Marie-France Valois

The short-term influence of temperature on daily mortality in the temperate climate of Montreal, Canada ☆

The purpose of this study was to determine whether short-term changes in ambient temperature were associated with daily mortality among persons who lived in Montreal, Canada, and who died in the urban area between 1984 and 2007. We made use of newly developed distributed lag non-linear Poisson models, constrained to a 30 day lag period, and we adjusted for temporal trends and nitrogen dioxide and ozone. We found a strong non-linear association with high daily maximum temperatures showing an apparent threshold at about 27°C; this association persisted until about lag 5 days. For example, we found across all lag periods that daily non-accidental mortality increased by 28.4% (95% confidence interval: 13.8-44.9%) when temperatures increased from 22.5 to 31.8°C (75-99th percentiles). This association was essentially invariant to different smoothers for time. Cold temperatures were not found to be associated with daily mortality over 30 days, although there was some evidence of a modest increased risk from 2 to 5 days. The adverse association with colder temperatures was sensitive to the smoother for time. For cardio-respiratory mortality we found increased risks for higher temperatures of a similar magnitude to that of non-accidental mortality but no effects at cold temperatures.

Associations between ambient air pollution and daily mortality among persons with congestive heart failure

We conducted a mortality time series study to investigate the association between daily mortality for congestive heart failure (CHF), and daily concentrations of particles and gaseous pollutants in the ambient air of Montreal, Quebec, during the period 1984-1993. In addition, using data from the universal Quebec Health Insurance Plan, we identified individuals >/=65 years of age who, one year before death, had a diagnosis of CHF. Fixed-site air pollution monitors in Montreal provided daily mean levels of pollutants. We regressed the logarithm of daily counts of mortality on the daily mean levels of each pollutant, after accounting for seasonal and subseasonal fluctuations in the mortality time series, non-Poisson dispersion, weather variables, and other gaseous and particle pollutants. Using cause of death information, we did not find any associations between daily mortality for CHF and any air pollutants. The analyses of CHF defined from the medical record showed positive associations with coefficient of haze, the extinction coefficient, SO(2), and NO(2). For example, the mean percent increase in daily mortality for an increase in the coefficient of haze across the interquartile range was 4.32% (95% CI: 0.95-7.80%) and for NO(2) it was 4.08% (95% CI: 0.59-7.68%). These effects were generally higher in the warm season.

Associations between ambient air pollution and daily mortality among elderly persons in Montreal, Quebec.

BACKGROUND Persons with underlying health conditions may be at higher risk for the short-term effects of air pollution. We have extended our original mortality time series study in Montreal, Quebec, among persons 65 years of age and older, for an additional 10 years (1990-2003) to assess whether these associations persisted and to investigate new health conditions. METHODS AND RESULTS We created subgroups of subjects diagnosed with major health conditions one year before death using billing and prescription data from the Quebec Health Insurance Plan. We used parametric log-linear Poisson models within the distributed lag non-linear models framework, that were adjusted for long-term temporal trends and daily maximum temperature, for which we assessed associations with NO2, O3, CO, SO2, and particles with aerodynamic diameters 2.5 μm in diameter or less (PM2.5). We found positive associations between daily non-accidental mortality and all air pollutants but O3 (e.g., for a cumulative effect over a 3-day lag, with a mean percent change (MPC) in daily mortality of 1.90% [95% confidence interval: 0.73, 3.08%] for an increase of the interquartile range (17.56 μg m(-3)) of NO2). Positive associations were found amongst persons having cardiovascular disease (cumulative MPC for an increase equal to the interquartile range of NO2=2.67%), congestive heart failure (MPC=3.46%), atrial fibrillation (MPC=4.21%), diabetes (MPC=3.45%), and diabetes and cardiovascular disease (MPC=3.50%). Associations in the warm season were also found for acute and chronic coronary artery disease, hypertension, and cancer. There was no persuasive evidence to conclude that there were seasonal associations for cerebrovascular disease, acute lower respiratory disease (defined within 2 months of death), airways disease, and diabetes and airways disease. CONCLUSIONS These data indicate that individuals with certain health conditions, especially those with diabetes and cardiovascular disease, hypertension, atrial fibrillation, and cancer, may be susceptible to the short-term effects of air pollution.

