Respiratory Cancer and Inhaled Inorganic Arsenic in Copper Smelters Workers: A Linear Relationship with Cumulative Exposure that Increases with Concentration

Background

Inhalation of high levels of airborne inorganic arsenic is a recognized cause of respiratory cancer. Although multiple epidemiologic studies have demonstrated this association, there have been few analyses of the mathematical relationship between cumulative arsenic exposure and risk of respiratory cancer, and no assessment as to whether and how arsenic concentration may modify this association.

Objectives

The objective is an evaluation of the shape of the relationship between respiratory cancer mortality and cumulative inhaled arsenic exposure among copper smelter workers, and the modification of that relationship by arsenic concentration.

Methods

We used Poisson regression methods to analyze data from a cohort of arsenic-exposed copper smelter workers under a linear-exponential model for the excess relative risk.

Results

Within categories of arsenic concentration, the association between respiratory cancer and cumulative arsenic exposure was consistent with linearity. The slope of the linear relationship with cumulative exposure increased with increasing arsenic concentration category.

Conclusions

Our results suggested a direct concentration effect from inhaled inorganic arsenic, whereby the excess relative risk for a fixed cumulative exposure was greater when delivered at a higher concentration and shorter duration than when delivered at a lower concentration and longer duration.     

Work-related health symptoms among compost facility workers: a cross-sectional study

Background

Industrial composting is a relatively new and expanding activity. Several studies indicate that compost workers are at risk to develop health symptoms. The aim of this study was to assess the prevalence of work-related health symptoms among compost workers compared with control subjects.

Methods

A questionnaire was distributed among 62 workers (31 exposed and 31 non-exposed workers). Data were analyzed using simple and multiple logistic regression analyses.

Results

Workers exposed to organic dust reported significantly more often respiratory, irritation (e.g., eyes, nose and throat), gastrointestinal, and skin symptoms than the non-exposed group. Moreover, all work-related symptoms were significantly more often reported by exposed than non-exposed workers. After adjustment for smoking status and age, the associations between exposure and respiratory, gastrointestinal, and skin symptoms remained statistically significant, in particular if these symptoms were work-related.

Conclusions

This study confirms that workers at compost facilities are at risk to develop occupational health problems, most likely related to organic dust exposure.     

Exposure to airborne asbestos in thermal power plants in Mongolia

Background:

Coal-fired thermal power plants (TPPs) in Mongolia use various types of asbestos-containing materials (ACMs) in thermal insulation of piping systems, furnaces, and other products.Objective: To investigate the occupational exposure of insulation workers to airborne asbestos in Mongolian power plants.

Methods:

Forty-seven air samples were collected from four power plants in Mongolia during the progress of insulation work. The samples were analyzed by phase contrast microscopy (PCM) and transmission electron microscopy (TEM).

Results:

The average phase contrast microscopy equivalent (PCME) asbestos fiber concentration was 0.93 f/cm³. Sixteen of the 41 personal and one of the area samples exceeded the United States Occupational Safety and Health Administration (US OSHA) short-term exposure limit of 1.0 f/cm³. If it is assumed that the short-term samples collected are representative of full-shift exposure, then the exposures are approximately 10 times higher than the US OSHA 8-hour permissible exposure limit of 0.1 f/cm³.

Conclusion:

Power plant insulation workers are exposed to airborne asbestos at concentrations that exceed the US OSHA Permissible Exposure Limit. Action to mitigate the risks should be taken in Mongolia.     

A cross sectional study of the respiratory health of workers handling printing toner dust

Background

Although recent case reports have suggested possible respiratory effects of solid toner dust inhalation, this hypothesis has not been verified by epidemiological studies.

Objectives

To conduct a cross sectional study to evaluate the association between the biological indices of lung fibrosis and toner dust exposure in an occupational cohort handling solid toner dust in their work life.

Methods

A total of 600 male toner workers and 212 control subjects were surveyed in terms of their subjective respiratory symptoms, pulmonary functions, and chest radiographic findings. In addition to the exposure history, the current working conditions and personal exposure levels to toner dust were also examined.

Results

Although subjects handling toner for more than 20 years tended to show a higher prevalence of respiratory symptoms and minimal chest x ray abnormalities, there was no consistent relation between the exposure to toner dust and the biological responses of the respiratory system.

