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Biomedical subjects

H Kromhout

Publications and source records attributed to H Kromhout.

At least 73 records · Page 4Linked to original sources
PubMed1998

Effect of airborne particles from selected indoor and outdoor environments on gap-junctional intercellular communication.

The effect of airborne particles from diesel exhaust, rubber and metal industry, urban air and biological sources (poultry, pig farming, compost industry) on gap-junctional intercellular communication (GJIC) were compared, using HEPA1c1c7 cells. Particles as such were compared with aqueous and organic extracts. Significant inhibition of GJIC by particle suspensions was only observed for the diesel and rubber samples, and for one biological sample (compost). Up to 83% of the inhibition of the whole suspension could be attributed to the particles as such. Washing the particles with organic solvents (aceton, methanol, hexane) did not result in a significant loss of activity from the particles, although the organic fractions showed a significant activity towards GJIC. More active organics was eluted from the rubber industry particles than from the diesel particles by the organic solvent. It is suggested that cancer promoting potential as measured by inhibition of GJIC may vary widely depending on the particle source, and that this effect may be exerted by the particles as such and/or by means of tightly bound bio-active material to the surface.

Agriculture↗
PubMed1998

Exposure to captan in fruit growing.

This study characterized occupational exposure to pesticides in fruit growing in The Netherlands to assess determinants of exposure. Large-scale exposure surveys were carried out during application of pesticides and during reentry activities. Data on contamination inside the fruit growers' homes were obtained, and total potential exposure for the fruit grower and his family during the growing and harvesting season was estimated. Repeated measurements on the same subject were collected to study components of exposure variability. Relative contribution of the respiratory route and different skin sites to total exposure were assessed. Captan was used as a marker for exposure. Inhalable dust exposure was measured with a personal monitor and potential dermal exposure with skin pads and hand rinsing. Dislodgeable foliar residue was measured by taking leaf punches. For respiratory exposure and potential dermal exposure, differences were observed between several tasks. Workers were categorized according to tasks performed depending on the exposure measure(s) (e.g., hands, forehead, inhalable dust) considered relevant for a specific study purpose. In general, within-worker variability of all exposure measurements was larger than between-worker variability. Variability in dermal exposure on the same body location was small relative to variability between different body locations. Differences in total exposure, including exposure inside the home, between the fruit grower and the son were small. Exposure of the wife was two to three times lower than for the fruit grower and the son. As exposure per unit of time was in the same order of magnitude for different tasks, individual time spent on these tasks is crucial for estimating total potential exposure. Repeated measurements are necessary to estimate individual exposure accurately because of the large within-worker variability.

Adolescent↗
PubMed1998

Determinants of exposure to captan in fruit growing.

A series of studies investigated occupational exposure to pesticides among fruit growers in The Netherlands during spraying and reentry of orchards between 1990 and 1992 to identify and quantify determinants of exposure. Determinants of exposure are discussed as a starting point for hazard identification and control. Captan was used as a marker for exposure. Cabin use of the tractor was the most prominent determinant of dermal exposure during spraying. For respiratory exposure, factors related to preparation of pesticides were most prominent. A long duration of exposure may reflect a different exposure situation compared with a short duration of exposure. As different determinants of exposure prevailed for each subgroup, consideration should be given to constructing exposure models for each group separately. Dislodgeable foliar residue (DFR) was the most prominent determinant of exposure for both respiratory and dermal exposure during reentry. However, no significant relation between DFR and dermal exposure of forehead and sternal area was found, perhaps because there was no direct contact with foliage here. Therefore, use of a transfer factor based on DFR to estimate total dermal exposure is only a crude estimate. The half-life of captan on crops varied from 10-17 days, so substantial exposure when entering the orchard is very likely, particularly when spraying frequency is high. The main starting points for reduction of exposure are use of a cabin, DFR, and individual time spent on different tasks. Determinants that are constant over time (cabin use) may have an especially great influence on grouping workers, according to long-term exposure in epidemiological studies. As determinants of exposure vary for the different exposure routes and body locations (for dermal exposure), the measure of interest for a specific study design will decide which determinants are most relevant.

Adult↗
PubMed1998

Cancer risk in the rubber industry: a review of the recent epidemiological evidence.

