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[Incidence of sporadic cases of the most frequent intestinal infections in Castellon].

BACKGROUND: Intestinal infections are highly frequent processes of which solely a part are identified by the epidemiological monitoring systems. This study is aimed at estimating the incidence on the population, by age groups, of the sporadic intestinal infections diagnosed in one healthcare district in Castellón in the year 2000. METHODS: Based on the routine coprocultures, the basic demographic data for each patient was gathered for calculating the diagnosis and hospitalization rates. For children up to five years of age, the per annum rates were calculation for each microorganism. RESULTS: Campylobacter showed the highest rates (114.5 x 10(5)), followed by rotavirus (94.7) and Salmonella (83.0). Rotavirus is predominant among children under one year of age (3,194 x 10(5)), Campylobacter among those 1-4 year-olds, with a maximum of 3,850 x 10(5) among one-year olds, while Salmonella was predominant among all ages starting as of 5 years of age. The rates for cases hospitalized showed a different pattern, rotavirus ranking first (34.9 x 10(5)), Salmonella (21.7 x 10(5)) and Campylobacter (9.9 x 10(5)). With the exception of Salmonella, there were no outbreaks during the period under study. The predominance of Campylobacter was observed at the expense of the cases among children within the 1-4 age range who were not hospitalized. CONCLUSIONS: Up to 4 years of age, the distribution of the germs causing these infections differs every year. A knowledge of the descriptive epidemiology of these infections contributes to the study of the social impact thereof and provides support for delving deeper into some questions that are posed with a view to these diseases and the preventive aspects which can be implemented.

Adenoviridae Infections↗
PubMed1997

Molecular epidemiology of rabies epizootics in Texas.

BACKGROUND: Texas is in the midst of two independent epizootics of rabies, involving coyotes (Canis latrans) and domestic dogs (Canis familiaris) in southern Texas and grey foxes (Urocyon cinereoargenteus) in west central Texas. The domestic dog/coyote (DDC) and grey for (TF) rabies virus variants cannot be differentiated by antigenic typing with currently available monoclonal antibodies. These two variants also cannot be distinguished from a third variant, Sonora dog (SD) rabies, that is not enzootic in Texas, but occasionally occurs in animals along the western border with Mexico. OBJECTIVES: To determine a method for the differentiation of the DDC. TF and SD variants, which is essential for epidemiologic monitoring of the Oral Rabies Vaccination Program (ORVP), a program instituted to control rabies in coyotes and grey foxes in Texas. STUDY DESIGN: Primers complementary to nucleoprotein sequence of either the DDC or TF rabies virus permit specific reverse transcription and amplification by polymerase chain reaction. In addition, general primers, which recognize a broad range of rabies variants, used in conjunction with a restriction digest for the differentiation of DDC, TF of SD rabies virus were investigated. RESULTS AND CONCLUSIONS: Of 122 specimens tested with specific primers. 111 (91%) were specifically identified as either DDC (33 samples) or TF (78 samples). Overly stringent conditions, enzyme inhibitors, or limiting RNA may account for the 11 non-amplifications. Amplification of RNA under less stringent conditions, with primers recognizing a broad range of rabies variants followed by digestion with either restriction enzyme Desulfovibrio desulfuricans I (Dde I) or Haemophilus influenzae Rf. (HinfI), was used to identify the 11 isolates that did not amplify with specific primers (6 DDC, 4 TF and 1 SD). In addition to these 11 isolates, the less stringent method of amplification, followed by enzyme digestion has identified a total of 125 additional specimens (26 DDC, 94 TF and 5 SD) that were not tested by variant-specific amplification. These data provide a means to track the spread of the different rabies virus variants and allow the ORVP to plan its vaccine disbursement by defining the two epizootic boundaries.

Animals↗
PubMed1997

Childhood lead poisoning and vinyl miniblind exposure.

