Potential Sources Of Contamination Research Articles

Effects of Desiccation and Freezing on Microbial Ionizing Radiation Survivability: Considerations for Mars Sample Return.

Increasingly, national space agencies are expanding their goals to include Mars exploration with sample return. To better protect Earth and its biosphere from potential extraterrestrial sources of contamination, as set forth in the Outer Space Treaty of 1967, international efforts to develop planetary protection measures strive to understand the danger of cross-contamination processes in Mars sample return missions. We aim to better understand the impact of the martian surface on microbial dormancy and survivability. Radiation resistance of microbes is a key parameter in considering survivability of microbes over geologic times on the frigid, arid surface of Mars that is bombarded by solar and galactic cosmic radiation. We tested the influence of desiccation and freezing on the ionizing radiation survival of six model microorganisms: vegetative cells of two bacteria (Deinococcus radiodurans, Escherichia coli) and a strain of budding yeast (Saccharomyces cerevisiae); and vegetative cells and endospores of three Bacillus bacteria (B. subtilis, B. megaterium, B. thuringiensis). Desiccation and freezing greatly increased radiation survival of vegetative polyploid microorganisms when applied separately, and when combined, desiccation and freezing increased radiation survival even more so. Thus, the radiation survival threshold of polyploid D. radiodurans cells can be extended from the already high value of 25 kGy in liquid culture to an astonishing 140 kGy when the cells are both desiccated and frozen. However, such synergistic radioprotective effects of desiccation and freezing were not observed in monogenomic or digenomic Bacillus cells and endospores, which are generally sterilized by 12 kGy. This difference is associated with a critical requirement for survivability under radiation, that is, repair of genome damage caused by radiation. Deinococcus radiodurans and S. cerevisiae accumulate similarly high levels of the Mn antioxidants that are required for extreme radiation resistance, as do endospores, though they greatly exceed spores in radioresistance because they contain multiple identical genome copies, which in D. radiodurans are joined by persistent Holliday junctions. We estimate ionizing radiation survival limits of polyploid DNA-based life-forms to be hundreds of millions of years of background radiation while buried in the martian subsurface. Our findings imply that forward contamination of Mars will essentially be permanent, and backward contamination is a possibility if life ever existed on Mars.

Appraisal Of Knowledge And Practice Of Food Hygiene Among Food Vendors In University Of Calabar, Calabar, Nigeria

Food vendors with poor knowledge and practice of food hygiene are potential source of food contamination and food borne diseases in institutions of learning in developing countries. The study was conducted to appraise the knowledge and practice of food hygiene among food vendors in the University of Calabar, Calabar, Nigeria using a cross - sectional descriptive survey as the research design. A total of sixty – seven food vendors were purposely recruited for the study. Researcher’s developed and validated questionnaire was used for data collection. Collated data were sorted, coded, and analysed with SPSS software. The results were described using frequency counts and percentages. Findings from the study indicated that majority of the respondents 57 (85.1%) had adequate knowledge of food hygiene and the same percentage also engaged in good food hygienic practices. The result also revealed that, there was a statistically significant relationship between knowledge and practice of food hygiene (=28.134; p<0.05). Thus, the researchers suggested continuous education of food vendors on the need to maintain hygiene practices during preparation and handling of food to safeguard the health of the students.

A Gap-Filling Tool: Predicting Daily Sediment Loads Based on Sparse Measurements

Sediment load in streams is known as both a carrier and a potential source of contaminants, while sediment deposition can alter stream flow, stage and morphology, and thereby has broad impacts on stream hydrology, aquatic life, and recreation activity. For vast amounts of watersheds around the world, sparse daily measured sediment data may exist, but continuous and multi-year daily measured sediment data are largely unavailable because of time-consuming and budget constraint for measurements. However, when developing total maximum daily load (TMDL) and calibrating/validating watershed models for sediments, such continuous and multi-year datasets are inevitably required. This study extended the flow-weighted method, developed by Ouyang (Ouyang, Y. Environ. Monit. Assess. 193, 422 (2021)) to predict the continuous and multi-year daily sediment loads based on sparse, limited, and discontinuous measured data. This daily sediment load gap-filling tool was validated using measured data from six different US Geological Survey (USGS) gage stations across US. Results showed that the flow-weighted method well predicted daily sediment loads when a good linear correlation existed between measured seasonal sediment loads and measured seasonal stream discharges, which is a prerequisite to apply the flow-weighted method. Five out of six selected USGS gage stations used in this study met this prerequisite. The flow-weighted method (along with an example R script for implementing the method) is a useful tool for filling the daily sediment load gaps.

