Probable Source Of Contamination Research Articles

Evaluation of Heavy Metal Contamination and Associated Human Health Risk in Soils around a Battery Industrial Zone in Henan Province, Central China

This research investigated the contamination characteristics, sources, and health risks of five metals in soils from two villages named DK and SXC, downstream from a battery industry hub in Xinxiang city, Henan Province, China. The average concentrations of Cd, Pb, Ni, Cu, and Zn in DK were 5.93, 41.31, 71.40, 62.20, and 115.83 mg/kg, respectively, and in SXC were 2.04, 30.41, 41.22, 36.18, and 96.04 mg/kg, respectively. The single factor pollution index (Pi) revealed a consistent descending order of Cd > Cu > Zn > Ni > Pb in DK and SXC. The geo-accumulation index (Igeo) indicated that the Cd pollution in DK was extreme, and in SXC was at a heavy to extreme level. The potential ecological risk index (PERI) indicated that Cd presented a significantly high ecological risk while it was low for other metals. Principal component analysis classified them into the anthropogenic origin of Cd and common mixed origin of others. The elevated levels and pollution load of heavy metals with closer proximity to the battery factory imply that the factory is a probable source of contamination. Overall, the health risks posed by heavy metals were more pronounced for local children compared to adults, with Cd being the primary contributor to both pollution and health risks. This investigation provides a crucial basis for the heavy metal pollution management and related risk prevention in areas affected by electronic waste irrigation.

Evaluation of urban tree barks as bioindicators of environmental pollution using the X-ray fluorescence technique

Some chemical elements released in nature due to anthropogenic actions are harmful to living beings, and finding efficient and low-cost ways to measure their presence is a challenge. The major goal of this work was to use the barks of urban trees as bioindicators of the presence of these elements. For this purpose, tree barks of sixteen individual trees were collected, including Ipê (Bignoniaceae Family); Sibipiruna (Fabaceae Family); Pine (Pinaceae Family), in the city of Sorocaba, SP, Brazil, in three different districts. Two samples, one of Ipê and another of Sibipiruna, collected in the Mata Atlântica forest in Juquitiba, SP, Brazil, were used as control samples. They were also analyzed; six soil samples were collected in the same places as the tree barks in Sorocaba. The samples were analyzed using the Energy Dispersion X-Ray Fluorescence Spectroscopy technique. The elements studied ranged from Al to Bi. The results were submitted to univariate and multivariate statistical analysis showing that Sibipiruna presented a high concentration of the element Ca. At the same time, Ipê and Pine showed high concentrations of K. In the identified elements, the probable sources of contamination were pointed out, such as elements from the dust of braking automobiles (Al, Si, S, Ti, Fe, Cu, and Ba), elements from the paint used to paint the asphalt (Si, Ca, Cr and Pb) and elements from the tire tread wear (Al, S, Ca and Zn). From the analysis of soil samples and trees, it was found that there was high pollution by the element Pb in the specimens collected in front of the old Saturnia battery factory, located in the district of Éden in the city of Sorocaba, SP, Brazil (Coordinates: Lat 23K253141 m E; Long 23K7405583 m S).

Potentially toxic metals in sediments, lake water and groundwater of the Ramsar wetlands Bakhtegan–Tashk, South Iran: Distribution and source assessment

Bakhtegan–TashkLakes (BTL) and Kamjan Marsh, one of the Ramsar sites with an area of 1323 km 2 , have been shrunk due to groundwater overexploitation, construction of two new dams and drought. Evaporation of the BTL water significantly increased potentially toxic metal (PTMs) and average total dissolved solids (TDS) from 45000 to 382000 mg/l. This study focuses on contamination and sources of 16 PTMs. The sampling sites include 24 sediments, 2 surface salts, 17 water samples from Bakhtegan Lake (BL), and two wells. The PTMs were analyzed in Act Lab. The BTL sediments are contaminated by Hg, Ni, Mo and Se based on CF, EF, I geo indices and at ecological risks by Hg, Ni and Cr based on SQGs index and by Hg based on ecological Risk index. Kamjan Marsh and adjacent aquifer were at negligible ecological risk. Most PTMs concentrations in water samples were not measured due to dilution. The BL water and groundwater below the BL bed were contaminated and/or at ecological risk by significantly high values of TDS and measurable PTMs Mo, Pb, V, As, Mn and Sb. The most probable sources of contamination are chromite mines, sewage of petrochemical and industrial complexes, contaminated dust from west of Iran and Iraq, combustion of fossil fuel and fertilizers. The BTL can be restored by a new water resource plan to save water by installing water meters on all exploited wells, modern irrigation systems, optimizing crop patterns, enhancement crop yield per unit of applied water, and stakeholder cooperation. • The BTL has shrunk in recent decades, resulting in enhancement of TDS and PTMs. • The BTL sediments and water are contaminated for irrigation and aquatic life. • Hg, Mo, Se, Ni, Cr and As are the main sediment contaminants in parts of the BTL. • The BTL contaminations originate from mixed geogenic and anthropogenic sources. • The BTL can be restored by a new water resources plan with water-saving strategies.

