic, natural, and ion exchange processes were also identified as controlling groundwater major ion distribution. Insanitary conditions were identified as potential sources of contamination during field observations. As a result, the regular monitoring of groundwater resources could reveal more about the area's groundwater quality status.

Investigation of microbial communities across swine slaughter stages and disinfection efficacy assessment in a pig slaughterhouse

The processing environment of pig slaughterhouses is a significant potential source of bacterial contamination in pork products for sale. In this study, we employed 16S rRNA sequencing and diversity analysis to characterize the heterogeneity of microbiota on carcass surfaces and environment of a swine slaughterhouse. Furthermore, we assess variations in microbiota across swine slaughter stages, as well as the effectiveness of disinfection by analysing microbial diversity before and after disinfection. The results indicated that the predominant genus present in all samples were Psychrobacter spp., followed by Acinetobacter spp. The occurrence of cross-contamination within the slaughterhouse is prevalent, particularly during interactions involving fresh pig carcasses, including worker operations, tools, and machinery. Remarkably, trimming emerges as a critical control point and a pivotal factor in cross-contamination. The disinfection procedure were partly effective in reducing of microbial contamination of the environment, significantly reducing bacterial diversity and favoring some genera such as Psychrobacter and Weissella confusa. This study provides a deeper understanding of microbial contamination in abattoirs and emphasizes the importance of disinfection. Moreover, it offers scientific suggestions for implementing effective disinfection.

Two-Step Flux Synthesis of Ultrapure Transition-Metal Dichalcogenides.

Two-dimensional transition-metal dichalcogenides (TMDs) have attracted tremendous interest due to the unusual electronic and optoelectronic properties of isolated monolayers and the ability to assemble diverse monolayers into complex heterostructures. To understand the intrinsic properties of TMDs and fully realize their potential in applications and fundamental studies, high-purity materials are required. Here, we describe the synthesis of TMD crystals using a two-step flux growth method that eliminates a major potential source of contamination. Detailed characterization of TMDs grown by this two-step method reveals charged and isovalent defects with densities an order of magnitude lower than those in TMDs grown by a single-step flux technique. For WSe2, we show that increasing the Se/W ratio during growth reduces point defect density, with crystals grown at 100:1 ratio achieving charged and isovalent defect densities below 1010 and 1011 cm-2, respectively. Initial temperature-dependent electrical transport measurements of monolayer WSe2 yield room-temperature hole mobility above 840 cm2/(V s) and low-temperature disorder-limited mobility above 44,000 cm2/(V s). Electrical transport measurements of graphene-WSe2 heterostructures fabricated from the two-step flux grown WSe2 also show superior performance: higher graphene mobility, lower charged impurity density, and well-resolved integer quantum Hall states. Finally, we demonstrate that the two-step flux technique can be used to synthesize other TMDs with similar defect densities, including semiconducting 2H-MoSe2 and 2H-MoTe2 and semimetallic Td-WTe2 and 1T'-MoTe2.

Adding value to pineapple waste: Characterization and evaluation of potential for bacteria and yeast culture medium

In the use of fresh pineapple, whether in consumption or in the production of other foods, there is a release of 77.5% of waste from the total fruit consumed, generating tons of waste that, when not disposed of correctly, are potential sources of contamination. These residues could become by-products with high added value. One of these by-products could be a culture medium to be used in microbiology classes. In this way, the objective of this work was the production and characterization of flours from the pearl pineapple peel with subsequent evaluation of the efficiency of these flours as a culture medium in the growth of bacteria and yeasts. For this, the pineapple peels were sanitized, dried, transformed into flour and properly packaged and labeled. Physical-chemical analyzes were performed with these flours and culture media were prepared. With the microorganisms, a serial dilution was prepared and inoculated in plates with ACA culture medium – pineapple peel agar and in standard culture medium for comparison of the results. It was found that all yeasts grew abundantly on the ACA medium and only 30% of the bacteria were able to grow on this medium.

Prevalence and Antimicrobial Resistance Profile of Diarrheagenic Escherichia coli from Fomites in Rural Households in South Africa.