Traffic-related air pollution and prostate cancer risk: a case–control study in Montreal, Canada

Objectives There is a paucity of information on environmental risk factors for prostate cancer. We conducted a case–control study in Montreal to estimate associations with exposure to ground-level nitrogen dioxide (NO2), a marker for traffic-related air pollution. Methods Cases were 803 men with incident prostate cancer, ≤75 years of age, and diagnosed across all French hospitals in Montreal. Concurrently, 969 controls were drawn from electoral lists of French-speaking individuals residing in the same electoral districts as the cases and frequency-matched by age. Concentrations of NO2 were measured across Montreal in 2005–2006. We developed a land use regression model to predict concentrations of NO2 across Montreal for 2006. These estimates were back-extrapolated to 1996. Estimates were linked to residential addresses at the time of diagnosis or interview. Unconditional logistic regression was used, adjusting for potential confounding variables. Results For each increase of 5 parts per billion of NO2, as estimated from the original land use regression model in 2006, the OR5ppb adjusted for personal factors was 1.44 (95% CI 1.21 to 1.73). Adding in contextual factors attenuated the OR5ppb to 1.27 (95% CI 1.03 to 1.58). One method for back-extrapolating concentrations of NO2 to 1996 (about 10 years before the index date) gave the following OR5ppb: 1.41 (95% CI 1.24 to 1.62) when personal factors were included, and 1.30 (95% CI 1.11 to 1.52) when contextual factors were added. Conclusions Exposure to ambient concentrations of NO2 at the current address was associated with an increased risk of prostate cancer. This novel finding requires replication.

Postmenopausal breast cancer and occupational exposures

Objective To determine whether exposures in the workplace to organic solvents and to other agents, such as polycyclic aromatic hydrocarbons, are associated with increased risks of developing postmenopausal breast cancer. Methods Between 1996 and 1997 a case–control study was conducted in Montreal, Quebec. Cases comprised 556 women, aged 50–75 years, with incident malignant breast cancer, and their controls were 613 women with other cancers, frequency matched for age, date of diagnosis and hospital. An expert team of chemists and industrial hygienists translated their job histories into exposure to about 300 agents. Results Odds ratios (ORs) were increased for the usual risk factors for breast cancer and, adjusting for these, risks increased with occupational exposure to several agents, and were highest for exposures occurring before age 36 years. Increased ORs were found for each 10-year increment in duration of exposure, before age 36 years (OR<36), to acrylic fibres (OR<36=7.69) and to nylon fibres (OR<36=1.99). For oestrogen-positive and progesterone-negative tumours, the OR doubled or more for each 10-year increase in exposure to monoaromatic hydrocarbons, and to acrylic and rayon fibres. The OR<36 also doubled for exposure to organic solvents that metabolise into reactive oxygen species, and to acrylic fibres. A threefold increase was found for oestrogen- and progesterone-positive tumours, with exposure to polycyclic aromatic hydrocarbons from petroleum sources. Conclusion Certain occupational exposures appear to increase the risk of developing postmenopausal breast cancer, although some findings might be due to chance or to undetected bias. Our findings are consistent with the hypothesis that breast tissue is more sensitive to adverse effects if exposure occurs when breast cells are still proliferating. More refined analyses, adjusting for hormonal receptor subtypes and studies focusing on certain chemical exposures are required to further our understanding of the role of chemicals in the development of breast cancer.