OBJECTIVE: To determine the contribution of vinyl miniblinds to childhood lead poisoning. DESIGN: A descriptive investigation was undertaken to estimate attributable risk among all reported childhood lead poisoning cases in North Carolina for which home environmental sampling was conducted between March and August 1996. PARTICIPANTS: Ninety-two children, aged 6 to 72 months, identified through a statewide screening program were included. Blood lead and environmental sampling test results were obtained from routine surveillance data collected for all lead-poisoned children. RESULTS: Exposure to vinyl miniblinds with dust lead levels of 100 micrograms/ft2 or more occurred for 44 (48%) of the lead-poisoned children; 25 (27%) of the children were exposed to levels of 500 micrograms/ft2 or more. Vinyl miniblinds were the predominant source (ie, other major sources of lead were not identified) for 8 (9%) of the children. Overall, the median dust lead level for vinyl miniblind field samples was 590 micrograms/ft2, and the highest level reported was 73,302 micrograms/ft2. Even new vinyl miniblinds manufactured before July 1996 contained dust lead levels that on average exceeded 100 micrograms/ft2. The levels for recently available nonleaded vinyl miniblinds were below the limits of detection. CONCLUSIONS: Vinyl miniblinds, introduced into this country 10 years ago, with sales estimated at 30 million sets a year, include brands containing lead. Although new formulations with no lead added are available, millions of children may still be at risk because a product recall has not been issued (ie, lead-contaminated vinyl miniblinds are still in general use). In addition, the risk assessment evaluations proposed in lieu of universal blood lead screening for low-risk communities could overlook children with exposure to this source.

Air Pollution, Indoor↗
PubMed1996

Differential recall bias and spurious associations in case/control studies.

Consider a case/control study designed to investigate a possible association between exposure to a putative risk factor and development of a particular disease. Let E denote the information required to specify a subject's exposure to the risk factor. We examine the effect that errors in the recorded values of E (which we denote by E*) have on inferences of an association between disease and the risk factor. We concentrate on situations where the errors in recorded exposure are such that exposure is underestimated for controls and overestimated for cases. This phenomenon is referred to as differential recall bias and may lead to spurious inferences of an association between exposure and disease. We describe how the standard inferential techniques used in the analysis of data from case/control studies may be adjusted to take account of specified mechanisms whereby E is distorted to produce E*. Such adjustments may be used to determine the sensitivity of an analysis to the phenomenon of differential recall bias and to quantify the extent of such bias that would be required to overturn the conclusions of the analysis. There remains the matter of judging whether a given distortion mechanism is reasonable in a particular context. This emphasizes the need for investigators to take account of differential recall bias in validation studies of exposure assessment techniques. The methodology developed here is applied to a recent major study investigating the possible association between lung cancer and exposure to environmental tobacco smoke. The log-odds ratio of 0.23 based on recorded exposure differs significantly from 0 (P < 0.02). However, the association is rendered non-significant by a very modest degree of differential recall bias. For example, if 3.8 per cent of exposed controls report no exposure, 3.8 per cent of unexposed cases report exposure, and all other subjects report exposure accurately, the log-odds ratio drops to 0.07 and the corresponding p-value increases to 0.49.

Adult↗
PubMed1999

Case-control isotonic regression for investigation of elevation in risk around a point source.

Stone's isotonic regression method for analysing count data to estimate disease risk in relation to a point source of environmental pollution is now routinely used. This paper develops the corresponding procedure for case-control data consisting of the locations of individual cases with controls with associated covariate information. In this setting, the generalized likelihood ratio statistic to test the null hypothesis of constant risk against the alternative that risk is a monotone non-increasing function of distance from the point source is intractable. An approximate Monte Carlo test is described, extending an exact test proposed by Bithell for the situation in which there are no covariates. Interval estimates of risk as a function of distance from the point source are constructed by simulation of the sampling distribution of the isotonic regression estimator. The methodology is illustrated by two applications: one to the relative risk of larynx cancers and lung cancers near a now-disused industrial incinerator; the other to the risk of asthma in children in relation to distance of residence from the nearest main road.

Adolescent↗
PubMed1996

Hematotoxicity among Chinese workers heavily exposed to benzene.

