Anthony Del Monaco

Impact of Fine Particulate Matter (PM2.5) Exposure During Wildfires on Cardiovascular Health Outcomes

Background Epidemiological studies investigating the role of fine particulate matter (PM2.5; aerodynamic diameter <2.5 μm) in triggering acute coronary events, including out-of-hospital cardiac arrests and ischemic heart disease (IHD), during wildfires have been inconclusive. Methods and Results We examined the associations of out-of-hospital cardiac arrests, IHD, acute myocardial infarction, and angina (hospital admissions and emergency department attendance) with PM2.5 concentrations during the 2006–2007 wildfires in Victoria, Australia, using a time-stratified case-crossover study design. Health data were obtained from comprehensive health-based administrative registries for the study period (December 2006 to January 2007). Modeled and validated air exposure data from wildfire smoke emissions (daily average PM2.5, temperature, relative humidity) were also estimated for this period. There were 457 out-of-hospital cardiac arrests, 2106 emergency department visits, and 3274 hospital admissions for IHD. After adjusting for temperature and relative humidity, an increase in interquartile range of 9.04 μg/m3 in PM2.5 over 2 days moving average (lag 0-1) was associated with a 6.98% (95% CI 1.03% to 13.29%) increase in risk of out-of-hospital cardiac arrests, with strong association shown by men (9.05%,95%CI 1.63% to 17.02%) and by older adults (aged ≥65 years) (7.25%, 95% CI 0.24% to 14.75%). Increase in risk was (2.07%, 95% CI 0.09% to 4.09%) for IHD-related emergency department attendance and (1.86%, 95% CI: 0.35% to 3.4%) for IHD-related hospital admissions at lag 2 days, with strong associations shown by women (3.21%, 95% CI 0.81% to 5.67%) and by older adults (2.41%, 95% CI 0.82% to 5.67%). Conclusion PM2.5 exposure was associated with increased risk of out-of-hospital cardiac arrests and IHD during the 2006–2007 wildfires in Victoria. This evidence indicates that PM2.5 may act as a triggering factor for acute coronary events during wildfire episodes.

Forest Fire Smoke Exposures and Out-of-Hospital Cardiac Arrests in Melbourne, Australia: A Case-Crossover Study.

Background Millions of people can potentially be exposed to smoke from forest fires, making this an important public health problem in many countries. Objective In this study we aimed to measure the association between out-of-hospital cardiac arrest (OHCA) and forest fire smoke exposures in a large city during a severe forest fire season, and estimate the number of excess OHCAs due to the fire smoke. Methods We investigated the association between particulate matter (PM) and other air pollutants and OHCA using a case-crossover study of adults (≥ 35 years of age) in Melbourne, Australia. Conditional logistic regression models were used to derive estimates of the percent change in the rate of OHCA associated with an interquartile range (IQR) increase in exposure. From July 2006 through June 2007, OHCA data were collected from the Victorian Ambulance Cardiac Arrest Registry. Hourly air pollution concentrations and meteorological data were obtained from a central monitoring site. Results There were 2,046 OHCAs with presumed cardiac etiology during our study period. Among men during the fire season, greater increases in OHCA were observed with IQR increases in the 48-hr lagged PM with diameter ≤ 2.5 μm (PM2.5) (8.05%; 95% CI: 2.30, 14.13%; IQR = 6.1 μg/m3) or ≤ 10 μm (PM10) (11.1%; 95% CI: 1.55, 21.48%; IQR = 13.7 μg/m3) and carbon monoxide (35.7%; 95% CI: 8.98, 68.92%; IQR = 0.3 ppm). There was no significant association between the rate of OHCA and air pollutants among women. One hundred seventy-four “fire-hours” (i.e., hours in which Melbourne’s air quality was affected by forest fire smoke) were identified during 12 days of the 2006/2007 fire season, and 23.9 (95% CI: 3.1, 40.2) excess OHCAs were estimated to occur due to elevations in PM2.5 during these fire-hours. Conclusions This study found an association between exposure to forest fire smoke and an increase in the rate of OHCA. These findings have implications for public health messages to raise community awareness and for planning of emergency services during forest fire seasons. Citation Dennekamp M, Straney LD, Erbas B, Abramson MJ, Keywood M, Smith K, Sim MR, Glass DC, Del Monaco A, Haikerwal A, Tonkin AM. 2015. Forest fire smoke exposures and out-of-hospital cardiac arrests in Melbourne, Australia: a case-crossover study. Environ Health Perspect 123:959–964; http://dx.doi.org/10.1289/ehp.1408436

Cancer incidence, mortality, and blood lead levels among workers exposed to inorganic lead.