Vulnerability methods in hard rock formation as a basis for groundwater risk assessment – from resource to source

Groundwater in a hard rock formation is most endangered at places where a potential source can discharge contaminants that can reach the saturated zone of an aquifer. In these circumstances, an essential tool for groundwater protection is the contamination risk map. This map is based on the integration of two maps: a hazards map, i.e., map of potential sources of contamination and a vulnerability map. The selection of a proper vulnerability method is an important task since the resulting vulnerability map can significantly impact the final risk of contamination map. The most appropriate method for groundwater vulnerability assessment was considered in the case study of Tara National park, in Western Serbia. The four commonly used methods were applied to assess the intrinsic vulnerability maps: DRASTIC, EPIK, PI and COP. All the applied methods resulted in different vulnerability maps in assessing the degree of vulnerability, consequently influencing the groundwater contamination risk maps. The applied research presents an example of how contamination risk should be assessed in a specific area. Comparison of the results obtained for the area of Tara National Park indicates the preference of the PI method as a well-balanced method, taking into account all the specifics of the study area. A detailed analysis of the assessed risks in the catchments of the existing sources was also conducted to indicate probable sources of contamination and confirm the degree of accuracy of the created vulnerability and risk maps. The conducted research emphasizes the necessity to adopt a clear conceptual hydrogeological model and to apply several methods simultaneously to determine the optimal one for each individual area.

Levels and health risk assessment of heavy metals in dried fish consumed in Bangladesh

As a cheap source of high-quality protein, healthy fats and essential nutrients, dried fish is a common item in the daily diet of the Bangladesh populace. In this study, ten types of widely consumed dried fish (H. neherius, T. lepturu, P.chinensis, P. affinis, A. mola, P. microdon, I. megaloptera, C. dussumieri, L. calcarifer, and G. chapra) were analyzed for Cr, Mn, Fe, Co, Cu, Zn, Se, Rb, Hg, Pb, Ni and As by using an Energy Dispersive X-ray Fluorescence (EDXRF) technique. The concentration of the studied metals was found in the order Fe > Zn > Hg > Cu > Se > Cr > Mn > Co > Rb > Pb, while As and Ni were below the limit of detection. All fish species showed moderate to high pollution, where the species H. Neherius and P. Chinensis are the most and least polluted ones, respectively. The probable source of contamination is the leaching from the drying pans into the fish samples, atmospheric deposition, anthropogenic contamination, etc. of the water body where these fish were harvested. The calculated hazard index for the general population was below the maximum limiting value (i.e., < 1) except for Hg to children. The carcinogenic risk showed values lower than the acceptable limit for cancer risks (10–6 to 10–4). Periodic monitoring of trace metals in the aquatic organisms along with fish is recommended to avoid any unexpected health hazards caused by the toxic heavy metals via fish consumption.

Occurrence of Cryptosporidium and Giardia in surface water supply from 2016 to 2020 in South Brazil.

The objectives of this research are to evaluate Giardia and Cryptosporidium contamination in surface water supply in Rio Grande do Sul (RS) State in South Brazil in the years 2016 to 2020, assess seasonality, and to infer the population that may have been exposed to these protozoa through drinking water based on drinking water treatment efficiency. Data were obtained through the drinking water surveillance national information system. From 204 DWT plants in the state, 66 have been analyzed for protozoa. A total of 2304 analyses of protozoa in raw water were evaluated, of which 223 had both Giardia spp. cysts and/or Cryptosporidium spp. oocysts in concentrations that varied from 0.1 to 21.5/L. A total of 2,712,125 people from 48 cities were at risk of having the presence of pathogenic protozoa in their drinking water. The probability of finding these protozoa was higher in winter. Giardia cysts were more likely to be found in a period without rain, suggesting that sewage was the main source of contamination. It is concluded that the springs of Rio Grande do Sul are impacted and the circulation of pathogenic protozoa through the territory is endemic with a probable source of contamination to sewage and livestock activity.

