Malcolm Ross Sim

Leukemia Risk Associated With Low-Level Benzene Exposure

Background: Men who were part of an Australian petroleum industry cohort had previously been found to have an excess of lympho-hematopoietic cancer. Occupational benzene exposure is a possible cause of this excess. Methods: We conducted a case-control study of lympho-hematopoietic cancer nested within the existing cohort study to examine the role of benzene exposure. Cases identified between 1981 and 1999 (N = 79) were age-matched to 5 control subjects from the cohort. We estimated each subject’s benzene exposure using occupational histories, local site-specific information, and an algorithm using Australian petroleum industry monitoring data. Results: Matched analyses showed that the risk of leukemia was increased at cumulative exposures above 2 ppm-years and with intensity of exposure of highest exposed job over 0.8 ppm. Risk increased with higher exposures; for the 13 case-sets with greater than 8 ppm-years cumulative exposure, the odds ratio was 11.3 (95% confidence interval = 2.85-45.1). The risk of leukemia was not associated with start date or duration of employment. The association with type of workplace was explained by cumulative exposure. There is limited evidence that short-term high exposures carry more risk than the same amount of exposure spread over a longer period. The risks for acute nonlymphocytic leukemia and chronic lymphocytic leukemia were raised for the highest exposed workers. No association was found between non-Hodgkin lymphoma or multiple myeloma and benzene exposure, nor between tobacco or alcohol consumption and any of the cancers. Conclusions: We found an excess risk of leukemia associated with cumulative benzene exposures and benzene exposure intensities that were considerably lower than reported in previous studies. No evidence was found of a threshold cumulative exposure below which there was no risk.

Biological dust exposure in the workplace is a risk factor for chronic obstructive pulmonary disease

Background: Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality. Although the main risk factor is smoking, 15–19% of COPD even in smokers has been attributed to occupational exposures. The aim of this study was to investigate the association between occupational exposure and risk of COPD. Methods: Participants were part of a cross sectional study of risk factors for COPD. A total of 1232 completed a detailed respiratory questionnaire, spirometric testsing and measurement of gas transfer. Job histories were coded according to the International Standard Classification of Occupations. These codes were then used to establish occupational exposures using the ALOHA job exposure matrix. Results: The prevalence of emphysema was 2.4%, chronic obstructive bronchitis 1.8%, and COPD 3.4%. Subjects ever exposed to biological dusts had an increased risk of chronic obstructive bronchitis (OR 3.19; 95% CI 1.27 to 7.97), emphysema (OR 3.18; 95% CI 1.41 to 7.13), and COPD (OR 2.70, 95% CI 1.39 to 5.23). These risks were higher in women than in men. For biological dust, the risk of emphysema and COPD was also significantly increased in both the duration of exposure categories, again in women but not in men. No significant increased risks for COPD were found for mineral dust (OR 1.13; 95% CI 0.57 to 2.27) or gases/fumes (OR 1.63; 95% CI 0.83 to 3.22). Conclusion: In this general population sample of adults, occupational exposures to biological dusts were associated with an increased risk of COPD which was higher in women. Preventive strategies should be aimed at reducing exposure to these agents in the workplace.

Comparison of occupational exposure using three different methods: hygiene panel, job exposure matrix (JEM), and self reports.

This study was undertaken to compare the agreement of occupational exposure assessment by a panel of occupational hygienists with a job exposure matrix and self-reported exposures in a community-based case-control study. We also investigated the intra-rater reliability and degree of attenuation of the hypothetical odds ratio of the panel in retrospective chemical exposure assessment. A panel of three occupational hygienists was recruited to assess exposure to chemicals for 5,620 jobs. The agreement between the panel, a job exposure matrix (FINJEM), and the self-reported exposures was then assessed. A further 172 jobs were resubmitted to the panel to assess intra-rater reliability. The kappa for intra-rater reliability ranged from 0.60-0.71. The agreement between the panel and FINJEM ranged from 0.07 to 0.46 (for similar exposures), and agreement between the panel and among the self-reports ranged from 0.00 to 0.48. Agreement between hygienists when rating exposure to the same chemical ranged from 0.48 to 0.57. Based on these findings, the degree of exposure misclassification by the panel where the true odds ratio was 2 would result in the observed odds ratio ranging between 1.70 and 1.88. The results indicated good intra-rater reliability for the hygiene panel. However, the agreement among the panel, FINJEM, and self-reported exposures was found to be only poor to fair. The attenuation of the odds ratios due to exposure misclassification by the panel was variable and dependent upon the exposure.

Disabling musculoskeletal pain in working populations: is it the job, the person, or the culture?

