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Biomedical subjects

J Ribak

Publications and source records attributed to J Ribak.

At least 19 recordsLinked to original sources
PubMed1999

Lead exposure in battery-factory workers is not associated with anemia.

Anemia is a manifestation of lead toxicity. However, there are conflicting reports of its prevalence among lead-exposed workers, and it is uncertain whether they should be monitored by periodic hemoglobin (Hb) examinations. To explore the relationship between Hb and lead exposure, we examined the correlation between Hb, blood lead (PbB), and zinc protoporphyrin (ZPP) levels in 961 blood samples obtained from 94 workers in a lead-acid battery plant in Israel between 1980 and 1993. Blood lead levels exceeded 60 micrograms/dL (2.90 mumol/L) in 105 (14%) of the blood samples. The correlation between PbB and logZPP was 0.594. Hb levels did not correlate with PbB or ZPP. We conclude that (a) periodic Hb determinations are not a useful indicator of lead exposure in Israeli industrial workers; (b) the discrepancies between the reported correlation between PbB and Hb levels remain unexplained and in need of further study; and (c) a finding of anemia in a person with PbB levels of up to 80 micrograms/dL should be considered to be due to lead toxicity only after other causes for anemia have been excluded.

Adult↗
PubMed1998

Calcitropic hormones and occupational lead exposure.

The authors sought to clarify in a cross-sectional study the possible associations between homeostatic regulators of calcium and occupational exposure to lead. Subjects were 146 industrial male employees, 56 with and 90 without occupational lead exposure. The main outcome measures were serum concentration of parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D (calcitriol). The median values of blood lead were 40.5 microg/dl in the exposed group and 4.0 microg/dl in the controls. There were no differences between groups in dietary history and serum calcium levels. PTH and calcitriol levels were significantly higher in the exposed than in the nonexposed subjects (42.0+/-24.2 vs. 33.6+/-14.9 pg/ml, p <0.05; and 83.8+/-27.0 vs. 67.9+/-17.6 pmol/liter, p <0.001, respectively). Multivariate analyses showed that after controlling for possible confounders, occupational lead exposure (no/yes) was independently associated with PTH level (pg/ml) (beta = 7.81, 95% confidence interval (CI) 3.7-11.5) and with calcitriol (pmol/liter) (beta = 12.3, 95% CI 3.84-20.8). It is concluded that subjects occupationally exposed to lead show a substantial compensatory increase in PTH and calcitriol activities which keep serum calcium levels within normal range. This may be of clinical significance since a sustained increase in calcitropic hormones in susceptible subjects may eventually increase the risk of bone disorders.

Adult↗
PubMed1998

Impact of managers' personal determinants in notifying workplace hazards.

Notification about work hazards is a legal requirement in advanced industrial countries, but workers have claimed, that in many cases, they do not receive enough information regarding risks, exposure, and medical problems. The recent professional literature on the subject has explored the ways in which notification is delivered without sufficiently considering the psychological incentives and barriers that may affect managers in transmitting risk information. The present study aimed at examining managers' personal determinants and notification of work hazards in a sample of 106 managers and 460 workers in 40 departments of three industrial plants in Israel. Results of our study showed that both managers and workers perceived the importance of the delivery of safety information as quite high (means of 3.43 and 3.7, respectively, out of 5), with managers reporting that they rely primarily on personal modes of communication. Immediate supervisors were regarded by both groups as the most important persons in notification. Managers having past experience in treating injured workers notified more, primarily using personal notification. The most important personal determinants that positively predicted managers' notification were their sense of self-efficacy and positive expectation of notification. Outcome denial and coping by distancing were negatively correlated with notifying about these risks.

Adult↗
PubMed1998

Prevention of needle-stick injury by the scooping-resheathing method.

BACKGROUND: The objective of this study was to determine the effects of teaching the scooping-resheathing method on the incidence of needle-stick injuries in medical students. METHODS: Before starting their first clerkship, 81 medical students were given a 15-min lecture on the high incidence and dangers of needle-stick injuries and a demonstration of the scooping-resheathing method. The number of needle-stick injuries that occurred during the 3-month clerkship was compared with the number reported by 86 medical students who had completed their first clerkship 1 year previously and had not been given such instruction. RESULTS: Compared with controls, the study group had a 3.8-fold lower risk of needle-stick injury (95% confidence interval, 2.0-7.4, P < 0.0001) and a 8.3-fold lower risk of multiple needle-stick injuries (95% confidence interval, 2.0-35.0, P < 0.001). Those in the study group, who consistently used the scooping method had a much lower risk of injury than those who did not (1 of 36 [2.8%] vs. 8 of 45 [17.4%], P = 0.039). CONCLUSIONS: We conclude that a lecture recommending the scooping-resheathing method is effective in reducing the risk of needle-stick injuries in medical students during their first rotation. Because this is the first time that an intervention not requiring change in equipment has been successful, further studies are warranted to substantiate our findings and for extrapolation to other medical personnel in other cultural settings.