Diarrheagenic Escherichia coli (DEC) pathotypes are the leading cause of mortality and morbidity in South Asia and sub-Saharan Africa. Daily interaction between people contributes to the spreading of Escherichia coli (E. coli), and fomites are a common source of community-acquired bacterial infections. The spread of bacterial infectious diseases from inanimate objects to the surrounding environment and humans is a serious problem for public health, safety, and development. This study aimed to determine the prevalence and antibiotic resistance of diarrheagenic E. coli found in toilets and kitchen cloths in the Vhembe district, South Africa. One hundred and five samples were cultured to isolate E. coli: thirty-five samples were kitchen cloths and seventy-five samples were toilet swabs. Biochemical tests, API20E, and the VITEK®-2 automated system were used to identify E. coli. Pathotypes of E. coli were characterised using Multiplex Polymerase Chain Reaction (mPCR). Nine amplified gene fragments were sequenced using partial sequencing. A total of eight antibiotics were used for the antibiotic susceptibility testing of E. coli isolates using the Kirby-Bauer disc diffusion method. Among the collected samples, 47% were positive for E. coli. DEC prevalence was high (81%), with ETEC (51%) harboring lt and st genes being the most dominant pathotype found on both kitchen cloths and toilet surfaces. Diarrheagenic E. coli pathotypes were more prevalent in the kitchen cloths (79.6%) compared with the toilet surfaces. Notably, hybrid pathotypes were detected in 44.2% of the isolates, showcasing the co-existence of multiple pathotypes within a single E. coli strain. The antibiotic resistance testing of E. coli isolates from kitchen cloths and toilets showed high resistance to ampicillin (100%) and amoxicillin (100%). Only E. coli isolates with hybrid pathotypes were found to be resistant to more than three antibiotics. This study emphasizes the significance of fomites as potential sources of bacterial contamination in rural settings. The results highlight the importance of implementing proactive measures to improve hygiene practices and antibiotic stewardship in these communities. These measures are essential for reducing the impact of DEC infections and antibiotic resistance, ultimately safeguarding public health.

Evaluation of a biosecurity survey approach for contamination by Chlamydia pecorum in koala rehabilitation, field capture, and captive settings.

Transmission of Chlamydia pecorum between koalas is a potential risk in field capture or rehabilitation settings, where koalas are held in proximity to each other, or equipment is shared between animals. Given the impact of C. pecorum on koala welfare and population viability it is surprising that quarantine and disinfection protocols in a koala rehabilitation facility or capture settings have not previously been evaluated. This study aimed to evaluate an approach, based on the detection of chlamydial DNA and cell viability, to determine the degree of environmental contamination within a koala care facility. Various fomite sites associated with koala care at a koala rehabilitation facility in New South Wales, Australia were identified as potential sources of chlamydial contamination, following exposure to koalas known to be infected with C. pecorum. Fomite sites were swabbed following exposure, and again after decontamination procedures were carried out. Samples were tested for the presence of chlamydial DNA using qPCR and viability using both RT-qPCR and cell culture. From a total of 239 sampling events, 30 tested qPCR positive for chlamydial DNA, with 19 and 11 samples corresponding to pre-decontamination and post-decontamination events respectively. Detection of chlamydial DNA appeared to be most common in the examination room, especially on fomite sites in direct contact with koalas. Physical removal of chlamydial DNA, or its degradation by the elements, appeared to be more common on outdoor enclosures, clothing, and hands. Based on the cell culture assay, of the pre-decontamination samples with chlamydial DNA, eight had viable chlamydial cells, two of these at low levels. Of the post-decontamination samples with chlamydial DNA, one had a moderate number, and one had a very low number of viable chlamydial cells. RT-qPCR was unsuccessful in determining cell viability due to low yields of RNA and high levels of contaminants from the environmental samples. The outcomes of this study provide a knowledge base for the design of future biosecurity evaluation guidelines in captive and koala rehabilitation facilities. The higher incidence of chlamydial DNA detection by qPCR than viable organism highlights the need to use viability assays in similar studies. However, further investment is still needed to optimise these methods and improve sensitivity for complex environmental samples.

