G M Swaen

Dow Chemical Company, Midland, Michigan, United States

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Publications (131)334.7 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: Background Slips, trips and falls (STF) are a major cause of workplace injury.AimsTo examine risk factors for STF at a large US chemical manufacturing company.Methods We conducted a case-control study of occupational STF. Cases were identified from company injury records between 1 April 2009 and 1 May 2011. Four controls per case were randomly selected from all active company workers employed during the same time. Data were collected through a questionnaire and from company medical examinations. Logistic regression was used to calculate odds ratio (OR) and 95% confidence intervals (95% CI) for personal, environmental and health-related risk factors for STF.ResultsThere were 74 cases and 309 controls. The response rate was 65% for the cases and 68% for the controls. Most STF were unrelated to production activities. When examining all factors in a logistic regression model, increased OR were observed for increased body mass index (OR = 1.44, 95% CI: 1.03-2.02), having arthritis (OR = 2.11, 95% CI: 1.01-4.37), lack of exercise (OR = 2.25, 95% CI: 1.01-5.05), carrying materials (OR = 3.01, 95% CI: 1.41-6.43) and being female (OR = 2.46, 95% CI: 1.17-5.19). Reduced risk of STF was observed for never having smoked (OR = 0.48, 95% CI: 0.24-0.95), long service (OR = 0.53, 95% CI: 0.34-0.81) and persons working over 8h a day (OR = 0.42, 95% CI: 0.20-0.88).Conclusions Risk factors for STF in a large US chemical company are similar to those reported from other workplaces, but we found that staying fit and healthy is important for reducing risk.
    Occupational Medicine 01/2014; · 1.45 Impact Factor
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    Carol J Burns, Gerard M H Swaen
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    ABSTRACT: A qualitative review of the epidemiological literature on the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) and health after 2001 is presented. In order to compare the exposure of the general population, bystanders and occupational groups, their urinary levels were also reviewed. In the general population, 2,4-D exposure is at or near the level of detection (LOD). Among individuals with indirect exposure, i.e. bystanders, the urinary 2,4-D levels were also very low except in individuals with opportunity for direct contact with the herbicide. Occupational exposure, where exposure was highest, was positively correlated with behaviors related to the mixing, loading and applying process and use of personal protection. Information from biomonitoring studies increases our understanding of the validity of the exposure estimates used in epidemiology studies. The 2,4-D epidemiology literature after 2001 is broad and includes studies of cancer, reproductive toxicity, genotoxicity, and neurotoxicity. In general, a few publications have reported statistically significant associations. However, most lack precision and the results are not replicated in other independent studies. In the context of biomonitoring, the epidemiology data give no convincing or consistent evidence for any chronic adverse effect of 2,4-D in humans.
    Critical Reviews in Toxicology 08/2012; 42(9):768-86. · 6.25 Impact Factor
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    ABSTRACT: Although regulatory agencies formally encourage the integration of all available data in chemical risk assessment, consistent implementation of this practice has been constrained by the lack of a clear, systematic method for doing so. In this paper, we describe a methodology for evaluating, classifying and integrating human and animal data into the risk assessment process that incorporates: (1) a balanced appraisal of human and animal data, (2) relevance to different stages of the risk assessment process, and (3) accommodation for different data quality requirements. The proposed framework offers a flexible, step-wise approach for determining which set of available data best support the chemical risk assessment that involves the rating and relative ranking of human and animal data quality. The evaluation of human data incorporates seven data quality elements, nature and specificity of the lead effect; evaluation of animal data incorporates data quality and relevance to humans. Results of simulations with selected chemicals previously evaluated in a formal risk assessment generally agreed with existing regulatory guidance. Application of the proposed framework across a wider range of chemical agents will improve transparency of the risk assessment process and validity of results, while informing continuous refinements to this evolving methodology.
