RESUMEN
INTRODUCTION: The United States and Western Europe have seen great improvements in air quality, presumably in response to various regulations curtailing emissions from the broad range of sources that have contributed to local, regional, and global pollution. Such regulations, and the ensuing controls, however, have not come without costs, which are estimated at tens of billions of dollars per year. These costs motivate accountability-related questions such as, to what extent do regulations lead to emissions changes? More important, to what degree have the regulations provided the expected human health benefits?Here, the impacts of specific regulations on both electricity generating unit (EGU) and on-road mobile sources are examined through the classical accountability process laid out in the 2003 Health Effects Institute report linking regulations to emissions to air quality to health effects, with a focus on the 1999-2013 period. This analysis centers on regulatory actions in the southeastern United States and their effects on health outcomes in the 5-county Atlanta metropolitan area. The regulations examined are largely driven by the 1990 Clean Air Act Amendments (C). This work investigates regulatory actions and controls promulgated on EGUs: the Acid Rain Program (ARP), the NOx Budget Trading Program (NBP), and the Clean Air Interstate Rule (CAIR) - and mobile sources: Tier 2 Gasoline Vehicle Standards and the 2007 Heavy Duty Diesel Rule. METHODS: Each step in the classic accountability process was addressed using one or more methods. Linking regulations to emissions was accomplished by identifying major federal regulations and the associated state regulations, along with analysis of individual facility emissions and control technologies and emissions modeling (e.g., using the U.S. Environmental Protection Agency's [U.S. EPA's] MOtor Vehicle Emissions Simulator [MOVES] mobile-source model). Regulators, including those from state environmental and transportation agencies, along with the public service commissions, play an important role in implementing federal rules and were involved along with other regional stakeholders in the study. We used trend analysis, air quality modeling, satellite data, and a ratio-of-ratios technique to investigate a critical current issue, a potential large bias in mobile-source oxides of nitrogen (NOx) emissions estimates.The second link, emissions-air quality relationships, was addressed using both empirical analyses as well as chemical transport modeling employing the Community Multiscale Air Quality (CMAQ) model. Kolmogorov-Zurbenko filtering accounting for day of the year was used to separate the air quality signal into long-term, seasonal, weekday-holiday, and short-term meteorological signals. Regression modeling was then used to link emissions and meteorology to ambient concentrations for each of the species examined (ozone [O3], particulate matter ≤ 2.5 µm in aerodynamic diameter [PM2.5], nitrogen dioxide [NO2], sulfur dioxide [SO2], carbon monoxide [CO], sulfate [SO4-2], nitrate [NO3-], ammonium [NH4+], organic carbon [OC], and elemental carbon [EC]). CMAQ modeling was likewise used to link emissions changes to air quality changes, as well as to further establish the relative roles of meteorology versus emissions change impacts on air quality trends. CMAQ and empirical modeling were used to investigate aerosol acidity trends, employing the ISORROPIA II thermodynamic equilibrium model to calculate pH based on aerosol composition. The relationships between emissions and meteorology were then used to construct estimated counterfactual air quality time series of daily pollutant concentrations that would have occurred in the absence of the regulations. Uncertainties in counterfactual air quality were captured by the construction of 5,000 pollutant time series using a Monte Carlo sampling technique, accounting for uncertainties in emissions and model parameters.Health impacts of the regulatory actions were assessed using data on cardiorespiratory emergency department (ED) visits, using patient-level data in the Atlanta area for the 1999-2013 period. Four outcome groups were chosen based on previous studies identifying associations with ambient air pollution: a combined respiratory disease (RD) category; the subgroup of RD presenting with asthma; a combined cardiovascular disease (CVD) category; and the subgroup of CVD presenting with congestive heart failure (CHF).Models were fit to estimate the joint effects of multiple pollutants on ED visits in a time-series framework, using Poisson generalized linear models accounting for overdispersion, with a priori model formulations for temporal and meteorological covariates and lag structures. Several parameterizations were considered for the joint-effects models, including different sets of pollutants and models with nonlinear pollutant terms and first-order interactions among pollutants. Use of different periods for parameter estimates was assessed, as associations between pollutant levels and ED visits varied over the study period. A 7-pollutant, nonlinear model with pollutant interaction terms was chosen as the baseline model and fitted using pollutant and outcome data from 1999-2005 before regulations might have substantially changed the toxicity of pollutant mixtures. In separate analyses, these models were fitted using pollutant and outcome data from the entire 1999-2013 study period. Daily counterfactual time series of pollutant concentrations were then input into the health models, and the differences between the observed and counterfactual concentrations were used to estimate the impacts of the regulations on daily counts of ED visits. To account for the uncertainty in both the estimation of the counterfactual time series of ambient pollutant levels and the estimation of the health model parameters, we simulated 5,000 sets of parameter estimates using a multivariate normal distribution based on the observed variance-covariance matrix, allowing for uncertainty at each step of the chain of