RESUMEN
The relationship between enterotoxigenic Escherichia coli (ETEC) and hospitalized patients with acute diarrhea was examined in a study conducted in two hospitals from June 2000 to May 2001 in Denpasar, Bali, Indonesia. A total of 489 hospitalized patients with acute diarrhea were enrolled, and their rectal swabs were screened for enteric bacterial pathogens. Toxins, colonization factor antigens (CFAs), in vitro antimicrobial susceptibility and seasonal distribution patterns associated with ETEC were ascertained. The diagnosis of ETEC infection and CFAs association were performed with GM-1 ELISA and Dot blot immunoassays. Enterotoxigenic Escherichia coli was isolated from the rectal swabs of 14.9% of the patients. The distribution of toxins among the ETEC strains found was ST in 51 (69.9%), while LT and ST/LT were found in 28.8% and 1.3% respectively. The highest isolation rate for ETEC was found among children between the ages of 1 and 15 years. Colonization factor antigens were identified in 28.8% of the ETEC strains. A high prevalence of CFA was found among the rectal swabs of patients with ST isolates. High frequency of resistance to ampicillin, trimethoprim/sulfamethoxazole, chloramphenicol, tetracycline and cephalothin was displayed among the ETEC strains. All ETEC strains were susceptible to norfloxacin, ciprofloxacin and nalidixic acid. The results of this study document the prevalence of ETEC in hospitalized patients with acute diarrhea in Denpasar, Bali, Indonesia. Data generated in this study depicts the prevalence of ETEC diarrhea and CFA types among diarrhea patients in the tourist city of Denpasar, Bali, Indonesia.
Asunto(s)
Toxinas Bacterianas/metabolismo , Diarrea/epidemiología , Enterotoxinas/metabolismo , Proteínas de Escherichia coli , Escherichia coli/aislamiento & purificación , Hospitalización , Enfermedad Aguda , Adolescente , Adulto , Antibacterianos/farmacología , Niño , Preescolar , Diarrea/microbiología , Escherichia coli/efectos de los fármacos , Infecciones por Escherichia coli/epidemiología , Infecciones por Escherichia coli/microbiología , Femenino , Proteínas Fimbrias/metabolismo , Humanos , Indonesia/epidemiología , Masculino , Pruebas de Sensibilidad Microbiana , Prevalencia , Recto/microbiología , Estaciones del Año , Manejo de Especímenes/métodosRESUMEN
Over 1.3 million civilian and military personnel are occupationally exposed to hydrocarbon fuels, emphasizing gasoline, jet fuel, diesel fuel, or kerosene. These exposures may occur acutely or chronically to raw fuel, vapor, aerosol, or fuel combustion exhaust by dermal, respiratory inhalation, or oral ingestion routes, and commonly occur concurrently with exposure to other chemicals and stressors. Hydrocarbon fuels are complex mixtures of 150-260+ aliphatic and aromatic hydrocarbon compounds containing varying concentrations of potential neurotoxicants including benzene, n-hexane, toluene, xylenes, naphthalene, and certain n-C9-C12 fractions (n-propylbenzene, trimethylbenzene isomers). Due to their natural petroleum base, the chemical composition of different hydrocarbon fuels is not defined, and the fuels are classified according to broad performance criteria such as flash and boiling points, complicating toxicological comparisons. While hydrocarbon fuel exposures occur typically at concentrations below permissible exposure limits for their constituent chemicals, it is unknown whether additive or synergistic interactions may result in unpredicted neurotoxicity. The inclusion of up to six performance additives in existing fuel formulations presents additional neurotoxicity challenge. Additionally, exposures to hydrocarbon fuels, typically with minimal respiratory or dermal protection, range from weekly fueling of personal automobiles to waist-deep immersion of personnel in raw fuel during maintenance of aircraft fuel tanks. Occupational exposures may occur on a near daily basis for from several months to over 20 yr. A number of published studies have reported acute or persisting neurotoxic effects from acute, subchronic, or chronic exposure of humans or animals to hydrocarbon fuels, or to certain constituent chemicals of these fuels. This review summarizes human and animal studies of hydrocarbon fuel-induced neurotoxicity and neurobehavioral consequences. It is hoped that this review will support ongoing attempts to review and possibly revise exposure standards for hydrocarbon fuels.
Asunto(s)
Combustibles Fósiles/toxicidad , Hidrocarburos/toxicidad , Sistema Nervioso/efectos de los fármacos , Animales , Exposición a Riesgos Ambientales , Humanos , Aprendizaje/efectos de los fármacosRESUMEN
U.S. Navy submarines reported a yellowing of metal surfaces on their internal surfaces. The yellowing was initially identified on the painted steel bulkheads but further examination indicated that it was not limited to steel surfaces and included bedding, thread tape, Formica, plastisol covered hand-wheels, and aluminum lockers. Crew members also reported to the medical department that their skin turned yellow when they came in contact with these contaminated surfaces and requested information on the effects of exposure. Studies conducted by General Dynamics' Electric Boat Division (EBD) determined that the agent was 2,6-Di-tertbutyl-4-Nitrophenol (DBNP). 2,6-Di-butylphenol (DBP) is an antioxidant additive used in lubricating oils and hydraulic fluids. In the enclosed atmosphere of a submarine, the oil mist could be spread throughout the boat by venting the lube oil to the atmosphere. Submarines use electrostatic precipitators (ESP) to clean the air of particulate materials. During passage through the ESP, oil mist containing DBP is nitrated to DBNP, which is then moved throughout the boat in the ventilation system. Analysis of the EBD data indicated 24-hour exposure concentrations to be in the range of <3.0 to 122 ppb in the laboratory and submarine settings. Submarine crews may be exposed to these concentrations for as many as 24 hours/ day for 90 days during underway periods. Toxicity studies regarding the oral and dermal uptake of DBNP were conducted. From the literature the lethal dose to 50 percent of the population (LD50) of DBNP (rat) was reported by Vesselinovitch et al. in 1961 to be 500 mg/kg. Our studies indicated that the LD50 is in the range of 80 mg/kg in the rat. Our work also includes dermal absorption studies, which indicated that DBNP is not well absorbed through intact skin. Within this study, no no-observable adverse effect level (NOAEL) or lowest observable adverse effect level (LOAEL) was identified. Calculation of a reference dose was completed using standard methods based on the LD50 as a numerator with several uncertainty and modifying factors. EBD's determination of airborne concentrations aboard submarines fall in the range of these anticipated allowable concentrations and could indicate significant chronic exposures. No adverse effects from DBNP exposures have been reported to date.