    Regulatory Toxicology and Pharmacology 11/2011; 62(2):302-12. · 2.13 Impact Factor
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    ABSTRACT: Despite showing no evidence of carcinogenicity in laboratory animals, the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) has been associated with non-Hodgkin lymphoma (NHL) in some human epidemiology studies, albeit inconsistently. We matched an existing cohort of 2,4-D manufacturing employees with cancer registries in three US states resulting in 244 cancers compared to 276 expected cases. The Standardized Incidence Ratio (SIR) for the 14 NHL cases was 1.36 (95% Confidence Interval (CI) 0.74-2.29). Risk estimates were higher in the upper cumulative exposure and duration subgroups, yet not statistically significant. There were no clear patterns of NHL risk with period of hire and histology subtypes. Statistically significant results were observed for prostate cancer (SIR = 0.74, 95% CI 0.57-0.94), and "other respiratory" cancers (SIR = 3.79, 95% CI 1.22-8.84; 4 of 5 cases were mesotheliomas). Overall, we observed fewer cancer cases than expected, and a non statistically significant increase in the number of NHL cases.
    International Journal of Environmental Research and Public Health 09/2011; 8(9):3579-90. · 2.00 Impact Factor
  • Gerard M H Swaen, Neil Carmichael, John Doe
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    ABSTRACT: To evaluate the need for the creation of a system in which observational epidemiology studies are registered; an Observational Studies Register (OSR). The current scientific process for observational epidemiology studies is described. Next, a parallel is made with the clinical trials area, where the creation of clinical trial registers has greatly restored and improved their credibility and reliability. Next, the advantages and disadvantages of an OSR are compared. The advantages of an OSR outweigh its disadvantages. The creation of an OSR, similar to the existing Clinical Trials Registers, will improve the assessment of publication bias and will provide an opportunity to compare the original study protocol with the results reported in the publication. Reliability, credibility, and transparency of observational epidemiology studies are strengthened by the creation of an OSR. We propose a structured, collaborative, and coordinated approach for observational epidemiology studies that can provide solutions for existing weaknesses and will strengthen credibility and reliability, similar to the approach currently used in clinical trials, where Clinical Trials Registers have played a key role in strengthening their scientific value.
    Journal of clinical epidemiology 05/2011; 64(5):481-6. · 2.96 Impact Factor
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    ABSTRACT: Occupational studies typically observe a 20% deficit in overall mortality, broadly characterized as the healthy worker effect (HWE). Components of the HWE may be addressed by various analytical approaches. To explore the HWE in a modern industrial cohort. Standardized mortality ratios (SMRs) were calculated for 114,683 US chemical industry employees, who worked at least 3 days between 1960 and 2005. SMRs were 79 (95% confidence interval 78-80) for all causes, 81 (95% confidence interval 79-82) for heart disease, 70 (95% confidence interval 67-73) for non-malignant respiratory disease, 83 (95% confidence interval 81-85) for smoking-related cancers (buccal, cervix, oesophagus, stomach, pancreas, lung, larynx, bladder and kidney) combined and 97 (95% confidence interval 95-100) for other cancers. The low SMRs observed in this study are likely due to differential smoking between the cohort and the background population. Future considerations to control for the HWE should take this into account.