Kidney transplantation in the time of COVID-19: Dilemmas, experiences, and perspectives.

IntroductionHospital do Rim is a high‐volume kidney transplant (KT) center located in São Paulo, a city with 12.2 million inhabitants. Over the last 18 years, we performed 11 436 KT, 70% of which from deceased donors. To mitigate the effects of reduction in the number of transplants on the waiting list, sequential measures were implemented when COVID‐19 was declared pandemic.MethodsThe first step was to provide SARS‐COV‐2 RT‐PCR testing for all symptomatic employees and patients and the compulsory use of personal protective equipment in the hospital facilities. Living donor KT were postponed, and all deceased donors and recipients were tested before the transplantation. The immunosuppressive protocols were maintained, and telehealth strategies were developed.ResultsAmong the 1013 employees, there were 214 cases of COVID‐19, nine required ward hospitalization, and no deaths occurred. In 26%, the probable source of contamination was occupational. From the first patient diagnosed with COVID‐19 in 03/20/2020 till 10/21/2020, 523 deceased KT were performed, a 21% increase compared with 2019, with no confirmed donor‐derived SARS‐CoV‐2 infection. Four patients were transplanted with a positive pretransplant SARS‐CoV‐2 test, but none of them developed the disease. Overall, of 11 875 KT followed in our center, 674 developed COVID‐19. Among the hospitalized, 53% required mechanical ventilation, and 45% required hemodialysis. Their overall mortality rate was 27.5%.ConclusionThis experience shows the challenges that transplant centers faced as the pandemic unfolded and illustrates the effectiveness of the sequential measures implemented to provide a safe environment for transplantation.

Polyclonal Burkholderia cepacia Complex Outbreak in Peritoneal Dialysis Patients Caused by Contaminated Aqueous Chlorhexidine.

Whether Burkholderia cepacia complex should be an objectionable organism in antiseptic solutions with acceptable total bacterial counts is controversial. By using next-generation sequencing, we documented a polyclonal B. cepacia complex outbreak affecting peritoneal dialysis patients in Hong Kong that was caused by contaminated chlorhexidine solutions. Epidemiologic investigations at a manufacturing site identified a semiautomated packaging machine as the probable source of contamination in some of the brands. Use of whole-genome sequencing differentiated the isolates into 3 brand-specific clonal types. Changes in exit site care recommendations, rapid recall of affected products, and tightening of regulatory control for chlorhexidine-containing skin antiseptics could prevent future similar outbreaks. Environmental opportunistic pathogens, including B. cepacia complex, might be included in regular surveillance as indicator organisms for monitoring environmental contamination.

ASPECTOS EPIDEMIOLÓGICOS DE HEPATITE B E C NO MUNICÍPIO DE CASCAVEL/PR NO PERÍODO DE 2013 A 2017

As hepatites B e C são doenças que afetam o fígado e podem acarretar graves problemas se não diagnosticadas e tratadas de maneira correta e precocemente. Este estudo visa analisar o sexo, a faixa etária, a provável fonte de contaminação, a forma clínica em que os pacientes foram diagnosticados e a situação vacinal em que os mesmos se encontravam, no caso da hepatite B, notificadas no Departamento de Vigilância Epidemiológica da Secretaria de Saúde do Município de Cascavel/PR no período de 2013 a 2017, para que medidas sejam tomadas a fim de que haja redução dos casos dessas doenças no município e região, já que o oeste do Paraná tem alta taxa de prevalência das mesmas. Esse estudo demonstrou que nessa região o sexo afetado predominantemente foi o masculino e a provável fonte de contaminação foi a sexual, nos dois tipos de hepatite estudados.