Associations between personal exposure to air pollutants and lung function tests and cardiovascular indices among children with asthma living near an industrial complex and petroleum refineries

OBJECTIVE The acute cardiorespiratory effects of air quality among children living in areas with considerable heavy industry have not been well investigated. We conducted a panel study of children with asthma living in proximity to an industrial complex housing two refineries in Montreal, Quebec, in order to assess associations between their personal daily exposure to air pollutants and changes in pulmonary function and selected indicators of cardiovascular health. METHODS Seventy-two children with asthma age 7-12 years in 2009-2010 participated in this panel study for a period of 10 consecutive days. They carried a small backpack for personal monitoring of sulphur dioxide (SO2), benzene, fine particles (PM2.5), nitrogen dioxide (NO2) and polycyclic aromatic hydrocarbons (PAHs) and underwent daily spirometry and cardiovascular testing (blood pressure, pulse rate and oxygen saturation). To estimate these associations, we used mixed regression models, adjusting for within-subject serial correlation, and for the effects of a number of personal and environmental variables (e.g., medication use, ethnicity, temperature). RESULTS Children with asthma involved in the study had relatively good pulmonary function test results (mean FEV1 compared to standard values: 89.8%, mean FVC: 97.6%, mean FEF25-75: 76.3%). Median diastolic, systolic blood pressures and oxygen saturation were 60/94 mmHg and 99%, respectively. Median personal concentrations of pollutants were NO2, 5.5 ppb; benzene, 2.1 µg/m(3); PM2.5, 5.7 µg/m(3); and total PAH, 130 µg/m(3). Most personal concentrations of SO2 were below the level of detection. No consistent associations were observed between cardio-pulmonary indices and personal exposure to PM2.5, NO2 and benzene, although there was a suggestion for a small decrease in respiratory function with total concentrations of PAHs (e.g., adjusted association with FVC: -9.9 ml per interquartile range 95%CI: -23.4, 3.7). CONCLUSIONS This study suggests that at low daily average levels of exposure to industrial emissions, effects on pulmonary and cardiovascular functions in children with asthma may be difficult to detect over 10 consecutive days.

Association between alcohol consumption and postmenopausal breast cancer: results of a case-control study in Montreal, Quebec, Canada

OBJECTIVES: To determine the association between postmenopausal breast cancer and prior consumption of alcoholic beverages.METHODS: This case–control study, conducted in all Montreal hospitals between 1996 and 1997, included 556 postmenopausal women (age 50–75 years) who had a new histologically confirmed diagnosis of primary, malignant breast cancer. Control subjects (577) were selected from other histologically confirmed sites of cancer. A detailed history of alcohol consumption and other risk factors was obtained by interview. Indices reflecting alcohol consumption were developed and unconditional logistic regression was used to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI).RESULTS: Current regular drinkers of any type of alcohol were at an increased risk of breast cancer (OR = 1.5; 95% CI 1.0–2.2). For all beverages considered, current regular drinkers showed higher risks than ever regular drinkers. The risk of breast cancer was highest among women who reported exclusive drinking of wine on a weekly or daily basis (e.g. current regular drinking: OR = 2.3; 95% CI 1.2–4.3). Women who started to drink wine on or before the age of 40 were at a 2.5 times increased risk (95% CI 1.4–4.4).CONCLUSIONS: Our findings provide further support for a positive association between the risk of postmenopausal breast cancer and alcohol consumption.

A panel study in congestive heart failure to estimate the short-term effects from personal factors and environmental conditions on oxygen saturation and pulse rate