OBJECTIVES: To examine the recent epidemiological evidence on cancer risk among workers in the rubber industry. METHODS: Epidemiological studies published after the last detailed review by the International Agency for Research on Cancer (IARC) in 1982 were reviewed. 12 cohort studies in nine countries that examined distinct populations of workers in the rubber industry, seven industry based nested case-control studies, 48 community based case-control studies in 16 countries, and 23 studies based on administrative data that reported risks for employment in the rubber industry were identified. RESULTS: Excess risks of bladder cancer, lung cancer, and leukaemia were found in most studies, with risks above 1.5 in about half of the studies. A moderate excess risk for laryngeal cancer was consistent across studies. Excess risks were found in a few studies for cancers of the oesophagus, stomach, colon, liver, pancreas, skin, prostate, kidney, brain, and thyroid, and for malignant lymphoma and multiple myeloma, but overall results were not consistent for these neoplasms. CONCLUSIONS: Magnitude of the observed risks varied considerably between studies, but overall the findings indicate the presence of a widespread moderate increased cancer risk among rubber workers. The most consistent results were for bladder, laryngeal, and lung cancer and for leukaemia. Excess risks were also found for other neoplasms but an evaluation of the consistency of the findings is difficult because of the possible selective reporting of results. Recent studies do not provide information associating specific exposures with cancer risk. The preventive measures taken in the rubber industry in recent years may decrease risks, but this has not been documented yet in epidemiological studies.

Case-Control Studies↗
PubMed1998

Assessment of exposure to solvents among hairdressers: reliability of a classification scheme and questionnaire.

OBJECTIVES: To assess the reliability of a classification scheme and interview questions to be used for retrospective expose assessment in a study on reproductive disorders among hairdressers. Based on the presence of an air cleaning device (yes or no) and setting waves (yes or no), this scheme divides hairdressers into groups with potentially high and low exposure to solvents. The reliability of this and other schemes was assessed. Also; the reliability of self reports on other job characteristics was evaluated. METHODS: The monitored hairdressers were interviewed one or two years after measurements were performed. Based on the interview information, hairdressers were classified into exposure groups according to the original and other classification schemes. Measured ethanol concentrations were compared between the classified exposure groups. Furthermore, the interview answers were compared with the registered information one to two years ago. RESULTS: Using self reports, the original scheme resulted in mean ethanol concentrations (used as indicator variable) of 11.8 and 7.4 mg/m3 for the high and low exposure groups, respectively. The resolution was slightly less than for the original classification based on observations (15.0 and 7.1 mg/m3). Surprisingly, the self reported presence of any ventilation device resulted in more contrast in mean exposure concentration between the groups (17.4 and 7.5 mg/m3, respectively). Hairdressers reported validly on salon characteristics such as the type of salon, the number of hairdressers that worked in the salon, and the presence of ventilation devices, but could not make a distinction between different kinds of ventilation devices. The numbers of customers and tasks performed were largely overreported, but most variables correlated significantly with the information registered during the measurements. CONCLUSION: The self reported presence of any ventilation device is most predictive for the level of exposure to ethanol in the hairdressing salon. Questionnaire data on work characteristics should be treated with caution.

Air Pollutants, Occupational↗
PubMed1998

Pulmonary ventilatory defects and occupational exposures in a population-based study in Spain. Spanish Group of the European Community Respiratory Health Survey.

We assessed the association between occupational exposures and symptoms of chronic bronchitis and pulmonary ventilatory defects in a general population-based study of five areas in Spain. This study forms part of the European Community Respiratory Health Study (ECRHS). Subjects (n = 1,735; age range, 20-44 yr; 52.4% of those initially selected) completed a respiratory questionnaire on symptoms and occupation and underwent baseline spirometry. Occupation was translated with an ad hoc developed job-exposure matrix (EM) into none, low, and high exposure to biological dust, mineral dust, and gases and fumes. Exposure to high levels of biological dust was associated with cough for more than 3 mo (odds ratio [OR], 1.9; p = 0.07), a reduction in FEF(25-27) to 478 ml/s (SD 178), and a reduction in FEV1 to 151 mL (SD 71). These associations remained after excluding subjects with asthma symptoms or bronchial responsiveness. Smokers tended to have a higher risk for respiratory symptoms, but smoking did not modify the association of occupation with pulmonary function. Exposure to mineral dust and gases/fumes was less consistently related to pulmonary function or to respiratory symptoms and this association further decreased after excluding subjects with asthma. In conclusion, exposure to high levels of biological dust in young adults is associated with symptoms of chronic bronchitis and pulmonary ventilatory defects, independently of asthma and smoking.