accountability. Sensitivity tests were conducted to assess the robustness of the results. RESULTS: EGU NOx and SO2 emissions in the Southeast decreased by 82% and 83%, respectively, between 1999 and 2013, while mobile-source emissions controls led to estimated decreases in Atlanta-area pollutant emissions of between 61% and 93%, depending on pollutant. While EGU emissions were measured, mobile-source emissions were modeled. Our results are supportive of a potential high bias in mobile-source NOx and CO emissions estimates. Air quality benefits from regulatory actions have increased as programs have been fully implemented and have had varying impacts over different seasons. In a scenario that accounted for all emissions reductions across the period, observed Atlanta central monitoring site maximum daily 8-hour (MDA8h) O3 was estimated to have been reduced by controls in the summertime and increased in the wintertime, with a change in mean annual MDA8h O3 from 39.7 ppb (counterfactual) to 38.4 ppb (observed). PM2.5 reductions were observed year-round, with average 2013 values at 8.9 µg/m3 (observed) versus 19.1 µg/m3 (counterfactual). Empirical and CMAQ analyses found that long-term meteorological trends across the Southeast over the period examined played little role in the distribution of species concentrations, while emissions changes explained the decreases observed. Aerosol pH, which plays a key role in aerosol formation and dynamics and may have health implications, was typically very low (on the order of 1-2, but sometimes much lower), with little trend over time despite the stringent SO2 controls and SO42- reductions.Using health models fit from 1999-2005, emissions reductions from all selected pollution-control policies led to an estimated 55,794 cardiorespiratory disease ED visits prevented (i.e., fewer observed ED visits than would have been expected under counterfactual scenarios) - 52,717 RD visits, of which 38,038 were for asthma, and 3,057 CVD visits, of which 2,104 were for CHF - among the residents of the 5-county area over the 1999-2013 period, an area with approximately 3.5 million people in 2013. During the final two years of the study (2012-2013), when pollution-control policies were most fully implemented and the associated benefits realized, these policies were estimated to prevent 5.9% of the RD ED visits that would have occurred in the absence of the policies (95% interval estimate: -0.4% to 12.3%); 16.5% of the asthma ED visits (95% interval estimate: 7.5% to 25.1%); 2.3% of the CVD ED visits (95% interval estimate: -1.8% to 6.2%); and -.6% of the CHF ED visits (95% interval estimate: 26.3% to 10.4%). Estimates of ED visits prevented were generally lower when using health models fit for the entire 1999-2013 study period.Sensitivity analyses were conducted to show the impact of the choice of parameterization of the health models and to assess alternative definitions of the study area. When impacts were assessed for separate policy interventions, policies affecting emissions from EGUs, especially the ARP and the NBP, appeared to have had the greatest effect on prevention of RD and asthma ED visits. CONCLUSIONS: This study demonstrates the effectiveness of regulations on improving air quality and health in the southeastern United States. It also demonstrates the complexities of accountability assessments as uncertainties are introduced in each step of the classic accountability process. While accounting for uncertainties in emissions, air quality-emissions relationships, and health models does lead to relatively large uncertainties in the estimated outcomes due to specific regulations, overall the benefits of regulations have been substantial.
RESUMEN
BACKGROUND: Emergency department (ED) visit and hospital admissions (HA) data have been an indispensible resource for assessing acute morbidity impacts of air pollution. ED visits and HAs are types of health care visits with similarities, but also potentially important differences. Little previous information is available regarding the impact of health care visit type on observed acute air pollution-health associations from studies conducted for the same location, time period, outcome definitions and model specifications. METHODS: As part of a broader study of air pollution and health in St. Louis, individual-level ED and HA data were obtained for a 6.5 year period for acute care hospitals in the eight Missouri counties of the St. Louis metropolitan area. Patient demographic characteristics and diagnostic code distributions were compared for four visit types including ED visits, HAs, HAs that came through the ED, and non-elective HAs. Time-series analyses of the relationship between daily ambient ozone and PM2.5 and selected cardiorespiratory outcomes were conducted for each visit type. RESULTS: Our results indicate that, compared with ED patients, HA patients tended to be older, had evidence of greater severity for some outcomes, and had a different mix of specific outcomes. Consideration of 'HA through ED' appeared to more effectively select acute visits than consideration of 'non-elective HA'. While outcomes with the strongest observed temporal associations with air pollutants tended to show strong associations for all visit types, we found some differences in observed associations for ED visits and HAs. For example, risk ratios for the respiratory disease-ozone association were 1.020 for ED visits and 1.004 for 'HA through ED'; risk ratios for the asthma/wheeze-ozone association were 1.069 for ED visits and 1.106 for 'HA through ED'. Several factors (e.g. age) were identified that may be responsible, in part, for the differences in observed associations. CONCLUSIONS: Demographic and diagnostic differences between visit types may lead to preference for one visit type over another for some questions and populations. The strengths of observed associations with air pollutants sometimes varied between different health care visit types, but the relative strengths of association generally were specific to the pollutant-outcome combination.