Integrating the theory of sampling into a nuclear forensic investigation

We present a study case where the theory of sampling (TOS) is used to make defensible inferences in a nuclear forensic investigation. The forensic investigations focused on five suspicious radioactive materials seized in 2019. All errors introduced by sampling and sub-sampling the radioactive materials are evaluated according to TOS. A maximum sampling error of 35% was tolerated. The uses of TOS enabled the forensic team to make inferences about the seized materials and therefore make confidence-based statements about the exceeding of limits established in the Swiss Radiological Protection Ordinance for radioactive substances. The analysis of the isotope and activity ratios allowed the team to exclude some potential sources of the radioactive contamination; however, it was not possible to determine its origin precisely.

Genomic Surveillance of Listeria monocytogenes in Taiwan, 2014 to 2019.

Listeria monocytogenes is a life-threatening foodborne pathogen. Here, we report the genomic characterization of a nationwide dataset of 411 clinical and 82 food isolates collected in Taiwan between 2014 and 2019. The observed incidence of listeriosis increased from 0.83 to 7 cases per million population upon implementation of mandatory notification in 2018. Pregnancy-associated cases accounted for 2.8% of human listeriosis and all-cause 7-day mortality was of 11.9% in nonmaternal-neonatal listeriosis. L. monocytogenes was isolated from 90% of raw pork and 34% of chicken products collected in supermarkets. Sublineages SL87, SL5, and SL378 accounted for the majority (65%) of clinical cases. SL87 and SL378 were also predominant (57%) in food products. Five cgMLST clusters accounted for 57% clinical cases, suggesting unnoticed outbreaks spanning up to 6 years. Mandatory notification allowed identifying the magnitude of listeriosis in Taiwan. Continuous real-time genomic surveillance will allow reducing contaminating sources and disease burden. IMPORTANCE Understanding the phylogenetic relationship between clinical and food isolates is important to identify the transmission routes of foodborne diseases. Here, we performed a nationwide study between 2014 and 2019 of both clinical and food Listeria monocytogenes isolates and sequenced their genomes. We show a 9-fold increase in listeriosis reporting upon implementation of mandatory notification. We found that sublineages SL87 and SL378 predominated among both clinical (50%) and food (57%) isolates, and identified five cgMLST clusters accounting for 57% of clinical cases, suggestive of potential protracted sources of contamination over up to 6 years in Taiwan. These findings highlight that mandatory declaration is critical in identifying the burden of listeriosis, and the importance of genome sequencing for a detailed characterization of the pathogenic L. monocytogenes genotypes circulating in Asia.

Microbial Contamination of Groundwater Self‐Supply in Urban Indonesia: Assessment of Sanitary and Socio‐Economic Risk Factors

AbstractIn urban Indonesia, more than 40 million people rely on groundwater self‐supply, but the extent to which self‐supply delivers safe water and the associated risk factors for fecal contamination remain unclear. This study quantifiedEscherichia coli(E.coli) for 511 self‐supply sources and at point‐of‐use for 173 households in the Indonesian cities of Bekasi and Metro. A structured questionnaire collected information about the household, water sources, and potential contamination sources. Univariate and multivariate logistic regression analysis examined risk factors for fecal contamination.E.coliwas detected in 66% of sources, including 55% of boreholes, 64% of protected dug wells, and 82% of unprotected dug wells. Widespread boiling of water meant microbial quality improved significantly between source and point‐of‐use, withE.colidetected in 30% of self‐supply samples at point‐of‐use. Unprotected dug wells were significantly more likely to be contaminated than boreholes. In Bekasi, the analysis found a significant association between presence ofE.coliand sanitation systems located within 10 m of the groundwater source. In Metro, poorer households had significantly higher odds of contamination than wealthier households. Other significant factors included shallower borehole depths in Bekasi, use of a rope and bucket, and absence of a concrete platform in Metro. In Bekasi,E.coliconcentration at source was significantly associated with water quality at point‐of‐use. Risk of fecal contamination could be reduced by supporting households to invest in improved protection, and by facilitating promotion for safe household water treatment. Support for self‐supply improvements should be weighed against the expansion and improvement of piped water services.

