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Biomedical subjects

Hans Kromhout

Publications and source records attributed to Hans Kromhout.

At least 37 records · Page 2Linked to original sources
PubMed2005

Effects of errors in the measurement of agricultural exposures.

The measurement error in agricultural exposures can be expected to be substantial given the nature of agricultural production. Agricultural work is often seasonal, and exposures to chemical and biological agents vary in a temporal sense due to the task variety and intermittent nature of most agricultural exposures. Exposure patterns are also often complex in terms of the specific agents involved and entail mixed exposure situations. However, farmers often have stable careers and tend to stay in the same working and living environment. Their conservative attitudes also make them reliable sources of past production patterns, machinery, and chemical use. To reduce the measurement error that potentially obscures relations between agricultural exposures and health outcomes, more effort should be put into revealing actual determinants of agricultural exposures. Knowledge of these determinants can be used in questionnaires for retrospective exposure assessment, either in studies of the general population or within agricultural populations, and can be used to predict exposure more reliably.

Agricultural Workers' Diseases↗
PubMed2004

Evaluating exposures to complex mixtures of chemicals during a new production process in the plastics industry.

The goal of this study was to monitor emission of chemicals at a factory where plastics products were fabricated by a new robotic (impregnated tape winding) production process. Stationary and personal air measurements were taken to determine which chemicals were released and at what concentrations. Principal component analyses (PCA) and linear regression were used to determine the emission sources of different chemicals found in the air samples. We showed that complex mixtures of chemicals were released, but most concentrations were below Dutch exposure limits. Based on the results of the principal component analyses, the chemicals found were divided into three groups. The first group consisted of short chain aliphatic hydrocarbons (C2-C6). The second group included larger hydrocarbons (C9-C11) and some cyclic hydrocarbons. The third group contained all aromatic and two aliphatic hydrocarbons. Regression analyses showed that emission of the first group of chemicals was associated with cleaning activities and the use of epoxy resins. The second and third group showed strong association with the type of tape used in the new tape winding process. High levels of CO and HCN (above exposure limits) were measured on one occasion when a different brand of impregnated polypropylene sulphide tape was used in the tape winding process. Plans exist to drastically increase production with the new tape winding process. This will cause exposure levels to rise and therefore further control measures should be installed to reduce release of these chemicals.

Air Pollutants, Occupational↗
PubMed2004

Characteristics of peaks of inhalation exposure to organic solvents.

OBJECTIVES: To determine which exposure metrics are sufficient to characterize 'peak' inhalation exposure to organic solvents (OS) during spraying operations. METHODS: Personal exposure measurements (n=27; duration 5-159 min) were collected during application of paints, primers, resins and glues in 15 companies. A MiniRAE Photo-Ionization Detector measured OS concentrations every second. These readings were adjusted for OS composition, which was determined by charcoal tubes. A peak was defined as a period during which exposure exceeded the time-weighted average (TWA) exposure. Five second and 1 and 15 min moving average times were considered in defining a peak. The number of peaks per hour, the duration of a peak, the maximum concentration within a peak, the average concentration within a peak, the ratio between maximum and average concentration within a peak and the average time between two peaks were recorded for each sample. Data were analyzed using factor analysis on 13 variables for the 27 samples: TWA concentration of the task and the six peak characteristics based on the 5 s and 1 min moving averaging time. RESULTS: There were three statistically independent sources of correlation among metrics of peak exposure, explaining 87% of the multiple correlation. The first factor reflected the intensity of peak exposure; it was also associated with the TWA. The second and third factors were related to measures of variability (in frequency and intensity) and duration of peaks, respectively. CONCLUSIONS: We present a method for describing peak profiles for inhalation exposure in terms of various distinguishable and independent parameters. Pending development of toxicologically justified peak exposure metrics, such investigations can be of value in identifying exposure metrics for which non-confounded risk estimates can be obtained in epidemiological studies.

Environmental Monitoring↗
PubMed2004

Interaction of atopy and smoking on respiratory effects of occupational dust exposure: a general population-based study.

