Potential Human Health Hazards Research Articles

Isolation and molecular characterization of Acanthamoeba genotypes isolated from soil sources of public and recreational areas in Iran.

Pathogenic strains of Acanthamoeba are causative agents of a sight threating infection of the cornea known as Acanthamoeba keratitis. AK cases have been reported in Iran recently due to inappropriate usage of contact lens maintenance and most patients report a contact with contaminated sources such as dust, water or soil. Sixty soil samples were collected from public and recreational areas in the province of East Azerbaijan, Iran and checked for the presence of Acanthamoeba spp. Samples were cultured on non-nutrient agar plates seeded with heat killed Escherichia coli. PCR and sequencing of the DF3 region were carried out in order to genotype the isolated strains of Acanthamoeba. Thermotolerance and osmotolerance assays were performed in order to investigate the pathogenic potential of isolated Acanthamoeba strains. Acanthamoeba spp. was isolated from 41.6% of soil samples and genotyping of the strains resulted in the identification of genotypes T3, T4, T5 and T11. Most of the isolates belonging to genotypes T3 and T4 showed high pathogenic potential, indicating that they might present a potential health hazard for humans and other animals in this region. To the best of our knowledge, this is the first report on the identification of genotypes T3 and T11 from soil sources in the country.

Human Health Effects of Biphenyl: Key Findings and Scientific Issues.

Background:In support of the Integrated Risk Information System (IRIS), the U.S. Environmental Protection Agency (EPA) has evaluated the human health hazards of biphenyl exposure.Objectives:We review key findings and scientific issues regarding expected human health effects of biphenyl.Methods:Scientific literature from 1926 through September 2012 was critically evaluated to identify potential human health hazards associated with biphenyl exposure. Key issues related to the carcinogenicity and noncancer health hazards of biphenyl were examined based on evidence from experimental animal bioassays and mechanistic studies.Discussion:Systematic consideration of experimental animal studies of oral biphenyl exposure took into account the variety of study designs (e.g., study sizes, exposure levels, and exposure durations) to reconcile differing reported results. The available mechanistic and toxicokinetic evidence supports the hypothesis that male rat urinary bladder tumors arise through urinary bladder calculi formation but is insufficient to hypothesize a mode of action for liver tumors in female mice. Biphenyl and its metabolites may induce genetic damage, but a role for genotoxicity in biphenyl-induced carcinogenicity has not been established.Conclusions:The available health effects data for biphenyl provides suggestive evidence for carcinogenicity in humans, based on increased incidences of male rat urinary bladder tumors at high exposure levels and on female mouse liver tumors. Kidney toxicity is also a potential human health hazard of biphenyl exposure.Citation:Li Z, Hogan KA, Cai C, Rieth S. 2016. Human health effects of biphenyl: key findings and scientific issues. Environ Health Perspect 124:703–712; http://dx.doi.org/10.1289/ehp.1509730

Characterization of Leptospira interrogans serovar Pomona isolated from swine in Brazil

Leptospira interrogans swine infection is a cause of serious economic loss and a potential human health hazard. In Brazil, the most common serovars associated with swine infections are Pomona, Icterohaemorrhagie and Tarassovi. Cross-reactions among serovars and the failure of infected animals to seroconvert may complicate the interpretation of serological tests. Molecular methods with better discriminatory powers are useful tools for swine leptospirosis characterization and diagnosis. This study evaluated nine L. interrogans isolates from the States of Sao Paulo and Minas Gerais during different time periods. Isolates from diseased and apparently healthy swine were characterized by microscopic agglutination tests with polyclonal antibodies and were genotyped by VNTR, PFGE and MLST techniques. Broth microdilution was used to determine the minimal inhibitory concentration of the antimicrobials of veterinary interest. The strains were identified as L. interrogans serogroup Pomona serovar Pomona Genotype A, while MLST grouped all of the isolates in sequence type 37. The PFGE analysis resulted in two pulsotypes with more than 70% similarity, distinguishing serovar Pomona isolates from the serovar Kennewicki reference strain. All of the isolates presented low MIC values to penicillin, ampicillin, ceftiofur and tulathromycin. High MIC values for fluoroquinolones, tiamulin, gentamicin, tetracyclines, neomycin, tilmicosin and sulfas were also observed. All molecular techniques were concordant in L. interrogans serovar Pomona identification. This serovar may have a different antibiotic susceptibility profile than previously reported for Leptospira isolates.