Activity coefficients, phase diagram and separation process design for NaNO3 and Pb(NO3)2 of waste liquor in the production of lead–chromium pigments

Lead contamination is one of the common soil heavy metal pollution elements, and the waste solution discharged from chromium–lead pigment plants is one of the potential sources of lead contamination. In order to separate and recover sodium nitrate and lead nitrate from waste liquid of the production of lead–chromium pigments, it is necessary to make systematical studies on thermodynamic properties, and thermodynamic phase diagram of the salt–water system containing NaNO3 and Pb(NO3)2. Accordingly, in this work, the cell potential method were chosen to measure the thermodynamic activity coefficients of mixed solutions NaNO3– Pb(NO3)2–H2O. The thermodynamic properties (mean activity coefficient, osmotic coefficient, water activity, excess Gibbs free energy) of NaNO3–Pb(NO3)2–H2O mixed solutions at 308.15 K were also determined by Pitzer model. Furthermore, the phase equilibria of the NaNO3–Pb(NO3)2–H2O system was investigated by the isothermal dissolution equilibrium method, and its isothermal equilibrium phase diagram was drawn in detail. The solubility data were used to obtain the Pitzer mixing ion parameters, and the solubilities of salts in the ternary system were predicted by Pitzer model. Based on the plotted phase diagrams, as a result, the process to separate NaNO3 and enrich the recycling of Pb(NO3)2 was designed based on the calculated phase diagram. Among them, the recovery of NaNO3 reached 70.82% and the enrichment of Pb(NO3)2 reached about 15 times. The designed separation process in this work has the advantages of green, low energy consumption and sustainability, which is of positive practical significance for the full utilization of resources and the prevention of environmental pollution.

Assessment of the prevalence, serotype, and antibiotic resistance pattern of Salmonella enterica in integrated farming systems in the Maryland-DC area.

Implementation of organic/pasture farming practices has been increasing in the USA regardless of official certification. These practices have created an increasingly growing demand for marketing safe products which are produced through these systems. Products from these farming systems have been reported to be at greater risk of transmitting foodborne pathogens because of current trends in their practices. Salmonella enterica (SE) is a ubiquitous foodborne pathogen that remains a public health issue given its prevalence in various food products, but also in the environment and as part of the microbial flora of many domestic animals. Monitoring antibiotic resistance and identifying potential sources contamination are increasingly important given the growing trend of organic/pasture markets. This study aimed to quantify prevalence of SE at the pre- and post-harvest levels of various integrated farms and sites in Maryland-Washington D.C. area, as well as identify the most prevalent serovars and antibiotic resistance patterns. Samples from various elements within the farm environment were collected and screened for SE through culture and molecular techniques, which served to identify and serotype SE, using species and serovar-specific primers, while antibiotic resistance was evaluated using an antibiogram assay. Results showed a prevalence of 7.80% of SE pre-harvest and 1.91% post-harvest. These results also showed the main sources of contamination to be soil (2.17%), grass (1.28%), feces (1.42%) and unprocessed produce (1.48%). The most commonly identified serovar was Typhimurium (11.32%) at the pre-harvest level, while the only identified serovar from post-harvest samples was Montevideo (4.35%). With respect to antibiotic resistance, out of the 13 clinically relevant antibiotics tested, gentamycin and kanamycin were the most effective, demonstrating 78.93 and 76.40% of isolates, respectively, to be susceptible. However, ampicillin, amoxicillin and cephradine had the lowest number of susceptible isolates with them being 10.95, 12.36, and 9.83%, respectively. These results help inform farms striving to implement organic practices on how to produce safer products by recognizing areas that pose greater risks as potential sources of contamination, in addition to identifying serotypes of interest, while also showcasing the current state of antibiotic efficacy and how this can influence antibiotic resistance trends in the future.

Microbiota Profiling on Veterinary Faculty Restroom Surfaces and Source Tracking.

In this study, we aimed to develop a comprehensive microbial source amplicon database tailored for source tracking in veterinary settings. We rigorously tested our locally curated source tracking database by selecting a frequently accessed environment by veterinary students and veterinarians. By exploring the composition of resident microbiota and identifying potential sources of contamination, including animals, the environment, and human beings, we aimed to provide valuable insights into the dynamics of microbial transmission within veterinary facilities. The 16S rDNA amplicon sequencing was used to determine the bacterial taxonomic profiles of restroom surfaces. Bacterial sources were identified by linking our metadata-enriched local database to the microbiota profiling analysis using high-quality sequences. Microbiota profiling shows the dominance of four phyla: Actinobacteria, Bacteroidetes, Proteobacteria, and Firmicutes. If the restroom cleaning process did not appear to impact microbiota composition, significant differences regarding bacterial distribution were observed between male and female users in different sampling campaigns. Combining 16S rDNA profiling to our specific sources labeling pipeline, we found aquatic and human sources were the primary environment keywords in our campaigns. The probable presence of known animal sources (bovids, insects, equids, suids…) associated with bacterial genera such as Chryseobacterium, Bergeyella, Fibrobacter, and Syntrophococcus was also involved in restroom surfaces, emphasizing the proximity between these restrooms and the exchange of bacteria between people involved in animals handling. To summarize, we have demonstrated that DNA sequence-based source tracking may be integrated with high-throughput bacterial community analysis to enrich microbial investigation of potential bacterial contamination sources, especially for little known or poorly identified taxa. However, more research is needed to determine the tool's utility in other applications.

