RESUMEN
PURPOSE: To describe the functional consequences of health care utilization for wheezing symptoms and diagnosed asthma in a multiracial school-based population. METHODS: Wheezing symptoms and physician-diagnosed asthma were measured in 2059 eighth graders with the International Study of Asthma and Allergies in Children video questionnaire. The sample site population was 40% African-American, 53% White, and 49% girls. Thirty-two percent of the children were on the free school lunch program. Adolescents self-reported their wheezing symptoms and physician diagnosis in response to the video wheezing scenes. They also answered questions on activity limitations, school attendance, and sleep disturbances owing to their wheezing symptoms. Multiple logistic regression was used to calculate odds ratios and adjust for potential confounders. RESULTS: Nine percent of the adolescents reported physician-diagnosed asthma with current symptoms and 27% reported current wheezing with no diagnosis of asthma. Physician-diagnosed asthmatics and wheezers were 2.6 (95% confidence interval [CI] 1.9, 3.6) and 1.8 (95% CI 1.4, 2.2) times more likely, respectively, to miss school days because of wheezing symptoms than asymptomatic adolescents. Diagnosed asthmatics were 7.8 (95% CI 5.5, 11.2) times and wheezers 4.7 (95% CI 3.5, 6.1) times more likely to have sleep disturbances than asymptomatic adolescents. Diagnosed asthmatics were 49 (95% CI 30.0, 79.8) times and wheezers 4.8 (95% CI 3.0, 7.5) times as likely to report a clinic visit for wheezing than asymptomatic adolescents. African-Americans had similar prevalence of wheezing, compared with Whites, although African-Americans were 1.4 (95% CI 1.1, 1.9) times as likely to have physician-diagnosed asthma. Girls were twice as likely to report physician-diagnosed asthma and wheezing symptoms as were boys. CONCLUSIONS: Adolescents with wheezing experienced functional consequences comparable to those of adolescents with physician-diagnosed asthma. Although wheezers may have less severe asthma than diagnosed asthmatics, the functional consequences of wheezing are likely to impair school performance and limit activity.
Asunto(s)
Asma/diagnóstico , Asma/etnología , Negro o Afroamericano/estadística & datos numéricos , Aceptación de la Atención de Salud/etnología , Ruidos Respiratorios/diagnóstico , Población Blanca/estadística & datos numéricos , Niño , Intervalos de Confianza , Femenino , Encuestas Epidemiológicas , Humanos , Masculino , Oportunidad Relativa , Prevalencia , Factores de Riesgo , Servicios de Salud Escolar , Factores Socioeconómicos , Estudiantes , Encuestas y Cuestionarios , Estados Unidos/epidemiología , Grabación en VideoRESUMEN
This study investigated the chronic effects of emissions from three different waste incinerators on pulmonary function of both healthy and sensitive subjects with chronic respiratory symptoms. Participants were 8-80 years old, not currently smoking, and living in one of three communities each with an incinerator or one of three matched comparison communities. In total, 1018 subjects underwent a spirometric test once a year during 1992-1994. Exposure was assessed by three methods: living in an incinerator community; distance from the incinerator; and an incinerator exposure index, a function of the distance and direction of each subject's residence to the incinerator, days downwind, and average time spent outdoors. The results generally showed no statistically significant association between pulmonary function and these three incinerators, adjustment for gas oven/range use at home, length of residency, and smoking history in the mixed linear models. Two significant associations were that exposure to the hazardous waste incinerator in 1994 and to the municipal waste incinerator in 1993 were related to poor forced vital capacity. Sensitive subjects were not more adversely affected by incineration emissions than were hay fever or normal subjects. Possible explanations for the negative findings are low exposure levels and bias due to nondifferential misclassification of exposures.
Asunto(s)
Contaminantes Atmosféricos/efectos adversos , Incineración , Enfermedades Pulmonares/etiología , Pulmón/efectos de los fármacos , Eliminación de Residuos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Exposición a Riesgos Ambientales , Estudios Epidemiológicos , Femenino , Humanos , Exposición por Inhalación , Pulmón/patología , Masculino , Persona de Mediana Edad , Pruebas de Función RespiratoriaRESUMEN
Lack of daily data on airborne particles has been a common problem in an air pollution research. To deal with this problem, a regression model was developed to estimate daily PM10 concentration using visibility in Bangkok from 1992 to 1997, based on 1092 visibility/PM10 pair-observations on low humidity days (humidity < or = 76.5%). Visibility was significantly and inversely associated with PM10 (r = 0.71), after adjusting for minimum temperature and winter indicator variable. The R2 of the model was 0.51.