Epidemiological investigation of Pseudomonas aeruginosa isolates including multidrug-resistant serogroup O12 isolates, by use of a rapid and simplified multiple-locus variable-number of tandem repeats analysis and whole genome sequencing

Clustered cases of Pseudomonas aeruginosa infection in immunocompromised patients' wards require rapid characterization of a potential epidemic to guide investigations and identify the potential source of contamination. To design and evaluate a rapid and simple typing method for P.aeruginosa in comparison to whole genome sequencing (WGS). A simplified polymerase chain reaction based on multiple-locus variable-number of tandem repeats analysis (MLVA) was designed and used to investigate cases of P.aeruginosa infection and colonization in a paediatric haematology department. The method was compared to WGS by using the Illumina method. On the 17 isolates recovered from 15 children (eight from blood cultures, three from urinary tract infections, one from sputum and five stool isolates), MLVA distinguished 10 different profiles, and seven isolates from six children shared the same profile. Analysis by WGS revealed that these seven isolates belonged to sequence type ST111 and serotype O12, allowing at least three different genotypes to be distinguished among them. Five environmental strains had three MLVA profiles; one was shared with a clinical isolate but WGS excluded any relationship. The simplified and inexpensive MLVA method enabled the exclusion, in less than 5h, of most of the unrelated isolates and thus to focus investigations on a small number of cases, whereas WGS, taking several days of work, drew definitive conclusions concerning the outbreak and the genetic relationships of the ST111 isolates circulating in the department. We conclude that sequential use of both methods is the optimal strategy to investigate clustered cases of P.aeruginosa infections.

High-Throughput 16 S rRNA Gene Sequencing Reveals Bacterial Diversity of Infant Formula Production Line Samples in Spring and Summer

The trend of low breastfeeding rates increases the demand for infant milk formula (IMF) worldwide, but the use of IMF may be one of the causes of bacterial infections in infants. Complete sterility in the whole production line of IMF cannot be guaranteed; therefore, it is necessary to closely monitor the microbial content in the process. In the present study, an IMF powder production line based on the wet mixing process was sampled at 27 suspicious points in spring and summer to analyze the bacterial diversity by high-throughput sequencing. We found that 70 and 69 different bacterial phyla were present in spring and summer samples, respectively, with Proteobacteria and Firmicutes being the dominant phyla (>80% relative abundance). Moreover, 13 dominant genera each were present in spring (e. g., Pseudomonas and Lactococcus) and summer (e. g., Pseudomonas, Bacillus, and Streptococcus). Samples associated with workers showed higher bacterial species diversity (Shannon index) and richness (Chao1 index) in summer than in spring. The bacterial community composition showed high similarity between liquid milk after pasteurization and concentrated milk after evaporation. The potential bacterial pathogens were identified as Pseudomonas aeruginosa in spring and Acinetobacter baumannii in summer. Through retrospective analysis of the two opportunistic pathogens identified, it was found that the workshop environment was the potential contamination point in spring, whereas the auxiliary ingredients were the potential source of contamination in summer. The results highlight the effect of season on bacterial diversity associated with the production process of IMF and are useful in controlling the microbial quality and safety of infant dairy products.

Transport and removal of spores of Bacillus subtilis in an alluvial gravel aquifer at varying flow rates and implications for setback distances

To guarantee proper protection from fecally transmitted pathogen infections, drinking water wells should have a sufficiently large setback distance from potential sources of contamination, e.g. a nearby river. The aim of this study was to provide insight in regards to microbial contamination of groundwater under different flow velocities, which can vary over time due to changes in river stage, season or pumping rate. The effects of these changes, and how they affect removal parameters, are not completely understood. In this study, field tracer tests were carried out in a sandy gravel aquifer near Vienna, Austria to evaluate the ability of subsurface media to attenuate Bacillus subtilis spores, used as a surrogate for Cryptosporidium and Campylobacter. The hydraulic gradient between injection and extraction was controlled by changing the pumping rate (1, 10 l/s) of a pumping well at the test site, building upon previously published work in which tracer tests with a 5 l/s pumping rate were carried out. Attachment and detachment rate coefficients were determined using a HYDRUS-3D model and ranged from 0.12 to 0.76 and 0–0.0013 h−1, respectively. Setback distances were calculated based on the 60-day travel time, as well as a quantitative microbial risk assessment (QMRA) approach, which showed similar results at this site; around 700 m at the highest pumping rate. Removal rates (λ) in the field tests ranged from 0.2 to 0.3 log/m, with lower pumping rates leading to higher removal. It was shown that scale must be taken into consideration when determining λ for the calculation of safe setback distances.