Accidents, Occupational↗
PubMed1998

Malingering assessment in behavioral toxicology: what, why, and how.

Neurobehavioral assessment is frequently made in a forensic context. The cognitive assessment may be biased due to an international manipulation of data by the patient motivated by attainment of compensation, that is, malingering. Although malingering is highly relevant in behavioral toxicology, the issue and its assessment are underrepresented in the literature. A routine assessment of malingering is important to reduce false-positive and false-negative errors in assessment, thereby establishing the credibility and validity of behavioral assessment. In the long run, the routine inclusion of malingering measurements might reduce claims and encourage employers to be more cooperative in behavioral toxicology studies. Guidelines for malingering assessment and research, inferred from the clinical and research literature, are discussed. Sensitivity to the problematic issues involved in assessing malingering behavior is an important step toward malingering detection in the clinical setting and to the establishment of assessment methods that are less confounded by these issues.

Behavior↗
PubMed1998

Effect of dietary calcium on blood lead concentrations in occupationally exposed and nonexposed workers.

Workers exposed to lead may benefit from a calcium-rich diet, since calcium competes with lead for intestinal absorption. We studied the effect of dietary calcium on blood lead levels. We assessed blood lead levels, dietary intake of calcium, smoking and alcohol consumption, and anthropometric and demographic data in 56 workers exposed to lead and 90 workers without such exposure. Mean intake of dietary calcium was 775 +/- 370 mg/day in the nonexposed workers and 858 +/- 423 mg/day in the exposed workers. Occupational lead exposure explained nearly 90% of the variance in blood lead levels of the entire cohort. Smoking and alcohol intake also showed significant associations with blood lead levels, but their combined effect was less than 2%. When the exposed and nonexposed workers were considered separately, no association was found between blood lead levels and calcium intake. The amount of calcium in the diet does not influence blood lead levels. Further studies are warranted to determine whether dietary calcium influences blood lead levels in exposed and nonexposed workers in other settings and in subjects with lower intakes of calcium.

Adult↗
PubMed1998

Evaluation of an occupational health education program among 11th grade students.

BACKGROUND: There is a paucity of publications on occupational health as part of the educational curricula in high schools. We investigated the extent to which a new occupational health education program for 11th graders succeeded in achieving changes in their knowledge and attitudes. METHODS: Six classrooms were randomly assigned to either 96 participating students or to a control group (n = 100) that did not participate. Data on knowledge, attitudes, and beliefs were collected before and 4 months after completion of the course by means of an anonymous self-reported questionnaire. One point was assigned to each answer that was either correct or in the desired direction. Scoring was measured by adding up the points and then converting the total into a scale of 100. RESULTS: The experimental group had a statistically higher mean score (from 24.56 to 80.74) after completing the course. The control group had low scores at both time 1 (20.15) and time 2 (17.00). At least 50% more students of the experimental group gave correct answers after the course, while there was no such change in the control group. CONCLUSIONS: Our findings indicate that occupational health learning can occur in the secondary school setting and confirm the program's effectiveness in achieving desired changes in the immediate outcome of knowledge, attitudes, and beliefs in different areas of occupational health. The subject of occupational health is a topic with relevance to larger educational objectives and policies. In many countries all over the world as well as in Israel, this curriculum can potentially be integrated into the body of the current instruction of "Life Abilities," which are courses that cover topics that prepare the youngsters for adult lifestyles.

Adolescent↗
PubMed1998

Variation in the ambulatory blood pressure response to daily work load--the moderating role of job control.

OBJECTIVES: This quasi-experimental study tested the ambulatory blood pressure responsivity to daily variation in the work load of the same workers and examined whether this responsivity is moderated by perceived job control. METHODS: The subjects were 79 nonshift, normotensive men who reported nearly almost equal occurrences of low and high work load in a typical workday. Job control was assessed by questionnaire. The workers recorded their situational work load and other parameters at each recording of ambulatory blood pressure. RESULTS: An analysis of covariance showed the main effects of both situational work load and job control on systolic ambulatory blood pressure, as well as a significant work load by job control interaction, even after control for clinic blood pressure, age, and body mass index. A blood pressure response to increased work load was observed only for workers with low job control. These workers also had a higher average systolic ambulatory blood pressure than workers reporting high control. The difference was 6.2 mm Hg (0.82 kPa) during the low workload periods and 10.2 mm Hg (1.36 kPa) during the high workload periods. A further multiple regression analysis confirmed the interaction and the main effect of job control but not that of work load, after control for work-related activities, body position, and hour of examination. CONCLUSIONS: This study showed that ambulatory blood pressure at work can fluctuate with variations in work load but only for workers with low job control. Low job control is independently associated with higher systolic ambulatory blood pressure.