Salmonella spp., Escherichia coli and Enterobacteriaceae Control at a Pig Abattoir: Are We Missing Lairage Time Effect, Pig Skin, and Internal Carcass Surface Contamination?

To provide meat safety and consumer protection, appropriate hygiene control measures at an abattoir are required. This study aimed to evaluate the influence of visual fecal contamination level (VFCL) and lairage time (LT) on pig skin (PS) and external (ECS) and internal (ICS) carcass surfaces. The presence of Enterobacteriaceae, Escherichia coli (E. coli) and Salmonella in PS, ECS, and ICS were evaluated. A total of 300 paired samples were collected from 100 pigs. Results underlined the importance of the skin (Enterobacteriaceae: 3.27 ± 0.68 log CFU/cm2; E. coli: 3.15 ± 0.63 log CFU/cm2; Salmonella: 21% of samples) as a direct or indirect source of carcass contamination. Although VFCL revealed no significant effect (p > 0.05), the increase of LT had a significant impact (p < 0.001) on Enterobacteriaceae and E. coli levels across all analysed surfaces, and Salmonella presence on ICS (p < 0.01), demanding attention to LT. Also, the ICS showed a higher level of these bacteria compared to ECS. These results highlight the need of food business operators to consider ICS as an alternative area to sample for Salmonella, as a criterion for process hygiene based on EC Regulation No. 2073/2005, and as a potential contamination source to be integrated in the hazard analysis critical control point (HACCP) plans.

Iodine enrichment in the groundwater in South China and its hydrogeochemical control

In North China, iodine-rich groundwater has been extensively studied, but few in South China. This study aimed to investigate the characteristics of iodine-rich groundwater in South China and identify potential contamination sources. The results revealed that the average concentration of iodine in groundwater was 890 µg/L, with a maximum concentration of 6350 µg/L, exceeding the permitted levels recommended by the World Health Organization (5–300 µg/L). Notably, the enrichment of iodide occurred in acidic conditions (pH = 6.6) and a relatively low Eh environment (Eh = 198.4 mV). Pearson correlation and cluster analyses suggested that the enrichment of iodide could be attributed to the intensified redox process involving Mn(II), iodine (I2), or iodate (IO3−) in the soil. The strong affinity between Mn(II) and I2/IO3− facilitated their interaction, resulting in the formation and mobilization of I− from the soil to the groundwater. Leaching experiments further confirmed that reducing substances (such as sodium sulfides, ascorbic acids, and fulvic acids) in the soil with low dissolved oxygen (DO) levels (< 1.0 mg/L) enhanced the dissolution of iodine species. Conversely, higher DO content (> 3.8 mg/L) promoted the oxidation of I− into I2 or IO3−, leading to its stabilization. This research provides new insights into the characteristics and mechanisms of I− enrichment in groundwater in South China, and emphasizes the significance of the redox reactions involving Mn(II) and I2/IO3−, as well as the influence of soil properties in regulating the occurrence and transportation of iodine species within groundwater systems.

An integrated overview of metals contamination, source-specific risks investigation in coal mining vicinity soils.