BACKGROUND: For individual exposures, effect modification by atopy or smoking has been reported on the occurrence of occupational airway disease. It is unclear if effect modification can be studied in a general population by an aggregated exposure measure. Assess relationship between airway obstruction and occupational exposure using a job-exposure-matrix (JEM) classifying jobs into 3 broad types of exposure, and test for effect modification by atopy, and smoking. METHODS: Data from 1,906 subjects were analyzed, all participants of the European Community Respiratory Health Survey. Job titles were categorized by an a priori constructed job exposure matrix into three classes of exposure to respectively organic dust, mineral dust, and gases/ fumes. Relationships were assessed for 'current wheeze', bronchial hyperresponsiveness (BHR), 'current asthma' (wheeze+BHR), and 'chronic bronchitis' (morning phlegm or morning cough), and lung function. RESULTS: Subjects with organic dust exposure in their work environment more frequently had 'current asthma' (OR 1.48, 95% C.I. 0.95;2.30), and a lower FEV1 (-59 mL, 95% C.I. -114;-4). The relationship was only present in asthmatic workers, and their risk was four-fold greater than in subjects with either atopy or exposure alone. Mineral dust exposure was associated with 'chronic bronchitis' (OR 2.22, 95% C.I. 1.16;4.23) and a lower FEV1/FVC ratio (-1.1%, 95% C.I. -1.8;-0.3). We observed an excess risk in smokers, greater than the separate effects of smoking or mineral dust exposure together. CONCLUSION: Occupational exposure to organic dust is associated with an increased risk of asthma, particularly in atopics. Chronic bronchitis occurs more frequently among individuals exposed to mineral dust, and smoking doubles this risk.

Adult↗
PubMed2004

Occupational dermal exposure to cyclophosphamide in Dutch hospitals: a pilot study.

INTRODUCTION: Several studies have shown that exposure to antineoplastic drugs can cause reproductive toxic effects as well as carcinogenic effects. Presence of these drugs in the urine of hospital personnel has been widely studied and some work has been done on exposure by inhalation. So far, assessment of dermal exposure to antineoplastic drugs has not been extensively studied. In this pilot study we assessed potential and actual dermal exposure for several common hospital tasks. Results were used to derive an optimal measurement strategy for a currently ongoing exposure survey. METHODS: Dermal exposure to cyclophosphamide was determined in three Dutch hospitals during five tasks (preparation, decanting urine, washing the patient, removing bed sheets and cleaning the toilet) using pad samples on 10 body locations. In addition, protective medical gloves (worn during the performance of these activities) were collected to estimate potential exposure of the hands. Subsequently, hands were washed to measure actual exposure of the hands. Bulk samples (i.e. application and body fluids) were collected and possible contact surfaces were monitored to assess the amount of cyclophosphamide potentially available for exposure. RESULTS: The results show that hospital personnel (i.e. pharmacy technicians and oncology nurses) are dermally exposed to cyclophosphamide during performance of their daily duties. Exposure occurred predominantly on the hands and sporadically on other body locations (i.e. forehead and forearms). Gloves used during preparation of cyclophosphamide were more contaminated than gloves used in other tasks, however, actual exposure of the hands (underneath the gloves) was highest during decanting of urine of treated patients. Glove samples correlated significantly with handwash samples (r = 0.57, P = 0.03, n = 15). The level of protection from gloves varied between tasks, being highest for gloves used during preparation (median = 98%) and lowest for gloves used during decanting urine (median = 19%). CONCLUSION: This pilot study demonstrated that dermal exposure to cyclophosphamide is common among hospital personnel. The results showed that hands, forearms and forehead accounted for 87% of the cyclophosphamide total body exposure. Glove samples together with handwash samples enabled estimation of glove efficiency, which appeared to vary strongly between tasks observed.

Antineoplastic Agents, Alkylating↗
PubMed2004

Exposure variability: concepts and applications in occupational epidemiology.