Microbial pollution characterization at a TMDL site in Michigan: Source identification

Abstract Communities throughout the Great Lakes basin are developing and implementing watershed management plans to address non-point sources of pollution and meet Total Maximum Daily Load (TMDL) requirements. Investigating sources of microbial contamination in key streams and creeks is critical for the development of effective watershed management plans. This work aims to present an approach that will facilitate source identification. In addition to conventional indicator analysis, the approach includes molecular analysis of species-specific markers and microbial community diversity analysis. We characterized microbial pollution in the Sloan Creek subwatershed in Ingham County MI, an impaired area, located in the Great Lakes Basin. To identify pollution sources (human or animal) and major sites of origin (tributaries with highest pollution loads) water samples were collected from three locations in the subwatershed representing the main creek upstream, main creek downstream, and tributary. A fecal indicator (E. coli) and host-specific human and bovine-associated Bacteroides genetic markers were quantified in all water samples. Results indicated that 54% of the samples from the three locations exceeded the recreational E.coli water quality guidelines. High concentrations of both human and bovine associated-Bacteroides indicated influence of multiple sources of fecal contamination. Statistical tests showed significantly different water characteristics between two of the sampling locations. Whole genome shotgun sequencing indicated fecal and sewer signatures, wastewater metagenome, human gut metagenome, and rumen gut metagenome in the water samples. Results suggested that probable sources of contamination were leakage from septic systems and runoff from agriculture activities nearby to Sloan Creek.

Investigation of Dioxin/Furans, PAHs and Heavy Metals in Sarcheshmeh Copper Complex Soil, Iran

Surface soil samples were collected from Sarcheshmeh Copper Smelter Plant and analyzed for 16 Polycyclic Aromatic Hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxin/furans (PCDD/Fs), and heavy metals to determine their concentrations, distributions, and probable sources of contamination. The mean concentrations of ΣPAHs, As, Pb, Zn, Se, Cd, and Cr in the soil samples were 878.8, 850, 2185, 2455, 21, and 24 mg/kg, respectively. Besides, their Toxic Equivalents (TEQs) were calculated. The samples generally displayed elevated concentrations of heavy metals when finding the toxic values of dioxin/furan compounds in comparison to the limit values for industrial uses. The background concentrations, molecular indices, and ring classes of the heavy metals indicated that their sources and those of PAHs were both geogenic and pyrolitic. The mean concentrations of total PAHs, PCDD/Fs, and heavy metals were compared with the reports from industrial areas throughout the world and the contamination rates at Sarcheshmeh Copper Plant were found to be moderate.

American Lobsters (Homarus Americanus) not Surviving During Air Transport: Evaluation of Microbial Spoilage.

Eighteen American lobsters (Homarus americanus), dead during air transport, were analysed in order to evaluate the microbial population of meat, gills and gut: no specific studies have ever been conducted so far on the microbiological quality of American lobsters’ meats in terms of spoilage microbiota. The meat samples showed very limited total viable counts, in almost all the cases below the level of 6 Log CFU/g, while higher loads were found, as expected, in gut and gills, the most probable source of contamination. These data could justify the possibility to commercialise these not-surviving subjects, without quality concerns for the consumers. Most of the isolates resulted to be clustered with type strains of Pseudoalteromonas spp. (43.1%) and Photobacterium spp. (24.1%), and in particular to species related to the natural marine environment. The distribution of the genera showed a marked inhomogeneity among the samples. The majority of the isolates identified resulted to possess proteolytic (69.3%) and lipolytic ability (75.5%), suggesting their potential spoilage ability. The maintanance of good hygienical practices, especially during the production of ready-to-eat lobsters-based products, and a proper storage could limit the possible replication of these microorganisms.

Impact of applying hygienic practices at farm on bacteriological quality of raw milk