Heavy metals in soil are harmful to natural biodiversity and human health, and it is difficult to estimate the effects accurately. To reduce pollution and manage risk in coal-mining regions, it is essential to evaluate risks for heavy metals in soil. The present study reviews the levels of 21 metals (Nb, Zr, Ag, Ni, Na, K, Mg, Rb, Zn, Ca, Sr, As, Cr, Fe, Pb, Cd, Co, Hg, Cu, Mn and Ti) in soils around Barapukuria coal-mining vicinity, Bangladesh which were reported in literature. An integrated approach for risk assessments with the positive matrix factorization (PMF) model, source-oriented ecological and health hazards were applied for the study. The contents of Rb, Ca, Zn, Pb, As, Ti, Mn, Co, Ag, Zr, and Nb were 1.63, 1.10, 1.97, 14.12, 1.20, 3.13, 1.22, 3.05, 3.85, 5.48, and 7.21 times greater than shale value. About 37%, 67%, 12%, and 85% of sampling sites posed higher risks according to the modified contamination factor, Nemerow pollution index, Nemerow integrated risk index, and mean effect range median quotient, respectively. Five probable metal sources were computed, including industrial activities to coal mining (17%), agricultural activities (33%), atmospheric deposition (19%), traffic emission (16%), and natural sources (15%). Modified Nemerow integrated risk index reported that agricultural activities, industrial coal mining activities, and atmospheric deposition showed moderate risk. Health hazards revealed that cancer risk values computed by the PMF-HHR model with identified sources were higher than the standard value (1.0E-04) for children, adult male, and female. Agricultural activities showed higher cancer risks to adult male (39%) and children (32%) whereas traffic emission contributed to female (25%). These findings highlight the ecological and health issues connected to potential sources of metal contamination and provide useful information to policymakers on how to reduce such risks.

Removal of silicon-containing contaminants from TEM specimens

Contaminant-free specimens are an essential prerequisite for high-quality electron microscopy. Silicon is the second most abundant element in the earth's crust with similar chemical properties to that of carbon. However, as a potential source of contamination, silicon has been occasionally reported but not specifically addressed in the electron microscopy community to date. This work highlights the widespread presence of silicon-containing contaminants on TEM specimens, and proposes a general solution for this type of contaminants by using SF6 as a silicon remover. After the treatment, both hydrocarbons and silicon-containing contaminants were removed and no further electron beam showering was needed for most of the specimens to achieve time-invariant imaging. It is expected that this method could be beneficial not only for electron microscopes but also for other surface-sensitive analytical instruments.

Identifying and sharing per-and polyfluoroalkyl substances hot-spot areas and exposures in drinking water

Exposure to per- and polyfluoroalkyl substances (PFAS) in drinking water is widely recognized as a public health concern. Decision-makers who are responsible for managing PFAS drinking water risks lack the tools to acquire the information they need. In response to this need, we provide a detailed description of a Kentucky dataset that allows decision-makers to visualize potential hot-spot areas and evaluate drinking water systems that may be susceptible to PFAS contamination. The dataset includes information extracted from publicly available sources to create five different maps in ArcGIS Online and highlights potential sources of PFAS contamination in the environment in relation to drinking water systems. As datasets of PFAS drinking water sampling continue to grow as part of evolving regulatory requirements, we used this Kentucky dataset as an example to promote the reuse of this dataset and others like it. We incorporated the FAIR (Findable, Accessible, Interoperable, and Reusable) principles by creating a Figshare item that includes all data and associated metadata with these five ArcGIS maps.

Parasitological assessment of some fruits and vegetables commonly sold in retail outlets in the Mfoundi Division of Cameroon

BackgroundFruits and vegetables are very important for human diet as they provide all the nutrients needed to be healthy with just a daily-recommended intake of 400 to 600 mg. However, they constitute one of the major sources of human infectious agents. Thus monitoring of the microbial contaminants of the fruits and vegetables is very crucial for human safety. MethodA cross sectional study was conducted on fruits and vegetables in four markets (Mfoundi, Mokolo, Huitième and Acacia) of the Yaoundé city from October 2020 to March 2021. In all, 528 samples were purchased (carrots, cucumbers, cabbages, lettuces, leeks, green beans, okra, celeries, pepper, green peppers and tomatoes) and processed for infective agents using the centrifugation methods (Formalin, distilled and saline water). Seventy-four (74) soil/water samples collected from the sale environment were analysed using the same technics. ResultsOverall, 149/528 (28.21%) were contaminated by at least one infective agent: 130 (24.62%) and 19 (3.6%) having one and two pathogen species respectively. Vegetables had high contamination rate (22.34%) than fruits (5.87%). Lettuce (52.08%), carrot (41.66%) and cabbage (35.41%), were the most contaminated while okra was the least (6.25%). Candida spp. (14.01%) and larva of Strongyloides stercoralis (7.76%) were more observed while Hookworms (1.13%) was the least. Frequency of Strongyloides stercoralis (p = 0.001) and Candida spp. (p = 0.01) were statistically high than other pathogens. Contamination rates were similar for washed (27.65%) and unwashed (28.78%) samples before sale. Candida spp. (p = 0.001), Strongyloides stercoralis (p = 0.01) and Entamoeba histolytica/dispar (p = 0.017) showed significant contamination rates by month. Contamination trends were high in the rainy season (42.6%) than the dry season (15.1%). Correlation between environment and products sold revealed same pathogens in both cases. ConclusionThe study highlights that the sale environment and products constitute potential source of microbial contamination. These data raised the concern of stakeholders about health risk related to vegetables and fruits sold in some local markets in Cameroon. Thus the necessity for them to development more appropriate policies on the surveillance of sale environment and on the management of these products during the different process phases by the population.