Asunto(s)
Contaminación del Aire/efectos adversos , Enfermedades Cardiovasculares/epidemiología , Servicio de Urgencia en Hospital/estadística & datos numéricos , Hospitalización/estadística & datos numéricos , Enfermedades Respiratorias/epidemiología , Adolescente , Adulto , Anciano , Contaminantes Atmosféricos/toxicidad , Niño , Preescolar , Humanos , Lactante , Recién Nacido , Persona de Mediana Edad , Ozono/toxicidad , Material Particulado/toxicidad , Factores de Tiempo , Adulto JovenRESUMEN
BACKGROUND: Relationships between ambient air pollution levels during pregnancy and adverse pregnancy outcomes have been investigated using one of three analytic approaches: ambient pollution levels have been contrasted over space, time or both space and time. Although the three approaches share a common goal, to estimate the causal effects of pollution on pregnancy outcomes, they face different challenges with respect to confounding. METHODS: A framework based on counterfactual effect definitions to examine issues related to confounding in spatial, temporal, and spatial-temporal analyses of air pollution and pregnancy outcomes is presented, and their implications for inference are discussed. RESULTS: In spatial analyses, risk factors that are spatially correlated with pollution levels are confounders; the primary challenges relate to the availability and validity of risk factor measurements. In temporal analyses, where smooth functions of time are commonly used to control for confounding, concerns relate to the adequacy of control and the possibility that abrupt changes in risk might be systematically related to pollution levels. Spatial-temporal approaches are subject to challenges faced in both spatial and temporal analyses. CONCLUSION: Each approach faces different challenges with respect to the likely sources of confounding and the ability to control for that confounding because of differences in the type, availability, and quality of information required. Thoughtful consideration of these differences should help investigators select the analytic approach that best promotes the validity of their research.
Asunto(s)
Contaminación del Aire/efectos adversos , Resultado del Embarazo/epidemiología , Contaminación del Aire/análisis , Factores de Confusión Epidemiológicos , Monitoreo del Ambiente/métodos , Monitoreo Epidemiológico , Femenino , Humanos , Exposición Materna/efectos adversos , EmbarazoRESUMEN
OBJECTIVE: Non-Hodgkin's lymphoma (NHL) encompasses diverse subtypes, and analyzing NHL as a single outcome may mask associations. In a new approach we evaluated associations with subtypes defined by the t(14;18) translocation, reasoning that cases within these subtypes would have more common risk factors than all NHL combined. METHODS: Archival biopsies from cases in a population-based NHL study were assayed for t(14;18) using polymerase chain reaction amplification. Exposures in 68 t(14;18)-positive and 114-negative cases were compared with 1245 controls. The expectation-maximization algorithm was used to fit polytomous regression models based on all available information, including data from 440 unclassified cases. RESULTS: Family history of hemolymphatic cancer was associated with t(14;18)-negative NHL (odds ratio (OR) 2.4, 95% confidence interval (CI) 1.4 3.9). but not t(14;18)-positive NHL. Cigarette smoking was weakly associated with t(14;18)-positive NHL (OR 1.7, CI 0.9-3.3), but ORs decreased as smoking increased. Chewing tobacco was associated with t(14;18)-positive NHL, particularly when used before age 18 (OR 2.5. CI 1.0-6.0, 13 exposed cases). Odds ratios for both case-subtypes were doubled among hair-dye users. CONCLUSIONS: Cigarette smoking was not clearly associated with t(14;18)-positive NHL. Family history may be a marker for factors that act specifically through t(14;18)-negative pathogenic mechanisms.
Asunto(s)
Cromosomas Humanos Par 14/genética , Cromosomas Humanos Par 18/genética , Linfoma no Hodgkin/etiología , Linfoma no Hodgkin/genética , Exposición Profesional , Fumar/efectos adversos , Translocación Genética , Adolescente , Adulto , Anciano , Estudios de Casos y Controles , Salud de la Familia , Humanos , Incidencia , Linfoma no Hodgkin/epidemiología , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Factores de RiesgoRESUMEN
In the early 1970s, the largest industrial accident in the United States resulted in widespread contamination of the food supply in Michigan with polybrominated biphenyls (PBBs). The chemical similarity of PBBs to compounds implicated as endocrine disruptors has raised the question of whether PBBs could affect the reproductive system. In the present analysis we examine the relation between serum measurements of PBBs and the frequency and duration of lactation. Persons who lived on or received food from farms exposed to PBBs were enrolled in a registry by the Michigan Department of Public Health. Female members of the cohort were invited to participate in a telephone survey of reproductive outcomes. The three outcomes of interest in the present analysis were a) the decision to breast-feed (yes/no); b) the duration, in months, of breast-feeding as the main source of nutrition; and c) the total duration, in months, of breast-feeding. None of the three outcomes was significantly associated with serum PBB levels, even after controlling for maternal age, previous history of breast-feeding, body mass index, maternal education, household income, history of smoking in the year before pregnancy, consumption of alcohol during the first trimester of pregnancy, history of thyroid disorder, gestational age of the infant in weeks, time to pregnancy, and year of birth.
