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Biomedical subjects

D Heederik

Publications and source records attributed to D Heederik.

At least 109 records · Page 6Linked to original sources
PubMed1995

Cancer risk for European asphalt workers.

OBJECTIVES: The feasibility of a European epidemiologic study of cancer risk among asphalt workers was examined in Western Europe. The study was motivated by occupational and public health concern about possible health risk from exposure to bitumen fumes. METHODS: Information on the accessibility and quality of epidemiologic resources, retrospective worker records, mortality and cancer incidence records, and exposures was requested from research institutes and road paving and asphalt mixing companies in 15 European countries. RESULTS: Research institutes and asphalt companies in 12 countries responded. It was found that at least 44 companies in seven countries can be included in a retrospective mortality study of a minimum of 32,000 employees with 356,000 person-years (over 100 lung cancers). Coal tar will be an important confounder for these data. The power of a cohort study of workers who have never worked with tar-containing materials remains insufficient. Even in an ambispective study extending to the year 2005, the expected lung cancer deaths in a tar-free cohort would be only four. CONCLUSIONS: The results suggest that a case-referent study of lung cancer, nested in an international cohort of asphalt workers, represents the design of choice, conditionally on the possibility of assessing relevant individual life-time exposures. A cross-sectional determination of relevant biomarkers of exposure such as adducts in lymphocytes or the presence of metabolites of polycyclic aromatic compounds in urine in a group of workers exposed to bitumen fumes will provide further relevant information.

Adult↗
PubMed1995

Modeling long-term average exposure in occupational exposure-response analysis.

OBJECTIVES: Estimates of long-term average exposure to occupational hazards are often imprecise because intraindividual variability in exposure can be large and exposure is usually based on one or few measurements. One potential result is bias of exposure-response relationships. The possibility was studied of a more valid measure of exposure being obtained by modeling exposure and consequently increasing the number of days with exposure estimates, using simple measurable exposure surrogates. METHODS: In a group of 198 Dutch pig farmers, exposure to endotoxins was measured on one workday in summer and one day in winter. Farmers recorded activity patterns during one week in both seasons, and farm characteristics were evaluated. Relationships between farm characteristics and activities and log-transformed measured exposure levels were quantified in a multiple regression analysis. Exposure was estimated for 14 d with known activity patterns. RESULTS: The ratio of intraindividual and interindividual variance in log-transformed measured exposure was 4.7. Given this ratio, the true regression coefficient of lung function on exposure would potentially be attenuated by 70%. The variance ratio for predicted exposures was only 1.2, and the potential attenuation by variation in exposure estimates was decreased to 8%. There was no relationship between lung function and measured exposure. Modeled long-term average exposure was inversely related to base-line lung function; it reached statistical significance for asymptomatic farmers. CONCLUSIONS: The results suggest that the presented strategy offers a possibility to minimize measurement effort in occupational epidemiologic studies, without apparent loss of statistical power.

Adult↗
PubMed1995

Determinants of dust and endotoxin exposure of pig farmers: development of a control strategy using empirical modelling.

Personal exposure to dust and endotoxin was measured among 198 Dutch pig farmers. For each participant 8-h measurements were made on 2 days, one in summer 1991 and one in winter 1992. Mean time-weighted average (TWA) exposure to dust was 3.0 mg m-3 (arithmetic mean, range 0.3-27 mg m-3) and mean TWA exposure to endotoxin was 130 ng m-3 (arithmetic mean, range 6-1503 mg m-3). Empirical statistical modelling was applied to identify activities and farm characteristics associated with exposure. In a multiple least-squares regression analysis, aspects of hygiene and feeding were major characteristics associated with dust exposure. Flooring and feeding were predominant characteristics explaining variation in endotoxin exposure. Activities performed frequently, like feeding and controlling, cleaning activities and activities in which very active animals were involved, such as teeth cutting and ear tagging, were associated with exposure to dust and endotoxin. The models were used to set priorities for the development of control measures to eliminate the dust and endotoxin hazard of pig farmers.

Animal Husbandry↗
PubMed1994

Dust-related decline in lung function among animal feed workers.