Benzene is a well-established hematotoxin. However, reports of its effects on specific blood cells have been somewhat inconsistent and the relative toxicity of benzene metabolites on peripheral blood cells in humans has not been evaluated. We compared hematologic outcomes in a cross-sectional study of 44 workers heavily exposed to benzene (median: 31 parts permillion [ppm] as an 8-hr time-weighted average [TWA] and 44 age and gender-matched unexposed controls from Shanghai, China. All hematologic parameters (total white blood cells [WBC], absolute lymphocyte count, platelets, red blood cells, and hematocrit) were decreased among exposed workers compared to controls, with the exception of the red blood cell mean corpuscular volume (MCV), which was higher among exposed subjects. In a subgroup of workers who were not exposed to more than 31 ppm benzene on any of 5 sampling days (n = 11, median 8 hr TWA = 7.6 ppm, range = 1-20 ppm), only the absolute lymphocyte count was significantly different between exposed workers (mean [sd]1.6 [0.4] x 10(3) mu L) and controls (1.9 [0.4] x l0(3) uL, p = 0.03). Among exposed subjects, a dose response relationship with various measures of current benzene exposure (i.e., personal air monitoring, benzene metabolites in urine) was present only for the total WBC count, the absolute lymphocyte count, and the MCV. Correlations between benzene metabolites and hematologic parameters were generally similar, although hydroquinone was somewhat more strongly associated with a decrease in the absolute lymphocyte count, and catechol was more strongly associated with an increase in MCV. Morphologic review of peripheral blood slides demonstrated an excess of red blood cell abnormalities (i.e., stomatocytes and target cells) only in the most heavily exposed workers, with no differences in granulocyte, lymphocyte, or platelet morphology noted. Although benzene can affect all the major peripheral blood elements, our results support the use of the absolute lymphocyte count as the most sensitive indicator of benzene-induced hematotoxicity.

Adult↗
PubMed1996

Lead poisoning in telephone cable strippers: a new setting for an old problem.

Lead poisoning among workers processing lead sheathed telephone cable was identified at five worksites. High blood lead levels (BLLs) were identified during the medical evaluation of symptomatic workers following employer mandated air monitoring and through employer mandated blood lead levels. Once high BLLs were identified, governmental agencies became involved at every site, either as a result of worker complaints to OSHA or as a registry reporting mechanism. Workplace evaluation revealed significant overexposure to lead, particularly among workers mechanically stripping the lead sheaths. After intervention by a government agency, four of the workplaces chose to stop lead cable processing. Because the ongoing replacement of lead sheathed telephone cable with fiber optics may be continuing in many areas of the country, there is concern that the clusters we have identified represents a widespread and little recognized setting for lead overexposure. Recommendations for preventing overexposure to lead in this setting are given.

Conservation of Natural Resources↗
PubMed1997

Respiratory symptoms and lung function abnormalities among machine operators in automobile production.

This cross-sectional study was designed to assess differences in prevalence of respiratory symptoms and lung function between machine operators exposed to semisynthetic or soluble metal-working fluids (MWFs) and unexposed assemblers and to assess exposure-response relationships with MWF type, total aerosol, endotoxin, culturable bacteria and fungi. We evaluated 183 machine operators and 66 assemblers from one large automobile transmission plant using questionnaires, spirometry data, and cross-shift assessment of both lung function and respiratory symptoms. We found that airborne exposures to total aerosol, endotoxin, culturable bacteria and fungi were higher in machine operations than in the assembly area. There was a correlation between bulk and airborne culturable bacteria, but not between bulk and airborne culturable fungi. Machine operators had significantly more usual cough, usual phlegm, work-related chest tightness and post-shift symptoms of chest tightness, throat irritation, and cough compared with assemblers. We found exposure-response relationships between respiratory symptoms and total aerosol, as well as culturable fungi and bacteria. Associations with endotoxin were not strong or consistent, possibly because airborne levels were generally low. Cross-shift lung function decrements did not differ between machine operators and assemblers and there were no associations with MWF or specific exposures. The finding of respiratory symptoms at low levels of exposure in this study suggests the need to re-assess total aerosol thresholds. Associations between airborne fungal exposures and respiratory symptoms need further study to characterize sources of exposure other than MWF in machining operations.