Targeted analysis and Total Oxidizable Precursor assay of several insecticides for PFAS

Targeted analysis for 24 Per- and Polyfluoroalkyl Substances (PFAS) was conducted on 10 insecticide formulations used on a United States Department of Agriculture crop research field. Perfluorooctane sulfonic acid (PFOS) was found in 6 of the 10 formulations with concentrations ranging from 3.92 to 19.2 mg/kg. Further analysis of soil and plant samples collected at the site found several additional PFAS, with PFOS being the most prominent. Suspect screening was then conducted on the formulations and provided several suspected PFAS in addition to the 24 targeted analyzed PFAS in 7 of the 10 samples, one of which showed no PFAS during targeted analysis. PFAS-precursor oxidation was then conducted on the two insecticide formulations with the greatest lists of suspected PFAS as validation of potential unknown PFAS in the formulations. This study revealed a previously unknown potential PFAS contamination source for rural and agricultural environments.

Identifying contamination of heavy metals in soils of Peruvian Amazon plain: use of multivariate statistical techniques.

The Peruvian Amazon plain has abundant natural resources and is home to great biodiversity, which makes it an area with high economic potential. However, the use of its resources through various activities has contributed to the release of heavy metals (HMs) into its soils, generating severe pollution problems which have mainly affected the health of local populations and their ecosystems. Currently, there are no comprehensive studies that have identified the specific sources of contamination by HMs in the soils of this part of the Peruvian territory. In this sense, this research aims to identify the possible sources of contamination by HMs in the soils of the Peruvian Amazon plain to focus efforts on the establishment of adequate measures for the protection of the health of people and the ecosystem. In the present study, samples of topsoils (0-20cm depth) and subsoils (100-150cm depth) were collected for the analysis of 11 HMs (Co, Cr, Cu, Fe, Mn, Ni, Pb, V, Zn, Be, and Hg) in 48 sites located in four regions of the Peruvian Amazon plain (Loreto, Amazonas, San Martín, and Ucayali), over the year 2019. The enrichment factor and geoaccumulation index were applied to assess contamination levels of HMs. The results indicated that topsoils and subsoils presented a greater enrichment by the elements Be and Pb, and were classified as moderately contaminated. Likewise, the integral analysis of these indexes together with principal component analysis, hierarchical cluster analysis, correlation analysis, and coefficient of variation allowed the identification of potential sources of contamination by HMs. As a result, Fe, Co, Zn, Ni, V, and Cr were associated with natural or lithogenic sources (parent material, crude oil deposits, and organic matter decomposition). Hg was attributed to anthropogenic sources (illegal gold mining, atmospheric deposition, and vehicle emissions). Be, Pb, Cu, and Mn originated from natural sources (parent material, crude oil deposits, decomposition of organic matter, and forest fires) and anthropogenic (areas degraded by solid waste, illegal gold mining, agriculture, and hydrocarbons). These findings provide essential information to establish regulations and prevent and control HM contamination in soils of the Peruvian Amazon plain.

Pyrethroid insecticides in urban catch basins: A potential secondary contamination source for urban aquatic systems

Pesticide contamination is a threat to many aquatic habitats, and runoff from residential homes is a major contributor of these chemicals in urban surface streams and estuaries. Improved understanding of their fate and transport can help identify areas of concern for monitoring and management. In many urban areas, runoff water congregates in numerous underground catch basins before draining into the open environment; however, at present essentially no information is available on pesticide presence in these systems. In this study, we collected water samples from a large number of underground urban catch basins in different regions of California during the active pest management season to determine the occurrence and profile of the widely used pyrethroid insecticides. Detectable levels of pyrethroids were found in 98% of the samples, and the detection frequency of individual pyrethroids ranged from no detection for fenpropathrin to 97% for bifenthrin. In the aqueous phase, total pyrethroid concentrations ranged from 3 to 726 ng/L, with a median value of 32 ng/L. Pyrethroids were found to be enriched on suspended solids, with total concentrations ranging from 42 to 93,600 ng/g and a median value of 2,350 ng/g. In approximately 89% of the samples, whole water concentrations of bifenthrin were predicted to have toxic units >1 for sensitive aquatic invertebrates. The high detection frequency of bifenthrin and overall pyrethroid concentrations, especially for particle-bound residues, suggest that underground urban catch basins constitute an important secondary source for extended and widespread contamination of downstream surface waters by pesticides such as pyrethroids in urban regions.