Barbecue Fumes: An Overlooked Source of Health Hazards in Outdoor Settings?

Barbecuing or charcoal-grilling has become part of popular outdoor recreational activities nowadays; however, potential human health hazards through outdoor exposure to barbecue fumes have yet to be adequately quantified. To fill this knowledge gap, atmospheric size-fractioned particle and gaseous samples were collected near an outdoor barbecuing vendor stall (along with charcoal-grilled food items) in Xinjiang of Northwest China with a 10-stage micro-orifice uniform deposit impactor and a polyurethane foam (PUF) sampler and were analyzed for particulate matter and polycyclic aromatic hydrocarbons (PAHs). Exposure to PAHs through inhalation and dermal contact by adult consumers who spent 1 h per day near a charcoal-grilling vendor for a normal meal (lunch or dinner) amounted to a BaP equivalent (BaPeq) dosage of 3.0-77 ng day(-1) (inhalation: 2.8-27 ng day(-1) of BaPeq; dermal contact: 0.2-50 ng day(-1) of BaPeq), comparable to those (22-220 ng day(-1) of BaPeq) from consumer exposure through the consumption of charcoal-grilled meat, assumed to be at the upper limit of 50-150 g. In addition, the potential health risk was in the range of 3.1 × 10(-10) to 1.4 × 10(-4) for people of different age groups with inhalation and dermal contact exposure to PAHs once a day, with a 95% confidence interval (7.2 × 10(-9) to 1.2 × 10(-5)) comparable to the lower limit of the potential cancer risk range (1 × 10(-6) to 1 × 10(-4)). Sensitivity analyses indicated that the area of dermal contact with gaseous contaminants is a critical parameter for risk assessment. These results indicated that outdoor exposure to barbecue fumes (particularly dermal contact) may have become a significant but largely neglected source of health hazards to the general population and should be well-recognized.

Approach to using mechanism-based structure activity relationship (SAR) analysis to assess human health hazard potential of nanomaterials

With the increasing use and development of engineered nanoparticles in electronics, consumer products, pesticides, food and pharmaceutical industries, there is a growing concern about potential human health hazards of these materials. A number of studies have demonstrated that nanoparticle toxicity is extremely complex, and that the biological activity of nanoparticles will depend on a variety of physicochemical properties such as particle size, shape, agglomeration state, crystal structure, chemical composition, surface area and surface properties. Nanoparticle toxicity can be attributed to nonspecific interaction with biological structures due to their physical properties (e.g., size and shape) and biopersistence, or to specific interaction with biomolecules through their surface properties (e.g., surface chemistry and reactivity) or release of toxic ions. The toxic effects of most nanomaterials have not been adequately characterized and currently, there are many issues and challenges in toxicity testing and risk assessment of nanoparticles. Based on the possible mechanisms of action and available in vitro and in vivo toxicity database, this paper proposes an approach to using mechanism-based SAR analysis to assess the relative human health hazard/risk potential of various types of nanomaterials.

Toxicology of decamethylcyclopentasiloxane (D5)

Decamethylcyclopentasiloxane (D5) is a cyclic siloxane used in the formulation of consumer products as well as an industrial intermediate. A summary of the previous studies on the toxicology of D5 is provided. Toxicokinetic studies with D5 after dermal administration demonstrate a very low uptake of due to rapid evaporation. Following inhalation exposure, exhalation of unchanged D5 and excretion of metabolites with urine are major pathways for clearance in mammals. Due to this rapid clearance by exhalation, the potential for bioaccumulation of D5 is considered unlikely. The available toxicity data on D5 adequately cover the relevant endpoints regarding potential human health hazards. D5 was not DNA reactive or mutagenic in standard in vitro and in vivo test systems. D5 also did not induce developmental and reproductive toxicity in appropriately performed studies. In repeated studies in rats with subacute, subchronic and chronic inhalation exposure, mild effects on the respiratory tract typically seen after inhalation of irritating materials, increases in liver weight (28- and 90-day inhalation studies), and a small increase in the incidence of uterine adenocarcinoma (uterine tumor) in female rats (two-year inhalation chronic bioassay) were observed. The liver effects induced by D5 were consistent with D5 as a weak “phenobarbital-like” inducer of xenobiotic metabolizing enzymes and these effects are considered to be an adaptive response. Mechanistic studies to elucidate the mode-of-action for uterine tumor induction suggest an interaction of D5 with dopamine signal transduction pathways altering the pituitary control of the estrus cycle. The resulting estrogen imbalance may cause the small increase in uterine tumor incidence at the highest D5-exposure concentration over that seen in control rats. A genotoxic mechanism or a direct endocrine activity of D5 is not supported as a mode-of-action to account for the induction of uterine tumors by the available data.