Conclusion

Deterioration of respiratory health related to toner dust exposure is less likely to occur in current well controlled work environments, especially if the powdered toner is handled carefully. Nonetheless, it is important to collect further epidemiological evidence on the biological effects of toner dust inhalation, preferably using a longitudinal study design.     

A Proton Magnetic Resonance Spectroscopy Study of the Chronic Lead Effect on the Basal Ganglion and Frontal and Occipital Lobes in Middle-Age Adults

Background

Lead is known to be a health hazard to the human brain and nervous system based on data from epidemiologic studies. However, few studies have examined the mechanism or biochemical changes caused by lead in the human brain, although recently some have used magnetic resonance spectroscopy (MRS) to test brain metabolism in vivo.

Objectives

In this study, we used 3-T MRS to investigate brain metabolism in workers chronically exposed to lead and matched nonexposed controls.

Materials

Methods: Twenty-two workers at a lead paint factory served as chronically exposed subjects of this study. These workers did not have any clinical syndromes. Eighteen age- and sex-matched nonexposed healthy volunteers served as controls. We measured blood and bone lead and used a 3-T MRS to measure their levels of brain N-acetyl aspartate (NAA), choline (Cho), and total creatine (tCr). A structural questionnaire was used to collect demographic, work, and health histories and information about their life habits.

Results

All the MRS measures were lower in the lead-exposed group. Increased blood and bone lead levels correlated with declines in Cho:tCr ratios, especially in the occipital lobe, where changes in all gray, subcortical, and white matter were significant. Increases in blood and patella lead in every layer of the frontal lobe correlated with significant decreases in NAA:tCr ratios. One of the strongest regression coefficients was −0.023 (SE = 0.005, p < 0.001), which was found in the NAA:tCr ratio of frontal gray matter.

Discussion

We conclude that chronic exposure to lead might upset brain metabolism, especially NAA:tCr and Cho:tCr ratios. Brain NAA and Cho are negatively correlated to blood and bone lead levels, suggesting that lead induces neuronal and axonal damage or loss. The most significant changes occurred in frontal and occipital lobes, areas in which previous neurobehavioral studies have shown memory and visual performance to be adversely affected by lead toxicity.     

Research Recommendations for Selected IARC-Classified Agents

Objectives

There are some common occupational agents and exposure circumstances for which evidence of carcinogenicity is substantial but not yet conclusive for humans. Our objectives were to identify research gaps and needs for 20 agents prioritized for review based on evidence of widespread human exposures and potential carcinogenicity in animals or humans.

Data sources

For each chemical agent (or category of agents), a systematic review was conducted of new data published since the most recent pertinent International Agency for Research on Cancer (IARC) Monograph meeting on that agent.

Data extraction

Reviewers were charged with identifying data gaps and general and specific approaches to address them, focusing on research that would be important in resolving classification uncertainties. An expert meeting brought reviewers together to discuss each agent and the identified data gaps and approaches.

Data synthesis

Several overarching issues were identified that pertained to multiple agents; these included the importance of recognizing that carcinogenic agents can act through multiple toxicity pathways and mechanisms, including epigenetic mechanisms, oxidative stress, and immuno- and hormonal modulation.

Conclusions

Studies in occupational populations provide important opportunities to understand the mechanisms through which exogenous agents cause cancer and intervene to prevent human exposure and/or prevent or detect cancer among those already exposed. Scientific developments are likely to increase the challenges and complexities of carcinogen testing and evaluation in the future, and epidemiologic studies will be particularly critical to inform carcinogen classification and risk assessment processes.     

Gynecologic pain related to occupational stress among female factory workers in Tianjin,China

Background:

Dysmenorrhea, dyspareunia, and non-cyclic pelvic pain are health concerns for factory workers in China and may be increased by occupational stress.

Objectives:

To estimate the prevalence and demographic and occupational factors associated with three types of gynecologic pain among female factory workers in Tianjin.

Methods:

The study included 651 female workers from three factories in Tianjin, China. Logistic regression models were estimated to determine associations between occupational stress and gynecologic pain.

Results:

Occupational stress including high job strain, exhaustion, and stress related to working conditions was a risk factor for gynecologic pain. High job strain and poor job security were associated with an increased risk for dysmenorrhea. Compulsory overtime and exhaustion were associated with increased non-cyclic pelvic pain. Working overtime and exhaustion were associated with increased dyspareunia.