Adult↗
PubMed1998

Determinants of airborne rat and mouse urinary allergen exposure.

OBJECTIVES: The purpose of this study was to determine the factors affecting exposure to rat and mouse urinary allergens. METHODS: Ambient and personal air sampling was performed on a large scale in 7 laboratory animal facilities. RESULTS: Allergens were mainly present as large particles (>5.8 microm). The higher the number of animals in a room, the higher the allergen concentrations. Allergen levels were twice as high on Mondays as on other days due to the tasks performed on Mondays. Filter tops on animal cages were associated with 6-17 times lower ambient allergen levels. An inverse day-night rhythm for rats produced > or = 10 times higher rat urinary allergen levels. Personal exposure to rat and mouse urinary allergens differed between job titles but especially between facilities, probably because of differences in task performance and technology. Task-specific sampling revealed that the highest personal exposure levels occurred when contaminated bedding and high numbers of conscious animals were handled. The proportion of time spent on these tasks determined the degree of allergen exposure to a large extent. CONCLUSIONS: This study showed that the number of animals present in the room, use of filter top cages, and an inverse day-night rhythm were important determinants of rat and mouse urinary allergens in ambient air. Personal exposure to rat and mouse urinary allergens was predominantly determined by the task and site and, to a limited extent, by ambient exposure levels. The presented determinants can be used to develop exposure reduction strategies and also to aid epidemiologic studies of laboratory animal allergy.

Air Pollution, Indoor↗
PubMed1997

A collaborative European study of personal inhalable aerosol sampler performance.

Following the adoption of new international sampling conventions for inhalable, thoracic and respirable aerosol fractions, a working group of Comité Européen de Normalisation (CEN) drafted a standard for the performance of workplace aerosol sampling instruments. The present study was set up to verify the experimental, statistical and mathematical procedures recommended in the draft performance standard and to check that they could be applied to inhalable aerosol samplers. This was achieved by applying the tests to eight types of personal inhalable aerosol sampler commonly used for workplace monitoring throughout Europe. The study led to recommendations for revising the CEN draft standard, in order to simplify the tests and reduce their cost. However, some further work will be needed to develop simpler test facilities and methods. Several of the samplers tested were found to perform adequately with respect to the inhalable sampling convention, at least over a limited range of typical workplace conditions. In general the samplers were found to perform best in low external wind speeds, which are the test conditions thought to be closest to those normally found in indoor workplaces. The practical implementation of the CEN aerosol sampling conventions requires decisions on which sampling instruments to use, estimation of the likely impact that changing sampling methods could have on apparent exposures, and adjustment where necessary of exposure limit values. The sampler performance data obtained in this project were affected by large experimental errors, but are nevertheless a useful input to decisions on how to incorporate the CEN inhalable sampling convention into regulation, guidance and occupational hygiene practice.

Europe↗
PubMed1997

Monitoring and modelling of exposure to ethanol in hairdressing salons.

Personal exposure to solvents was studied among hairdressers in 28 salons in two regions during two seasons in The Netherlands. Ethanol was used as a marker for solvent exposure. Auxiliary data, such as salon and work characteristics, meteorological conditions and information on the presence of control measures, were collected during the measurements. The average exposure to ethanol was almost a factor of 200 below the occupational exposure limit, but differences in average ethanol concentrations up to a factor of 30 were present between salons. Exposure concentrations were significantly higher on Fridays than on other days of the week. Contrary to expectation, exposures were somewhat lower in the spring than in the summer and in an urban than a semi-rural area. An empirical statistical model based on exposure data collected during the first measurement period appeared not to be valid for the encountered circumstances in the second measurement period. An alternative classification scheme based on two easily obtainable salon and task characteristics was elaborated. This scheme will be applied in an ongoing epidemiological study on reproductive disorders among hairdressers and their offspring.

Acetaldehyde↗
PubMed1997

Grouping strategies for exposure to inhalable dust, wheat allergens and alpha-amylase allergens in bakeries.