Asunto(s)
Contaminación del Aire/análisis , Monitoreo del Ambiente/estadística & datos numéricos , Modelos Teóricos , Movimientos del Aire , Contaminación del Aire/estadística & datos numéricos , Monitoreo del Ambiente/métodos , Predicción , Tamaño de la Partícula , Análisis de Regresión , Estaciones del Año , TemperaturaRESUMEN
There is an increasing trend toward using incineration to solve the problem of waste management; thus, there are concerns about the potential health impact of waste incineration. A critical review of epidemiologic studies will enhance understanding of the potential health effects of waste incineration and will provide important information regarding what needs to be investigated further. This study reviews the epidemiologic research on the potential health impact of waste incineration. Previous studies are discussed and presented according to their study population, incinerator workers or community residents, and health end points. Several studies showed significant associations between waste incineration and lower male-to-female ratio, twinning, lung cancer, laryngeal cancer, ischemic heart disease, urinary mutagens and promutagens, or blood levels of certain organic compounds and heavy metals. Other studies found no significant effects on respiratory symptoms, pulmonary function, twinning, cleft lip and palate, lung cancer, laryngeal cancer, or esophageal cancer. In conclusion, these epidemiologic studies consistently observed higher body levels of some organic chemicals and heavy metals, and no effects on respiratory symptoms or pulmonary function. The findings for cancer and reproductive outcomes were inconsistent. More hypothesis-testing epidemiologic studies are needed to investigate the potential health effects of waste incineration on incinerator workers and community residents.
Asunto(s)
Contaminantes Atmosféricos/envenenamiento , Exposición a Riesgos Ambientales , Incineración , Exposición Profesional , Salud Pública , Ambiente , Estudios Epidemiológicos , Femenino , Humanos , Masculino , Formulación de PolíticasRESUMEN
This Six Communities Study conducted at six communities in southwestern North Carolina investigates the respiratory health status of residents whose households are located near an incinerator. This diary study makes it possible to estimate the daily variation of pulmonary function measured as peak expiratory flow rate (PEFR) related to 24-h mean PM10 levels, which were observed at each monitoring station placed in the six study communities, as a surrogate exposure measure of outdoor air pollution. Observations of PEFR among participants in each community were analyzed to determine how they varied according to the degree of exposure to ambient pollutants as well as to other cofactors including, sex, age, respiratory hypersensitivity, hours spent outdoors within the area of the selected community, and surrogate measures for indoor air pollution exposure (vacuum use and experience of air irritants at work). The findings revealed that respiratory hypersensitivity status is a predictor of declining PEFR. PM10 concentrations measured in each study area did not seem to be related to the variations of respiratory health as measured by PEFR. This study did not show any difference in respiratory health between subjects of an incinerator community and those of its comparison community. Even though this community-based study with free-living subjects shows negative findings on the relationship between respiratory health and PM10, it is worth noting that these findings must be interpreted cautiously because exposure estimation based on monitoring of ambient air likely results in misclassification of true exposure levels.