&NA; Large international variation in the prevalence of disabling forearm and low back pain was only partially explained by established personal and socioeconomic risk factors. &NA; To compare the prevalence of disabling low back pain (DLBP) and disabling wrist/hand pain (DWHP) among groups of workers carrying out similar physical activities in different cultural environments, and to explore explanations for observed differences, we conducted a cross‐sectional survey in 18 countries. Standardised questionnaires were used to ascertain pain that interfered with everyday activities and exposure to possible risk factors in 12,426 participants from 47 occupational groups (mostly nurses and office workers). Associations with risk factors were assessed by Poisson regression. The 1‐month prevalence of DLBP in nurses varied from 9.6% to 42.6%, and that of DWHP in office workers from 2.2% to 31.6%. Rates of disabling pain at the 2 anatomical sites covaried (r = 0.76), but DLBP tended to be relatively more common in nurses and DWHP in office workers. Established risk factors such as occupational physical activities, psychosocial aspects of work, and tendency to somatise were confirmed, and associations were found also with adverse health beliefs and group awareness of people outside work with musculoskeletal pain. However, after allowance for these risk factors, an up‐to 8‐fold difference in prevalence remained. Systems of compensation for work‐related illness and financial support for health‐related incapacity for work appeared to have little influence on the occurrence of symptoms. Our findings indicate large international variation in the prevalence of disabling forearm and back pain among occupational groups carrying out similar tasks, which is only partially explained by the personal and socioeconomic risk factors that were analysed.

Comorbidity of PTSD and depression in Korean War veterans: prevalence, predictors, and impairment.

BACKGROUND Rates of PTSD and depression are high in Korean War veterans. The prevalence and impact of the two disorders occurring comorbidly, however, has not been investigated. This paper aims to investigate the extent to which PTSD and depression co-occur in Australian veterans of the Korean War, the symptom severity characteristics of comorbidity, the impact on life satisfaction and quality, and the association with war-related predictors. METHODS Veterans (N=5352) completed self-report questionnaires including the Posttraumatic Stress Disorder Checklist, the Hospital Anxiety and Depression Scale, the Life Satisfaction Scale, the brief World Health Organisation Quality of Life questionnaire and the Combat Exposure Scale. RESULTS Seventeen percent of veterans met criteria for comorbid PTSD and depression, 15% had PTSD without depression, and a further 6% had depression without PTSD. Compared with either disorder alone, comorbidity was associated with impaired life satisfaction, reduced quality of life, and greater symptom severity. Several war-related factors were associated with comorbidity and with PTSD alone, but not with depression alone. LIMITATIONS The reliance on self-reported measures and the necessity for retrospective assessment of some deployment-related factors renders some study data vulnerable to recall bias. CONCLUSIONS Comorbid PTSD and depression, and PTSD alone, are prevalent among Korean War veterans, are both associated with war-related factors 50 years after the Korean War, and may represent a single traumatic stress construct. The results have important implications for understanding complex psychopathology following trauma.

Primary prevention of latex related sensitisation and occupational asthma: a systematic review.

Methods: Eight primary prevention intervention studies on natural rubber latex (NRL) published since 1990 were identified and reviewed. This is the largest evidence base of primary prevention studies for any occupational asthmagen. Results: Review of this small and largely observational evidence base supports the following evidence statement: Substitution of powdered latex gloves with low protein powder-free NRL gloves or latex-free gloves greatly reduces NRL aeroallergens, NRL sensitisation, and NRL-asthma in healthcare workers. Evidence in support of this statement is ranked SIGN level 2+, referring to well conducted case-control or cohort studies with a low risk of confounding, bias, or chance and a moderate probability that the relationship is causal. Conclusion: Substitution of powdered latex gloves with low protein powder-free NRL gloves or latex-free gloves promises benefits to both workers’ health and cost and human resource savings for employers. This message should be broadly disseminated beyond the hospital sector to include other healthcare settings (such as aged care facilities) as well as food service and other industries where latex gloves might be used.

Symptoms and medical conditions in Australian veterans of the 1991 Gulf War: relation to immunisations and other Gulf War exposures.

Aims: To investigate whether Australian Gulf War veterans have a higher than expected prevalence of recent symptoms and medical conditions that were first diagnosed in the period following the 1991 Gulf War; and if so, whether these effects were associated with exposures and experiences that occurred in the Gulf War. Methods: Cross-sectional study of 1456 Australian Gulf War veterans and a comparison group who were in operational units at the time of the Gulf War, but were not deployed to that conflict (n = 1588). A postal questionnaire was administered and the likelihood of the diagnosis of self-reported medical conditions was assessed and rated by a medical practitioner. Results: Gulf War veterans had a higher prevalence of all self-reported health symptoms than the comparison group, and more of the Gulf War veterans had severe symptoms. Increased symptom reporting was associated with several exposures, including having more than 10 immunisations, pyridostigmine bromide tablets, anti-biological warfare tablets, pesticides, insect repellents, reportedly being in a chemical weapons area, and stressful military service experiences in a strong dose-response relation. Gulf War veterans reported psychological (particularly post-traumatic stress disorder), skin, eye, and sinus conditions first diagnosed in 1991 or later more commonly than the comparison group. Over 90% of medical conditions reported by both study groups were rated by a medical practitioner as having a high likelihood of diagnosis. Conclusion: More than 10 years after the 1991 Gulf War, Australian veterans self-report all symptoms and some medical conditions more commonly than the comparison group. Further analysis of the severity of symptoms and likelihood of the diagnosis of medical conditions suggested that these findings are not due to over-reporting or to participation bias.