This paper describes repeated measurements of inhalable flour dust, wheat allergens and alpha-amylase allergens in the bakery industry. A total of 571 full-shift personal dust samples was collected. Wheat allergens and alpha-amylase allergens were measured in 449 and 507 samples, respectively, by the use of recently developed immunoassays. For all three measures of exposure, the main components of exposure variability were determined. Different grouping strategies for studying exposure-response relationships were compared. The specific job of a bakery worker was identified as the most important source of variability in inhalable flour dust concentrations. For exposure to wheat allergens, the job performed was also the most important source of variation, but type of bakery also explained some of the variability. For alpha-amylase allergen exposure, information on type of bakery was more important then job information. For exposure to inhalable dust and wheat allergens, a classification by job title would lead to sufficient contrast in average exposure levels. By contrast, a grouping strategy based on a combination of job and type of bakery appeared to be essential to obtain a useful classification of exposure to alpha-amylase allergens. 1997 British Occupational Hygiene Society.

Allergens↗
PubMed1997

Sensitivity of the relation between cumulative magnetic field exposure and brain cancer mortality to choice of monitoring data grouping scheme.

We examined the effectiveness of alternative grouping strategies with respect to cumulative exposure to magnetic fields and brain cancer mortality among electric utility workers. We applied a statistically optimal job-exposure matrix to calculate cumulative exposure over full work histories. We studied the sensitivity of the exposure-disease relation by assigning an array of different quantitative exposure estimates based on six schemes for grouping exposure measurements. The quantitative relation between cumulative magnetic field exposure and brain cancer mortality appeared to be sensitive to the choice of grouping scheme, with the optimized grouping scheme indicating stronger relations than standard schemes.

Analysis of Variance↗
PubMed1997

Compliance versus risk in assessing occupational exposures.

Assessments of occupational exposures to chemicals are generally based upon the practice of compliance testing in which the probability of compliance is related to the exceedance [gamma, the likelihood that any measurement would exceed an occupational exposure limit (OEL)] and the number of measurements obtained. On the other hand, workers' chronic health risks generally depend upon cumulative lifetime exposures which are not directly related to the probability of compliance. In this paper we define the probability of "overexposure" (theta) as the likelihood that individual risk (a function of cumulative exposure) exceeds the risk inherent in the OEL (a function of the OEL and duration of exposure). We regard theta as a relevant measure of individual risk for chemicals, such as carcinogens, which produce chronic effects after long-term exposures but not necessarily for acutely-toxic substances which can produce effects relatively quickly. We apply a random-effects model to data from 179 groups of workers, exposed to a variety of chemical agents, and obtain parameter estimates for the group mean exposure and the within- and between-worker components of variance. These estimates are then combined with OELs to generate estimates of gamma and theta. We show that compliance testing can significantly underestimate the health risk when sample sizes are small. That is, there can be large probabilities of compliance with typical sample sizes, despite the fact that large proportions of the working population have individual risks greater than the risk inherent in the OEL. We demonstrate further that, because the relationship between theta and gamma depends upon the within- and between-worker components of variance, it cannot be assumed a priori that exceedance is a conservative surrogate for overexposure. Thus, we conclude that assessment practices which focus upon either compliance or exceedance are problematic and recommend that employers evaluate exposures relative to the probabilities of overexposure.

Air Pollutants, Occupational↗
PubMed1997

Efficiency of different grouping schemes for dust exposure in the European carbon black respiratory morbidity study.

OBJECTIVES: The aim of this study was to assess the theoretical efficiencies of different grouping strategies and its effect on the exposure-response relation in a study of respiratory morbidity associated with exposure to total inhalable and respirable carbon black dust. METHODS: A large epidemiological study is being undertaken to investigate the respiratory health of employees in the European carbon black manufacturing industry in relation to exposure to carbon black dust. In phase 2 of the study, repeated measurements of total inhalable and respirable dust were taken which enabled estimation of various components of variability in the exposure data (within and between worker variance and within and between group variance). These variance components were used to calculate the contrast in exposure between the groups in various classification schemes and to calculate the theoretical attenuation of the exposure-response relation and the standard error (SE) of the slope. RESULTS: High contrast in exposure was found when workers were classified according to the combination of their factory and job category as well as when these combinations were amalgamated into five exposure groups. Attenuation was minimal with most grouping schemes; only with the individual based strategy was the attenuation large. The SE of the theoretically attenuated exposure-response slope was smallest for the strategy based on individual people followed by the classification scheme based on factory and job category. CONCLUSIONS: It was concluded that, although some assumptions for the calculations of the attenuation of the exposure-response slope were not met, the most appropriate classification scheme of the worker seems to be by the combination of factory and job category.