Adult↗
PubMed1997

Risk factors for systemic illnesses following agricultural exposures to restricted organophosphates in California, 1984-1988.

Organophosphate (OP)-related systemic illnesses reported to the Worker Health and Safety (WH&S) Branch, and restricted OP-related agricultural use data reported to the Information Services Branch at the California Department of Food and Agriculture (CDFA) (now CAL-EPA) during 1984-1988 were used to assess factors associated with OP-related systemic illnesses. Counts of OP-related systemic illnesses (numerator), relative to OP-related use data (denominator), such as pounds applied, number of applications, and acres treated (pounds applied/acres treated), were analyzed by crop treated, season of application, method of application, geographic region, and by specific OP applied. A Relative Illness/Use Ratio (RIUR) was calculated by Poisson regression. The highest risk of systemic illness was associated with OP applications to fleshy fruit (mainly fruit trees) compared to all other crops combined (RIUR = 2.9, 95%CI = 2.2-3.9) using pounds applied in the denominator, followed by vegetables and melons (RIUR = 1.9, 95%CI = 1.4-2.4). Air applications resulted in higher RIURs for systemic illness than did ground applications (RIUR = 2.1, 95%CI = 1.7-2.5). Specific OPs that showed significantly elevated RIURs for systemic illness when compared to other OPs were Mevinphos (RIUR = 5.8, 95%CI = 5.0-6.8), Demeton (RIUR = 4.3, 95%CI = 2.6-7.1), Oxydemeton-Methyl (RIUR = 3.8, 95%CI = 3.0-4.9), Methamidophos (RIUR = 1.6, 95%CI = 1.2-2.0) and Azinphos-Methyl (RIUR = 1.3, 95% CI = 1.1-1.6).

Adult↗
PubMed1997

Work-related musculoskeletal disorders: comparison of data sources for surveillance.

Work-related upper extremity musculoskeletal disorders "associated with repeated trauma" account for more than 60% of all newly reported occupational illness, 332,000 in 1994 according to the U.S. Department of Labor. These numbers do not include, for example, those disorders categorized as "injuries due to overexertion in lifting," approximately 370,000. Early identification of potential disorders and associated risk factors is needed to reduce these disorders. There are a number of possible methods for conducting surveillance for work-related musculoskeletal disorders (WMDs) based on health outcome: workers' compensation, sickness and accident insurance, OSHA 200 logs, plant medical records, self-administered questionnaires, professional interviews, and physical examinations. In addition, hazard surveillance based on evaluation of job exposures to physical stressors by nonoccupational health personnel is possible. As part of a large labor-management-initiated intervention study to reduce the incidence of WMDs in four automotive plants, we were able to compare the strengths and limitations of each of these surveillance tools. University administered health interviews yielded the highest rate of symptoms; combined physical examinations plus interview (point prevalence) rates were similar to self-administered questionnaires (period prevalence) rates. Plant medical records yielded the lowest rate of WMDs. WMD status on self-administered questionnaire and on physical examination were associated with risk factor exposure scores. This study suggests that symptoms questionnaires and checklist-based hazard surveillance are feasible within the context of joint labor-management ergonomics programs and are more sensitive indicators of ergonomic problems than pre-existing data sources.

Cumulative Trauma Disorders↗
PubMed1998

Acute lung function changes and low endotoxin exposures in the potato processing industry.

Work-related respiratory symptoms, acute lung function changes and personal endotoxin exposure were studied in 61 workers from a potato processing plant. According to their job title mean endotoxin exposure level, workers were divided into low (AM = 21 EU/m3) and high (AM = 56 EU/m3) exposure categories. Shortness of breath and chest tightness during work were reported by 18% and 16% of the workers, respectively, mainly in the low endotoxin exposure category. A total of 148 across-shift lung function changes were measured during three consecutive afternoon shifts. The mean FEV1 and MMEF showed a decrease over the work shift, being largest on the first working day after a 3-day absence from work. Workers exposed to high endotoxin levels showed a larger across-shift decrease in lung function than workers exposed to low endotoxin exposures, the effect being most pronounced on the first day after a 3-day absence from work. At the start of the second work shift, FVC, FEV1 and MMEF were lower than at the start of the first work shift. This difference was larger for high exposed workers. High exposed workers with work-related respiratory symptoms showed an 8-10% across-shift change in FVC, FEV1 and MMEF We conclude that significant across-shift decreases in lung function of potato processing workers is related to endotoxin exposure levels above 53 EU/m3 over 8 hr.