Conclusions:

As China’s population of female factory workers grows, research on the reproductive health of this population is essential.     

Perception and prevalence of work-related health hazards among health care workers in public health facilities in southern India

Background:

Health care workers (HCWs) are exposed to occupational related health hazards. Measuring worker perception and the prevalence of these hazards can help facilitate better risk management for HCWs, as these workers are envisaged to be the first point of contact, especially in resource poor settings.

Objective:

To describe the perception of occupational health hazards and self-reported exposure prevalence among HCWs in Southern India.

Methods:

We used cross sectional design with stratified random sampling of HCWs from different levels of health facilities and categories in a randomly selected district in Southern India. Data on perception and exposure prevalence were collected using a structured interview schedule developed by occupational health experts and administered by trained investigators.

Results:

A total of 482 HCWs participated. Thirty nine percent did not recognize work-related health hazards, but reported exposure to at least one hazard upon further probing. Among the 81·5% who reported exposure to biological hazard, 93·9% had direct skin contact with infectious materials. Among HCWs reporting needle stick injury, 70·5% had at least one in the previous three months. Ergonomic hazards included lifting heavy objects (42%) and standing for long hours (37%). Psychological hazards included negative feelings (20·3%) and verbal or physical abuse during work (20·5%).

Conclusion:

More than a third of HCWs failed to recognize work-related health hazards. Despite training in handling infectious materials, HCWs reported direct skin contact with infectious materials and needle stick injuries. Results indicate the need for training oriented toward behavioral change and provision of occupational health services.     

Case Report: Analytical Electron Microscopy of Lung Granulomas Associated with Exposure to Coating Materials Carried by Glass Wool Fibers

Context

Man-made vitreous fibers (MMVFs) are noncrystalline inorganic fibrous material used for thermal and acoustical insulation (e.g., rock wool, glass wool, glass microfibers, and refractory ceramic fibers). Neither epidemiologic studies of human exposure nor animal studies have shown a noticeable hazardous effect of glass wools on health. However, MMVFs have been anecdotally associated with granulomatous lung disease in several case reports.

Case presentation

Here, we describe the case of a patient with multiple bilateral nodular opacities who was exposed to glass wool fibers and coating materials for 7 years. Bronchoalveolar lavage fluid revealed an increased total cell count (predominantly macrophages) with numerous cytoplasmic particles. Lung biopsy showed peribronchiolar infiltration of lymphoid cells and many foreign-body–type granulomas. Alveolar macrophages had numerous round and elongated platelike particles inside the cytoplasm. X-ray microanalysis of these particles detected mainly oxygen/aluminum/silicon and oxygen/magnesium/silicon, compatible with kaolinite and talc, respectively. No elemental evidence for glass fibers was found in lung biopsy.

Discussion

The contribution of analytical electron microscopy applied in the lung biopsy was imperative to confirm the diagnosis of pneumoconiosis associated with a complex occupational exposure that included both MMVFs and coating materials.

Relevance to clinical or professional practice

This case study points out the possible participation of other components (coating materials), beyond MMVFs, in the etiology of pneumoconiosis.     

A cluster of lead poisoning among consumers of Ayurvedic medicine

Background

Use of alternative medications and herbal remedies is widespread in the United States and across the globe. These traditional medications can be contaminated with toxic metals. Despite several case reports of poisoning from such contamination, the epidemiological data are still limited.

Objectives

To report on a cluster of lead and mercury toxicity cases in 2011 among a community of adherents of traditional medical practice of Ayurveda.

Methods

Adherents of Ayurveda were offered heavy metals screening following the identification of the index case.

Results

Forty-six of 115 participants (40%) had elevated blood lead levels (BLLs) of 10 μg/dl or above, with 9.6% of BLLs at or above 50 μg/dl.

Conclusions

This is the largest cluster of lead and mercury toxicity following use of Ayurvedic supplements described in the literature in the US. Contamination of herbal products is a public health issue of global significance. There are few regulations addressing contamination of “natural” products or supplements.     

Exposure Science: A View of the Past and Milestones for the Future

Background

The study of human exposure to environmental toxicants has evolved as a scientific field over the past 30 years.

Objectives

This review provides a historical perspective on the growth of exposure science as a field, with some emphasis on the results from initial observational studies in obtaining information needed for generating hypotheses on significant human contact with environmental agents, testing the performance of models, and reducing exposures to protect public health.