Aim: The present study was carried out to explore the potential source of contamination and the efficacy of different washing practices towards quality milk production. Materials and Methods: Probable sources of contamination viz. stored water, potable water, milker’s hands, milking pail, udder of individual buffalo and milk cans were subjected to different types of bacterial counts before the actual experiment to start. Twenty milch buffaloes thereafter were divided randomly into four treatment groups where washing was performed in each step viz. milker hands, udder of individual buffalo, milking pail and milk cans before milking either with water (T0: stored water, T1: potable water) or sanitizers (T2: 200 ppm chlorine solution, T3: 50 ppm iodophore solution) for 60 days. Bacterial counts again were performed for last 5 alternate days for all the sources involved along with the microbial load of raw milk. Data obtained were subjected to standard statistical analysis. Results: It was found that for all bacterial count stored water contributed significantly higher as compared to the potable water. Among the other potential sources of contamination (log/6 cm2), standard plate count (SPC) and coliform count were significantly highest for milking pail (6.73±0.02) and udder of milch buffaloes (3.77±0.12), respectively, while for Staphylococci count both milking pail (3.24±0.02) and milking can (3.22±0.04) were contributed maximally (p 0.05) for most of the parameters, even for the raw milk quality. Conclusion: Study revealed that milker hands, milking pails, udder of animals, milk cans and stored water used for washing of equipment are the potential source of contamination in raw milk. These were counted as critical point which needs attention for the production of high-quality milk. Potable water was found to be better than stored water. The use of either chlorine 200 ppm and iodophor 50 ppm is highly effective in reducing the bacterial population for quality milk production.

Aliphatic and polycyclic aromatic hydrocarbons in Gulf of Trieste sediments (northern Adriatic): potential impacts of maritime traffic.

The Gulf of Trieste (northern Adriatic) is one of the most urbanized and industrialized areas in the northern Adriatic, with intense maritime traffic experienced at multiple ports. The impact of maritime traffic on contamination by hydrocarbons in this area was assessed. Concentrations of hydrocarbons were higher near the expected contamination sources and still elevated in the adjacent offshore areas. Aliphatic hydrocarbons were mainly of petrogenic origin, with some contribution of biogenic origin. A continuous contamination by aliphatic hydrocarbons and degradation processes were hypothesized. Concentrations of total polycyclic aromatic hydrocarbons (PAH) were generally greater near the contamination sources. Compared to the prevailing pyrolytic origin, the petrogenic PAH origin seemed to be less important, but not negligible. Results revealed that intensive maritime traffic is a probable source of contamination by hydrocarbons in the investigated area, which is largely limited to areas near the contamination sources.

The Breast: A Clean-Contaminated Surgical Site

Capsular contracture is one of the most common complications associated with breast implants. While the cause of this process has not yet been elucidated, subclinical infection is a likely culprit. The authors assess the hypothesis that a probable source of contamination is endogenous breast bacteria, likely originating in the ducts themselves and most concentrated near the nipple. Twenty-five healthy patients presenting for routine reduction mammaplasty were recruited as study participants. Tissue samples were taken intraoperatively from the periareolar, inframammary, and axillary regions of each sampled breast. Specimens were then processed in the microbiology laboratory, and quantitative bacterial counts were obtained. Of the 50 breasts sampled, 19 yielded positive culture results, for a rate of 38%. There was a significant difference in the positive culture rate among all three sites, with increasing quantitative bacterial counts in the axillary, inframammary, and periareolar regions, respectively. The most commonly-identified organisms in this study included various species of Staphylococcus and Propionibacterium acnes, with S. epidermidis being the most common. The breast harbors significant endogenous bacteria that can become the source of spontaneous or postoperative infection. Positive intraoperative cultures with high quantitative counts suggest that breast tissue harbors more bacteria than normal skin flora. Routine perioperative antibiotic prophylaxis may be suboptimal for the prevention of foreign body seeding in this setting. Furthermore, bacterial concentrations are highest in areas with the most ductal tissue, namely the periareolar region. These findings may be helpful when considering which incision site to select for augmentation mammaplasty.

Cluster of Legionnaires´ disease associated with a public whirlpool spa, France, April – May 2010

In May 2010, a cluster of three cases of Legionnaires' disease was identified in France. The results of the epidemiological, environmental and microbiological investigations allowed the rapid identification of a public whirlpool spa as the most probable source of contamination and the implementation of appropriate control measures. This investigation has stressed the need for good cooperation between partners and the importance of the molecular analysis of Legionella strains.

Guidelines to Implement Quality Management Systems in Microbiology Laboratories for Tissue Banking

Human tissues for implants are a biomedical product that is being used more frequently by many medical disciplines. There are infections in the patients related to the implanted tissues. The early detection of infections transmitted by blood and the microbiological study of tissues before their clinical use are strategies in tissue banks to prevent these situations. This work sought to contribute to establish the bases for the operation of a laboratory applied to the microbiological quality control of tissues. Based on classical microbiological principles, we defined the operation of microbiological control and tissues sterilization since 2003. We determine lists of acceptable microorganisms for every tissue, criteria for the interpretation of results, and a diagnostic algorithm of microbiological quality. We observed that the circumstances of donor death can be a determinant of the quality. The environment and the operator should be investigated as probable sources of contamination in outbreaks. The criteria of work based on a solid methodology must help to avoid the transmission of infections between donor and recipient. This is a critical point in the quality management of a tissue bank.