Asunto(s)
Accidentes de Trabajo , Contaminantes Ambientales/efectos adversos , Contaminación de Alimentos , Lactancia , Leche Humana/química , Bifenilos Policlorados/efectos adversos , Adolescente , Adulto , Factores de Edad , Índice de Masa Corporal , Niño , Preescolar , Estudios de Cohortes , Toma de Decisiones , Contaminantes Ambientales/análisis , Femenino , Encuestas Epidemiológicas , Humanos , Renta , Lactante , Recién Nacido , Michigan , Paridad , Bifenilos Policlorados/análisis , Embarazo , Factores de RiesgoRESUMEN
The t(14;18) translocation is a common somatic mutation in non-Hodgkin's lymphoma (NHL) that is associated with bcl-2 activation and inhibition of apoptosis. We hypothesized that some risk factors might act specifically along t(14;18)-dependent pathways, leading to stronger associations with t(14;18)-positive than t(14;18)-negative non-Hodgkin's lymphoma. Archival biopsies from 182 non-Hodgkin's lymphoma cases included in a case-control study of men in Iowa and Minnesota (the Factors Affecting Rural Men, or FARM study) were assayed for t(14;18) using polymerase chain reaction amplification; 68 (37%) were t(14;18)-positive. We estimated adjusted odds ratios (OR) and 95% confidence intervals (CI) for various agricultural risk factors and t(14;18)-positive and -negative cases of non-Hodgkin's lymphoma, based on polytomous logistic regression models fit using the expectation-maximization (EM) algorithm. T(14;18)-positive non-Hodgkin's lymphoma was associated with farming (OR 1.4, 95% CI = 0.9-2.3), dieldrin (OR 3.7, 95% CI = 1.9-7.0), toxaphene (OR 3.0, 95% CI = 1.5-6.1), lindane (OR 2.3, 95% CI = 1.3-3.9), atrazine (OR 1.7, 95% CI = 1.0-2.8), and fungicides (OR 1.8, 95% CI = 0.9-3.6), in marked contrast to null or negative associations for the same self-reported exposures and t(14;18)-negative non-Hodgkin's lymphoma. Causal relations between agricultural exposures and t(14;18)-positive non-Hodgkin's lymphoma are plausible, but associations should be confirmed in a larger study. Results suggest that non-Hodgkin's lymphoma classification based on the t(14;18) translocation is of value in etiologic research.
Asunto(s)
Enfermedades de los Trabajadores Agrícolas/genética , Cromosomas Humanos Par 14/efectos de los fármacos , Cromosomas Humanos Par 18/efectos de los fármacos , Linfoma no Hodgkin/genética , Translocación Genética/genética , Adulto , Anciano , Enfermedades de los Trabajadores Agrícolas/inducido químicamente , Enfermedades de los Trabajadores Agrícolas/epidemiología , Agroquímicos/efectos adversos , Algoritmos , Apoptosis/genética , Estudios de Casos y Controles , Cromosomas Humanos Par 14/genética , Cromosomas Humanos Par 18/genética , Intervalos de Confianza , Genes bcl-2/genética , Humanos , Hidrocarburos Clorados/efectos adversos , Iowa/epidemiología , Linfoma no Hodgkin/inducido químicamente , Linfoma no Hodgkin/epidemiología , Masculino , Persona de Mediana Edad , Minnesota/epidemiología , Oportunidad Relativa , Reacción en Cadena de la Polimerasa/métodos , Factores de RiesgoRESUMEN
Agricultural exposures differ across the United States by region, calendar time period, and agricultural practice, but most of the published literature focuses on white men in the Midwest. A pilot study was conducted to explore the breadth and diversity of farming practices over time among African-American farmers in Georgia whose exposures may differ in important ways. Using a comprehensive life events calendar questionnaire, 17 male African-American farmers aged 36 to 86 yr residing in southeastern Georgia were interviewed regarding their agricultural history in July 1997. Most men (15/17) reported working on multiple farms in their lifetime; 3 men worked on 5 different farms during their lifetime. These farmers reported using more chemicals during their lifetime than farmers in the Midwest. Used motor oil was the most frequently reported insecticide applied to animals; this apparently common practice has not been described in the literature and should be better understood since its use may result in dermal exposure to polyaromatic hydrocarbons. Better characterization of regionally specific farming history and individual farming practices will facilitate studies of the health effects of farming.
Asunto(s)
Enfermedades de los Trabajadores Agrícolas/epidemiología , Exposición Profesional/estadística & datos numéricos , Adulto , Negro o Afroamericano , Anciano , Anciano de 80 o más Años , Recolección de Datos , Georgia/epidemiología , Humanos , Masculino , Persona de Mediana Edad , Plaguicidas , Encuestas y CuestionariosRESUMEN
Pancreatic cancer is a highly fatal cancer with few identified risk factors. Increased risk of pancreatic cancer in tobacco smokers and among diabetic patients is well established, and some reports have suggested associations with coffee consumption and occupational exposure to organochlorines. At present, there is little information regarding the possible association of these risk factors with the known genetic alterations found in pancreatic cancers, such as activation of the K-ras oncogene and inactivation of the p53 tumor suppressor gene. Knowledge of such relationships may help to understand the molecular pathways of pancreatic tumorigenesis. We investigated the association between these molecular defects and risk factors for pancreatic cancer in 61 newly diagnosed patients identified through an ongoing study of pancreatic cancer in the San Francisco Bay Area. Interview information was obtained regarding environmental exposures, medical history, and demographic factors. Serum levels of dichlorodiphenyltrichloroethylene (DDE) and polychlorinated biphenyls were available on a subset of 24 patients. Tumor blocks were located from local hospitals and used for K-ras mutational analysis at codon 12 and for p53 protein immunohistochemistry. The molecular analyses were facilitated through the use of laser capture microdissection, which provides a reliable method to obtain almost pure populations of tumor cells. Mutations in K-ras codon 12 were found in 46 (75%) of 61 pancreatic cancers. A prior diagnosis of diabetes was significantly associated with K-ras negative tumors (P = 0.002, Fisher's exact test). The absence of this mutation was also associated with increased serum levels of DDE, although this association was not statistically significant (P = 0.16, Wilcoxon's test). There was no difference in polychlorinated biphenyl levels between the K-ras wild-type and mutant groups. Immunohistochemical staining for p53 protein did not differ by patient characteristics or clinical history, but significant associations were found with poor glandular differentiation (P = 0.002, chi2 trend test), severe nuclear atypia (P = 0.0007, chi2 trend test), and high tumor grade (P = 0.004, chi2 trend test). Our results are suggestive of the presence of K-ras codon 12 mutation-independent tumorigenesis pathways in patients with prior diabetes and possibly in patients with higher serum levels of DDE. Our results also support a role for the p53 tumor suppressor protein in the maintenance of genomic integrity.