    Occupational Medicine 11/2010; 61(1):40-4. · 1.45 Impact Factor
  • G M H Swaen, S P Tsai, C Burns
    Occupational and environmental medicine 04/2010; 67(4):286-7; author reply 287. · 3.64 Impact Factor
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    ABSTRACT: At high and prolonged exposure levels (e.g. >30 ppm), benzene can cause hematological effects. However, there is conflicting evidence on potential hematological effects at lower concentrations. We conducted a study to examine hematological effects at low benzene exposure levels in an occupational setting. Extensive exposure data and data from routine hematology examinations were available for Dow employees at the Terneuzen site in the Netherlands. We compared 8532 blood samples of Dow employees with low benzene exposure to 12,173 samples of employees with no benzene exposure that were available for the period between 1981 and 2007. Based on 21,584 benzene air measurements, a Job Exposure Matrix (JEM) was constructed for all employees with exposure. The JEM was used to estimate benzene exposure in the year in which each blood sample was collected. The average lymphocyte counts for the exposed and non-exposed group were similar. By means of mixed model regression adjustments were made for smoking, age and month of blood sample. These adjustments did not change the results and there was no indication for an adverse effect on any of the hematological parameters under investigation. A further stratification of the exposed population into three subgroups (<0.5 ppm, 0.5-1 ppm and >1 ppm) showed no significant differences for any of the hematological parameters between the three exposure categories or compared with the non-exposed group. The analysis modeling the continuous exposure effect relationship showed similar findings. This study does not indicate that workers exposed to low benzene concentrations are at an increased risk for hematological effects.
    Chemico-biological interactions 03/2010; 184(1-2):94-100. · 2.46 Impact Factor
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    ABSTRACT: We sought to determine if workers exposed to dioxins in pentachlorophenol (PCP) manufacturing were at increased risk of death from specific causes. We examined death rates among 773 workers exposed to chlorinated dioxins during PCP manufacturing from 1937 to 1980 using serum dioxin evaluations to estimate exposures to five dioxins. Deaths from all causes combined, all cancers combined, lung cancer, diabetes, and ischemic heart disease were near expected levels. There were eight deaths from non-Hodgkin lymphoma (standardized mortality ratios = 2.4, 95% CI = 1.0 to 4.8). We observed no trend of increasing risk for any cause of death with increasing dioxin exposure. However, the highest rates of non-Hodgkin lymphoma were found in the highest exposure group (standardized mortality ratios = 4.5, 95% CI = 1.2 to 11.5). Other than possibly an increased risk of non-Hodgkin lymphoma, we find no other cause of death related to the mixture of the dioxin contaminants found in PCP.
    Journal of occupational and environmental medicine / American College of Occupational and Environmental Medicine 09/2009; 51(10):1212-9. · 1.88 Impact Factor
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    ABSTRACT: To investigate the long-term mortality patterns of workers with past exposure to ethylene oxide (EO). We redefined and updated a cohort of male workers employed in industrial facilities where EO was produced or used. All 2063 men were employed between 1940 and the end of 1988 and were observed for mortality through 2003. Cause specific Standardized Mortality Ratios were calculated. Internal analyses were made by applying Cox proportional hazards models to the data. No indications were found for excess cancer risks from EO exposures, including the lymphohematopoietic malignancies. There were 11 leukemia deaths and 11.8 expected and 12 non-Hodgkin lymphoma deaths and 11.5 expected. Proportional hazards modeling for all cause, leukemia and lymphoid malignancies mortality revealed no trends or associations with cumulative exposure. Despite the relatively high EO exposures in the past and extensive mortality follow-up, the cause specific mortality rates are comparable with those of the general US population. The Standardized Mortality Ratio analyses and the proportional hazards modeling for all cause mortality, leukemia and lymphoid malignancies mortality do not indicate exposure related effects in this cohort.
    Journal of occupational and environmental medicine / American College of Occupational and Environmental Medicine 06/2009; 51(6):714-23. · 1.88 Impact Factor
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    ABSTRACT: To develop and validate a screening instrument to identify employees at high risk for future long-term sickness absence. The instrument was developed (n=5,601) and internally validated (n=3,383) through data analyses of the Maastricht Cohort Study, among a group of office workers not absent from work. External validation was performed in a cohort of 3,895 bank employees. The screening instrument, Balansmeter, captures 34 questions on demographics, work environment, private situation, (mental) health, and sickness absence history. The Balansmeter showed good predictive values for future sickness absence (>28 days) in men (internal validation relative risk [RR] 4.69 [95% confidence interval (CI): 2.74, 8.02]; external validation RR 3.90 [95% CI: 2.35, 6.45]) and women (internal validation RR 4.16 [95% CI: 2.05, 8.43]; external validation RR 2.62 [95% CI: 1.44, 4.77]). It is possible to predict future sickness absence. The Balansmeter can be considered a valuable screening instrument.