Adult↗
PubMed1998

Predictive value of determinations of zinc protoporphyrin for increased blood lead concentrations.

Blood lead (PbB) and red cell zinc protoporphyrin (ZPP) concentrations are widely used biomarkers for lead toxicity. It is uncertain, however, whether either or both are needed for monitoring lead exposure and how discordant PbB and ZPP values should be interpreted. We reviewed the results of PbB and ZPP determinations in 94 workers in a lead-battery plant over a 13-year period and retrieved all 807 sets of tests in which both PbB and ZPP were available, with a follow-up PbB value 6 months later. PbB exceeded 1.93 micromol/L (40 microg/dL) in 414 (51%), and 2.90 micromol/L (60 microg/dL) in 105 (14%) of the blood samples. We derived the test properties of various ZPP concentrations for concurrent "toxic" PbB concentrations, defined as > or = 1.93 and 2.90 micromol/L (40 and 60 microg/dL). The results indicated that, given a population of lead-exposed workers with a 10% prevalence of PbB of > or = 2.90 micromol/L (60 microg/dL), a policy of testing PbB only in those with ZPP > 0.71 micromol/L (40 microg/dL) would obviate 42% of the PbB tests, but would miss about three cases with toxic PbB concentrations in every 200 workers at risk. A finding of increased ZPP concentrations with a concurrent "nontoxic" PbB was associated with an increased risk of a toxic PbB concentration 6 months later. We conclude that (a) screening by testing only ZPP does not safeguard exposed persons against lead toxicity, and (b) the frequency of PbB monitoring should be guided by estimates of the risk of future lead toxicity in individual workers.

Biomarkers↗
PubMed1997

Asymptomatic microscopic hematuria--is investigation necessary?

Microscopic hematuria is common in asymptomatic adults, but the benefit of screening the general population for blood in the urine has not been established. On the other hand, most studies of referred patients with putatively asymptomatic microscopic hematuria have reported a 2-11% prevalence of urothelial malignancies, leading to the recommendation that all patients with microscopic hematuria be thoroughly investigated. Urinalysis is inexpensive and highly acceptable to the general population, but is neither a sensitive, nor specific test, and has poor predictive value for urothelial malignancies, and nephrological diseases. Furthermore the benefits of early detection of such diseases has not been established. We conclude that screening urinalysis cannot be recommended. Studies are needed to determine which constellation of findings primary physicians use to select patients for referral to centers with urological and nephrological expertise.

Adult↗
PubMed1997

Pressure response to successive clinic readings predicts an elevated blood pressure at 2.6 years' follow-up: the Israeli CORDIS Study. Cardiovascular Occupational Risk Factor Determination in Israeli Industries.

BACKGROUND: Many persons exhibit an elevation in blood pressure (BP) when examined in a medical setting. We examined whether individuals exhibiting an exaggerated pressure response (high responders) to BP determination would have an elevated baseline BP on follow-up, independent of the initial BP level. METHODS AND RESULTS: A total of 1217 employed men not on hypertensive medication, aged 20-64 years were examined over 2-4 years (mean 2.6 years) following the baseline measurements at entry. Pressure response was assessed at entry and defined as the difference between the first and fourth values in successive readings. Such a response was apparent for systolic BP (SBP) but was negligible for diastolic BP (DBP) and the former was negatively related to the baseline BP value. High responders were defined as persons showing a pressure response greater than the average for the respective subgroup with an initially similar baseline BP value. Logistic regression results indicated that those with high SBP responsivity had a 2.7 times greater chance of having an elevated SBP (> or = 140 mm Hg) on follow-up (95% CI 1.8-4.1, P < 0.001), independently of initial SBP, age, or body mass index. Other significant predictors were the initial baseline SBP value and age. In those with an initial SBP of 130-139 mm Hg, the baseline SBP was not predictive of future readings whereas high responders had a four times higher risk of having an elevated SBP on follow-up (OR = 4.0, 95% CI 2.0-8.0, P < 0.001). CONCLUSIONS: These findings suggest that SBP hyperresponsivity, to BP determination at the clinic independently predicts elevated SBP 2.6 years later. Further studies are warranted to determine the predictive value over a longer follow-up period.

Adult↗
PubMed1997

Occupational physicians in Israel: work structure, job and personal characteristics, and job satisfaction.