The study describes results of the first part of a follow-up study among 50 animal feed and grain elevator workers. The initial results suggest that the change in lung function over a 5 year period is related to the dust exposure. Workers in the high exposure category showed a greater decline in lung function than workers in the low exposure category. The decline in lung function was strongest for workers who were low exposed at the beginning of the study and who became high exposed during the follow-up period.

Adult↗
PubMed1994

Dust- and endotoxin-related acute lung function changes and work-related symptoms in workers in the animal feed industry.

Reported respiratory and related symptoms during work were compared between 265 exposed animal feed workers and a control group consisting of 175 external controls and nonexposed workers in the animal feed industry. Symptoms indicating respiratory and nasal irritation were significantly increased in the animal feed workers. Prevalences ranged from 9% (cough) to 21% (sneezing). Reported cough after work was also significantly increased. In 119 workers, a total of 457 across-shift spirometric lung function changes were measured. Almost all lung function variables showed a decrease during the work shift, as could be expected since the circadian rhythm is in a downward phase during the measurement period (2 p.m.-10 p.m.). When the workers were grouped into dust and endotoxin exposure categories according to their job titles, and exposure-response trend was seen for maximum mid-expiratory flow (MMEF) and maximum expiratory flow rate at 50% of vital capacity (MEF50). The effect of endotoxin was stronger than that of dust, both in magnitude and significance. For the same lung function variables and for forced expiratory volume in 1 second (FEV1) and MEF25, a significant across-week change was also detected. The results of this study are in concordance with other studies that indicate acute effects on lung function and elevated prevalences of respiratory symptoms during work caused by exposure to grain dust.

Adult↗
PubMed1994

Dust exposure indices and lung function changes in longshoremen and dock workers.

A group of Dutch harbor workers involved in loading and unloading bulk products from sea vessels such as coal, cokes, and some other products like alumina, borax, phosphate ore, and vermiculite was studied. Exposures were characterized by personal and environmental monitoring. This information was subsequently used to estimate several dust exposure indices and to study relationships with lung function variables and respiratory symptoms. Average respirable dust exposure levels ranged from 0.3-4.0 mg/m3. Workers involved in unloading products from sea vessels were exposed to the highest dust levels. Supervisors and workers with tasks in the dock had an intermediate to low exposure. Office workers had the lowest exposure to respirable dust. Inhalable dust levels were considerably higher and average exposures ranged from 0.3-80 mg/m3. The ranking of occupational titles by inhalable dust exposure was almost identical to the rank order of respirable dust levels. Workers with higher current and cumulative dust exposures tended to have a lower lung function, and only shortness of breath had a statistically significant relationship with current and cumulative inhalable dust exposure. In general, relationships between lung function and inhalable dust levels tended to be somewhat stronger in terms of statistical significance, because inhalable dust is an estimate of dust deposition in the upper airways and lung function is a measurable parameter of airway obstruction in that region. However, the differences with respirable dust were minimal, and variability in dust exposure levels was extremely large for this population. It was concluded that harbor workers involved in unloading ships containing coal and various kinds of ore can be exposed to high dust levels. Relationships between dust exposure and lung function illustrate that these exposures are a respiratory hazard. Our finding that inhalable dust levels have a somewhat stronger relationship with lung function level than respirable dust levels deserves further attention.

Adult↗
PubMed1994

Time to pregnancy and occupational exposure to pesticides in fruit growers in The Netherlands.