Mycotoxins Contamination in Rice: Analytical Methods, Occurrence and Detoxification Strategies.

The prevalence of mycotoxins in the environment is associated with potential crop contamination, which results in an unavoidable increase in human exposure. Rice, being the second most consumed cereal worldwide, constitutes an important source of potential contamination by mycotoxins. Due to the increasing number of notifications reported, and the occurrence of mycotoxins at levels above the legislated limits, this work intends to compile the most relevant studies and review the main methods used in the detection and quantification of these compounds in rice. The aflatoxins and ochratoxin A are the predominant mycotoxins detected in rice grain and these data reveal the importance of adopting safety storage practices that prevent the growth of producing fungi from the Aspergillus genus along all the rice chain. Immunoaffinity columns (IAC) and QuECHERS are the preferred methods for extraction and purification and HPLC-MS/MS is preferred for quantification purposes. Further investigation is still required to establish the real exposition of these contaminants, as well as the consequences and possible synergistic effects due to the co-occurrence of mycotoxins and also for emergent and masked mycotoxins.

Antimicrobial resistance profile of Staphylococcus spp. and Listeria spp. isolated from refrigerators of retailers and schools in the Tolon District, Ghana

Refrigeration is one of the common and safest food methods aided by the refrigerator which works by distorting the activities/growth of microorganisms. Nevertheless, the refrigerator could be a transmission source of non-pathogenic and pathogenic bacterial strains involved in food spoilage and foodborne infections. The study seeks to assess the knowledge of students and retailers on microbial contamination of refrigerators. Also, the study would determine the occurrence and antimicrobial resistance profile of Staphylococcus spp. and Listeria spp. isolates. The swab-rinse method was employed for sampling refrigerators used by students (n=86) and retailers (n=38) with a total of 248 samples (Interior surfaces n=124, Exterior surfaces n=124). The swab samples were directly streaked on Mannitol Salt Agar and Oxford Listeria Agar Base for the isolation of Staphylococcus spp. and Listeria spp., respectively. Antimicrobial-resistant profile was determined using the Kirby-Bauer disc diffusion method against vancomycin (30 µg), ampicillin (10 µg), and penicillin-G (10 µg). Of the 110 isolates identified, Staphylococcus spp. were (95) with a prevalence of (86.36%) and Listeria spp. were (15) with a prevalence of (13.64%). Antibiotic resistance was most common to penicillin-G (67.27%) followed by ampicillin (60%), and vancomycin (22.73%). This study confirms the presence of cold-tolerant bacteria in refrigerators. Thus, making refrigerators used by students and retailers a potential source of bacterial transmission and/or contamination.

STUDIES ON GAMMA DOSE RATES IN OUTDOOR ENVIRONMENT AND ASSESSMENT OF EXTERNAL EXPOSURE TO PUBLIC IN STEPNOGORSK AREA, NORTHERN KAZAKHSTAN.

The present study is based on a pilot study, which showed that the Stepnogorsk area of Northern Kazakhstan represents sources of potential contamination of the living environment. The aim of the study was measurement of outdoor gamma radiation levels, activity concentration in soil samples and assessment of external exposure to the public. According to our analysis, the highest ${\boldsymbol{H}}^{\ast}$(10) values ∼2870 nGy h-1 were detected in the Aqsu school territory, which were slightly higher than the control readings for this region. The average 226Ra, 232Th and 40K activities were 617.8±3.2Bqkg-1, 188.3±2.9Bqkg-1 and 731.5±6.2Bqkg-1, respectively. The annual effective dose received by the Aqsu population ranged from 0.08 to 3.5mSv y-1, which was found higher by an order of magnitude than the upper annual dose limit. Changes in radiation background are an unfavourable factor for the population and may possibly become potential radiation risks for long-term effects.