Asunto(s)
Contaminantes Atmosféricos/efectos adversos , Contaminantes Atmosféricos/análisis , Monitoreo del Ambiente/métodos , Estado de Salud , Incineración , Ápice del Flujo Espiratorio , Hipersensibilidad Respiratoria/diagnóstico , Hipersensibilidad Respiratoria/etiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Niño , Estudios Transversales , Femenino , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , North Carolina , Hipersensibilidad Respiratoria/fisiopatología , Rinitis Alérgica Estacional/diagnóstico , Rinitis Alérgica Estacional/etiología , Rinitis Alérgica Estacional/fisiopatología , Factores de Riesgo , Factores de TiempoRESUMEN
An analysis was conducted of 27,982 deaths among 106,020 persons employed at four Federal nuclear plants in Oak Ridge, Tennessee, between 1943 and 1985. The main objectives were to extend the evaluation of the health effects of employment in the nuclear industry in Oak Ridge to include most workers who were omitted from earlier studies, to compare the mortality experience of workers among the facilities, to address methodological problems that occur when individuals employed at more than one facility are included in the analysis, and to conduct dose-response analyses for those individuals with potential exposure to external radiation. All-cause mortality and all-cancer mortality were in close agreement with national rates. The only notable excesses occurred for white males for lung cancer [standardized mortality ratio (SMR) = 1.18, 1,849 deaths] and non-malignant respiratory disease (SMR = 1.12, 1,568 deaths). A more detailed analysis revealed substantial differences in death rates among workers at the Oak Ridge plants. Evaluation of internally adjusted log SMRs using Poisson regression showed that workers employed only at Tennessee Eastman Corporation or K-25 and at multiple facilities had higher death rates than similar workers employed only at X-10 or Y-12, and that the differences were primarily due to non-cancer causes. Analysis of selected cancer causes for white males indicated large differences among the workers at the different facilities for lung cancer, leukemia and other lymphatic cancer. Dose-response analyses for external penetrating radiation were limited to a subcohort of 28,347 white males employed at X-10 or Y-12. Their collective recorded dose equivalent was 376 Sv. There was a strong "healthy worker effect" in this subcohort-all-cause SMR = 0.80 (4,786 deaths) and all-cancer SMR = 0.87 (1,134 deaths). Variables included in the analyses were age, birth cohort, a measure of socioeconomic status, length of employment, internal radiation exposure potential and facility. For external radiation dose with a 10-year lag, the excess relative risk was 0.31 per Sv (95% CI = -0.16, 1.01) for all causes and 1.45 per Sv (95% CI = 0.15, 3.48) for all cancer. The estimated excess relative risk for leukemia was negative but imprecisely determined. A preliminary dose adjustment procedure was developed to compensate for missing dose but not other dosimetry errors. Results of the analyses using the adjusted doses suggest that the effect of missing dose is an upward bias in dose-response coefficients and test statistics.
Asunto(s)
Neoplasias/mortalidad , Enfermedades Profesionales , Exposición Profesional , Relación Dosis-Respuesta en la Radiación , Femenino , Agencias Gubernamentales , Humanos , Masculino , Riesgo , Tennessee , Factores de TiempoRESUMEN
Academic epidemiology has failed to develop the scientific methods and the knowledge base to support the fundamental public health mission of preventing disease and promoting health through organized community efforts. As a basic science of public health, epidemiology should attempt to understand health and disease from a community and ecologic perspective as a consequence of how society is organized and behaves, what impact social and economic forces have on disease incidence rates, and what community actions will be effective in altering incidence rates. However, as taught in most textbooks and as widely practiced by academicians, epidemiology has become a biomedical discipline focused on the distribution and determinants of disease in groups of individuals who happen to have some common characteristics, exposures, or diseases. The ecology of human health has not been addressed, and the societal context in which disease occurs has been either disregarded or deliberately abstracted from consideration. By essentially assuming that risk factors for disease in individuals can be summed to understand the causes of disease in populations, academic epidemiology has limited itself to a narrow biomedical perspective, thereby committing the bio-medical fallacy of inferring that disease in populations can be understood by studying risk factors for disease in individuals. Epidemiology should be redefined as a study of the distribution and societal determinants of the health status of populations. This definition provides a stronger link to be the primary mission of public health and places an appropriate emphasis on the social, economic, environmental, and cultural determinants of population health. Epidemiology must cross the boundaries of other population sciences and add to its scope a macro-epidemiology, a study of causes from a truly population perspective, considering health and disease within the context of the total human environment.