Objectives: Recent studies suggest that persons with congestive heart failure (CHF) may be at higher risk for short-term effects of air pollution. This daily diary panel study in Montreal, Quebec, was carried out to determine whether oxygen saturation and pulse rate were associated with selected personal factors, weather conditions and air pollution. Methods: Thirty-one subjects with CHF participated in this study in 2002 and 2003. Over a 2-month period, the investigators measured their oxygen saturation, pulse rate, weight and temperature each morning and recorded these and other data in a daily diary. Air pollution and weather conditions were obtained from fixed-site monitoring stations. The study made use of mixed regression models, adjusting for within-subject serial correlation and temporal trends, to determine the association between oxygen saturation and pulse rate and personal and environmental variables. Depending on the model, we accounted for the effects of a variety of personal variables (eg, body temperature, salt consumption) as well as nitrogen dioxide (NO2), ozone, maximum temperature and change in barometric pressure at 8:00 from the previous day. Results: In multivariable analyses, the study found that oxygen saturation was reduced when subjects reported that they were ill, consumed salt, or drank liquids on the previous day and had higher body temperatures on the concurrent day (only the latter was statistically significant). Relative humidity and decreased atmospheric pressure from the previous day were associated with oxygen saturation. In univariate analyses, there was negative associations with concentrations of fine particulates, ozone, and sulphur dioxide (SO2), but only SO2 was significant after adjustment for the effects of weather. For pulse rate, no associations were found for the personal variables and in univariate analyses the study found positive associations with NO2, fine particulates (aerodynamic diameter of 2.5 μm or under, PM2.5), SO2, and maximum temperature, although only the latter two were significant after adjustment for environmental effects. Conclusions: The findings from the present investigation suggest that personal and environmental conditions affect intermediate physiological parameters that may affect the health of CHF patients.

Associations Between Atmospheric Concentrations of Spores and Emergency Department Visits for Asthma Among Children Living in Montreal

ABSTRACT The authors carried out a time-series study to determine whether short-term increases in the concentrations of spores were associated with emergency department visits from asthma among children 0 to 9 years of age in Montreal, 1994–2004. Concentrations of spores were obtained from one sampling monitor. The authors used parametric Poisson models to model the association between daily admissions to emergency rooms for asthma and ambient exposures to a variety of spores, adjusting for secular trends, changes in weather, and chemical pollutants. For first admissions and exposures to Basidiomycetes, the authors found positive associations at all lags but the concurrent day. For Deuteromycetes and Cladosporium, risks were positive starting at lag 3 days and diminished at lag 6 days. There was little evidence of associations for readmissions, except for Basidiomycetes. The results indicate that Basidiomycetes and Cladosporium spores may be implicated in the exacerbation of asthma among children, most notably in the case of first-time visits to emergency departments, and that the effects appear to be delayed by several days.

Shortness of breath at night and health status in congestive heart failure: Effects of environmental conditions and health-related and dietary factors ☆

OBJECTIVES Recent studies suggest that persons with congestive heart failure (CHF) may be at higher risk for the short-term effects of air pollution. We carried out this daily diary panel study in Montreal, Quebec, to determine whether indicators of self-reported health status and shortness of breath at night were associated with selected health-related and dietary factors, weather conditions, and air pollution. METHODS Thirty-one subjects with CHF participated in this study in 2002 and 2003. Over a 2-month period, they measured their oxygen saturation, pulse rate, weight, and temperature each morning and recorded these and other data in a daily diary. Every morning they recorded on visual analogue scales their assessments of their general health, shortness of breath, and weakness, their weight, temperature and other data in a daily diary. Air pollution and weather conditions were obtained from fixed-site monitoring stations. This paper deals only with the daily self-reported health outcomes of general health and shortness of breath. We made use of mixed regression models, adjusting for within-subject serial correlation and temporal trends, to determine the association between oxygen saturation and pulse rate and health-related, dietary and environmental variables. Depending on the model, we accounted for the effects of a variety of health-related and dietary variables as well as NO(2), ozone, maximum temperature and change in barometric pressure at 8:00AM from the previous day. RESULTS Of the many associations for self-reported general health and shortness of breath, we found only a few statistically significant predictors, although increases in many variables showed decrements in self-reported general health and shortness of breath. The statistically significant associations with general health were increases in daily pulse rate and body weight, higher maximum ambient air temperature, higher relative humidity, and ozone (on the concurrent day). Statistically significant predictors of worsened shortness of breath at night were increases in blood pressure, body weight, and higher maximum ambient air temperature (lag 0 and 1 days). We also found that there was little confounding between environmental variables and health and dietary factors. CONCLUSIONS The findings from the present investigation suggest that certain health-related indices and environmental conditions affect self-reported health and shortness of breath in CHF patients, although larger studies are needed to confirm these findings.