Descriptive Epidemiology of Somatising Tendency: Findings from the CUPID Study

Somatising tendency, defined as a predisposition to worry about common somatic symptoms, is importantly associated with various aspects of health and health-related behaviour, including musculoskeletal pain and associated disability. To explore its epidemiological characteristics, and how it can be specified most efficiently, we analysed data from an international longitudinal study. A baseline questionnaire, which included questions from the Brief Symptom Inventory about seven common symptoms, was completed by 12,072 participants aged 20–59 from 46 occupational groups in 18 countries (response rate 70%). The seven symptoms were all mutually associated (odds ratios for pairwise associations 3.4 to 9.3), and each contributed to a measure of somatising tendency that exhibited an exposure-response relationship both with multi-site pain (prevalence rate ratios up to six), and also with sickness absence for non-musculoskeletal reasons. In most participants, the level of somatising tendency was little changed when reassessed after a mean interval of 14 months (75% having a change of 0 or 1 in their symptom count), although the specific symptoms reported at follow-up often differed from those at baseline. Somatising tendency was more common in women than men, especially at older ages, and varied markedly across the 46 occupational groups studied, with higher rates in South and Central America. It was weakly associated with smoking, but not with level of education. Our study supports the use of questions from the Brief Symptom Inventory as a method for measuring somatising tendency, and suggests that in adults of working age, it is a fairly stable trait.

Patterns of multisite pain and associations with risk factors

Summary In a large cross‐sectional survey, pain affecting 6–10 anatomical sites showed substantially different associations with risk factors from pain limited to 1–3 sites. ABSTRACT To explore definitions for multisite pain, and compare associations with risk factors for different patterns of musculoskeletal pain, we analysed cross‐sectional data from the Cultural and Psychosocial Influences on Disability (CUPID) study. The study sample comprised 12,410 adults aged 20–59 years from 47 occupational groups in 18 countries. A standardised questionnaire was used to collect information about pain in the past month at each of 10 anatomical sites, and about potential risk factors. Associations with pain outcomes were assessed by Poisson regression, and characterised by prevalence rate ratios (PRRs). Extensive pain, affecting 6–10 anatomical sites, was reported much more frequently than would be expected if the occurrence of pain at each site were independent (674 participants vs 41.9 expected). In comparison with pain involving only 1–3 sites, it showed much stronger associations (relative to no pain) with risk factors such as female sex (PRR 1.6 vs 1.1), older age (PRR 2.6 vs 1.1), somatising tendency (PRR 4.6 vs 1.3), and exposure to multiple physically stressing occupational activities (PRR 5.0 vs 1.4). After adjustment for number of sites with pain, these risk factors showed no additional association with a distribution of pain that was widespread according to the frequently used American College of Rheumatology criteria. Our analysis supports the classification of pain at multiple anatomical sites simply by the number of sites affected, and suggests that extensive pain differs importantly in its associations with risk factors from pain that is limited to only a small number of anatomical sites.

Outdoor air pollution as a trigger for out-of-hospital cardiac arrests.

Background: Epidemiologic studies have reported associations between fine particulate air pollution and cardiovascular mortality or hospitalization for cardiac events. However the evidence regarding the association between air pollution and acute cardiac events, such as out-of-hospital cardiac arrest, is inconsistent. Methods: We investigated the association between particulate matter (PM) air pollution and out-of-hospital cardiac arrest using a case-crossover study of adults (age, 35+ years) in Melbourne, Australia. We included 8434 cases identified through the Victorian Cardiac Arrest Registry from 2003 through 2006. We excluded arrests with an obvious preceding noncardiac event such as trauma, poisoning, or drowning, leaving only those events that were presumed to have cardiac etiology. Air pollution concentrations obtained from a central monitoring site were used for day of the arrest and for lag 1, lag 2, and lag 3, including the average lag 0–1. Results: An interquartile range increase of 4.26 &mgr;g/m3 in PM2.5 over 2 days (lag 0–1) was associated with an increase in risk for an out-of-hospital cardiac arrest of 3.6% (95% confidence interval = 1.3% to 6.0%). PM10 and carbon monoxide also showed associations, but not as strong as for PM2.5. Longer lag periods did not show such strong relationships. There was no association of these cardiac events with ozone, sulfur dioxide, or nitrogen dioxide in any lag period. Individuals age 65–74 years old were most susceptible to PM2.5 exposure, while those 75 years and older had the lowest risk. Conclusion: These findings support an association between daily average PM2.5 concentrations and an increased risk of out-of-hospital cardiac arrests.