Carbon↗
PubMed1997

Acetylcholinesterase Inhibition as an Indicator of Organophosphate and Carbamate Poisoning in Kenyan Agricultural Workers.

Acetylcholinesterase inhibition was determined for 666 Kenyan agricultural workers; 390 (58.6%) mainly pesticide applicators exposed to organophosphate and carbamate pesticides and 276 (41.4%) unexposed controls from four rural agricultural areas during 1993 and 1994. Baseline levels were depressed in the exposed group (6.1 +/- 0.84; 4.09 +/- 0.84) but not in the unexposed group (5.83 +/- 0.91; 5.60 +/- 0.87). Acetylcholinesterase inhibition was found in all exposed individuals and led, on average, to a decrease of baseline acetylcholinesterase levels of 33% (+/-12%). The control groups had a nonsignificant decrease of only 4% (+/- 8%). The exposed subjects in Naivasha (flower growers) had the largest inhibition (36%), followed by Homabay (cotton growers) (35%) and Wundanyi (vegetable growers) (33%). Those in Migori (tobacco growers) had, by far, the least inhibition of acetylcholinesterase activity (26%), indicating inherent factors that led to less inhibition. Acetylcholinesterase activity levels of 115 exposed individuals (29.6%) and no controls were depressed to values below 60% of baseline levels. The dramatic inhibition observed could lead to chronic clinical and subclinical intoxication. These findings show that acetylcholinesterase inhibition can be used as an indicator of organophosphate and carbamate poisoning in occupationally exposed agricultural workers. There is, therefore, an urgent need for primary prevention programs to monitor and address occupational exposures to these hazardous substances in agriculture in Kenya and other developing countries, as well as to use integrated pest management strategies in crop protection.

Journal Article↗
PubMed1996

An investigation of systematic changes in occupational exposure.

Nonstationary behavior in occupational exposure was examined among a number of job groups from different industries. A change in the mean level of exposure between two survey periods was evaluated by applying mixed-effects models. Overall, differences between surveys were observed in slightly more than one-third of the industries analyzed and in about one-quarter of the total number of comparisons performed. Exposures in the majority of cases decreased in the later survey. Further analyses examined the impact of nonstationary exposures on the estimation of the between- and within-worker components of variance. When changes in the mean exposure level were detected, point estimates of the variance components generated under the mixed model were compared with those estimates obtained under the one-way random-effects model, which assumes that the mean exposure level remains constant over time. The results indicate that the magnitude of the bias in the variance component estimates can be substantial when the misspecified model is applied. It is concluded that, in the absence of changes known to affect exposure, data collected within a year are likely to result in relatively valid inferences about mean and variance parameters using models that assume stationarity; for periods extending beyond a year, systematic changes in exposure are more likely to occur. Thus, exposure assessment strategies should be designed so that sufficient data are collected among groups of workers to investigate systematic changes and to ensure that appropriate statistical models are applied. In this way, occupational hygienists will be able to make reliable inferences about the underlying distribution of exposures pertinent to each occupational group.

Analysis of Variance↗
PubMed1996

Paraquat Exposure of Knapsack Spray Operators on Banana Plantations in Costa Rica.

A study of occupational exposure to paraquat was performed among 11 knapsack spray operators at banana plantations in Costa Rica. External and internal exposures were quantified and determinants of exposure identified by measurements, observations, and interviews. Dermal exposure was measured with skin pads, respiratory exposure by personal air sampling, and internal exposure by urine sampling. The wrists, back, and legs were the areas with the highest levels of dermal exposure. Respiratory exposures appeared to be strongly influenced by differences between days, while dermal exposures varied mostly due to differences between plantations. The use of protective clothing did not effectively protect against dermal exposures. Both respiratory and dermal exposures were significantly related to internal exposures, and both should be considered possible routes for systemic absorption of paraquat. It cannot be excluded that measurable levels of exposure can lead to acute as well as chronic health effects. Furthermore, due to poor conditions within the working environment, the spray operators are continuously at risk for high exposures that could lead to severe intoxication, and therefore a strategy for control of exposure is necessary.

Journal Article↗