Acute Disease↗
PubMed1998

Prevalence of occupational lung disease in a random sample of former mineworkers, Libode District, Eastern Cape Province, South Africa.

BACKGROUND: Gold mineworkers in South Africa are exposed to high levels of silica dust as a result of which they are at risk of developing silicosis, which is a compensable disease. The incidence of tuberculosis is also high. METHODS: To determine the prevalence of occupational lung disease and the previous compensation history in former migrant mineworkers, a study was undertaken in a random sample of men living in Libode, a rural district of Eastern Cape Province, South Africa. Two hundred thirty-eight ex-mineworkers were examined according to a protocol that included chest radiography and spirometry. Chest radiographs were read into the International Labour Organisation (ILO) classification for pneumoconioses by two readers. RESULTS: The mean age was 52.8 years, and the mean length of service was 12.15 years. The prevalence of pneumoconiosis (> or = ILO 1/0) was 22% and 36% (variation by reader). For both readers, a significant association between length of service and pneumoconiosis and between pneumoconiosis and reduction in FVC and FEV was found. Twenty-four percent of study subjects were eligible for compensation. CONCLUSION: There is a high prevalence of previously undiagnosed, uncompensated pneumoconiosis in the study group. As a result of the failure to diagnose and compensate occupational lung disease, the social and economic burden of such disease is being borne by individuals, households, and the migrant labor-sending communities as a whole.

Adult↗
PubMed1998

Lung health among boilermakers in Edmonton, Alberta.

BACKGROUND: Construction boilermakers may be exposed to a variety of substances, including asbestos and welding fumes. Past studies of boilermakers have shown increases in mortality from lung cancer and asbestosis and radiographic changes consistent with asbestos exposure. METHODS: Respiratory symptoms, lung function, and radiographic changes were compared for 102 actively employed boilermakers with 20 or more years of union membership and 100 telephone workers. Posteroanterior chest radiographs were evaluated by two experienced chest physicians, with a third arbitrating disagreed films. Union members were further categorized as boilermakers (n = 50) or welders (n = 52), based on longest service. Lung health was also compared with employment in a number of work sectors for time, and time-weighted exposure to dust and fumes. RESULTS: Boilermakers had more respiratory symptoms than telephone workers, but lung function did not differ. Radiographic changes were more common among the boilermakers (20% with any change, 8% circumscribed, and 9% diffuse pleural thickening). None of the boilermakers had small radiographic opacities. Several symptoms suggestive of bronchial responsiveness were associated with fume exposures in the gas and oil industry. Workers whose longest service was as a boilermaker demonstrated more symptoms than did welders. FEV1, FEV1/FVC, FEF25-75, and FEF50 were significantly lower among boilermakers compared with welders. CONCLUSION: Health screening programs for these workers are warranted.

Adult↗
PubMed2000

Leukemia after exposure to benzene: temporal trends and implications for standards.

BACKGROUND: Benzene is a human leukemogen. Risk assessment, and the setting of occupational and environmental standards, has assumed that risk is constant in time after a unit of exposure. Leukemia risk is known to vary with time after exposure to ionizing radiation. METHODS: A matched case-control study of leukemia risk in relation to the temporal pattern of benzene exposures was performed using data from the National Institute of Occupational Safety and Health. RESULTS: Leukemia risk following exposure to benzene varied with time in a manner similar to that following exposure to ionizing radiation. More recent exposures were more strongly associated with risk than were more distant ones. There was no significant relation between leukemia death and benzene exposures incurred more than 20 years previously. CONCLUSIONS: Recent analyses of specific occupational and environmental carcinogens, including benzene and radon, have indicated that cancer risk tends to decline as the time from exposure increases. This suggests that standards for the control of occupational or public risk must be selected to control exposures over a narrower time frame than the usual lifetime one. In the case of benzene, it would appear that risk is attributable primarily to exposures incurred during the previous 10 to 20 years, with exposures in the most recent 10 years being the most potent. To limit risk, exposures must be controlled during that interval. It is important that epidemiologists explore the temporal pattern of risk in their studies to facilitate the risk assessment of other carcinogens.