Evaluation of the behavior of clouds in a region of severe acid rain pollution in southern China: species, complexes, and variations

Cloud samples were collected during the summer of 2011 and the spring of 2012 at a high-elevation site in southern China in an effort to examine the chemical characteristics of acid clouds. In total, 141 cloud samples were collected during 44 cloud events over the observation period. The dominant ionic species were SO4(2-), NH4(+), and NO3(-), contributing approximately 75% of the total inorganic ion concentration. The primary acidifying factors were sulfate and nitrate, and the primary neutralizing factors were ammonium and calcium. The volume-weighted mean (VWM) pH of the cloud water was 3.79, indicating an acidic nature. In these cloud samples, Zn and Al exhibited the highest trace metal concentrations, contributing approximately 60% of the total trace element concentration. Toxic metals, such as Pb, Ba, As, and Cr, were detected at high concentrations, indicating potential hazards for human health, vegetation, and waters in this region. Visual MINTEQ 3.0 results revealed that the majority of Zn(II) and Pb(II) existed in the form of free ions. The behavior of Al, however, differed from the behaviors of zinc and lead. The temporal variation in cloud chemistry indicated that temperature, sandstorms, and long-range transport could affect the concentrations of species. During the lifetime of a cloud event, the concentrations of the chemical species were controlled by the transfer of gases or particles to liquid droplets.

Putting Corporate Social Responsibility to Work in Mining Communities: Exploring Community Needs for Central Appalachian Wastewater Treatment

Due to the finite nature of non-renewable mineral and energy resources such as coal, resource extraction is inherently unsustainable; however, mining and related activities can contribute to sustainable development. Indeed, the principles of corporate social responsibility (CSR) require that mine operators design and conduct their activities in ways that provide for net positive impacts on surrounding communities and environments. In Central Appalachia, there appears to be a particularly ripe opportunity for the coal industry to put CSR to work: participation in sustainable solutions to the long-standing problem of inadequately treated wastewater discharges—which not only represent a potential human health hazard, but also contribute to the relatively high incidence of bacterial impairments in surface waters in the region. In this paper, we outline the underlying factors of this problem and the advantages of industry-aided solutions in a region where limited economic and technical resources are not always aligned with social and environmental needs. We also suggest a framework for problem-solving, which necessarily involves all interested stakeholders, and identify the primary challenges that must be overcome in pursuit of sustainable solutions.

Functional consequences for primary human alveolar macrophages following treatment with long, but not short, multiwalled carbon nanotubes.

PurposeMultiwalled carbon nanotubes (MWCNTs) are a potential human health hazard, primarily via inhalation. In the lung, alveolar macrophages (AMs) provide the first line of immune cellular defense against inhaled materials. We hypothesized that, 1 and 5 days after treating AMs with short (0.6 μm in length; MWCNT-0.6 μm) and long (20 μm in length; MWCNT-20 μm) MWCNTs for 24 hours, AMs would exhibit increased markers of adverse bioreactivity (cytokine release and reactive oxygen species generation) while also having a modified functional ability (phagocytosis and migration).MethodsPrimary human AMs were treated with short and long MWCNTs for 24 hours, 1 and 5 days after which toxicity end points, including cell death, reactive oxygen species generation, and inflammatory mediator release, were measured. AM functional end points involving phagocytic ability and migratory capacity were also measured.ResultsAM viability was significantly decreased at 1 and 5 days after treatment with MWCNT-20 μm, while superoxide levels and inflammatory mediator release were significantly increased. At the same time, there was reduced phagocytosis and migratory capacity alongside increased expression of MARCO; this coincided with frustrated phagocytosis observed by scanning electron microscopy. In contrast, the adverse bioreactivity of the shorter MWCNT-0.6 μm with AMs (and any resulting reduction in AM functional ability) was substantially less marked or absent altogether.ConclusionThis study shows that after 24-hour treatment with long, but not short, MWCNTs, AM function is severely affected up to 5 days after the initial exposure. This has potentially significant pathophysiological consequences for individuals who may be intentionally (via therapeutic applications) or unintentionally exposed to these nanomaterials.