    Journal of clinical epidemiology 12/2008; 62(4):408-414.e2. · 2.96 Impact Factor
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    ABSTRACT: Ethylenebisdithiocarbamates are widely used as fungicides in agriculture. Although EBDC's have a low acute toxicity, they are suspected to have immune effects at low doses. However, little human studies on these effects have been published. In the Netherlands, a study was conducted among pesticide exposed workers aimed at evaluating the short-term and long-term immune effects of exposure and the relation between ethylenebisdithiocarbamate and immune effects. Forty-one re-entry workers and 40 nonexposed controls were medically examined; furthermore, immune parameters were determined in blood, and all participants filled in a questionnaire regarding exposure and outcome parameters. The level of ethylenethiourea in urine was determined as indicator of exposure. No relevant adverse immune effects were found in the pesticide exposed workers compared with the nonexposed controls. Also no exposure response relationship between immune effects and ethylenebisdithiocarbamate in urine was found. This finding might be due to very low exposure levels of the re-entry work but might also be due to a lack of immunotoxicity of ethylenebisdithiocarbamate at normal exposure levels.
    Human &amp Experimental Toxicology 10/2008; 27(9):693-9. · 1.45 Impact Factor
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    Gerard Swaen, Ludovic van Amelsvoort
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    ABSTRACT: The Bradford Hill criteria are the best available criteria for causal inference. However, there is no information on how the criteria should be weighed and they cannot be combined into one probability estimate for causality. Our objective is to provide an empirical basis for weighing the Bradford Hill criteria and to develop a transparent method to estimate the probability for causality. All 159 agents classified by International Agency for Research of Cancer as category 1 or 2A carcinogens were evaluated by applying the nine Bradford Hill criteria. Discriminant analysis was used to estimate the weights for each of the nine Bradford Hill criteria. The discriminant analysis yielded weights for the nine causality criteria. These weights were used to combine the nine criteria into one overall assessment of the probability that an association is causal. The criteria strength, consistency of the association and experimental evidence were the three criteria with the largest impact. The model correctly predicted 130 of the 159 (81.8%) agents. The proposed approach enables using the Bradford Hill criteria in a quantitative manner resulting in a probability estimate of the probability that an association is causal.
    Journal of clinical epidemiology 10/2008; 62(3):270-7. · 2.96 Impact Factor
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    ABSTRACT: To assess the effectiveness of a preventive coaching intervention on sickness absence due to psychosocial health complaints and on general well being of employees. Employees at risk for sickness absence were identified and randomized. The intervention group received the preventive coaching program; the control group received usual care. Primary outcome measure of the trial is sickness absence due to psychosocial health complaints; secondary outcome measures are related to general well being, such as psychological distress, fatigue, and coping. No effect of coaching on self-reported sickness absence due to psychosocial health complaints was found. The intervention group reported statistically significant improved health, declined psychological distress, less burnout, less need for recovery, and an increased satisfaction with life. This study shows that the coaching intervention primarily has an effect on general well being of employees.