OBJECTIVES: Although pesticides are regularly used in agriculture, relatively little is known about possible adverse health effects, especially reproductive effects, due to occupational exposure. This explorative study investigates the relation between exposure of the fruit grower to pesticides and fecundability (probability of pregnancy) in a population of fruit growers. METHODS: The analysis is based on self reported data and includes 91 pregnancies during 1978-1990 of 43 couples. Cox' proportional hazards model was used to analyse time to pregnancy after correction for gravidity and consultation with a physician for fertility problems. RESULTS AND CONCLUSIONS: Application of pesticides solely by the owner was associated with a long time to pregnancy, resulting in a fecundability ratio of 0.46 (95% confidence interval (95% CI) 0.28-0.77). Similarly a low spraying velocity (< or = 1.5 hectares/h) resulted in a fecundability ratio of 0.47 (95% CI 0.29-0.76) and is associated with the use of older spraying techniques and tractors without a cabin. These factors were assumed to cause high exposure, which was confirmed by exposure measurements in the field. The effect of high exposure was mainly apparent if the couple had intended to become pregnant in the period from March-November (fecundability ratio 0.42, 95% CI 0.20-0.92). This is the period in which pesticides are applied. Out of the spraying season the effect of a high exposure was absent (fecundability ratio 0.82, 95% CI 0.33-2.02). In the high exposure group 28% of the pregnancies had been preceded by consulting a physician because of fertility problems, compared with 8% in the low exposure group. These findings indicate that an adverse effect of exposure to pesticides on fecundability is likely.

Adult↗
PubMed1994

Acute respiratory effects in the potato processing industry due to a bioaerosol exposure.

The relation between bioaerosol exposure in the potato starch industry and work related respiratory symptoms is described. One group of workers was exposed to high dust concentrations (geometric mean up to 56.0 mg/m3) with low endotoxin and antigen concentrations (geometric mean up to 12.6 ng/m3 and 90 relative antigen units (RAU) per m3). A second group was exposed to low dust concentrations (geometric mean up to 3.9 mg/m3), but the endotoxin and antigen concentrations were high (geometric means of environmental samples up to 72 ng/m3 and 2.9.10(2)RAU/m3). Twenty of the 48 workers had specific IgG4 titres to dust extract. Of these 20 workers, 14 showed an increase in IgG4 titre during the first month of the potato processing season. No specific IgE antibodies to dust extracts were found. Twenty two workers were equipped with a Mini-Wright peak flow meter during a four week period. Two workers showed a work related decline in peak flow values. It was concluded that exposure to dust made airborne during the refining process of potato starch may cause work related respiratory symptoms.

Aerosols↗
PubMed1994

Changes in ventilatory function in grain processing and animal feed workers in relation to exposure to organic dust.

OBJECTIVES: The effects of organic dust exposure on the configuration of the maximum expiratory flow volume (MEFV) curve was examined multivariately. METHODS: Data from 390 male workers in the animal feed industry in The Netherlands were analyzed. A multivariate technique called nonlinear canonical correlation analyses was used to study the relationship between a set of organic dust exposure variables and a set of ventilatory function variables. RESULTS: The results indicate an almost independent effect of the overall mean organic dust exposure and the number of years of organic dust exposure on ventilatory function. Increasing mean organic dust exposure was associated with a decrease in both forced expiratory volume in 1 s (FEV1.0) and forced vital capacity (FVC) and decreased flows at high lung volumes only. Increasing number of years of dust exposure was associated with a decrease in FEV1.0 and a decrease in flow at all lung volumes, while the FVC seemed relatively constant. These two distinct patterns of reduction in ventilatory function may represent two different pathological processes. Whereas workers with prolonged exposure showed reduced values for all of the MEFV curve variables, except the FVC, those with only a few years of exposure especially showed a decrease in FVC and peak expiratory flow. The effect of current organic dust exposure was more evident for nonsmokers than for ex-smokers and current smokers. CONCLUSION: The major finding of this study was an independent effect of overall mean organic dust exposure and the number of years of organic dust exposure on the MEFV curve.

Adult↗
PubMed1994

Occupational exposures estimated by a population specific job exposure matrix and 25 year incidence rate of chronic nonspecific lung disease (CNSLD): the Zutphen Study.