Isolation of Aspergillus ochraceus and Production of Ochratoxin in Coffee Samples

The occurrence of mycotoxins in foods and feeds has long been recognized as a potential hazard for human and animal health due to their severe toxic and carcinogenic properties. Among various mycotoxins, ochratoxin A (OTA) is the most hazardous one because of its serval contamination cases in the world. In this study contamination levels of Aspergillus ochraceus in coffee samples were assessed, where two strains of it were isolated from 65 coffee samples. They were confirmed by using Czapeck yeast extract agar (CYA). Fermentation was carried out for ochratoxin production at different moisture levels: 20%, 40% and 60% by using coffee as a substrate. The extract was assayed for the presence of ochratoxin by thin layer chromatography (TLC). Results showed that high production of this toxin (402 ppb) was obtained in coffee containing 60% of moisture after 19 days of incubation period with high load of fungal growth and the effect of roasting on coffee containing ochratoxin was observed where the level of it was decreased after roasting. It can be concluded that coffee substrate with high level of moisture favored good condition for the growth of A. ochraceus and ochratoxin formation.DOI: http://dx.doi.org/10.3126/njst.v15i1.12030 Nepal Journal of Science and TechnologyVol. 15, No.1 (2014) 133-138

Assessment of Heavy Metals Residues in Milk Powder and Infant Milk Formula Sold in Mansoura City, Egypt

A total of 75 samples including, 25 samples each of full cream powdered milk, skimmed powdered milk and infant formula collected from Mansoura city, Egypt at the period between April and September 2014 were analyzed for measuring Lead, Chromium and Cadmium levels. Flame Atomic Absorption Spectrophotometer could detect Lead, Chromium and Cadmium by means of 0.05±0.01, 2.70±0.34 and 0.09±0.02 mg/Kg in examined full cream powdered milk, 0.03±0.01, 1.98±0.24 and 0.03±0.01 mg/Kg in examined skimmed powdered milk and 0.03±0.01, 3.88±0.34 and 0.04±0.003 mg/Kg in examined infant milk formula, respectively. By comparing the concentration of heavy metals present in analyzed samples to their permissible limits, it was noted that most of tested samples contained heavy metals by levels exceeding maximum permissible limits proposed for them, hence powdered milk and infant milk formula may carry a potential health hazards for humans which needs a rigorous monitoring program to prevent food contamination by these toxic heavy metals and to ensure that their levels did not exceed the legal limits for human consumption.

Virulence characterization of Campylobacter jejuni isolated from resident wild birds in Tokachi area, Japan.

The prevalence of Campylobacter jejuni in wild birds is a potential hazard for human and animal health. The aim of this study was to establish the prevalence of C. jejuni in wild birds in Tokachi area, Hokkaido, Japan and investigate their virulence in vitro. In total, 173 cloacal swabs from individual wild birds were collected for the detection of Campylobacter spp. Thirty four samples (19.7%) were positive for Campylobacter of which 94.1% (32/34 samples) were C. jejuni. Additionally, one C. coli and one C. fetus were isolated. Seven C. jejuni isolates (one from crows and the other from pigeons) had important virulence genes including all three CDT genes (cdtA, cdtB and cdtC) and flaA, flaB, ciaB and cadF, and the other isolates were lacking cdtA gene. Further studies on in vitro virulence-associated phenotypes, such as motility assay on soft agar and invasion assay in Caco-2 cells, were performed. The wild bird C. jejuni isolates adhered and invaded human cells. Although the numbers of viable intracellular bacteria of wild bird isolates were lower than a type strain NCTC11168, they persisted at 48-hr and underwent replication in host cells.

The properties of Çan Basin coals (Çanakkale—Turkey): Spontaneous combustion and combustion by-products