Discussion

Advances in activity pattern and behavioral research that established a suite of variables needed to accurately define contact and factors that influence contact are also discussed. The identification and characterization of these factors have played a pivotal role in the growth of the field and in developing exposure reduction strategies. Answers to two key questions on the relevance and fundamental value of exposure science to the fields of environmental health and risk management are presented as a path forward: a) What does one do with such exposure information? b) What roles does exposure science play in situations beyond observational analyses and interpretation?

Conclusions

The discussion identifies the need for more focused use of observational studies of exposure for epidemiologic analyses. Further, the introduction and use of new tools and approaches for hypothesis testing that can improve the use of exposure science in prevention research for risk management is needed to affect the source-to-effect continuum. A major restructuring of the field is not required to achieve innovation. However, additional resources for training and education are required to ensure that the potential for exposure science to play a central role in reducing and preventing excess risk within environmental/occupational health is achieved.     

Modern Environmental Health Hazards: A Public Health Issue of Increasing Significance in Africa

Objectives

Traditional hazards such as poor sanitation currently account for most of Africa’s environmentally related disease burden. However, with rapid development absent appropriate safeguards for environment and health, modern environmental health hazards (MEHHs) may emerge as critical contributors to the continent’s disease burden. We review recent evidence of human exposure to and health effects from MEHHs, and their occurrence in environmental media and consumer products. Our purpose is to highlight the growing significance of these hazards as African countries experience urbanization, industrial growth, and development.

Data sources

We reviewed published epidemiologic, exposure, and environmental studies of chemical agents such as heavy metals and pesticides.

Data synthesis

The body of evidence demonstrates ongoing environmental releases of MEHHs and human exposures sometimes at toxicologically relevant levels. Several sources of MEHHs in environmental media have been identified, including natural resource mining and processing and automobile exhaust. Biomonitoring studies provided direct evidence of human exposure to metals such as mercury and lead and pesticides such as p,p′-dichlorodiphenyltrichloroethane (DDT) and organophosphates. Land and water resource pollution and industrial air toxics are areas of significant data gaps, notwithstanding the presence of several emitting sources.

Conclusion

Unmitigated MEHH releases and human exposure have implications for Africa’s disease burden. For Africans encumbered by conditions such as malnutrition that impair resilience to toxicologic challenges, the burden may be higher. A shift in public health policy toward accommodating the emerging diversity in Africa’s environmental health issues is necessary to successfully alleviate the burden of avoidable ill health and premature death for all its communities now and in the future.     

Occupational Lead Exposure and Associations with Selected Cancers: The Shanghai Men’s and Women’s Health Study Cohorts

Background

Epidemiologic studies of occupational lead exposure have suggested increased risks of cancers of the stomach, lung, kidney, brain, and meninges; however, the totality of the evidence is inconsistent.

Objective

We investigated the relationship between occupational lead exposure and cancer incidence at the five abovementioned sites in two prospective cohorts in Shanghai, China.

Methods

Annual job/industry-specific estimates of lead fume and lead dust exposure, derived from a statistical model combining expert lead intensity ratings with inspection measurements, were applied to the lifetime work histories of participants from the Shanghai Women’s Health Study (SWHS; n = 73,363) and the Shanghai Men’s Health Study (SMHS; n = 61,379) to estimate cumulative exposure to lead fume and lead dust. These metrics were then combined into an overall occupational lead exposure variable. Cohort-specific relative hazard rate ratios (RRs) and 95% confidence intervals (CIs) comparing exposed and unexposed participants were estimated using Cox proportional hazards regression and combined by meta-analysis.

Results

The proportions of SWHS and SMHS participants with estimated occupational lead exposure were 8.9% and 6.9%, respectively. Lead exposure was positively associated with meningioma risk in women only (n = 38 unexposed and 9 exposed cases; RR = 2.4; 95% CI: 1.1, 5.0), particularly with above-median cumulative exposure (RR = 3.1; 95% CI: 1.3, 7.4). However, all 12 meningioma cases among men were classified as unexposed to lead. We also observed non-significant associations with lead exposure for cancers of the kidney (n = 157 unexposed and 17 ever exposed cases; RR = 1.4; 95% CI: 0.9, 2.3) and brain (n = 67 unexposed and 10 ever exposed cases; RR = 1.8; 95% CI: 0.7, 4.8) overall.