    Journal of occupational and environmental medicine / American College of Occupational and Environmental Medicine 08/2008; 50(7):765-76. · 1.88 Impact Factor
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    ABSTRACT: Absence from work due to psychosocial health complaints has considerable negative effects for employees, employers and society. A better and more effective strategy would be early identification of employees at risk for psychosocial sickness absence and early intervention to prevent sickness absence as far as possible. To assess psychometric characteristics and the external validation of a recently developed screening instrument, called 'Werkwijzer', for the identification of employees at risk for sickness absence due to psychosocial health complaints. Exploratory factor analysis was applied on items of the instrument. Cronbach's alpha coefficient was used to determine internal consistency of the subscales. Sum scores on the screening instrument were correlated to absenteeism data to determine their potential for predicting sickness absence. Predictive value was investigated, using objective sickness absence data as criterion measure. Sensitivity and specificity rates were calculated for external validation. For both men and women, three interpretable factors were found. Sum scores on the instrument showed low correlations with sickness absence. The association between 'being at risk' (yes/no) and sickness absence (yes/no) was odds ratio (OR) 3.1 (95% CI 1.5-6.5) for men and OR 2.0 (95% CI 1.4-2.7) for women. Sensitivity scores were rather low, whereas specificity scores were remarkably high. The results of this study provide the screening instrument a theoretic and scientific basis. Predictive value is promising, when absence is treated as a dichotomous measure. Sensitivity and specificity were unvarying during the development and validation phases of the instrument.
    Occupational Medicine 07/2008; 58(6):413-8. · 1.45 Impact Factor
  • Toxicology Letters - TOXICOL LETT. 01/2008; 180.
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    ABSTRACT: About one in every three employees seen by their occupational physician is absent from work because of psychosocial health complaints. To implement preventive measures, it is necessary to identify predictors for this type of sickness absence. A meta-analysis was carried out to quantify the association between predictive factors and psychosocial sickness absence and to assess clinical outcomes and heterogeneity. Eligible for inclusion were prospective studies that examined this association and provided sufficient information to estimate summary odds ratios (SORs). Twenty prospective studies were included. Significant SORs for sick leave >3 days were found for being unmarried, 1.37 (95% confidence interval [CI]=1.15-1.64), experiencing psychosomatic complaints, 1.79 (95% CI=1.54-2.07), using medication, 3.13 (95% CI=1.71-5.72), having a burnout, 2.34 (95% CI=1.59-3.45), suffering from psychological problems, 1.97 (95% CI=1.37-2.85), having low job control, 1.28 (95% CI=1.23-1.33), having low decision latitude, 1.33 (95% CI=1.16-1.56), and experiencing no fairness at work, 1.30 (95% CI=1.18-1.45). This study shows that predictors of sickness absence can be identified in a homogeneous manner. The results provide leads to public health interventions to successfully improve psychosocial health and to reduce sickness absence.
    Journal of Clinical Epidemiology 11/2007; 60(11):1105-15. · 5.33 Impact Factor
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    ABSTRACT: The authors examined the long-term health effects of occupational exposure to acrylamide among production and polymerisation workers. An earlier study of 371 acrylamide workers was expanded to include employees hired since 1979. In this updated study, 696 acrylamide workers were followed from 1955 through 2001 to ascertain vital status and cause of death. Exposure to acrylamide was retrospectively assessed based on personal samples from the 1970s onwards and area samples over the whole study period. Fewer of the acrylamide workers died (n = 141) compared to an expected number of 172.1 (SMR 81.9, 95% CI 69.0 to 96.6). No cause-specific SMR for any of the investigated types of cancer was exposure related. The authors did, however, find more pancreatic cancer deaths than expected (SMR 222.2, 95% CI 72.1 to 518.5). With respect to non-malignant disease, more diabetes deaths were observed than expected (SMR 288.7, 95% CI 138.4 to 531.0). To assess the influence of regional factors, the analysis was repeated with an internal reference population. The elevated SMR for diabetes persisted. This study provides little evidence for a cancer risk from occupational exposure to acrylamide at production facilities. However, the increased rates of pancreatic cancer in this study and another larger study of acrylamide production workers indicate that caution is needed to rule out a cancer risk. The authors believe that the excess of diabetes mortality in this study is most likely not related to acrylamide exposure, because a larger study of acrylamide workers reported a deficit in this cause of death. The authors conclude that the increased SMR for diabetes mortality is probably not related to regional influences.