BACKGROUND: Standard approaches to assessing exposures for epidemiologic studies tend to concentrate resources on obtaining detailed data for each study participant at the expense of characterizing within-person variability. METHODS: This paper presents some basic, generalizeable concepts concerning exposure and its variability, describes methods that can be used to analyze, describe, and understand that variability, and reviews related implications for the design and interpretation of epidemiologic studies. RESULTS AND CONCLUSIONS: Insufficient attention to the balance of within- and between-person variation in exposure can reduce the efficiency of measurement efforts and attenuate estimates of exposure-disease association. Exposure variability should consequently be considered carefully in the planning, analysis, and interpretation of epidemiologic studies. Greater attention to these matters can lead to more meaningful characterization of exposure itself, and, most importantly, improve the chances that epidemiologic studies can identify and accurately characterize health hazards.

Analysis of Variance↗
PubMed2004

Evaluation of specific occupational asthma risks in a community-based study with special reference to single and multiple exposures.

OBJECTIVES: To compare two job exposure matrices (JEMs) for the evaluation of asthma risks related to specific occupational exposures in a community-based study. METHODS: A questionnaire on self-reported asthma, respiratory symptoms and current occupation was sent to the participants of the European Community Respiratory Health Survey in five areas in Spain. Both an asthma-specific JEM, including expert judgment steps and a general JEM, were applied to occupational codes. Risks of current asthma symptoms and wheeze in the last year associated with the obtained exposure estimates were evaluated. Correlations between specific exposures were investigated using explanatory factor analysis. RESULTS: Occupational exposures to the high-molecular-weight (MW) agents flour dust, enzymes, mites and animal-derived proteins as obtained by the asthma-specific JEM were positively associated with asthma outcomes. The effect of additional expert judgment steps was limited. High exposures to biological dust assessed by the general JEM without expert judgment was also associated with asthma. Many of the exposed individuals worked in environments with multiple exposures. CONCLUSIONS: Asthma risks associated with occupational exposures to specific high-MW agents could be identified from a population-based study using an asthma-specific JEM. Application of JEMs can be a useful tool to estimate asthma risks attributable to specific occupational exposures in the general population. However, these specific exposure risks should be interpreted in connection with the whole of concomitant exposures constituting the work environment.

Adult↗
PubMed2004

Variability of task-based dermal exposure measurements from a variety of workplaces.

INTRODUCTION: The RISKOFDERM project collected task-based estimates of potential dermal exposure from a wide range of industries and services from around Europe. A formal statistical analysis was carried out to explore the main components of variability in dermal exposure levels. The central research question was to what extent dermal exposure levels could be explained by generic grouping variables like 'exposure scenarios' and 'dermal exposure operation units' (DEOs) (grouping of scenarios on the basis of similarity in exposure patterns). METHODS: Mixed effect linear models were used to estimate variance components of potential dermal exposure for DEOs or scenarios and for factories, workers and time. In addition within- and between-worker variance components were estimated for single groups of workers performing a specific scenario in a specific location with potential dermal exposure to a specific agent. RESULTS: Variability in potential dermal exposure is very large. Differences in geometric mean potential dermal exposure can range over 3-5 orders of magnitude both for DEOs and scenarios. The range depends on how dermal exposure is expressed (amount or rate). Both DEOs and scenarios explain a considerable amount of variability, but large differences in dermal exposure still existed within DEOs and scenarios. In contrast, between-worker variability in mean potential dermal exposure is minimal for a given scenario carried out within a specific location with exposure to a particular agent. Temporal variability, however, is considerable, most likely due to the event-based nature of the dermal exposure process. CONCLUSION: The classification of tasks in DEOs and scenarios has proven to be useful since large differences in average dermal exposure estimates exist between DEOs and between scenarios. However, large differences also exist between scenarios within a DEO and even within a scenario. These differences are governed by local conditions determined by the actual handling of the agent, the agent's physical and chemical properties, its intrinsic toxicity, control measures taken and training and attitude of workers. For the time being, actual dermal exposure measurements and a better understanding of actual determinants of dermal exposure seem to be a necessity in order to evaluate dermal exposure hazards properly.

Analysis of Variance↗
PubMed2004

Cancer incidence of Nordic asphalt workers.