Adult↗
PubMed2002

Specific immune response to occupational antigens in asymptomatic egg processing workers.

BACKGROUND: Hen's egg proteins are known sensitizers and may cause occupational respiratory diseases in exposed workers. The study was conducted in order to ascertain the prevalence of sensitization to work-related antigens in asymptomatic egg processing factory workers. METHODS: Clinical history, respiratory function, atopy and the presence of specific antibodies to environmental and occupational antigens were evaluated in 77 workers. A total of 116 unexposed and non-professionally exposed controls were also studied. The antigen concentration of the factory environment was measured. RESULTS: Specific IgE and precipitin positivity to egg components was more frequently present in workers than in the two control groups. The egg white protein concentration was higher in the egg breaking area. CONCLUSIONS: The avian proteins inhaled induced immune responses to occupational antigens in asymptomatic, professionally exposed subjects. Measures to decrease environmental antigen concentrations and thorough clinical monitoring of sensitized workers are advocated.

Adult↗
PubMed2002

Occupation, exposure to chemicals and risk of gliomas and meningiomas in Sweden.

BACKGROUND: Occupational exposures may be related to the development of brain cancer. The objective was to estimate occupational-specific risk of gliomas and meningiomas among Swedish men and women gainfully employed in 1970 over the period 1971-1989, and the influence of occupational exposure to chemical substances. METHODS: A dataset linking cancer diagnoses from the Swedish national cancer register to occupational and demographical data obtained in the 1970 census was used to fit log-linear Poisson models, in order to obtain relative risks adjusted by age, period, geographical area and town size. Exposure to 13 chemicals was assessed using a Swedish job-exposure matrix. RESULTS: The main findings of this study among men were the increased risk of glioma with occupational exposure to arsenic, mercury, and petroleum products and of meningioma with lead. Women in occupational sectors with a higher socio-economic status showed an increased incidence of both, gliomas and meningiomas. CONCLUSIONS: Occupational exposure to some chemicals appeared to be related with an increased risk of glioma and meningioma in men. Exposures involved in glioma and meningioma development seemed to be different.

Adult↗
PubMed2002

Hematological changes among Chinese workers with a broad range of benzene exposures.

BACKGROUND: Depression of peripheral blood cells is a well-known indicator of benzene hematotoxicity. Previous studies of its effects on specific types of blood cells have yielded inconsistent results. We examine hematological findings and their possible relations with exposure markers validated in a recent biomarker project conducted in Tianjin, China. METHODS: Personal benzene exposures were sampled with 3-M organic vapor monitors, and analyzed by gas chromatography. The peripheral blood cells were counted by a cell counter. The WBC differential was manually counted on a total of 900 cells by a US commercial laboratory. RESULTS: A total of 130 exposed workers and 51 age- and gender-matched unexposed subjects were recruited in this study. Benzene exposure levels monitored on the day of biological sample collection for exposed workers ranged from 0.06 to 122 ppm. Their 4-week average and cumulative benzene exposure levels were 0.08-54.5 ppm and 6.1-623.2 ppm-years, respectively. Significant decreases of red blood cells (RBC), white blood cells (WBC), and neutrophils were observed and correlated with both personal benzene exposures and levels of urinary metabolites (S-phenylmercapuric acid and t,t-muconic acid) and albumin adducts of benzene oxide and 1,4-benzeoquinone. CONCLUSIONS: The depressions in RBC, WBC, and neutrophils observed in this study are not only exposure dependent, but also significantly different in the lowest exposed group (at or below 0.25 ppm) compared with unexposed subjects. The results of the present study appear to suggest that lymphocytes may not be more sensitive to chronic benzene exposure than neutrophils.

Adult↗