PURPOSE We aimed to measure mortality and cancer incidence in a cohort of lead-exposed workers by using blood lead levels to assess exposure. METHODS The cohort comprised male lead workers. Subjects were matched to cancer and death registries. Observed death and cancer incidence rates were compared with population rates to obtain standardized mortality ratios (SMR) and standardized incidence ratios (SIR). RESULTS There were 4114 male subjects with average follow-up time of 16.2 years, and 406 deaths were observed. There were significant results for overall death (SMR, 111; 95% confidence interval [95% CI], 101-123), digestive system deaths (SMR, 167; 95% CI, 110-250), and deaths from external causes (SMR, 135; 95% CI, 105-174). A total of 228 subjects had cancer, with an overall SIR of 83 (95% CI, 73-95); liver cancer SIR of 217 (95% CI, 103-454) and esophageal cancer SIR of 240 (95% CI, 129-447). The latter was seven-fold greater (SIR 755; 95% CI, 314-1813) among those with a blood lead level result above 30 μg/dL compared with population rates. No other increases in cancers were observed. CONCLUSIONS Overall mortality was elevated. Although incidence rates of overall cancer were low, further studies and analysis are required to investigate any biologically plausible associations between inorganic lead and liver or esophageal cancer.

All cause mortality and incidence of cancer in workers in bauxite mines and alumina refineries

Bauxite is a reddish clay that is refined to produce alumina, which is then reduced to aluminium. There have been studies examining the health of workers in aluminium smelters, but not workers in bauxite mining and alumina refining. A cohort of employees of 1 large aluminium company since 1983 was assembled (n = 6,485, 5,828 men). Deaths and incident cancers to 2002 were ascertained by linkage to national and state cancer and death registries. SIRs and SMRs were calculated compared to national rates standardizing for calendar year, sex and 5‐year age group. The mortality from all causes (SMR 0.68, 95% CI: 0.60–0.77), and from circulatory and respiratory diseases, all cancers combined and injury in the male cohort were lower than in the Australian male population and were similar across work groups and with duration of employment. The only significant increased mortality risk was from pleural mesothelioma. The incidence of all cancers combined was similar to the Australian rate. The cohort had a lower risk of incident lymphohaematopoietic cancer (SIR 0.50, 95% CI: 0.31–0.88) and a higher risk of melanoma (SIR 1.30, 95% CI: 1.00–1.69) although no dose‐responses were seen. There was also an increased risk of mesothelioma (SIR 3.49, 95% CI: 1.82–6.71), which was associated with exposures outside the aluminium industry. This study is the first to examine cancer and mortality amongst workers in bauxite mines and alumina refineries and found little evidence for increased cancer incidence or mortality in these workers.

Fractional Polynomials and Model Selection in Generalized Estimating Equations Analysis, With an Application to a Longitudinal Epidemiologic Study in Australia

In epidemiologic studies, researchers often need to establish a nonlinear exposure-response relation between a continuous risk factor and a health outcome. Furthermore, periodic interviews are often conducted to take repeated measurements from an individual. The authors proposed to use fractional polynomial models to jointly analyze the effects of 2 continuous risk factors on a health outcome. This method was applied to an analysis of the effects of age and cumulative fluoride exposure on forced vital capacity in a longitudinal study of lung function carried out among aluminum workers in Australia (1995-2003). Generalized estimating equations and the quasi-likelihood under the independence model criterion were used. The authors found that the second-degree fractional polynomial models for age and fluoride fitted the data best. The best model for age was robust across different models for fluoride, and the best model for fluoride was also robust. No evidence was found to suggest that the effects of smoking and cumulative fluoride exposure on change in forced vital capacity over time were significant. The trend 1 model, which included the unexposed persons in the analysis of trend in forced vital capacity over tertiles of fluoride exposure, did not fit the data well, and caution should be exercised when this method is used.

Causes of death and incidence of cancer in a cohort of Australian pesticide-exposed workers.

PURPOSE To determine the rates of mortality and of cancer incidence in a cohort of pesticide-exposed Australian workers. METHODS The study cohort was assembled using records of former government occupational health surveillance programs. The cohort was then linked to the Australian national registries of cancer and mortality and analyzed in comparison with the general Australian population. RESULTS Consistent with a healthy worker effect, we found no overall excesses in mortality or incident cancer. Non-injury-related causes of death were less than expected; however, non-intentional poisoning and suicide mortality were significantly elevated. All types of suicide were elevated, and firearm suicide deaths were significantly in excess. The suicides by poisoning were predominantly associated with pesticides, although other published research suggests this pattern is more often associated with developing countries. CONCLUSIONS This study did not find evidence of a relationship between occupational pesticide exposure and cancer or non-injury-related mortality. However, accidental poisoning and intentional self-harm warrant further investigation.