OBJECTIVES: The aim of the study was to investigate cancer risk following employment in the asphalt industry. METHODS: Cancer incidence was studied among 22 362 male asphalt workers employed for more than one season in jobs entailing exposure to bitumen (mainly road pavers) in Denmark, Finland, Norway, and Sweden. These workers are part of a European cohort of asphalt workers, for which results on mortality have been reported. The follow-up was almost complete, and reference rates were obtained from national cancer registries. RESULTS: The incidence of cancer was reduced in all four countries [overall standardized incidence ratio (SIR) 0.89, 95% confidence interval (95% CI) 0.86-0.94]. Lung cancer incidence was increased in all four countries, yielding an overall SIR of 1.21 (95% CI 1.07-1.36), but no trend was detected according to time since first employment. No overall increased incidence of bladder cancer was observed, but there was a suggestion of a tendency towards higher risk with longer time since first employment, with a relative risk of 1.85 (95% CI 0.90-3.78) for more than 30 years versus 1-14 years (P-value for trend 0.1). The incidence of lip and stomach cancer was nonsignificantly increased, and the excess was present mainly in Denmark. No increased incidence was detected for other neoplasms, notably malignant melanoma, nonmelanoma skin cancer, and kidney cancer. CONCLUSIONS: The results of this study confirm the pattern of cancer risk detected in the mortality analysis of the European cohort; in addition, they provide suggestive evidence of an excess risk of bladder cancer among asphalt workers.

Adolescent↗
PubMed2003

Mortality from obstructive lung diseases and exposure to polycyclic aromatic hydrocarbons among asphalt workers.

Work in the asphalt industry has been associated with nonmalignant respiratory morbidity and mortality, but the evidence is not consistent. A historical cohort of asphalt workers included 58,862 men (911,209 person-years) first employed between 1913 and 1999 in companies applying and mixing asphalt in Denmark, Finland, France, Germany, Israel, the Netherlands, and Norway. The relations between mortality from nonmalignant respiratory diseases (including the obstructive lung diseases: chronic bronchitis, emphysema, and asthma) and specific chemical agents and mixtures were evaluated using a study-specific exposure matrix. Mortality from obstructive lung diseases was associated with the estimated cumulative and average exposures to polycyclic aromatic hydrocarbons and coal tar (p values of the test for linear trend = 0.06 and 0.01, respectively). The positive association between bitumen fume exposure and mortality from obstructive lung diseases was weak and not statistically significant; confounding by simultaneous exposure to coal tar could not be excluded. The authors lacked data on smoking and full occupational histories. In conclusion, exposures to polycyclic aromatic hydrocarbons, originating from coal tar and possibly from bitumen fume, may have contributed to mortality from obstructive lung diseases among asphalt workers, but confounding and bias cannot be ruled out as an explanation for the observed associations.

Causality↗
PubMed2003

Epidemiologic study of cancer mortality among Israeli asphalt workers.

BACKGROUND: We describe the results of a cancer mortality study among asphalt workers in Israel. METHODS: Personal identifiers and employment histories of 2,176 workers were extracted from company records. RESULTS: Mortality from all malignant neoplasms was significantly reduced in the whole cohort (SMR 0.68, 95% confidence interval (CI) 0.56-0.83). SMR for lung cancer was elevated in workers exposed to bitumen (SMR 1.05, 95% CI 0.62-1.66). No significant elevation or reduction in mortality was observed in relation to a specific site. SMRs for lung cancer was higher among ever exposed to bitumen than among unexposed. There was no association between lung cancer risk and estimated exposure to bitumen fume, and no dose-response was apparent. CONCLUSIONS: While the results of this cohort study indicate a slightly increased SMR for lung cancer, it did not produce evidence of a causal link between lung cancer and exposure to bitumen fume.

Adult↗
PubMed2003

Lung cancer mortality in a Dutch cohort of asphalt workers: evaluation of possible confounding by smoking.