Asunto(s)
Epidemiología , Salud Pública , Indicadores de Salud , Humanos , Medicina Preventiva , Proyectos de InvestigaciónRESUMEN
To investigate acute, irreversible effects of exposure to ozone and other air pollutants, the authors examined daily death counts in relation to air pollution levels in Mexico City during 1990-1992. When considered singly in Poisson regression models accounting for periodic effects, the rate ratio for total mortality associated with a 100-ppb increment in 1-hour maximum ozone concentration was 1.024 (95% confidence interval (CI) 1.011-1.039). Measures of average ozone concentration were somewhat more strongly related to mortality. The rate ratio was 1.024 (95% CI 0.984-1.062) per 100 ppb for sulfur dioxide and 1.050 (95% CI 1.030-1.067) per 100 micrograms/m3 for total suspended particulates. However, when all three pollutants were considered simultaneously, only total suspended particulates remained associated with mortality, indicating excess mortality of 6% per 100 micrograms/m3 (rate ratio = 1.058, 95% CI 1.033-1.083), consistent with observations in other cities in the United States and Europe. The authors found no independent effect of ozone, but it is difficult to attribute observed effects to a single pollutant in light of the complexity and variability of the mixture to which people are exposed. Nevertheless, particulate matter may be a useful indicator of the risk associated with ambient air pollution.
Asunto(s)
Contaminantes Atmosféricos/análisis , Mortalidad , Ozono/análisis , Salud Urbana , Adolescente , Adulto , Anciano , Contaminantes Atmosféricos/efectos adversos , Niño , Preescolar , Intervalos de Confianza , Certificado de Defunción , Monitoreo del Ambiente , Monitoreo Epidemiológico , Femenino , Humanos , Lactante , Recién Nacido , Masculino , México/epidemiología , Persona de Mediana Edad , Ozono/efectos adversos , Análisis de Regresión , Factores de Riesgo , Tiempo (Meteorología)RESUMEN
Daily death counts in Mexico City were examined in relation to ambient ozone levels during 1990-1992 for the purpose of investigating the acute, irreversible effects of air pollution, with emphasis on ozone exposure. Air pollution data were obtained from nine monitoring stations operated by the Departamento del Distrito Federal. Mortality data were provided by the Instituto Nacional de Estadística, Geografía, e Informática. Increases in numbers of deaths were positively associated with elevated air pollution levels on the same day and on the previous day. The magnitude of the increases was small but statistically significant, after Poisson regression models were used to adjust for temperature and long-term trends. In models using data for a single pollutant, the "crude" ratio for total mortality associated with an increase of 100 parts per billion (ppb)* in one-hour maximum ozone concentration was 1.029 (95% CI 1.015, 1.044). A moving average of ozone showed a stronger association (rate ratio [RR] = 1.048, 95% CI 1.025, 1.070), and excess mortality (an increase in the number of deaths, relative to the average on days with low pollution levels) was more evident for persons over 65 years of age. Separate analyses of the effect of elevated ozone for different areas of the city showed similar results, but they were not statistically significant. Other pollutants also were related to mortality. The RR was 1.075 (95% CI 0.984, 1.062) per 100-ppb increase for sulfur dioxide and 1.049 (95% CI 1.030, 1.067) per 100 micrograms/m3 increase in total suspended particulates (TSP) when these pollutants were considered in separate models. However, when all three pollutants were considered simultaneously, only TSP remained associated with mortality, indicating excess mortality of 5% per 100 micrograms/m3 increase [RR = 1.052, 95% CI 1.034, 1.072]. The excess mortality associated with TSP is consistent with that observed in other cities in America and Europe. This study provides some evidence that ozone is associated with all-cause mortality and with mortality among the elderly after controlling for long-term cycles. However, ozone levels exhibited little or no effect on mortality rates when other air pollutants were considered simultaneously. Particulate matter appeared to be an important pollutant; it independently predicted changes in mortality. Nevertheless, because of the complexity and variability of the mixtures to which people are exposed, it is difficult to attribute the observed effects to a single pollutant. The technical feasibility and scientific validity of isolating the effect of single pollutants in such complex mixtures requires further research and careful consideration. Given the large population living in and exposed to ambient air pollution in Mexico City and other metropolises throughout the world, these small but significant associations of mortality with air pollution indices are of public health concern.