The goals of this study were to investigate the susceptibility of Çan Basin (Çanakkale—Turkey) coals to spontaneous combustion and to determine the composition of the gas produced from the coal during combustion. Coal properties were determined using burned and partly burned coal samples; gas samples were analyzed for their composition. The mineralogical variations of burning coals were also investigated. Our results indicated that the pyrite content of Çan Basin coals is a significant factor for promoting combustion in addition to rank and moisture. X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses indicated that the coal samples contained pyrite, quartz, cristobalite, tridymite, kaolinite, amorphous matter, and gypsum. Fumarolic minerals (sulfur blooming and ammonium chloride) forming on the surface of coal seams were monitored. Elements including beryllium, fluorine, scandium, vanadium, cobalt, nickel, copper, zinc, arsenic, selenium, zirconium, molybdenum, tungsten, mercury, tantalum, lead, and uranium were found to be higher in Çan coal samples than the world average. The concentration of arsenic (max. 3319.7μg/g) was relatively high and is the major hazardous element in the region.Gases emitted from coal-fire vents in Çan coalfields were found to consist of a complex mixture of hydrocarbons, greenhouse gases, and toxic concentrations of carbon monoxide (CO), hydrogen sulfide (H2S), and benzene. Hydrocarbon concentrations ranged from 77 to 92%, and the dominant hydrocarbon gas was methane. Ethane (0.3 to 2.1%) and propane (0.2 to 1.4%) were also detected. Hazardous compounds such as 5-methyl-3-propyl-1,2-oxazole (C7H11NO), ethanediimidic acid, 1,2-dihydrazide (C2H8N6), and 2,3-dihydrofuran (C4H6O); high concentrations of nitrogen (N2) (max. 6.8%) and carbon dioxide (CO2) (max. 18.2%); and low concentrations of carbon monoxide were also determined. Greenhouse gases (CO2 and methane (CH4)) from burning coal beds may contribute to climate change and alter ecosystems. Gas components including furan, H2S, CO, carbon disulfide (CS2), benzene etc., can be hazardous to human health, even in trace amounts. As a result, the uncontrolled release of pollutants from burning coal beds presents potential environmental and human health hazards.

Guidelines for experimental design protocol and validation procedure for the measurement of heat resistance of microorganisms in milk

Studies on the heat resistance of dairy pathogens are a vital part of assessing the safety of dairy products. However, harmonized methodology for the study of heat resistance of food pathogens is lacking, even though there is a need for such harmonized experimental design protocols and for harmonized validation procedures for heat treatment studies. Such an approach is of particular importance to allow international agreement on appropriate risk management of emerging potential hazards for human and animal health. This paper is working toward establishment of a harmonized protocol for the study of the heat resistance of pathogens, identifying critical issues for establishment of internationally agreed protocols, including a harmonized framework for reporting and interpretation of heat inactivation studies of potentially pathogenic microorganisms.

Genotoxicity of Organic Extracts in Water from Jilin City Section of the Second Songhua River

The second Songhua River has severe organic contamination due to domestic sewage and industrial wastewater. It is important to determine its genotoxic activity, which is a potential hazard for human health. The micronucleus assay and lymphocytes SCGE assay were employed to examine the genotoxic activity of organic extracts of water samples taken from upstream, midstream and downstream in Jilin City section of the second Songhua River in dry season and in wet season, respectively. Micronucleus assay results showed that there were significant increases in water samples at doses of 25L/kg and 50L/kg. The genotoxicity seemed to be less when compared with the results from dry season to wet season and to be strong from upstream to downstream. A similar result was also obtained in DNA damage on lymphocytes by SCGE assay. These results indicate that the organic extracts of water samples taken from the Songhua River show genotoxic activity. The risks of potential harm for human health in the Songhua River should be studied further.

In Vitro Study of Bisphenol A (BPA) in the early human placenta

In Vitro Study of Bisphenol A (BPA) in the early human placenta

Quantitative assessment of human MRSA risks from swine.

The public health community, news media, and members of the general public have expressed significant concern that methicillin-resistant Staphylococcus aureus (MRSA) transmitted from pigs to humans may harm human health. Studies of the prevalence and dynamics of swine-associated (ST398) MRSA have sampled MRSA at discrete points in the presumed causative chain leading from swine to human patients, including sampling bacteria from live pigs, retail meats, farm workers, and hospital patients. Nonzero prevalence is generally interpreted as indicating a potential human health hazard from MRSA infections, but quantitative assessments of resulting risks are not usually provided. This article integrates available data from several sources to construct a conservative (plausible upper bound) probability estimate for the actual human health harm (MRSA infections and fatalities) arising from ST398-MRSA from pigs. The model provides plausible upper bounds of approximately one excess human infection per year among all U.S. pig farm workers, and one human infection per 31 years among the remaining total population of the United States. These results assume the possibility of transmission events not yet observed, so additional data collection may reduce these estimates further.