Asunto(s)
Carcinógenos/efectos adversos , Exposición a Riesgos Ambientales , Genes p53/genética , Genes ras/genética , Neoplasias Pancreáticas/genética , Anciano , Estudios de Casos y Controles , Análisis Mutacional de ADN , Complicaciones de la Diabetes , Diclorodifenil Dicloroetileno/efectos adversos , Femenino , Humanos , Inmunohistoquímica , Insecticidas/efectos adversos , Masculino , Anamnesis , Persona de Mediana Edad , Neoplasias Pancreáticas/etiología , Factores de RiesgoRESUMEN
Substantial evidence supports an association of particulate matter (PM) with cardiorespiratory illnesses, but little is known regarding characteristics of PM that might contribute to this association and the mechanisms of action. The Atlanta superstation sponsored by the Electric Power Research Institute as part of the Aerosol Research and Inhalation Epidemiology Study (ARIES) study is monitoring chemical composition of ambient particles by size fraction, as well as a comprehensive suite of other pollutants, at a site in downtown Atlanta during the 25-month period, August 1, 1998-August 31, 2000. Our investigative team is making use of this unique resource in several morbidity studies, called the "Study of Particulates and Health in Atlanta (SOPHIA)". The study includes the following components: (1) a time series investigation of emergency department (ED) visits for the period during which the superstation is operating; (2) a time series investigation of ED visits during the 5 years prior to implementation of the superstation; and (3) a study of arrhythmic events in patients equipped with automatic implantable cardioverter defibrillators (AICDs) for the period January 1, 1993-August 31, 2000. Thirty-three of 39 Atlanta area EDs are participating in the ED studies, comprising over a million annual ED visits. In this paper, we present initial analyses of data from 18 of the 33 participating EDs. The preliminary data set includes 1,662,713 ED visits during the pre-superstation time period and 559,480 visits during the superstation time period. Visits for four case groupings--asthma, chronic obstructive pulmonary disease (COPD), dysrhythmia, and all cardiovascular diseases (CVDs) combined--have been assessed relative to daily air quality indices, controlling for long-term temporal trends and meteorologic variables, using general linear models, generalized estimating equations and generalized additive models. Single-pollutant models predicting case visitation rates using moving averages of 0-, 1-, and 2-day lagged air quality variables were run. For the pre-superstation period, PM10 (24-h), ozone (8-h), SO2 (1-h), NO2 (1-h) and CO (1-h) were studied. For the first 12 months of superstation operation, the following air quality variables of a priori interest were available: ozone (8-h), NO2 (1-h), SO2 (1-h), CO (1-h), and 24-h measurements of PM10, coarse PM (PM 2.5-10 microm), PM2.5, polar VOCs, 10-100 nm particulate count and surface area, and in the PM2.5 fraction: sulfates, acidity, water-soluble metals, organic matter (OM), and elemental carbon (EC). During the pre-superstation time period, statistically significant, positive associations were observed for adult asthma with ozone, and for COPD with ozone, NO2 and PM10. During the superstation time period, the following statistically significant, positive associations were observed: dysrhythmia with CO, coarse PM, and PM2.5 EC; and all CVDs with CO, PM2.5 EC and PM2.5 OM. While covariation of many of the air quality indices limits the informativeness of this analysis, the study provides one of the first assessments of PM components in relation to ED visits.
Asunto(s)
Contaminantes Atmosféricos/efectos adversos , Enfermedades Cardiovasculares/epidemiología , Servicio de Urgencia en Hospital/estadística & datos numéricos , Monitoreo del Ambiente/métodos , Enfermedades Respiratorias/epidemiología , Adulto , Contaminantes Atmosféricos/análisis , Enfermedades Cardiovasculares/etiología , Recolección de Datos , Monitoreo Epidemiológico , Femenino , Georgia/epidemiología , Humanos , Masculino , Persona de Mediana Edad , Marcapaso Artificial , Enfermedades Respiratorias/etiología , Estadísticas no Paramétricas , Población UrbanaRESUMEN
Accidental contamination of the Michigan food chain with polybrominated biphenyls (PBBs) led to the exposure of more than 4,000 individuals in 1973. Because PBB exposure is suspected to disrupt endocrine function, we assessed pubertal development in females 5-24 years of age (N = 327) who were exposed to PBB in utero and, in many cases, through breastfeeding. We estimated in utero PBB exposure using maternal serum PBB measurements taken after exposure (1976-1979) and extrapolated to time of pregnancy using a model of PBB decay. We found that breastfed girls exposed to high levels of PBB in utero (> or =7 parts per billion) had an earlier age at menarche (mean age = 11.6 years) than breastfed girls exposed to lower levels of PBB in utero (mean age = 12.2-12.6 years) or girls who were not breastfed (mean age = 12.7 years). This association persisted after adjustment for potential confounders (menarche ratio = 3.4, 95% confidence interval = 1.3-9.0). Perinatal PBB exposure was associated with earlier pubic hair stage in breastfed girls, but little association was found with breast development. The associations observed here lend support to the hypothesis that pubertal events may be affected by pre- and postnatal exposure to organohalogens.