Asunto(s)
Contaminantes Atmosféricos/efectos adversos , Mortalidad , Ozono/efectos adversos , Salud Urbana , Adolescente , Adulto , Distribución por Edad , Anciano , Contaminantes Atmosféricos/análisis , Niño , Preescolar , Monitoreo del Ambiente , Monitoreo Epidemiológico , Humanos , Lactante , Estudios Longitudinales , México/epidemiología , Persona de Mediana Edad , Mortalidad/tendencias , Ozono/análisis , Análisis de Regresión , Dióxido de Azufre/efectos adversos , Dióxido de Azufre/análisisRESUMEN
The purpose of the study presented here was to simultaneously measure air quality and respiratory function and symptoms in populations living in the neighborhood of waste incinerators and to estimate the contribution of incinerator emissions to the particulate air mass in these neighborhoods. We studied the residents of three communities having, respectively, a biomedical and a municipal incinerator, and a liquid hazardous waste-burning industrial furnace. We compared results with three matched-comparison communities. We did not detect differences in concentrations of particulate matter among any of the three pairs of study communities. Average fine particulate (PM2.5) concentrations measured for 35 days varied across study communities from 16 to 32 micrograms/m3. Within the same community, daily concentrations of fine particulates varied by as much as eightfold, from 10 to 80 micrograms/m3, and were nearly identical within each pair of communities. Direct measurements of air quality and estimates based on a chemical mass balance receptor model showed that incinerator emissions did not have a major or even a modest impact on routinely monitored air pollutants. A onetime baseline descriptive survey (n = 6963) did not reveal consistent community differences in the prevalence of chronic or acute respiratory symptoms between incinerator and comparison communities, nor did we see a difference in baseline lung function tests or in the average peak expiratory flow rate measured over a period of 35 days. Based on this analysis of the first year of our study, we conclude that we have no evidence to reject the null hypothesis of no acute or chronic respiratory effects associated with residence in any of the three incinerator communities.
Asunto(s)
Contaminantes Atmosféricos/efectos adversos , Sustancias Peligrosas/efectos adversos , Incineración , Enfermedades Pulmonares/inducido químicamente , Pulmón/efectos de los fármacos , Adolescente , Adulto , Anciano , Niño , Humanos , Estudios Longitudinales , Pulmón/fisiología , Persona de Mediana Edad , Zinc/efectos adversosRESUMEN
A nested case-control study was undertaken to identify the determinants of lung cancer mortality in a cohort of 8147 foundry men among whom an excess of lung cancer deaths was previously observed. The present study consisted of all lung cancer deaths (N = 220) that occurred within this cohort between 1950 and 1989. both living and dead controls, matched on race and attained age, were selected in the ratio of 10:1 (N = 2200) by means of the incidence density sampling procedure. All cases and two controls per case, randomly selected from each case's 10 controls, were included in a smoking history survey. Basic smoking history information was obtained for about 71% of these study subjects. For the purpose of this study, formaldehyde exposure levels were categorized as high, medium, low, and none. Airborne silica exposure was categorized only as high, medium, and low levels, because all foundry workers were known to be exposed to silica. Conditional logistic regression analyses indicated that cigarette smoking was a strong predictor of lung cancer mortality in this cohort. Neither exposure to formaldehyde nor silica exposure level, nor employment in any of the six major work areas within the foundry, showed an association with lung cancer.
Asunto(s)
Neoplasias Pulmonares/mortalidad , Metalurgia , Enfermedades Profesionales/mortalidad , Anciano , Estudios de Casos y Controles , Estudios de Cohortes , Formaldehído , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Exposición Profesional , Oportunidad Relativa , Dióxido de Silicio , Fumar/efectos adversosRESUMEN
To examine the relation between adverse pregnancy outcomes and work in cosmetology during pregnancy, we conducted a mail survey in North Carolina among 8,356 licensed female cosmetologists 22-36 years of age. We identified pregnancies between 1983 and 1988 by a brief screening questionnaire, followed by a more detailed mail questionnaire. Seventy-four per cent of eligible cosmetologists responded to each inquiry. We restricted the main analysis to 96 cosmetologists with a spontaneous abortion and 547 cosmetologists with a single livebirth who worked full-time in cosmetology or in other jobs during the first trimester of pregnancy. With adjusted odds ratios ranging from 1.4 to 2.0, we found associations between spontaneous abortion and the number of hours worked per day in cosmetology, the number of chemical services performed per week, the use of formaldehyde-based disinfectants, and work in salons where nail sculpturing was performed by other employees. We found no important associations among full-time cosmetologists who performed few chemical services and among cosmetologists who worked less than 35 hours per week.