Potentially toxic elements in foodcrops (Triticum aestivum L., Zea mays L.) grown on contaminated soils

Plants can uptake potentially toxic elements from the soil and accumulate them in the roots or translocate them to the aerial parts. Excessive content of these elements in edible parts can produce toxic effects and, through the food chain and food consumption, result in a potential hazard for human health. In this study soils and plants (Triticum aestivum L. and Zea mays L.) from a tannery district in North-East Italy were analyzed to determine the content of potentially harmful elements (Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Ni, P, Pb, S, Zn and V). According to the national legislation, the area is contaminated by Cr, Ni, Cu, Zn, Cd and V. The distribution of contaminants along the soil profile shows a general tendency to metal accumulation at surface as expected for anthropogenically enriched sites. Major anthropogenic origin was detected for Cr, Ni (from industrial activities), Zn, Cu, Cd (from agriculture practices). Major nutrients (K, P and S) and some micronutrients (Cu, Zn, Mg and Mn) are easily absorbed and translocated, while other potentially toxic elements (Ca, Fe, Al, Cd, Cr, Ni, Pb and V) are not accumulated in the seeds of the two considered species. However, the two edible species proved differently able to absorb and translocate elements, and this suggests to consider separately every species as potential PHEs transporter to the food chain and to humans. Chromium concentrations in seeds and other aerial parts of the examined plants are higher than the values found for the same species and for other cereals grown on unpolluted soils. Comparing the Cr levels in edible parts with recommended dietary intake, besides other possible Cr sources (dust ingestion, water), there seems to be no health risk for animal breeding and population due to the consumption of wheat and maize grown in the area.

Concentrations and human health risk assessment of organochlorine pesticides in edible fish species from a Rift Valley lake—Lake Ziway, Ethiopia

Fish consumption is known to have several health benefits for humans. However, the accumulation of organic pollutants, like organochlorine pesticides (OCPs) could pose health hazards. Thus, OCPs in edible fish species (Oreochromis niloticus, Tilapia zillii, Carassius spp., and Clarias gariepinus) from Lake Ziway, an Ethiopian Rift Valley Lake were investigated to assess the potential human health hazards of these contaminants. Dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), chlordanes, and heptachlors were observed with ΣOCPs concentration ranging from 1.41 to 63.8ngg−1 ww. DDTs were the predominant contaminants (0.9 to 61.9ngg−1 ww), followed by HCHs. The predominance of DDTs may be attributed to their current use in vector control and contamination from past usage. The estimated daily intakes (EDIs) of OCPs from all fish species were much lower than the acceptable daily intakes (ADIs), indicating that consumption of fish is at little risk to human health at present. However, the cancer risk estimates in the area of concern and the hazard ratios (HRs) of HCHs, DDTs, and heptachlors exceeded the threshold value of one, indicating daily exposure to these compounds is a potential concern. This may result in a lifetime cancer risk greater than of 1 in 106.

Intercomparison of Fire Size, Fuel Loading, Fuel Consumption, and Smoke Emissions Estimates on the 2006 Tripod Fire, Washington, USA

AbstractLand managers rely on prescribed burning and naturally ignited wildfires for ecosystem management, and must balance trade-offs of air quality, carbon storage, and ecosystem health. A current challenge for land managers when using fire for ecosystem management is managing smoke production. Smoke emissions are a potential human health hazard due to the production of fine particulate matter (PM2.5), carbon monoxide (CO), and ozone (O3) precursors. In addition, smoke emissions can impact transportation safety and contribute to regional haze issues. Quantifying wildland fire emissions is a critical step for evaluating the impact of smoke on human health and welfare, and is also required for air quality modeling efforts and greenhouse gas reporting. Smoke emissions modeling is a complex process that requires the combination of multiple sources of data, the application of scientific knowledge from divergent scientific disciplines, and the linking of various scientific models in a logical, progressive sequence. Typically, estimates of fire size, available fuel loading (biomass available to burn), and fuel consumption (biomass consumed) are needed to calculate the quantities of pollutants produced by a fire. Here we examine the 2006 Tripod Fire Complex as a case study for comparing alternative data sets and combinations of scientific models available for calculating fire emissions. Specifically, we use five fire size information sources, seven fuel loading maps, and two consumption models (Consume 4.0 and FOFEM 5.7) that also include sets of emissions factors. We find that the choice of fuel loading is the most critical step in the modeling pathway, with different fuel loading maps varying by 108 %, while fire size and fuel consumption show smaller variations (36 % and 23 %, respectively). Moreover, we find that modeled fuel loading maps likely underestimate the amount of fuel burned during wildfires as field assessments of total woody fuel loading were consistently higher than modeled fuel loadings in all cases. The PM2.5 emissions estimates from Consume and FOFEM vary by 37 %. In addition, comparisons with available observational data demonstrate the value of using local data sets where possible.