Asunto(s)
Contaminación de Alimentos , Menarquia/efectos de los fármacos , Bifenilos Polibrominados/farmacología , Efectos Tardíos de la Exposición Prenatal , Adolescente , Adulto , Lactancia Materna , Niño , Preescolar , Escolaridad , Femenino , Humanos , Modelos Logísticos , Edad Materna , Michigan , Bifenilos Polibrominados/sangre , Bifenilos Policlorados/sangre , Bifenilos Policlorados/farmacología , EmbarazoRESUMEN
Pediatric emergency room visits for asthma were studied in relation to air quality indices in a spatio-temporal investigation of approximately 130,000 visits (approximately 6,000 for asthma) to the major emergency care centers in Atlanta, Georgia, during the summers of 1993-1995. Generalized estimating equations, logistic regression, and Bayesian models were fitted to the data. In logistic regression models comparing estimated exposures of asthma cases with those of the nonasthma patients, controlling for temporal and demographic covariates and using residential zip code to link patients to spatially resolved ozone levels, the estimated relative risk per 20 parts per billion (ppb) increase in the maximum 8-hour ozone level was 1.04 (p < 0.05). The estimated relative risk for particulate matter less than or equal to 10 microm in aerodynamic diameter (PM10) was 1.04 per 15 microg/m3 (p < 0.05). Exposure-response trends (p < 0.01) were observed for ozone (>100 ppb vs. <50 ppb: odds ratio = 1.23, p = 0.003) and PM10 (>60 microg/m3 vs. <20 microg/m3: odds ratio = 1.26, p = 0.004). In models with ozone and PM10, both terms became nonsignificant because of collinearity of the variables (r= 0.75). The other analytical approaches yielded consistent findings. This study supports accumulating evidence regarding the relation of air pollution to childhood asthma exacerbation.
Asunto(s)
Contaminantes Atmosféricos/efectos adversos , Asma/terapia , Servicio de Urgencia en Hospital/estadística & datos numéricos , Adolescente , Asma/epidemiología , Niño , Preescolar , Exposición a Riesgos Ambientales , Femenino , Georgia/epidemiología , Humanos , Incidencia , Lactante , Recién Nacido , Masculino , Oxidantes Fotoquímicos/efectos adversos , Ozono/efectos adversos , Estudios RetrospectivosRESUMEN
Electric and magnetic fields (EMFs) have been hypothesized to increase the risk of breast cancer, and electric blankets represent an important source of exposure to EMFs. The authors examined the relation between electric blanket use and invasive breast cancer in the Nurses' Health Study. On the biennial questionnaire in 1992, 87,497 women provided information on this exposure during three consecutive time periods. In a prospective analysis with 301,775 person-years of follow-up through 1996 (954 cases), the relative risk for any electric blanket use was not elevated (relative risk (RR) = 1.08, 95% confidence interval (CI): 0.95, 1.24) after controlling for breast cancer risk factors. There was a weak association between breast cancer and electric blanket use at least 16 years before diagnosis and long-term use in age-adjusted analyses but not in multivariate models. In a retrospective analysis of 1,318,683 person-years of follow-up (2,426 cases), the multivariate relative risk associated with use before disease follow-up began was null (RR = 1.05, 95% CI: 0.95, 1.16). Similar results were obtained in analyses stratified by menopause and restricted to estrogen receptor-positive breast cancers. While 95% confidence intervals for these estimates did not exclude small risks, overall, results did not support an association between breast cancer risk and exposure to EMFs from electric blankets.