The influence of occupational exposures on total mortality and respiratory mortality and morbidity was examined, employing a population specific Job Exposure Matrix (JEM). Moreover, the relationship between time-related variables of exposure to dust and chronic nonspecific lung disease (CNSLD) incidence was analysed, using time since first exposure and duration of exposure. Occupational exposures in the Zutphen cohort were assessed by application of a JEM, arbitrarily considering jobs as exposed when at least 10% of men who had held the job of interest reported an exposure to one or more from a list of 27 chemical agents. None of the exposures was related to mortality due to CNSLD, although results were influenced by the healthy-worker effect and low mortality rates. Exposure to wood dust and a high probability of exposure to dust were associated with total mortality. Exposures to dust and solvents were statistically significantly related to CNSLD incidence. An exposure-response relationship was found for the probability of exposure to dust with CNSLD incidence. Time-related estimates of exposure to dust based on work history were negatively related to CNSLD incidence. The results suggest the presence of a healthy-worker effect, in a general population study, resulting in an underestimation of the relationship between occupational exposures and respiratory diseases based on the evidence published so far. The use of the full work history to determine exposure to dust leads to stronger relationships with CNSLD incidence, compared to conventional analyses using exposure at the start of follow-up.

Age Factors↗
PubMed1993

Dietary determinants of long-term incidence of chronic nonspecific lung diseases. The Zutphen Study.

The association between diet and the 25-year incidence of chronic nonspecific lung diseases (CNSLD) was studied in 793 middle-aged men in the town of Zutphen, the Netherlands, in 1960-1985. During follow-up, 232 new cases of CNSLD were identified. The incidence rate was 14.1 per 1,000 person-years. Habitual food intake was assessed by the cross-check dietary history method. The intake of linoleic acid was positively associated with the incidence of CNSLD. The relative risk was 1.55 (95% confidence interval (Cl) 1.11-2.16), comparing the highest with the lowest quartile of intake of linoleic acid, independent of potential cofounders (age, cigarette smoking, body mass index, and energy intake). Alcohol consumers showed a significantly lower risk than did non-consumers (relative risk (RR) = 0.72, 95% Cl 0.55-0.95) after adjustment for confounders. In addition, fruit intake was inversely related to incidence of CNSLD (RR = 0.73, 95% Cl 0.53-0.99). No association was observed with intake of several antioxidants. These results suggest that in addition to well-established determinants, such as cigarette smoking and occupational exposure, dietary factors may play a role in the onset of chronic nonspecific lung diseases.

Adult↗
PubMed1993

The relationship between polycyclic aromatic hydrocarbons in air and in urine of workers in a Söderberg potroom.

The relationships between increase of urinary 1-hydroxypyrene over the workweek and the airborne concentrations of benzo(a)pyrene and coal tar pitch volatiles (CTPVs) were studied among groups of workers in a vertical-stud Söderberg potroom of an aluminum smelter. There was a strong correlation between the natural logarithm of the pyrene concentration and the natural logarithm of the total polycyclic aromatic hydrocarbon (PAHs) concentration in personal air samples (r = 0.94). 1-Hydroxypyrene as the major metabolite of pyrene, a polycyclic aromatic hydrocarbon, was used as a marker for exposure to PAHs. A strong positive correlation was found between the natural logarithm of increase of urinary 1-hydroxypyrene and the natural logarithm of the estimated airborne PAH exposure (R2 = 0.84 with CTPV) when the use of facial protective clothing was taken into account. The relationship between increase of urinary 1-hydroxypyrene and PAHs differed for workers who used facial protective clothing under their respirators compared to those who did not. A contradictory fact was found: the use of facial protection seemed to lead to an elevated increase of 1-hydroxypyrene over the workweek. The regression model for the relationship between increase of urinary 1-hydroxypyrene over the workweek and airborne CTPV was: LN(change in 1-hydroxypyrene) = -4.7 + 1.2 LN(CTPV) -0.44 LN(CTPV)*(use of facial protection) + 3.5 (use of facial protection).

Air Pollutants, Occupational↗
PubMed1993

Inhibition and enhancement in the analysis of airborne endotoxin levels in various occupational environments.

Inhibition and enhancement effects on the Limulus Amebocyte Lysate (LAL) assay were studied in a series of endotoxin exposure samples from various occupational environments. Two types of analyses were performed, with various dilutions and with spiked samples. Results showed that inhibition and enhancement occurred in some samples, leading to respective underestimation and overestimation of the endotoxin concentration. When inhibition or enhancement is present, the result of this study shows that large differences in endotoxin concentration may be found, depending on the dilution at which the sample is analyzed. False conclusions about exposure levels and their potential health effects might be introduced. Results show that quality control procedures need to become standard practice when endotoxins are analyzed in occupational environments and development of a validated, generally accepted protocol should be encouraged.

