Biomedical subjects

C Peretz

Publications and source records attributed to C Peretz.

11 recordsLinked to original sources

PubMed2002

Upper airway inflammation and respiratory symptoms in domestic waste collectors.

OBJECTIVES: To compare respiratory symptoms and upper airway inflammation in domestic waste collectors and controls, and to find the association between measures of upper airway inflammation on the one hand and exposure concentrations of organic dust or respiratory symptoms on the other hand. METHODS: In a cross sectional study among 47 waste collectors and 15 controls, questionnaire data on respiratory symptoms were collected. Nasal lavage (NAL), to assess upper airway inflammation, was performed before and after a work shift at the beginning and at the end of the working week. In NAL fluid, cells were counted and differentiated and concentrations of interleukin 6 (IL6), IL8, tumour necrosis factor-alpha (TNF alpha), and IL1 beta were measured. In collectors, inhalable dust samples were collected in which bacterial endotoxin and mould beta(1-->3)-glucan were assessed. RESULTS: Prevalence of respiratory symptoms was higher in waste collectors than in controls. Geometric mean exposure concentrations were 0.58 mg/m(3) for dust, 39 EU/m(3) for endotoxin, and 1.3 microg/m(3) for beta(1-->3)-glucan. At the end of the week collectors had higher concentrations of total cells and IL8 in NAL before and after a shift than controls (cells, before 1.9-fold p<0.10, after 3.3-fold p<0.01; IL8, before and after 1.8-fold p<0.05), and after/before work shift ratios of total cells were also higher (2.3-fold p=0.06) in collectors than in controls. Cells in NAL fluid consisted predominantly of neutrophils and epithelial cells, whereas eosinophils and mononuclear cells were rarely found. Exposure to dust and endotoxin was associated with concentrations of IL8 after the shift (p<0.05). Increased concentrations of IL8 (p<0.05) and total cells (p<0.10) after the shift were associated with respiratory symptoms. Concentrations of IL6, TNF alpha, and IL1 beta were not associated with waste collecting, symptoms, or exposure. CONCLUSIONS: Waste collectors show signs of increased upper airway inflammation and respiratory symptoms compared with controls. Exposure to organic dust probably underlies the inflammation mediated by neutrophils that result in respiratory symptoms.

Adult↗

PubMed2001

Maximal versus feigned active cervical motion in healthy patients: the coefficient of variation as an indicator for sincerity of effort.

STUDY DESIGN: Maximal and submaximal (feigned) cervical motions in healthy patients were compared. OBJECTIVE: To test the efficiency of the coefficient of variation in differentiating maximal (sincere) from submaximal (feigned) cervical motion in healthy patients. SUMMARY OF BACKGROUND DATA: Although limitation of cervical motion is a recognized impairment, no well-founded approach for verifying the degree to which a patient is maximizing his or her performance is available currently. METHODS: A new ultrasound-based system for three-dimensional motion analysis of the head was used to test 25 healthy patients (22 women and 3 men) ages 26 to 48 years. During the first test, (Test 1), the patients were asked initially to move the head maximally at a self-determined velocity in all the primary directions: flexion, extension, right and left rotation, and right and left lateral flexion. They then were presented with a short vignette describing a fictitious accident and asked, using the same protocol, to perform the same types of cervical motions as if they had experienced an injury. No further instructions were provided. A retest (Test 2) in reverse order (feigned effort first) took place 1 to 16 weeks (mean, 3.3 weeks) later. RESULTS: The range of motion and average velocity were significantly smaller (P = 0.0001) in the feigned than in the maximal performance in all directions and on both tests. Feigned range of motion and velocity also were significantly reduced in Test 2 (P = 0.006), as compared with those in Test 1 (P = 0.0001). The range of motion coefficient of variation in the feigned performance (CVf) remained stable on the retest, but was significantly larger on both tests (P < 0.001) than the corresponding CV derived from maximal performance (CVm). Furthermore, a case-by-case analysis showed that whereas the American Medical Association guidelines identified only 16% of the feigned cases, the use of CVf and CVm resulted in a corresponding rate of 87%. Tolerance intervals at 95% and 99% indicated total separation between the distributions of CVf and CVm, respectively. The average velocity-based CVf and CVm were not of a comparable differentiating power. CONCLUSIONS: This study indicates that in healthy patients, feigned performance may be differentiated from maximal (sincere) performance effectively and reproducibly using the coefficient of variation.

Adult↗

PubMed1999

Workers' right-to-know legislation: does it work?