Conclusions

Our findings, though limited by small numbers of cases, suggest that lead is associated with the risk of several cancers in women and men.

Citation

Liao LM, Friesen MC, Xiang YB, Cai H, Koh DH, Ji BT, Yang G, Li HL, Locke SJ, Rothman N, Zheng W, Gao YT, Shu XO, Purdue MP. 2016. Occupational lead exposure and associations with selected cancers: the Shanghai Men’s and Women’s Health Study cohorts. Environ Health Perspect 124:97–103; http://dx.doi.org/10.1289/ehp.1408171     

Occupational and non-occupational factors associated with work-related injuries among construction workers in the USA

Background:

Many factors contribute to occupational injuries. However, these factors have been compartmentalized and isolated in most studies.

Objective:

To examine the relationship between work-related injuries and multiple occupational and non-occupational factors among construction workers in the USA.

Methods:

Data from the 1988–2000 National Longitudinal Survey of Youth, 1979 cohort (N = 12,686) were analyzed. Job exposures and health behaviors were examined and used as independent variables in four multivariate logistic regression models to identify associations with occupational injuries.

Results:

After controlling for demographic variables, occupational injuries were 18% (95% CI: 1.04–1.34) more likely in construction than in non-construction. Blue-collar occupations, job physical efforts, multiple jobs, and long working hours accounted for the escalated risk in construction. Smoking, obesity/overweight, and cocaine use significantly increased the risk of work-related injury when demographics and occupational factors were held constant.

Conclusions:

Workplace injuries are better explained by simultaneously examining occupational and non-occupational characteristics.     

Respiratory and allergic health effects of dampness, mold, and dampness-related agents: a review of the epidemiologic evidence

Objectives

Many studies have shown consistent associations between evident indoor dampness or mold and respiratory or allergic health effects, but causal links remain unclear. Findings on measured microbiologic factors have received little review. We conducted an updated, comprehensive review on these topics.

Data sources

We reviewed eligible peer-reviewed epidemiologic studies or quantitative meta-analyses, up to late 2009, on dampness, mold, or other microbiologic agents and respiratory or allergic effects.

Data extraction

We evaluated evidence for causation or association between qualitative/subjective assessments of dampness or mold (considered together) and specific health outcomes. We separately considered evidence for associations between specific quantitative measurements of microbiologic factors and each health outcome.

Data synthesis

Evidence from epidemiologic studies and meta-analyses showed indoor dampness or mold to be associated consistently with increased asthma development and exacerbation, current and ever diagnosis of asthma, dyspnea, wheeze, cough, respiratory infections, bronchitis, allergic rhinitis, eczema, and upper respiratory tract symptoms. Associations were found in allergic and nonallergic individuals. Evidence strongly suggested causation of asthma exacerbation in children. Suggestive evidence was available for only a few specific measured microbiologic factors and was in part equivocal, suggesting both adverse and protective associations with health.

Conclusions

Evident dampness or mold had consistent positive associations with multiple allergic and respiratory effects. Measured microbiologic agents in dust had limited suggestive associations, including both positive and negative associations for some agents. Thus, prevention and remediation of indoor dampness and mold are likely to reduce health risks, but current evidence does not support measuring specific indoor microbiologic factors to guide health-protective actions.     

Health Care Utilization and Costs Associated with Adherence to Clinical Practice Guidelines for Early Magnetic Resonance Imaging among Workers with Acute Occupational Low Back Pain

Objective

To estimate health care utilization and costs associated with adherence to clinical practice guidelines for the use of early magnetic resonance imaging (MRI; within the first 6 weeks of injury) for acute occupational low back pain (LBP).

Data Sources

Washington State Disability Risk Identification Study Cohort (D-RISC), consisting of administrative claims and patient interview data from workers’ compensation claimants (2002–2004).

Study Design

In this prospective, population-based cohort study, we compared health care utilization and costs among workers whose imaging was adherent to guidelines (no early MRI) to workers whose imaging was not adherent to guidelines (early MRI in the absence of red flags).

Data Collection/Extraction Methods

We identified workers (age >18) with work-related LBP using administrative claims. We obtained demographic, injury, health, and employment information through telephone interviews to adjust for baseline differences between groups. We ascertained health care utilization and costs from administrative claims for 1 year following injury.