Methodological issues in linking study participants to Australian cancer registries using different methods: lessons from a cohort study

Objective: To compare results of concurrent linkage of records from the same occupational cohort to cancer registries at both a State and national level. Methodological issues affecting the record registry linkage process will be explored in cases of discordant results between the State and national cancer linkages.

Mortality and cancer incidence among male volunteer Australian firefighters

Objectives This study aims to investigate mortality and cancer incidence of Australian male volunteer firefighters and of subgroups of firefighters by duration of service, era of first service and the number and type of incidents attended. Methods Participating fire agencies supplied records of individual volunteer firefighters, including incidents attended. The cohort was linked to the Australian National Death Index and Australian Cancer Database. standardised mortality ratios (SMRs) and standardised incidence ratios (SIRs) for cancer were calculated. Firefighters were grouped into tertiles by duration of service and by number of incidents attended and relative mortality ratios and relative incidence ratios calculated. Results Compared with the general population, there were significant decreases in overall cancer incidence and in most major cancer categories. Prostate cancer incidence was increased compared with the general population, but this was not related to the number of incidents attended. Kidney cancer was associated with increased attendance at fires, particularly structural fires. The overall risk of mortality was significantly decreased, and all major causes of death were significantly reduced for volunteer firefighters. There was evidence of an increased mortality from ischaemic heart disease, with increased attendance at fires. Conclusion Volunteer firefighters have a reduced risk of mortality and cancer incidence compared with the general population, which is likely to be a result of a ‘healthy-volunteer’ effect and, perhaps, lower smoking rates.

Cohort Profile: Health Watch—a 30-year prospective cohort study of Australian petroleum industry workers

Health Watch was established in 1980 at the University of Melbourne to ‘explore possible links between occupational experience in the [petroleum] industry’ and subsequent mortality and cancer incidence. There was concern that occupational exposure to fossil fuels could result in occupational cancers and it was anticipated that ‘well designed epidemiological studies, and carefully planned data bases’ were ‘capable of confirming or refuting such association’ rather than relying on clinician recognition of clusters. Health Watch was ‘designed to operate as a general health surveillance system’ comparable to a contemporary USA study funded by the American Petroleum Institute. Later reports expanded the aim to be ‘a prospective epidemiological study with the capacity to test specific hypotheses regarding the possible health consequences of occupationally determined exposure to hydrocarbon and other chemical substances’. This follows efforts by the industry’s occupational hygienists to link descriptive job categories to an index of hydrocarbon exposure. The main aims of tracking mortality and cancer incidence in the cohort have not changed over time, but subanalyses have been included e.g. for tanker drivers and for a group of men at a particular refinery. After an excess of lympho-haematopoetic (LH) cancer was identified, a case-control study was instituted to investigate whether benzene exposure was associated with this increased risk. This study was followed up in 2008 with a pooled analysis to identify which subtypes of LH cancer might be most strongly associated with benzene exposure. The industry has reduced benzene exposure over the period of the cohort. In 1999, the custodianship of the cohort was transferred to the University of Adelaide and then in 2005 to Monash University’s Centre for Occupational and Environmental Health in the Department of Epidemiology and Preventive Medicine, where it currently resides. The Australian Institute of Petroleum (AIP) has funded the relevant universities, including Monash University, to implement the study with funds from their member companies in the Australian petroleum industry. The study has an advisory committee that meets regularly and includes the relevant university investigators and trades union and company representatives. The committee is chaired by a representative of the participating companies on a rotating basis and the AIP provides the secretariat.

Longitudinal analysis of respiratory outcomes among bauxite exposed workers in Western Australia

INTRODUCTION Occupational exposure to bauxite is common in the aluminium industry but little is known about the associated health effects. This study investigates respiratory health in relation to respirable bauxite dust exposure longitudinally over a 13 year period. METHODS An inception cohort study recruited 91 male bauxite miners and 363 male alumina refinery workers. Annual measurements of respiratory symptoms and lung function were made. Cumulative exposure to bauxite was derived from job histories and air monitoring data. Mixed-effects modeling was used. RESULTS No associations were found between cumulative bauxite exposure and respiratory symptoms or lung function. However, when analysis was restricted to the first three rounds, FEV1 was significantly lower in all exposure groups than in those unexposed but with no significant trend. CONCLUSION Increasing exposure to bauxite dust in the aluminum industry was not associated with respiratory symptoms or consistent decrements in lung function.