Asunto(s)
Aborto Espontáneo/inducido químicamente , Cosméticos/efectos adversos , Enfermedades Profesionales/inducido químicamente , Aborto Espontáneo/epidemiología , Adulto , Intervalos de Confianza , Exposición a Riesgos Ambientales , Femenino , Formaldehído/efectos adversos , Humanos , North Carolina/epidemiología , Enfermedades Profesionales/epidemiología , Oportunidad Relativa , Embarazo , Resultado del Embarazo , Factores de RiesgoRESUMEN
Exposure to mercury vapour or inorganic mercury compounds can impair fertility in laboratory animals. To study the effects of mercury vapour on fertility in women, eligibility questionnaires were sent to 7000 registered dental assistants in California. The final eligible sample of 418 women, who had become pregnant during the previous four years, were interviewed by telephone. Detailed information was collected on mercury handling practices and the number of menstrual cycles without contraception it had taken them to become pregnant. Dental assistants not working with amalgam served as unexposed controls. Women with high occupational exposure to mercury were less fertile than unexposed controls. The fecundability (probability of conception each menstrual cycle) of women who prepared 30 or more amalgams per week and who had five or more poor mercury hygiene factors was only 63% of that for unexposed women (95% CI 42%-96%) after controlling for covariates. Women with low exposure were more fertile, however, than unexposed controls. Possible explanations for the U shaped dose response and limitations of the exposure measure are discussed. Further investigation is needed that uses biological measures of mercury exposure.
Asunto(s)
Técnicos Dentales , Infertilidad Femenina/inducido químicamente , Mercurio/efectos adversos , Enfermedades Profesionales/inducido químicamente , Adolescente , Adulto , Amalgama Dental , Relación Dosis-Respuesta a Droga , Femenino , Fertilidad , Humanos , Estudios Retrospectivos , Factores de TiempoRESUMEN
Neurotoxic, reproductive, and carcinogenic effects are potentially important health end points in epidemiological studies of complex mixtures, particularly when such mixtures contain volatile organic compounds or trace metals. Epidemiological studies of neurotoxicity often will require direct clinical, behavioral, and/or physiological testing of study subjects, because these effects are likely to be subtle and not identifiable as clearly defined diseases. Peripheral nervous system toxicity can be assessed by clinical neurologic examinations, by electrophysiological tests of nerve conduction, and by physiological tests of thresholds for neurosensory perception, though these tests require considerable standardization for use outside the clinical setting, and most of the available tests have not been assessed for their utility in detecting effects of neurotoxic exposures. Neurobehavioral effects of exposures to solvents, as examples of complex mixtures, have been studied widely; but batteries of tests are often used, and these have not been well standardized and are generally unfamiliar to most research investigators in this area. Recently standardized neurobehavioral test systems developed by the World Health Organization and by a U.S. group for use in field studies, show promise in detecting neurobehavioral effects at relatively low environmental exposures. Similarly, new and sensitive measures of disturbed reproductive function, such as time-to-conception and biochemical indices of early pregnancy loss, are affected by some low-concentration environmental agents; but those measures have not yet been applied to studies of complex mixtures.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Contaminantes Atmosféricos/efectos adversos , Monitoreo del Ambiente/métodos , Procesos Mentales/efectos de los fármacos , Neoplasias/epidemiología , Sistema Nervioso/efectos de los fármacos , Resultado del Embarazo/epidemiología , Monitoreo Epidemiológico , Femenino , Humanos , Neoplasias/inducido químicamente , EmbarazoRESUMEN
The purpose of this study was to identify personal characteristics that predict individual differences in acute FEV1 response to ozone exposure. Response and predictor data were collected on 290 white male volunteers 18 to 32 yr of age who were each exposed to one of six concentrations of ozone between 0.0 and 0.40 part per million. The sample was divided into an exploratory sample of 96 and a confirmatory sample of 194 subjects. Exploratory analysis indicated that ozone, age, and several other variables explained a significant proportion of the variance in response. In the confirmatory sample, only age and ozone concentration predicted FEV1 decrement. For the combined sample ozone explained 31% of the variance, with age accounting for an additional 4%. The model predicted a decreasing response with increasing age for all nonzero ozone concentrations. For exposure to 0.40 ppm, the model predicts decrements in FEV1 of 1.07 and 0.47 L for 18- and 30-yr-old subjects, respectively. We concluded that for white male subjects age was a significant predictor of response, with older subjects being less responsive to ozone. Furthermore, we demonstrated that exploratory analysis without control of type I statistical error rates may result in apparent findings that cannot be replicated.