Principal Findings

Of 1,770 workers, 336 (19.0 percent) were classified as nonadherent to guidelines. Outpatient and physical/occupational therapy utilization was 52–54 percent higher for workers whose imaging was not adherent to guidelines compared to workers with guideline-adherent imaging; utilization of chiropractic care was significantly lower (18 percent).

Conclusions

Nonadherence to guidelines for early MRI was associated with increased likelihood of lumbosacral injections or surgery and higher costs for out-patient, inpatient, and nonmedical services, and disability compensation.     

A Framework for Widespread Replication of a Highly Spatially Resolved Childhood Lead Exposure Risk Model

Background

Preventive approaches to childhood lead poisoning are critical for addressing this longstanding environmental health concern. Moreover, increasing evidence of cognitive effects of blood lead levels < 10 μg/dL highlights the need for improved exposure prevention interventions.

Objectives

Geographic information system–based childhood lead exposure risk models, especially if executed at highly resolved spatial scales, can help identify children most at risk of lead exposure, as well as prioritize and direct housing and health-protective intervention programs. However, developing highly resolved spatial data requires labor-and time-intensive geocoding and analytical processes. In this study we evaluated the benefit of increased effort spent geocoding in terms of improved performance of lead exposure risk models.

Methods

We constructed three childhood lead exposure risk models based on established methods but using different levels of geocoded data from blood lead surveillance, county tax assessors, and the 2000 U.S. Census for 18 counties in North Carolina. We used the results to predict lead exposure risk levels mapped at the individual tax parcel unit.

Results

The models performed well enough to identify high-risk areas for targeted intervention, even with a relatively low level of effort on geocoding.

Conclusions

This study demonstrates the feasibility of widespread replication of highly spatially resolved childhood lead exposure risk models. The models guide resource-constrained local health and housing departments and community-based organizations on how best to expend their efforts in preventing and mitigating lead exposure risk in their communities.     

Occupational benzene exposure and the risk of lymphoma subtypes: a meta-analysis of cohort studies incorporating three study quality dimensions

Background

The use of occupational cohort studies to assess the association of benzene and lymphoma is complicated by problems with exposure misclassification, outcome classification, and low statistical power.

Objective

We performed meta-analyses of occupational cohort studies for five different lymphoma categories: Hodgkin lymphoma (HL), non-Hodgkin lymphoma (NHL), multiple myeloma (MM), acute lymphocytic leukemia (ALL), and chronic lymphocytic leukemia (CLL).

Data extraction

We assessed three study quality dimensions to evaluate the impact of study quality variations on meta-relative risks (mRRs): stratification by the year of start of follow-up, stratification by the strength of the reported acute myelogenous leukemia association, and stratification by the quality of benzene exposure assessment.

Data synthesis

mRRs for MM, ALL, and CLL increased with increasing study quality, regardless of the study quality dimension. mRRs for NHL also increased with increasing study quality, although this effect was less pronounced. We observed no association between occupational benzene exposure and HL.

Conclusions

Our meta-analysis provides support for an association between occupational benzene exposure and risk of MM, ALL, and CLL. The evidence for an association with NHL is less clear, but this is likely complicated by the etiologic heterogeneity of this group of diseases. Further consideration of the association between benzene and NHL will require delineation of risks by NHL subtype.     

Routine dipstick urinalysis in daily practice of Belgian occupational physicians

Background

Little work has been done to assess the quality of health care and the use of evidence-based methods by occupational physicians in Belgium. Therefore, the main objective is to describe one aspect of occupational health assessments, namely the common use of dipstick urinalysis, and to compare the current practice with international guidelines.

Methods

A self-administered questionnaire was mailed to 211 members of the Scientific Association of Occupational Medicine in the Dutch speaking part of Belgium.

Results

A total of 120 occupational physicians responded, giving a response rate of 57%. Dipstick urinalysis was a routine investigation for the vast majority of physicians (69%). All test strips screened for protein and in 90% also for blood. Occupational health services offered clinical tests to satisfy customer wants as international guidelines do not recommend screening for haematuria and proteinuria in asymptomatic adults. A lack of knowledge concerning positive testing and referral criteria was demonstrated in almost half of the study participants.

Conclusions

Belgian occupational physicians still routinely perform dipstick testing although there is no evidence to support this screening in healthy workers. To practice evidence-based medicine, occupational physicians need more instruction and training. Development and implementation of more guidelines is not only of use for the individual practitioner, it may also enhance professionalization and efficiency of occupational health care.