Potential sources of microplastic contamination in laboratory analysis and a protocol for minimising contamination.

Measurements of microplastics in environmental and biological samples can be overestimated because of contaminants introduced during the analytical process. Knowledge of the potential sources and frequency of contamination during analysis is required to develop a protocol to prevent analytical errors. In this study, potential sources of contamination in the laboratory analysis of biological samples were evaluated, and reliable, inexpensive measures to prevent contamination were tested. Glass fibre filters, water samples, air samples, and chemicals [Fenton's reagent (H2O2 and FeSO4), and ZnCl2] were tested for the presence of contaminants. Particulate contamination, including microplastics, was found in all samples when tested before application of any preventative measures. The following measures were evaluated for preventing contamination: (1) filtration of the water and chemical solutions using a glass fibre filter, (2) pre-combustion of the glass fibre filters, and (3) use of a clean booth for experimental work. The preventative measures reduced the levels of microplastics in all samples by 70-100%. The dominant polymers identified by Fourier transform infrared spectroscopy were polyethylene terephthalate, cellulose fibre (rayon), polystyrene, polyacrylonitrile, and polyethylene. With the preventative measures, the number of microplastics in the laboratory blanks was low enough to set the limit of detection to < 1. This limit of detection would be suitable for examination of microplastics contamination at the individual organism level, even at trace levels. Preventative countermeasures are essential to reduce overestimation of microplastics in biological samples and can be implemented at low cost.

The Crucial Role of Microbiological Testing in Ensuring Safety and Efficacy of Medical Devices: An Overview

Microbiological testing is a critical aspect of the development and evaluation of medical devices, as it plays a vital role in ensuring their safety and efficacy. This article highlights the importance of microbiological testing in medical device development and the various types of tests that are commonly performed. Microbiological testing is essential for assessing the potential risks associated with medical devices, such as bacterial contamination or infections. Testing can also help to identify potential sources of contamination during the manufacturing process and to monitor the efficacy of sterilization methods. In addition, microbiological testing is crucial in determining the appropriate usage and maintenance procedures for medical devices. By providing accurate and reliable data, microbiological testing can aid in the development of safe and effective medical devices, while also ensuring compliance with regulatory standards. Overall, this article emphasizes the critical role of microbiological testing in the development and evaluation of medical devices, and highlights its significance in maintaining patient safety and improving health care outcomes.

Metal and semimetal loadings in sediments and water from mangrove ecosystems: A preliminary assessment of anthropogenic enrichment in São Tomé island (central Africa)

Mangroves act as buffer areas for marine systems, providing a barrier to contamination from continental sources by retaining metal pollutants. This study evaluates metal and semimetal contamination in the water column and sediments of four mangroves located on the volcanic island of São Tomé. Several metals had a widespread distribution, with occasional high concentrations, linked to potential sources of contamination. However, the two smaller mangroves, located in the northern part of the island, tended to have high metal concentrations. Arsenic and chromium concentrations were notably concerning, particularly if we consider this is an isolated and non-industrialized island. This work highlights the need for further assessments and a better understanding of processes and implications of metal contamination in mangroves. This assumes a particular relevance in areas that have specific geochemical compositions (i.e., volcanic origin) and in developing countries, where people often rely directly and heavily on resources obtained from these ecosystems.