First Data on Campylobacter spp. Presence in Shellfish in Croatia.

This study aimed to assess the presence of thermotolerant Campylobacter spp., as one of the most important foodborne zoonotic pathogens, in three shellfish species: mussels (Mytilus galloprovincialis), oysters (Ostrea edulis) and queen scallops (Aequipecten opercularis). The samples were collected from nine locations in the Istrian aquatory, Croatia. Isolation of Campylobacter was done according to standard ISO method, and species were identified using multiplex PCR. Isolates identified as C. jejuni and C. lari were genotyped using multilocus sequence typing (MLST) to determine the potential source of contamination. Among 108 examined samples of bivalve molluscs, mussels dominated and were the only ones found positive for the presence of Campylobacter (25.6%). In total, 19 C. lari and 1 C. jejuni strains were isolated. C. lari isolates found in this study belong to 13 sequence types (STs), and 9 of them are newly described in this paper. Two out of the four previously described C. lari STs that were found in this study were previously found in human stool. The only C. jejuni isolate was found to be sequence type 1268, which belongs to ST-1275 clonal complex that is almost exclusively found in seabirds and can sporadically cause infection in humans. Regarding the obtained results, introducing surveillance of thermotolerant Campylobacter in shellfish in the Republic of Croatia is advised as an improvement for public health safety.

Focus on Bioburden Culture Media and Medical Devices.

Medical devices are a vital part of the global health care system that can have a far-reaching impact on patient treatment. Therefore, they must be sterile to ensure patient safety. The prevalent microorganism's type on a medical device, also known as "bioburden", is a useful indicator of a potential contamination source. Indeed, bioburden is a potential risk to the patient not only because the sterilization process might not be completely effective, but also post-processing because of the possible presence of residual materials. Although bioburden may be confidently killed by destructive sterilization processes, its proliferation before sterilization should be avoided. For the bioburden determination, the culture media and incubation conditions must be carefully selected. The culture medium is of fundamental importance for most microbiological tests: to obtain pure cultures, to grow and count microbial cells, and to cultivate and select microorganisms. A culture medium is essentially composed of basic elements (water, nutrients) to which must be added different growth factors that will be specific to each bacterium and necessary for their growth. Without high-quality media, the possibility of achieving accurate, reproducible, and repeatable microbiological test results is reduced. In ISO 11737-1:2018 "Sterilization of Health Care Products-Microbiological Methods-Part 1: Determination of a Population of Microorganisms on Products", methods for the determination and microbial characterization of bioburden are proposed. However, few guidelines are given as to culture media other than examples and incubation times. Several studies show that other culture media can also be effective, such as Plate Count Agar (PCA). The purpose of this review was to focus on parameters that can have an impact on the bioburden evaluation, specifically the culture medium type for the microorganisms' detection on medical devices. Experimentations conducted in our laboratories showed that PCA appeared to be a medium of primary importance for the detection of bioburden on medical devices; this medium also respects the 3Rs rule.