BACKGROUND: Using data from a Dutch cohort of workers in road construction and asphalt mixing companies, this article describes possible confounding of the association between exposure to bitumen fume and lung cancer mortality by smoking. METHODS: A retrospective cohort of 3,714 workers with at least one season of employment was identified. Semi-quantitative exposure to bitumen fume was assessed by a job-exposure matrix. Information on smoking habits was available for a sub-cohort of 1,138 workers, who underwent medical examinations by the occupational health services in the past. RESULTS: Smoking habits differed between occupational title groups and there was a positive association between cumulative exposure and smoking. Internal analyses using the non-exposed subjects as reference category, showed a positive association between semi-quantitative bitumen fume exposure and lung cancer risk. After adjusting for differences in smoking habits, all relative risks were reduced, but a weak positive association could still be observed. CONCLUSION: Confounding by smoking on the association between exposure to bitumen fume and lung cancer mortality is possible, although the positive trend (not statistically significant) for lung cancer mortality remained. Only a nested case-control study may allow proper treatment of potential (residual) confounding by smoking in this population.

Adult↗
PubMed2003

Performance of different exposure assessment approaches in a study of bitumen fume exposure and lung cancer mortality.

BACKGROUND: We compared performance of different exposure assessment approaches in a cohort study of cancer risk among European asphalt workers. METHODS: Three bitumen fume exposure indices (duration of exposure (years), average exposure (mg/m3) and cumulative exposure (mg/m3*years)) and two latency models (with and without a 15 year lag) were considered for an association between lung cancer mortality and bitumen fume. RESULTS: There was no association between lung cancer risk and either duration or cumulative exposure. However, there was the suggestion of an increase in lung cancer risk accompanying rise in average exposure. Only models with average bitumen fume exposure (with or without lag) improved model fit, albeit to the same extent. CONCLUSIONS: Constructing quantitative indices of exposure intensity was justified because they produced the greatest improvement in fit of models that explored possible relationship between bitumen fume exposure and lung cancer risk. The identified associations require further investigation.

Cohort Studies↗
PubMed2003

Cancer mortality among European asphalt workers: an international epidemiological study. I. Results of the analysis based on job titles.

BACKGROUND: Inhalation of bitumen fumes is potentially carcinogenic to humans. METHODS: We conducted a study of 29,820 male workers exposed to bitumen in road paving, asphalt mixing and roofing, 32,245 ground and building construction workers unexposed to bitumen, and 17,757 workers not classifiable as bitumen workers, from Denmark, Finland, France, Germany, Israel, the Netherlands, Norway, and Sweden, with mortality follow-up during 1953-2000. We calculated standardized mortality ratios (SMRs) and 95% confidence intervals (CIs) based on national mortality rates. Poisson regression analyses compared mortality of bitumen workers to that of building or ground construction workers. RESULTS: The overall mortality was below expectation in the total cohort (SMR 0.92, 95% CI 0.90-0.94) and in each group of workers. The SMR of lung cancer was higher among bitumen workers (1.17, 95% CI 1.04-1.30) than among workers in ground and building construction (SMR 1.01, 95% CI 0.89-1.15). In the internal comparison, the relative risk (RR) of lung cancer mortality among bitumen workers was 1.09 (95% CI 0.89-1.34). The results of cancer of the head and neck were similar to those of lung cancer, based on a smaller number of deaths. There was no suggestion of an association between employment in bitumen jobs and other cancers. CONCLUSIONS: European workers employed in road paving, asphalt mixing and other jobs entailing exposure to bitumen fume might have experienced a small increase in lung cancer mortality risk, compared to workers in ground and building construction. However, exposure assessment was limited and confounding from exposure to carcinogens in other industries, tobacco smoking, and other lifestyle factors cannot be ruled out.

Adult↗
PubMed2003

Cancer mortality among European asphalt workers: an international epidemiological study. II. Exposure to bitumen fume and other agents.