This study concerns psychosocial factors among Israeli occupational physicians. Eighty-one participants (specialists, residents, and general practitioners) responded anonymously to questionnaires assessing activities demanded by the job, satisfaction from these activities, negative and positive job characteristics, job involvement, and global job satisfaction. There was little overlap between the most frequent activities (fitness for work assessments, statutory health surveillance examinations, and administrative tasks) and the activities the physicians enjoyed most (professional consultations and participation in continuing medical education (CME) activities, fitness for work assessments, and scheduled workplace visits). The most powerful predictors of job satisfaction were job involvement and satisfaction with job activities. Job involvement was related to job characteristics. The findings provide various insights for promoting job involvement and satisfaction, such as improving communication, social support, and feedback within the occupational health system and finding ways to increase quality.

Attitude of Health Personnel↗
PubMed1997

Association of calcitriol and blood pressure in normotensive men.

The purpose of this study was to clarify the possible associations between the serum 1,25-dihydroxyvitamin D (calcitriol) level and blood pressure. Cross-sectional analysis of data was performed. Data collected included levels of serum calcitriol, parathyroid hormone, serum calcium, and blood lead; blood pressure; dietary history; and demographic and anthropometric variables. One hundred normotensive male industrial employees made up the study population. Systolic blood pressure and diastolic blood pressure were main outcome measures. After possible confounders were controlled for, multivariate analyses yielded an inverse, independent, and statistically significant association between calcitriol level and systolic blood pressure (standardized beta= -0.2704, P=.0051). A similar trend of borderline significance was found for the association between calcitriol and diastolic blood pressure (standardized beta= -0.1814, P=.0611). Parathyroid hormone, serum calcium, and blood lead levels were not associated with blood pressure. When subjects were divided into four groups by calcitriol level, those in the lowest quartile showed significantly higher systolic and diastolic blood pressures than those in the upper quartile (difference=11 mmHg, P=.007, and difference=4 mmHg, P=.071, respectively). There is an inverse association between serum calcitriol level and blood pressure. This suggests that in addition to its role in calcium homeostasis, the active metabolite of vitamin D may play a role in determining blood pressure. The differences in both systolic and diastolic blood pressures between the upper and lower quartiles of serum calcitriol were substantial and may be of clinical significance.

Adult↗
PubMed1997

DNA-Protein Crosslinks and Sister Chromatid Exchanges as Biomarkers of Exposure to Formaldehyde.

Formaldehyde is classified as a probable human carcinogen. DNA-protein crosslinks (DPCs) and sister chromatid exchanges (SCEs) may represent early lesions in the carcinogenic process. The authors examined the DPCs and SCEs in peripheral-blood lymphocytes of 12 and 13 workers exposed to formaldehyde and eight and 20 unexposed workers, respectively. The amounts of DPCs and SCEs in the exposed and the unexposed differed significantly after adjustment for smoking. There was a linear relationship between years of exposure and the amounts of DPC and SCE. The authors conclude that the data indicate a possible mechanism of carcinogenicity of formaldehyde, and that formaldehyde is mutagenic to humans. These results support the use of DPCs as a biomarker of occupational exposure to formaldehyde and to detect high-risk populations for secondary prevention.

Journal Article↗
PubMed1997

The Need for Consistent Criteria for Impairment and Disability.

Medical committees that are responsible for pension funds (FMCs) rarely agree with decisions taken by occupational physicians to displace workers from their workplaces and to certify their eligibility for retirement on medical grounds. The major reason for this substantial disagreement, as demonstrated in this article, is a difference between the definition of disability used by the FMCs and that used by the employers or the occupational physicians. The dispute is usually about the evaluation of the worker's ability to function well in an alternative suitable job or with some modification in the customary job. It is also obvious that work options that existed in the past and were offered to disabled workers are diminishing nowadays due to technological and economic advances. The meaning of this disagreement to employers is that they can find their enterprises stuck with disabled workers who are unable to continue their jobs but are not entitled to pensions from the fund because they are considered suitable to cope with another theoretical job. The authors conclude with several approaches to avoiding certain dilemmas concerning the medical aspects associated with the displacement of disabled workers.

Journal Article↗
PubMed1997

Seasonal differences in blood cell parameters and the association with cigarette smoking.

Seasonal changes in red cell parameters need to be defined in order to properly interpret laboratory results. In this study blood counts were obtained prospectively in 104 healthy men (84 non-smokers and 20 smokers) aged 28-63 years during the summer and winter months. Seasonal changes in plasma volume were also calculated. In healthy non-smokers, their haemoglobin concentration and haematocrit ratio were lower in summer than in winter with a concomitant 5.5% increase in plasma volume. In smokers, there was no change in plasma volume, but haematocrit levels increased in summer. We conclude that both smoking status and seasonal variation should be taken into account in the evaluation of blood count results. Further studies are warranted to determine if our results can be extrapolated to subjects of both sexes and of various ages exposed to different climatic conditions.

Adult↗