Asunto(s)
Dermatitis Irritante/etiología , Dinitrofenoles/toxicidad , Desacopladores/toxicidad , Animales , Dermatitis Irritante/diagnóstico , Dinitrofenoles/análisis , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Exposición a Riesgos Ambientales/análisis , Femenino , Dosificación Letal Mediana , Masculino , Nivel sin Efectos Adversos Observados , Conejos , Ratas , Ratas Endogámicas F344 , Ratas Sprague-Dawley , Valores de Referencia , Factores de Riesgo , Medicina Submarina , Desacopladores/análisisRESUMEN
The military Tri-Service (Army, Navy & Marines, Air Force) Deployment Toxicology Assessment Program (DTAP) represents a 30-year (1996-2026) planning effort to implement comprehensive systems for the protection of internationally deployed troops against toxicant exposures. A major objective of DTAP is the implementation of a global surveillance system to identify chemicals with the potential to reduce human performance capacity. Implementation requires prior development of complex human risk assessment models, known collectively as the Neurobehavioral Toxicity Evaluation Instrument (NTEI), based on mathematical interpolation of results from tissue-based and in vivo animal studies validated by human performance assessment research. The Neurobehavioral Toxicity Assessment Group (NTAG) at the Naval Health Research Center Detachment-Toxicology (NHRC-TD), Dayton, OH, and associated academic institutions are developing and cross-validating cellular-level (NTAS), laboratory small animal (NTAB), nonhuman primate (GASP), and human-based (GASH) toxicity assessment batteries. These batteries will be utilized to develop and evaluate mathematical predictors of human neurobehavioral toxicity, as a function of laboratory performance deficits predicted by quantitative structural analysis relationship (QSAR-like) properties of potential toxicants identified by international surveillance systems. Finally, physiologically-based pharmacokinetic (PBPK) and pharmacodynamic (PBPD) modeling of NTAS, NTAB, GASP, GASH data will support multi-organizational development and validation of the NTEI. The validated NTEI tool will represent a complex database management system, integrating global satellite surveillance input to provide real-time decision-making support for deployed military personnel.
Asunto(s)
Conducta Animal/efectos de los fármacos , Sustancias Peligrosas/envenenamiento , Sistema Nervioso/efectos de los fármacos , Pruebas Neuropsicológicas , Animales , Conducta Animal/fisiología , Células Cultivadas , Modelos Animales de Enfermedad , Femenino , Sustancias Peligrosas/farmacocinética , Humanos , Masculino , Personal Militar , Sistema Nervioso/fisiopatología , Técnicas de Planificación , Medición de Riesgo , Pruebas de ToxicidadRESUMEN
The relationship between lead concentration in the dry film of lead based paints applied to steel bulkheads aboard ship, the lead concentration found in the air when the paint is removed by mechanical means, and blood lead concentrations of workers involved in lead based paint removal has not been well characterized. Intuitively a direct relationship must exist but confounding factors confuse the issue. Simultaneous sampling procedures from the same paint removal operation may differ by several orders of magnitude. The process from dried film to aerosol (airborne dust) exposure, and on to dose can be separated into two major phases; (1) generation of the dust and its transport through the air to the worker and (2) uptake and dose related factors within the body. Both phases involve complex interactions and there are a number of factors within each phase that significantly affect the potential lead dose for the worker. This study attempts to clarify the mechanisms involved in the generation and transportation of the dust to the worker by evaluating the relationship of a number of key factors on particle size and lead distribution within the aerosol dust generated when lead based paint is removed by sanding. The study examined the relationship between particle size in the dust and grit size of the abrasive. It also examined the distribution of lead within selected particle sizes. The Mass Median Aerodynamic Diameter (MMAD) was used as an indicator of change in the particle size distribution. Particle size distributions were evaluated using a TSI Aerodynamic Particle Sizer, a five stage cyclone and scanning electron microscopy. Lead distribution was determined using the five stage cyclone, and personal or area samples analyzed using inductively coupled plasma (ICP). Mass concentrations were evaluated using a MIE Mass Concentration Analyzer and gravimetric analysis of filter samples collected in the breathing zone. Student's t-tests were used to evaluate changes in MMADs, mass concentrations and other indices for inter and intra-grit size samples. Correlation coefficients (Pearson's r) were used to determine the relationship between factors. Findings of the research indicated that the particle size distribution in the dust is directly related to the grit size of the abrasive (i.e. inversely related to the abrasive grit number). Particulate mass concentrations of dust varied directly with abrasive grit number. The distribution of lead did not appear to be affected by grit size of the abrasive in that the lead distribution within the particle size ranges remained homogeneous and consistent with the lead concentration in the dried film. Mass concentrations of lead in air samples varied directly with lead concentration in the bulk coating. Results of this project, coordinated with deposition modeling and bioavailability studies will be useful in the development of a model to characterize lead dose to workers based on known parameters within the work specifications.