Air Pollutants↗
PubMed1993

Job exposure matrices in industry.

Job exposure matrices (JEM) are designed to link information on occupation with information on exposure to specific workplace hazards. In spite of some limitations, JEM are particularly useful in large retrospective epidemiological studies. The development of JEM designed for a company or an industrial sector have a more specific field of application than JEM used in population-based studies, and can therefore be based on a more detailed classification of occupations and better exposure information. This article reviews on-going research related to the design of JEM in support of industry-based studies. The review covers design aspects related to the structure of JEM, and specially the four main axes that may produce differences on exposure characteristics: agent (exposure), job, time and place. Attention has also been given to the different sources of information on exposure, the characteristics of the exposure and the validation of exposure estimates.

Data Collection↗
PubMed1992

Performance of two general job-exposure matrices in a study of lung cancer morbidity in the Zutphen cohort.

Data from a general population cohort of 878 men from the town of Zutphen, The Netherlands, were used to evaluate the performance of two general job-exposure matrices. Exposures generated by the job-exposure matrices on the basis of job histories were compared. The validity of those exposures was measured against exposures reported by the participants in 1977/1978. The performance of the different exposure measures was assessed in proportional hazards analyses of lung cancer morbidity incidence. The two general job-exposure matrices generally disagreed with regard to exposure classification because of differences in exposure assessment and level of detail of the job axis. When compared with self-reported exposures, the sensitivity of both job-exposure matrices was low (on average, below 0.51), while the specificity was generally high (on average, above 0.90). Self-reported exposures to asbestos, pesticides, and welding fumes showed elevated risk ratios for lung cancer which were absent for exposures generated by the two job-exposure matrices. Thus, a population-specific job-exposure matrix is proposed as an alternative to general job-exposure matrices developed elsewhere. Such a matrix can be constructed from the results of in-depth interviews of a job-stratified sample of cohort members. Sound validation and documentation of exposure assessment methods used in job-exposure matrices are recommended.

Adult↗
PubMed1992

Exposure to dust, endotoxins, and fungi in the animal feed industry.

In the Dutch animal feed industry, approximately 6000 workers are exposed to organic dust, originating mainly from raw materials such as grain, pulses (peas and beans), and waste products from the vegetable oil and starch industries. In this study, 79 stationary dust samples and 530 personal dust samples from eight animal feed production facilities were analyzed. The stationary total dust samples showed gravimetric concentrations ranging from 0.2 to 25 mg/m3 (geometric mean [GM] 1.3 mg/m3). Concentrations of smaller particle fractions (respirable, thoracic, and inspirable dust) were considerably lower. Personal inspirable dust concentrations were considerably higher than stationary concentrations and were strongly related to job titles. Pooled personal inspirable dust concentrations ranged from 0.2 to 450 mg/m3 (GM = 2.4 mg/m3). After adjusting for differences between inspirable and total dust, 25% of the measurements exceeded the Dutch maximum allowed concentration (MAC) for total nuisance dust (10 mg/m3) and 42% exceeded the American Conference of Governmental Industrial Hygienists' threshold limit value for grain dust (4 mg/m3). Endotoxin concentrations ranged from 0.2 to 1870 ng/m3 inspirable dust (GM = 5.1 ng/m3). Endotoxin appeared to be less prevalent in respirable dust than in larger dust fractions. Concentrations in dust appeared to be related to stages in the production process. Colony-forming units (cfu) of fungi ranged from 130 to 15,300 cfu/m3 (GM = 2300 cfu/m3) and were in parallel measurements more strongly related to endotoxin concentrations than to dust concentrations. Clearly, workers in the Dutch animal feed industry are frequently exposed to dust levels above recommended Dutch and American levels. Exposure levels to endotoxin and to fungi are quantified.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants, Occupational↗