Workers' right-to-know (WRTK) laws and regulations were established to empower workers to protect their health by providing them with information about the hazards to which they are exposed while at work. The present study was conducted to examine the implementation of WRTK regulations in Israel. We interviewed 552 workers and 33 safety officers from a random sample employed at 50 industrial plants. The workers' questionnaire included items on awareness and self-management of workplace hazards, and the safety officers answered questions about job experience and hazards communications to workers. In 36% of cases workers and their safety officers disagreed about the existence of hazards in the workplace (p < 0.001). Most (78%) of the workers' knowledge about work hazards was based on informal sources, i.e., not those stipulated by the regulations. There were also discrepancies between worker and safety officer reports regarding the provision of safety training upon employment (p < 0.001), recent instructions about special risks and distribution of relevant printed material. We found that more than 5% of workers were unable to read the language in which the hazards material was written and 22% had levels of education below that required to comprehend the technical terms used. There are serious problems in the implementation of WRTK regulations in Israel. We recommend that employers be made aware of the importance of these laws and of their proactive duty to comply with them and that the material distributed to workers be written in simpler terms and/or explained orally in a language they understand. These findings have important implications for all countries with similar legislation and should form the basis for further and more comprehensive studies world-wide.

Adolescent↗

PubMed1997

The variability of exposure over time: a prospective longitudinal study.

Four hundred and forty personal air measurements were carried out on 54 workers, employed in the main processes in six different factories (6-13 in each). Potential exposure was to lead, benzene and dust. Ten randomly repeated hygiene surveys were carried out over 1 year. In order to estimate the magnitude of the variability in workers' exposure over time, its sources, the variance between workers and the variance within a worker, a nested unbalanced analysis-of-variance model was fitted to the log-transformed data. Of the total exposure variance, the within variance of a worker's exposure over time was 51% (geometrical standard deviation, GSD = 3.1) and the between workers, factories and air contaminants variance was 49%. The exposure variance between all the workers was due mainly to variance between workers within the same factory (67%). Outdoor locations, mobility of the worker and mobility of the sources of exposure result in a positive influence on both the variance between (26%, ANOVA) and the variance of a worker over time (39%, regression). These variables are therefore important in the sampling strategy of workers' exposure. For valid compliance testing and assessment of workers' exposure the mean and the within- and between-variance of the workers' exposure over time should be considered. The exposure should be measured several times a year randomly in order to prevent workers misclassification. To assess yearly exposure, a GSD = 3.1 can be used to calculate confidence limits for the arithmetic mean of worker's exposure measurements, in circumstances similar to those in this study.

Air Pollution↗

PubMed1995

Determination of consumer satisfaction: a basic step for quality improvement of an occupational hygiene service.

In order to define priorities for improvement of the Occupational Hygiene Service, Institute for Occupational Health, Tel Aviv University, consumer satisfaction was evaluated by postal questionnaire. The questionnaire covered items on service accessibility and quality, including staff courtesy and respect for the consumer, cost, satisfaction with the service in general over time, and satisfaction with the last service received, and was sent to all 144 regular clients of the institute during the years 1990 and 1991. Satisfaction items were rated from 1 (not at all satisfied) to 5 (completely satisfied). Multivariant analysis showed that: (i) satisfaction with the waiting period for the last service report and satisfaction with the courtesy of the last service and respect for the consumer had the strongest influence on general satisfaction with the service over time; (ii) satisfaction with the waiting period for the last service report was also the most important component in satisfaction with the last service received. Despite the increasing interest in Israel in health service costs, and because the price of the service is subsidized (50%), this item was not found to be significant with regard to satisfaction with the service. In conclusion, we recommend the use of this relatively easy and inexpensive methodology which allowed us to define precisely the key factor for service improvement, ie the waiting period for the service report.

Consumer Behavior↗

PubMed1995

The effectiveness of regulations requiring periodic occupational hygiene monitoring.

The passing of regulations requiring periodic occupational hygiene monitoring surveys is one way of controlling workers' exposure to hazardous materials. The results of this study showed that this control is ineffective. The source of data was Occupational Hygiene Survey (OHS) records which were archived in the Institute for Occupational Health, Tel Aviv University and related only to workplaces that requested an OHS. The mean frequency of surveys carried out in the workplaces studied was significantly lower than the required one. Although the main factors required to ensure effective implementation of the regulations exist in Israel, i.e., monitoring services and enforcement authorities, excursions above permitted levels (overexposure) are still widely occurring. From all the measurements made over the study period (1989-1991) the ranges of overexposure were 31-75% for silica, 26-32% for talc, and 19-41% for lead. The results of the study highlighted the need to strengthen the authority of the bodies involved in occupational hygiene by increasing intervention. This could be achieved by enlarging the capabilities of the enforcement authorities by giving authority to occupational health physicians and to the organization carrying out the survey.

Environmental Monitoring↗

PubMed1992

Assessment of the extent of implementation of the recommendations made in occupational hygiene survey reports.