Asunto(s)
Ropa de Cama y Ropa Blanca , Neoplasias de la Mama/epidemiología , Neoplasias de la Mama/etiología , Electricidad/efectos adversos , Adulto , Femenino , Humanos , Incidencia , Persona de Mediana Edad , Enfermeras y Enfermeros , Estudios Prospectivos , Estudios Retrospectivos , Factores de Riesgo , Encuestas y CuestionariosRESUMEN
BACKGROUND: Epidemiologic data for an association between radiation exposure and non-Hodgkin's lymphoma (NHL) have been inconclusive though the strongest evidence has been provided by studies of patients treated with radiotherapy. METHODS: We evaluated the association between occupational radiation exposure and non-Hodgkin's lymphoma in men using a population-based case-control study with 1,056 case and 1,860 control subjects sampled from eight geographic areas in the United States. Because dosimetry data were not available, doses were estimated for individuals who reported occupational radiation exposure using a radiation job exposure matrix developed for this purpose. Conditional logistic regression was used to model the association between reported occupational radiation exposure and NHL incidence. RESULTS: We found that most men (> 90%) did not report exposure to occupational sources of radiation. Among those who reported exposure, estimated cumulative doses were low, with an estimated mean of less than 0.02 Gray and a maximum of 0.12 Gray. The risk for NHL was not associated with ever having reported an occupational radiation exposure (OR = 0.90, 95% CI = 0.74-1.10) nor was there evidence of a dose-response relationship between risk and either the estimated cumulative doses or duration of exposure. CONCLUSIONS: The findings in this study are consistent with results from most current research on occupational radiation and NHL risk that have found no increased risk of NHL at low levels of occupational radiation exposure. While it should be noted that exposure misclassification likely biased our results toward the null, this large population-based case-control study adds to existing evidence which suggests that there is little to no increased risk for NHL associated with exposure to low levels of radiation such as that commonly found in many occupational settings.
Asunto(s)
Linfoma no Hodgkin/epidemiología , Exposición Profesional/efectos adversos , Traumatismos por Radiación/epidemiología , Adulto , Estudios de Casos y Controles , Comorbilidad , Recolección de Datos , Relación Dosis-Respuesta en la Radiación , Femenino , Humanos , Incidencia , Modelos Logísticos , Linfoma no Hodgkin/etiología , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Dosis de Radiación , Medición de Riesgo , Tasa de SupervivenciaRESUMEN
BACKGROUND: Elevated rates of nasal and nasopharyngeal cancers have been associated with wood-related occupational exposures, including chlorophenols, formaldehyde, and wood dust. METHODS: Occupational information was obtained from 43 nasal carcinoma cases, 92 nasopharyngeal carcinoma cases, and 1909 controls, by interview. Exact conditional logistic regression was used to evaluate the association of these cancers with chlorophenol exposure, estimated from a review of verbatim responses. RESULTS: Both nasal and nasopharyngeal cancers were significantly associated with estimated duration of chlorophenol exposure. For nasopharyngeal cancer, elevated risk was observed among those who held jobs assigned medium or high intensity chlorophenol exposure (n(exposed)=18, OR=1.94, 95% CI=1.03-3.50) and among those with 10+ years in jobs assigned high intensity with high certainty (n(exposed)=3, OR=9.07, 95% CI=1.41-42. 9). Controlling for estimated formaldehyde and wood dust exposure did not alter these findings, as much of the estimated chlorophenol exposure was among machinists. CONCLUSIONS: These findings support the hypothesis that occupational exposure to chlorophenol is a risk factor for nasal and nasopharyngeal cancer, although the role of machining-related exposures warrants further assessment.
Asunto(s)
Clorofenoles/efectos adversos , Neoplasias Nasofaríngeas/epidemiología , Neoplasias Nasales/epidemiología , Enfermedades Profesionales/epidemiología , Exposición Profesional/estadística & datos numéricos , Adulto , Estudios de Casos y Controles , Intervalos de Confianza , Factores de Confusión Epidemiológicos , Polvo/efectos adversos , Fijadores/efectos adversos , Formaldehído/efectos adversos , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Vigilancia de la Población , Factores de Riesgo , Fumar/epidemiología , Factores de Tiempo , Estados Unidos/epidemiología , MaderaRESUMEN
Occupational exposure to p,p'-dichlorodiphenyltrichloroethane (DDT) has been associated with increased pancreatic cancer risk. We measured organochlorine levels in serum obtained at the study enrollment from 108 pancreatic cancer cases and 82 control subjects aged 32-85 years in the San Francisco Bay Area between 1996 and 1998. Cases were identified using rapid case-ascertainment methods; controls were frequency-matched to cases on age and sex via random digit dial and random sampling of Health Care Financing Administration lists. Serum organochlorine levels were adjusted for lipid content to account for variation in the lipid concentration in serum between subjects. Median concentrations of p,p'-dichlorodiphenyldichloroethylene (DDE, 1290 versus 1030 ng/g lipid; P = 0.05), polychlorinated biphenyls (PCBs; 330 versus 220 ng/g lipid; P<0.001), and transnonachlor (54 versus 28 ng/g lipid; P = 0.03) were significantly greater among cases than controls. A significant dose-response relationship was observed for total PCBs (P for trend <0.001). Subjects in the highest tertile of PCBs (> or =360 ng/g lipid) had an odds ratio (OR) of 4.2 [95% confidence interval (CI) = 1.8-9.4] compared to the lowest tertile. The OR of 2.1 for the highest level of p,p'-DDE (95% CI = 0.9-4.7) diminished (OR = 1.1; 95% CI = 0.4-2.8) when PCBs were included in the model. Because pancreatic cancer is characterized by cachexia, the impact of this on the serum organochlorine levels in cases is difficult to predict. One plausible effect of cachexia is bioconcentration of organochlorines in the diminished lipid pool, which would lead to a bias away from the null. To explore this, a sensitivity analysis was performed assuming a 10-40% bioconcentration of organochlorines in case samples. The OR associated with PCBs remained elevated under conditions of up to 25% bioconcentration.