Postmortem reference concentrations of elements in blood and urine

To establish postmortem reference concentrations of elements. Fatal intoxications, both accidental and intentional, are a global issue. In the western world intoxications with pharmaceuticals dominate, but in other parts of the world other substances are more common. Intoxication with elemental compounds is generally considered to be uncommon. In a forensic setting, elemental intoxications are of great importance when investigating both accidental, suicidal, and homicidal deaths. Arsenic, for example, is a classical poison which also has relevance in the modern era. Unlike for pharmaceuticals, postmortem reference concentrations for elements are scarce. For many elements it is therefore unknown if, and to what extent, they are affected by postmortem redistribution. The current study presents normal postmortem reference concentrations of 68 elements in femoral blood and urine. In addition, possible sources of error such as contamination from collection tubes, preservative potassium fluoride solution and storage time are evaluated. Paired blood and urine samples from 120 cases of death by suicidal hanging in Sweden were collected. 20 cases from each of the six local units of forensic medicine were used to account for possible regional differences. Additionally, the included cases reflected both short and long storage times. To account for possible elemental contamination from collection tubes and the added potassium fluoride solution, multiple batches of tubes and multiple samples of potassium fluoride solution were also analysed. Concentrations of elements were determined by double focusing sector field ICP-MS. Key descriptive statistics for all 68 elements are provided (including mean, median and percentiles) in blood and urine. Forensic highlights include blood concentrations of total arsenic (mean: 4.25 μg/g), thallium (mean: 0.14 μg/g) and antimony (mean: 14.82 μg/g). For several elements in blood and urine ( n = 24 and n = 25, respectively) a majority of elemental concentrations were below the limit of detection. The contribution of contamination from collection tubes were minor compared to the overall mean elemental concentrations in both blood and urine. Though the added solution of potassium fluoride contained a large assortment of elements, given the small amounts of this solution added to samples, the overall contribution is minor for most elements relative to the overall mean. However, there was a significant difference between samples with short and long storage time for 22 elements in blood and 17 elements in urine. These differences reflected both increases and decreases in concentration. Relative to antemortem elemental concentrations the postmortem concentrations show both increases and decreases. Of special note are markedly higher concentrations for several elements in blood (such as cadmium, chromium, manganese and antimony) compared to several antemortem populations. In general, it can be assumed the phenomenon of postmortem redistribution is as large for elements as it is for drugs and other substances. When evaluating individual concentrations, it is important to be aware of potential sources of contamination and the potential influence of storage time. Concentrations indicating overexposure must be evaluated together with autopsy findings and case circumstances to form a holistic view of the case as a whole. The present study provides an important tool when evaluating postmortem elemental concentrations. It fills a needed gap between large antemortem population studies and postmortem case reports or small case series of elemental intoxications. Together with the forensic autopsy and circumstantial information the present references will aid in diagnosing cases of potential elemental overexposure.

The impact of the mountain barrier on the spread of heavy metal pollution on the example of Gorce Mountains, Southern Poland

The main objective of this study was to determine the content, mobility, and the variability of concentration of zinc, lead, and cadmium in soils from the Gorce Mountains (south Poland), located over 100 km south-east from the potential industrial sources of contamination—zinc-lead sulfide ore mine and smelter in Bukowno, as well as hard coal mines of Silesia region and Kraków Nowa-Huta steelwork. The abovementioned problem is crucial in the context of the traditional mountain farming still extant in the region, as well as intensively developing tourism. The geoaccumulation index and potential ecological risk index were adopted to evaluate soil pollution in the study area and the BCR sequential extraction technique to assess mobility of the abovementioned elements. The obtained results clearly show that the pollution from distant industrial sources in the mountains is detectable. Apart from the increased concentrations of the tested metals in the soil (especially available forms), there is also a strong correlation between the concentrations of lead, zinc, and cadmium, which proves their common source of origin. The main evidence is the fact that differences in the concentrations of the tested metals on the windward and leeward sides were statistically significant. This also means that the studied mountain area, despite relatively low altitudes (up to 1310 m above sea level), constitutes a measurable barrier to the spread of atmospheric pollutants.

Detection of Giardia duodenalis and Toxoplasma gondii in soil and water samples in the Quindío River basin, Colombia

Two zoonotic protozoan pathogens, Giardia duodenalis and Toxoplasma gondii, are important causes of waterborne infections in the Quindío region in Colombia. No previous data exist on how contamination occurs at the source for drinking water consumed by the human population in this region. Our aim was to describe the frequency of G. duodenalis and T. gondii DNA in 11 sampling points during a five-month period in water and adjacent soil at the Quindío River basin (Andean region in the central western part of Colombia). The study employed nested PCR for T. gondii, using the B1 gene as the amplification target, and single-round PCR for G. duodenalis assemblage A and assemblage B, amplifying the gdh gene, followed by DNA sequencing. In 50 soil samples, 28% (14/50) were positive for T. gondii. For G. duodenalis, distribution was in equal parts for assemblage A (8%; 4/50) and assemblage B (8%, 4/50). Genotyping of T. gondii sequences showed two soil samples with type I strain, another two samples of soil with type III strain, but most samples were of unidentified strains. In water samples, T. gondii was detected in 9.1% (5/55), G. duodenalis assemblage A in 34.5% (19/55), and G. duodenalis assemblage B in 12.7% (7/55). T. gondii DNA positivity was associated with lower soil temperature (p = 0.0239). Presence of G. duodenalis and T. gondii was evidenced in soil and water samples in the Quindío River basin, indicating soil as the potential source of contamination for the river that it is destined for human consumption. Monitoring these protozoa in drinking water is necessary to prevent public health risks in human populations.