The extent of implementation of recommendations contained in field reports from the Occupational Hygiene Unit of the Institute for Occupational Health at the Tel Aviv University, was investigated. The results show that 33% were not carried out at all and 16% were only partially carried out. A number of factors influenced the extent of implementation, in particular the degree of involvement of the management in worker health and welfare, an active safety system in operation, the professional skill and seniority of the person in charge of safety, awareness by the workers of health and safety matters, the existence of a specific budget for health and safety and a regulatory system concerning occupational exposure.

Health Knowledge, Attitudes, Practice↗

PubMedDate not supplied

Improved non-negative estimation of variance components for exposure assessment.

Hygiene surveys of pollutants exposure data can be analyzed by analysis of variance (ANOVA) model with a random worker effect. Typically, workers are classified into homogeneous exposure groups, so it is very common to obtain a zero or negative ANOVA estimate of the between-worker variance (sigma2B). Negative estimates are not sensible and also pose problems for estimating the probability (theta) that in a job group, a randomly selected worker's mean exposure exceeds the occupational exposure standard. Therefore, it was suggested by Rappaport et al. to replace a non-positive estimate with an approximate one-sided 60% upper confidence bound. This article develops an alternative estimator, based on the upper tolerance interval suggested by Wang and Iyer. We compared the performance of the two methods using real data and simulations with respect to estimating both the between-worker variance and the probability of overexposure in balanced designs. We found that the method of Rappaport et al. has three main disadvantages: (i) the estimated sigma2B remains negative for some data sets; (ii) the estimator performs poorly in estimating sigma2B and theta with two repeated measures per worker and when true sigma2B is quite small, which are quite common situations when studying exposure; (iii) the estimator can be extremely sensitive to small changes in the data. Our alternative estimator offers a solution to these problems.

Bias↗

PubMedDate not supplied

Exposure to benzene in fuel distribution installations: monitoring and prevention.

The authors used a mixed-effects model on a cohort of 258 randomly chosen workers in 7 fuel-distribution facilities to examine the association between airborne benzene exposure and task and timing factors. During an 8-y period, 692 repeated personal measurements were performed. Filler task, warm month, Tuesday, credit day, and time period (1992-1996) were associated significantly with higher exposures to benzene. The authors controlled for the time period, and task type strongly affected the between-worker variance; therefore, two exposure groups (i.e., fillers and nonfillers) were adequate for purposes of exposure grouping strategy. Timing factors (after controlling for task and period effects) strongly affected the high within-worker variance (> 2 than between-worker variance). Long-term exposure would be better represented if the sample was stratified by warm/nonwarm months and if measurement days were selected randomly.

Adult↗

PubMedDate not supplied

Serum immunoglobulins in chronic lymphocytic leukemia.

Serum immunoglobulin levels were periodically determined in 70 CLL patients and the changes were correlated with several clinical and laboratory parameters. It was found that the IgG and IgA levels decreased significantly as the disease progressed. A low IgG concentration was found at the time of diagnosis in 18.7% and after six years in about 50% of the patients. The IgM concentration, although initially low, increased during the follow-up in 43% of the patients and in four of them a monoclonal fraction appeared in the serum. The changes in the immunoglobulins did not correlate with age, sex or initial leukocyte count. Stage O patients as well as untreated patients also had a decrease in their immunoglobulin levels but advanced disease stage and especially continuous chemotherapy seemed to augment the drop in the immunoglobulin levels. Neither the initial immunoglobulin levels nor the subsequent changes, absolute or relative, had a significant prognostic value.

Agammaglobulinemia↗

PubMedDate not supplied

Responses of occupational physicians and laboratory staff to reports of high blood lead levels.

We evaluated the responses of physicians specializing in occupational health and of laboratory personnel engaged in occupational lead monitoring when periodic blood lead analysis results exceeded the Biological Exposure Index (BEI). Legally, Israeli workers must be removed from the site of occupational lead exposure after a repeat test shows "value above BEI" (VABEI). The maximum legal period between a report of VABEI and the repeat test is 14 days. Physicians have the discretion to remove workers after the first VABEI test if deemed necessary. In 1987-88, 242 of 3,776 analyses had a VABEI, 167 of which were periodic tests. The average laboratory response time between receipt of the sample and VABEI reports to occupational physicians was 13 days (SE = 0.4). Medical records of 100 workers who had 134 tests with a VABEI were available. In 35 (26.1%) of these events the physicians recommended removing the workers from the exposure source, in 55 (41.0%) events the physicians required repeat tests, and in 44 (32.9%) they neither recommended removal nor repeated the tests. The minimum time lapse between the first and repeat test was 20 days. The second test yielded 24 VABEI. Physicians recommended removing workers from the source only in 13 (54.2%) of these cases. This study suggests that the system must be improved in order to ensure the proper response to VABEI results.

Attitude of Health Personnel↗