Asunto(s)
Hidrocarburos Clorados , Insecticidas/efectos adversos , Neoplasias Pancreáticas/etiología , Adulto , Anciano , Anciano de 80 o más Años , Caquexia , Estudios de Casos y Controles , Relación Dosis-Respuesta a Droga , Femenino , Humanos , Insecticidas/sangre , Masculino , Persona de Mediana Edad , Exposición Profesional , Neoplasias Pancreáticas/epidemiología , Neoplasias Pancreáticas/fisiopatología , Factores de RiesgoRESUMEN
Accidental contamination of the food chain in Michigan in 1973 with polybrominated biphenyls (PBBs) led to the establishment of a registry of exposed individuals in 1976. Serum was collected and analyzed for PBB at the time of enrollment and for targeted studies in the following years. We used the archived PBB data to study the elimination of PBB and to identify factors associated with elimination. A total of 380 women >= 16 years of age who had an initial PBB level of 2 ppb and at least two serum samples drawn when they were not pregnant were included in the analysis. The mean initial PBB level was 20.9 ppb (median 4) and mean time between the first and last measurement was 4.2 years (range 0.5-11.1). PBB was assumed to reach equilibrium in the body before substantial amounts were eliminated and before the first serum measurements were taken; therefore, the entire body was modeled as a single compartment for PBB with exponential decay. Subject-specific decay rate estimates were regressed on predictor variables including initial age, body mass index (BMI), smoking history, breast-feeding duration, and parity. In women with an initial PBB level < 10 ppb, the median half-life was 12.9 years; in those with > 10 ppb, the median half-life was 28.7 years. Decay was significantly slower among women with an initial BMI at or above the median (BMI >= 23). The calculated half-life values are estimates of decay and can be used to estimate body burden of PBB at various points in time other than at the time of serum collection.
Asunto(s)
Contaminantes Ambientales/farmacocinética , Contaminación de Alimentos , Bifenilos Polibrominados/farmacocinética , Adolescente , Adulto , Anciano , Índice de Masa Corporal , Estudios de Cohortes , Contaminantes Ambientales/sangre , Femenino , Semivida , Humanos , Estudios Longitudinales , Michigan , Persona de Mediana Edad , Bifenilos Polibrominados/sangre , Sistema de RegistrosRESUMEN
There are limited data on the concentrations of common contaminants--polychlorinated biphenyls (PCBs), dichlorodiphenyl dichloroethene (pp'-DDE) and hexachlorobenzene (HCB)--in umbilical cord blood. Cord blood provides the primary direct measure of prenatal exposure to these contaminants, the key determinant of PCBs' neurodevelopmental toxicities. The objective of this study was to characterize cord blood levels of PCBs, pp'-DDE, and HCB among 751 infants who were born between 1993 and 1998 to mothers residing adjacent to a PCB-contaminated harbor in New Bedford, Massachusetts, and for whom the neurodevelopmental toxicities of these compounds are being studied. We refined standard analytic methods to optimize the sensitivity and precision of trace-level PCB, p,p'-DDE, and HCB measurements in blood. Using these methods, we measured the concentrations of 51 individual PCBs, their sum (sum(PCB)), p,p'-DDE, and HCB in cord serum. With correction for background contamination, the respective mean+/-SD cord serum concentrations of sum(PCB), p,p'-DDE, and HCB were 0.54+/-0.83, 0.48+/-0.94, and 0.03+/-0.04 ng/g serum. These concentrations were generally lower than those in most of the few published studies with congener-specific measures of PCBs in cord blood. However, for less-chlorinated PCB congeners (e.g., congeners 99 and 118), study samples had concentrations comparable to those in other populations, including groups at risk for high dietary PCB exposure. Of note, the contaminated harbor sediment has a relatively high proportion of less-chlorinated PCB congeners. Thus, although the sum(PCB) in study infants was not higher than concentrations in infants studied elsewhere, the relative predominance of less-chlorinated congeners was generally consistent with the characteristics of the contaminated site.
Asunto(s)
Diclorodifenil Dicloroetileno/sangre , Exposición a Riesgos Ambientales , Contaminantes Ambientales/sangre , Sangre Fetal/química , Fungicidas Industriales/sangre , Hexaclorobenceno/sangre , Bifenilos Policlorados/sangre , Femenino , Residuos Peligrosos , Humanos , Bienestar del Lactante , Recién Nacido , Masculino , Factores de RiesgoRESUMEN
BACKGROUND: A job exposure matrix (JEM) was developed for a population based case control study to assess the possible association between occupational radiation and non-Hodgkin's lymphoma. METHODS: Using published radiation monitoring data, we developed a radiation JEM composed of estimated annual dose distributions, categorized by time period, for a broad range of occupational and industrial groups. RESULTS: When information is available to correctly assess an individual's exposure status, the annual dose distributions in the JEM can be used in conjunction with job histories to estimate the distribution of possible cumulative doses for individuals. The median of the cumulative dose distribution can then be used in standard epidemiologic analysis. In addition, methods can be applied that incorporate the uncertainty about each individual's true dose into risk estimates and associated confidence intervals. CONCLUSIONS: The JEM can be useful in estimating occupational radiation exposures in other studies, particularly population based case control studies which include detailed occupational histories.