BACKGROUND: An increased risk of lung cancers among asphalt workers has been suggested in epidemiological studies based on large scale statistical analyses. METHODS: In a multi-country study of 29,820 male workers employed in road paving, asphalt mixing and roofing, 32,245 ground and building construction workers and 17,757 other workers from Denmark, Finland, France, Germany, Israel, the Netherlands, Norway, and Sweden, with mortality that was documented from 1953-2000. Exposures to bitumen fume, coal tar, 4-6 ring polycyclic aromatic hydrocarbons, organic vapor, diesel exhaust, asbestos, and silica dust were assessed via a job-exposure matrix. Standardized mortality ratios (SMRs) and 95% confidence intervals (CIs) based on national mortality rates, as well as relative risks (RRs) based on Poisson regression models were calculated. RESULTS: The SMR of lung cancer among workers exposed to bitumen fume (1.08, 95% CI 0.99-1.18) was comparable to that of non-exposed workers (SMR 1.05, 95% CI 0.92-1.19). In a sub-cohort of bitumen-exposed workers without exposure to coal tar, the SMR of lung cancer was 1.23 (95% CI 1.02-1.48). The analysis based on the semi-quantitative, matrix-based exposures in the whole cohort did not suggest an increased lung cancer risk following exposure to bitumen fume. However, in an analysis restricted to road pavers, based on quantitative estimate of bitumen fume exposure, a dose-response was suggested for average level of exposure, applying a 15-year lag, which was marginally reduced after adjustment for co-exposure to coal tar. The results for cancer of the head and neck were similar to those of lung cancer, although they were based on a smaller number of deaths. There was no clear suggestion of an association with bitumen fume for any other neoplasm. CONCLUSIONS: The results of the analysis by bitumen fume exposure do not allow us to conclude on the presence or absence of a causal link between exposure to bitumen fume and risk of cancer of the lung and the head and neck.

Adult↗
PubMed2003

Estimating exposures in the asphalt industry for an international epidemiological cohort study of cancer risk.

BACKGROUND: An exposure matrix (EM) for known and suspected carcinogens was required for a multicenter international cohort study of cancer risk and bitumen among asphalt workers. METHODS: Production characteristics in companies enrolled in the study were ascertained through use of a company questionnaire (CQ). Exposures to coal tar, bitumen fume, organic vapor, polycyclic aromatic hydrocarbons, diesel fume, silica, and asbestos were assessed semi-quantitatively using information from CQs, expert judgment, and statistical models. Exposures of road paving workers to bitumen fume, organic vapor, and benzo(a)pyrene were estimated quantitatively by applying regression models, based on monitoring data, to exposure scenarios identified by the CQs. RESULTS: Exposures estimates were derived for 217 companies enrolled in the cohort, plus the Swedish asphalt paving industry in general. Most companies were engaged in road paving and asphalt mixing, but some also participated in general construction and roofing. Coal tar use was most common in Denmark and The Netherlands, but the practice is now obsolete. Quantitative estimates of exposure to bitumen fume, organic vapor, and benzo(a)pyrene for pavers, and semi-quantitative estimates of exposure to these agents among all subjects were strongly correlated. Semi-quantitative estimates of exposure to bitumen fume and coal tar exposures were only moderately correlated. EM assessed non-monotonic historical decrease in exposures to all agents assessed except silica and diesel exhaust. CONCLUSIONS: We produced a data-driven EM using methodology that can be adapted for other multicenter studies.

Cohort Studies↗
PubMed2003

Neurobehavioral effects among subjects exposed to high static and gradient magnetic fields from a 1.5 Tesla magnetic resonance imaging system--a case-crossover pilot study.

The interactive use of magnetic resonance imaging (MRI) techniques is increasing in operating theaters. A study was performed on 17 male company volunteers to assess the neurobehavioral effects of exposure to magnetic fields from a 1.5 Tesla MRI system. The subjects' neurobehavioral performances on a neurobehavioral test battery were compared in four 1-hr sessions with and without exposure to magnetic fields, and with and without additional movements. Adverse effects were found for hand coordination (-4%, P < 0.05; Pursuit Aiming II) and near visual contrast sensitivity (-16% and -15%, P < 0.10; Vistech 6000). The results from the remaining tests were inconclusive due to a strong learning effect. No additional effect from gradient fields was detected. The results indicate that working near a 1.5 Tesla MRI system may lead to neurobehavioral effects. Further research is recommended, especially in members of operating teams using interactive MRI systems.

Adult↗