Outbreak of Salmonella enterica serotype Manhattan infection associated with meat products, France, 2005.

Between August 2005 and March 2006 in France, 69 cases of Salmonella enterica serotype Manhattan (Salmonella Manhattan) were reported, 51 (74%) of them from southeastern France. At the time of the alert (November 2005), 13 cases and 33 controls were interviewed. Cases were more likely than controls to have eaten pork sausages (OR=5.9, confidence interval CI [1.3; 26.9]) and beef (OR=9.3, CI [1.3; 68.6]). At the same time, 19 strains of Salmonella Manhattan isolated from meat products in southeastern France, reported to the French food safety agency (Afssa, Agence française de sécurité sanitaire des aliments) in September and November 2005, had an indistinguishable PFGE profile to the 7 human isolates of Salmonella Manhattan from the outbreak in southeastern France. Trace-back investigations revealed that pork samples came from one wholesaler whose pork products had tested positive for S. Manhattan during routine food testing in August 2005. This wholesaler supplied retail outlets in southeastern France. Additionally, a slaughterhouse supplying the wholesaler was inspected and widespread contamination with Salmonella spp. and S. Manhattan was found. Cooperation between the national agencies in charge of human health (Institut de veille sanitaire, InVS) and food safety (Afssa) allowed us to determine the most probable source of contamination and to take appropriate control measures.

Application of Genotyping during an Extensive Outbreak of Waterborne Giardiasis in Bergen, Norway, during Autumn and Winter 2004

During the autumn and winter of 2004 and 2005, an extensive outbreak of waterborne giardiasis occurred in Bergen, Norway. Over 1,500 patients were diagnosed with giardiasis. Analysis of water from the implicated source revealed low numbers of Giardia cysts, but the initial contamination event probably occurred up to 10 weeks previously. While sewage leakage from a residential area is now considered to be the probable source of contamination, during the episode waste from one particular septic tank was thought to be a possible source. Genotyping of cysts from the septic tank demonstrated that they were assemblage A cysts, although the sequences were not identical to any previously published sequences. For the beta-giardin gene, the closest published subgenotype was subgenotype A3; for the gdh gene, the closest published subgenotype was subgenotype A2. Genotyping of cysts from 21 patient samples revealed that they were assemblage B cysts; thus, the septic tank was unlikely to be the contamination source. Sequencing of the beta-giardin and gdh genes from patient samples and a comparison of the sequences gave complex results. For the beta-giardin gene, three isolates had sequences identical to subgenotype B3 sequences. However, other isolates had between one and four single-nucleotide polymorphisms (SNPs). For the gdh gene, none of the sequences were identical to the sequence published for subgenotype B3, and the sequences had between one and three SNPs. One isolate, which was identical to subgenotype B3 at the beta-giardin gene, was more similar to subgenotype B2 at the gdh gene. Grouping the isolates on the basis of SNPs resulted in different groups for the two genes. The results are discussed in relation to giardiasis in Norway and to other Giardia genotyping studies.

An unusual case of carbon monoxide poisoning.

Carbon monoxide, a gas originating from incomplete combustion of carbon-based fuels, is an important cause of human deaths. In this paper, we describe an unusual carbon monoxide poisoning in a dwelling without obvious sources of combustion gases, for which two adults had to be treated in a hyperbaric chamber. Carbon monoxide readings were taken in the house and in the neighboring homes. Methane gas and nitrogen oxide levels were also monitored in the house air. Soil samples were collected around the house and tested for hydrocarbon residues. The investigation revealed the presence of a pocket of carbon monoxide under the foundation of the house. The first readings revealed carbon monoxide levels of 500 ppm in the basement. The contamination lasted for a week. The investigation indicated that the probable source of contamination was the use of explosives at a nearby rain sewer construction site. The use of explosives in a residential area can constitute a major source of carbon monoxide for the neighboring populations. This must be investigated, and public health authorities, primary-care physicians, governmental authorities, and users and manufacturers of explosives must be made aware of this problem.