Asunto(s)
Ozono/farmacología , Mecánica Respiratoria/efectos de los fármacos , Adolescente , Adulto , Factores de Edad , Relación Dosis-Respuesta a Droga , Volumen Espiratorio Forzado/efectos de los fármacos , Humanos , Modelos Logísticos , MasculinoRESUMEN
A previous study of mortality among white men hired at Oak Ridge National Laboratory between 1943 and 1972 (n = 8,318) revealed an association between low-dose external penetrating ionizing radiation and cancer mortality in follow-up through 1984. The association was not observed in follow-up through 1977. This report considers the role of possible selection and confounding factors not previously studied. Control for hire during the World War II era and employment duration of less than 1 year had little effect on the radiation risk estimates. Risks associated with length of time spent in 15 job categories were considered as proxies for the effects of other occupational carcinogens. Adjustment for employment duration in each job category one at a time produced only small changes in the radiation risk estimate. Adjustment for potential exposures to beryllium, lead, and mercury also had little effect on the radiation risk estimates. These analyses suggest that selection factors and potential for chemical exposure do not account for the previously noted association of external radiation dose with cancer mortality. However, power to detect effects of chemical exposures is limited by a lack of individual exposure measures.
Asunto(s)
Neoplasias Inducidas por Radiación/mortalidad , Neoplasias/mortalidad , Enfermedades Profesionales/mortalidad , Factores de Confusión Epidemiológicos , Relación Dosis-Respuesta en la Radiación , Estudios de Seguimiento , Humanos , Leucemia Inducida por Radiación/mortalidad , Masculino , Radiación Ionizante , Riesgo , Tennessee/epidemiología , Factores de TiempoRESUMEN
BACKGROUND: Fertility is reduced in female rats exposed to levels of nitrous oxide similar to those found in some dental offices. Epidemiologic studies have suggested an association between exposure to mixed anesthetic gases and impaired fertility. We investigated the effects of occupational exposure to nitrous oxide on the fertility of female dental assistants. METHODS: Screening questionnaires were mailed to 7000 female dental assistants, ages 18 to 39, registered by the California Department of Consumer Affairs. Sixty-nine percent responded. Four hundred fifty-nine women were determined to be eligible, having become pregnant during the previous four years for reasons unrelated to the failure of birth control, and 91 percent of these women completed telephone interviews. Detailed information was collected on exposure to nitrous oxide and fertility (measured by the number of menstrual cycles without contraception that the women required to become pregnant). RESULTS: After controlling for covariates, we found that women exposed to high levels of nitrous oxide were significantly less fertile than women who were unexposed or exposed to lower levels of nitrous oxide. The effect was evident only in the 19 women with five or more hours of exposure per week. These women were only 41 percent (95 percent confidence interval, 23 to 74 percent; P less than 0.003) as likely as unexposed women to conceive during each menstrual cycle. CONCLUSIONS: Occupational exposure to high levels of nitrous oxide may adversely affect women's ability to become pregnant.
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Asistentes Dentales , Fertilidad/efectos de los fármacos , Óxido Nitroso/efectos adversos , Exposición Profesional , Adolescente , Adulto , Femenino , Humanos , Estudios Retrospectivos , Encuestas y CuestionariosRESUMEN
Laboratory work aimed at improving the epidemiologic utility of an innovative genotoxicity assay is described. The exfoliated cell micronucleus assay involves microscopic analysis of epithelial smears to determine the prevalence of micronucleation, an indicator of structural or numerical chromosome aberrations. While the assay holds promise for the study of epithelial carcinogens, it is hampered by the fact that exfoliated cells are moribund and undergo degenerative phenomena that can produce extranuclear objects difficult to distinguish from classical micronuclei. Modifications in the protocol were assessed in sample buccal smears from several study populations: radiotherapy patients, nonusers of tobacco, and snuff users. Refinements in micronucleus scoring criteria and the inclusion of other nuclear anomalies in the scoring system are proposed. We demonstrate that our criteria are successful in detecting excess micronucleation in positive controls. We also provide evidence that other nuclear anomalies are at least as common as micronucleation and that therefore there is the potential for extensive misclassification. Reliability was assessed in duplicate readings.