    Occupational and environmental medicine 07/2007; 64(6):396-401. · 3.64 Impact Factor
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    ABSTRACT: The objective of this study was to update the mortality experience of a cohort of workers with and without potential exposure to acrylamide (AMD) at three U.S. plants (n = 8508) and one plant in The Netherlands (n = 344). We computed standardized mortality ratios (SMRs) using national and local rates and modeled internal cohort rates to assess site-specific cancer risks by demographic and work history factors and several exposure indicators for AMD. For the 1925-2002 study period, we observed both deficit and excess overall mortality risks among the U.S. cohort for cancer sites implicated in experimental animal studies: brain and other central nervous system (SMR = 0.67, confidence interval [CI] = 0.40-1.05), thyroid gland (SMR = 1.38, CI = 0.28-4.02), testis and other male genital organs (SMR = 0.64, CI = 0.08-2.30); and for sites selected in earlier exploratory analyses of this cohort: respiratory system cancer (RSC) (SMR = 1.17, CI = 1.06-1.27), esophagus (SMR = 1.20, CI = 0.86-1.63), rectum (SMR = 1.25, CI = 0.84-1.78), pancreas (SMR = 0.94, CI = 0.70-1.22), and kidney (SMR = 1.01, CI = 0.66-1.46). Except for RSC, attributed earlier to muriatic acid exposure, none of the mortality excesses was statistically significant. In the Dutch cohort, we observed deficits in deaths for all sites of a priori interest. An updated analysis of our previous exploratory findings for pancreatic cancer in the U.S. cohort revealed much less evidence of a possible exposure-response relationship with AMD. AMD exposure at the levels present in our study sites was not associated with elevated cancer mortality risks.
    Journal of Occupational and Environmental Medicine 02/2007; 49(1):82-95. · 1.85 Impact Factor
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    Saskia F A Duijts, Ijmert Kant, Gerard M H Swaen
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    ABSTRACT: It is unclear if objective selection of employees, for an intervention to prevent sickness absence, is more effective than subjective 'personal enlistment'. We hypothesize that objectively selected employees are 'at risk' for sickness absence and eligible to participate in the intervention program. The dispatch of 8603 screening instruments forms the starting point of the objective selection process. Different stages of this process, throughout which employees either dropped out or were excluded, were described and compared with the subjective selection process. Characteristics of ineligible and ultimately selected employees, for a randomized trial, were described and quantified using sickness absence data. Overall response rate on the screening instrument was 42.0%. Response bias was found for the parameters sex and age, but not for sickness absence. Sickness absence was higher in the 'at risk' (N = 212) group (42%) compared to the 'not at risk' (N = 2503) group (25%) (OR 2.17 CI 1.63-2.89; p = 0.000). The selection process ended with the successful inclusion of 151 eligible, i.e. 2% of the approached employees in the trial. The study shows that objective selection of employees for early intervention is effective. Despite methodological and practical problems, selected employees are actually those at risk for sickness absence, who will probably benefit more from the intervention program than others.
    BMC Public Health 02/2007; 7:67. · 2.08 Impact Factor

Publication Stats

2k Citations
334.70 Total Impact Points


  • 2007–2012
    • Dow Chemical Company
      Midland, Michigan, United States
    • University of Pittsburgh
      • Department of Biostatistics
      Pittsburgh, PA, United States
  • 1987–2008
    • Maastricht University
      • Department of Epidemiology
      Maastricht, Provincie Limburg, Netherlands
  • 2005
    • National Institute of Public Health, Denmark
      København, Capital Region, Denmark
    • RWTH Aachen University
      • Institut für Hygiene und Umweltmedizin
      Aachen, North Rhine-Westphalia, Germany
  • 1996
    • Gesellschaft für Hygiene, Umweltmedizin und Präventivmedizin
      Aachen, North Rhine-Westphalia, Germany
    • Council for Public Health and Health Care, Netherlands
      's-Gravenhage, South Holland, Netherlands
  • 1988
    • Netherlands Society Of Occupational Medicine
      Utrecht, Utrecht, Netherlands