Asunto(s)
Núcleo Celular/ultraestructura , Pruebas de Micronúcleos/métodos , Núcleo Celular/efectos de los fármacos , Mejilla , Humanos , Plantas Tóxicas , Reproducibilidad de los Resultados , Tabaco sin Humo/toxicidadRESUMEN
A revised protocol for the exfoliated cell micronucleus assay was field-tested in a population exposed to a genotoxic agent, snuff, at levels associated with a significant increase in cancer risk. The standard assay involves examination of epithelial smears to determine the prevalence of micronucleated cells, an indication of chromosome breakage or mitotic interference. The assay was revised to increase specificity and to include separate scoring of other nuclear anomalies associated with cytotoxicity and genotoxicity. The modified assay was applied to buccal smears of 38 female snuff users and 15 female nonusers recruited from a North Carolina clinic in 1987. The prevalence of micronucleation was elevated in the snuff users as compared with the nonusers (prevalence ratio = 2.4, 95% confidence interval 1.1-5.2) and, to a lesser extent, at the usual contact site as compared with a distal buccal site in the snuff users (prevalence ratio = 1.5, 95% confidence interval 0.9-2.5). The pattern of relative frequencies of several nuclear anomalies provided strong evidence of a cytotoxic effect, the prevalence ratios ranging from 2 to 13. Nuclear degenerative phenomena can be difficult to distinguish from classical micronuclei; thus, the observed association of indicators of cytotoxicity with exposure introduces the possibility of bias away from the null in micronucleus findings due to differential misclassification. Until methods to better distinguish extranuclear bodies of different origins become available, investigators should use the revised protocol and should focus on agents not thought to be cytotoxic.
Asunto(s)
Mejilla/patología , Aberraciones Cromosómicas/genética , Pruebas de Micronúcleos/normas , Plantas Tóxicas , Tabaquismo/complicaciones , Tabaco sin Humo/efectos adversos , Adulto , Anciano , Anciano de 80 o más Años , Aberraciones Cromosómicas/fisiología , Estudios de Evaluación como Asunto , Femenino , Humanos , Tamizaje Masivo/instrumentación , Tamizaje Masivo/métodos , Tamizaje Masivo/normas , Pruebas de Micronúcleos/instrumentación , Pruebas de Micronúcleos/métodos , Persona de Mediana Edad , North Carolina/epidemiología , Evaluación de Resultado en la Atención de Salud , Prevalencia , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Encuestas y CuestionariosRESUMEN
White men hired at the Oak Ridge (Tenn) National Laboratory between 1943 and 1972 were followed up for vital status through 1984 (N = 8318, 1524 deaths). Relatively low mortality compared with that in US white men was observed for most causes of death, but leukemia mortality was elevated in the total cohort (63% higher, 28 deaths) and in workers who had at some time been monitored for internal radionuclide contamination (123% higher, 16 deaths). Median cumulative dose of external penetrating radiation was 1.4 mSv; 638 workers had cumulative doses above 50 mSv (5 rem). After accounting for age, birth cohort, a measure of socioeconomic status, and active worker status, external radiation with a 20-year exposure lag was related to all causes of death (2.68% increase per 10 mSv) primarily due to an association with cancer mortality (4.94% per 10 mSv). Studies of this population through 1977 did not find radiation-cancer mortality associations, and identical analyses using the shorter follow-up showed that associations with radiation did not appear until after 1977. The radiation-cancer dose response is 10 times higher than estimates from the follow-up of survivors of the bombings of Hiroshima and Nagasaki, Japan, but similar to one previous occupational study. Dose-response estimates are subject to uncertainties due to potential problems, including measurement of radiation doses and cancer outcomes. Longer-term follow-up of this and other populations with good measurement of protracted low-level exposures will be critical to evaluating the generalizability of the results reported herein.