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Biomedical subjects

M Jerrett

Publications and source records attributed to M Jerrett.

11 recordsLinked to original sources
PubMed2006

The health relevance of ambient particulate matter characteristics: coherence of toxicological and epidemiological inferences.

The aim of this article is to review progress toward integration of toxicological and epidemiological research results concerning the role of specific physicochemical properties, and associated sources, in the adverse impact of ambient particulate matter (PM) on public health. Contemporary knowledge about atmospheric aerosols indicates their complex and variable nature. This knowledge has influenced toxicological assessments, pointing to several possible properties of concern, including particle size and specific inorganic and organic chemical constituents. However, results from controlled exposure laboratory studies are difficult to relate to actual community health results because of ambiguities in simulated PM mixtures, inconsistent concentration measurements, and the wide range of different biological endpoints. The use of concentrated ambient particulates (CAPs) coupled with factor analysis has provided an improved understanding of biological effects from more realistic laboratory-based exposure studies. Epidemiological studies have provided information concerning sources of potentially toxic particles or components, adding insight into the significance of exposure to secondary particles, such as sulfate, compared with primary emissions, such as elemental and organic carbon from transportation sources. Recent epidemiological approaches incorporate experimental designs that take advantage of broadened speciation monitoring, multiple monitoring stations, source proximity designs, and emission intervention. However, there continue to be major gaps in knowledge about the relative toxicity of particles from various sources, and the relationship between toxicity and particle physicochemical properties. Advancing knowledge could be facilitated with cooperative toxicological and epidemiological study designs, with the support of findings from atmospheric chemistry.

Carbon↗
PubMed2004

Linking perceptions of neighbourhood to health in Hamilton, Canada.

STUDY OBJECTIVE: To investigate the association between perceptions of neighbourhood physical and social characteristics and three health outcomes (self assessed health status, chronic conditions, and emotional distress). DESIGN: Cross sectional survey data analysed in small neighbourhoods. SETTING: Hamilton, Ontario, Canada, a medium sized industrial city, located at the western end of Lake Ontario (population at the time of the study about 380 000). PARTICIPANTS: Random sample of 1504 adults aged 18 years and older residing in four contrasting neighbourhoods. MAIN RESULTS: Significant differences across the four neighbourhoods are apparent in self assessed health status and emotional distress, but not in chronic conditions. Neighbourhoods with lower SES reported poorer health and more emotional distress. Perceptions of the physical environment dominated social concerns in all neighbourhoods. For all three health outcomes, individual risk factors followed expectations, with measures of poverty, age, and lifestyle all significantly associated with poor health outcomes. Physical environmental problems were positively and significantly associated with poor physical and emotional health. Specifically, people reporting they dislike aspects of their neighbourhood's physical environment are 1.5 times more likely to report chronic health conditions (OR 1.56, 95% CI 1.19 to 2.05), while those reporting physical likes with their neighbourhood are less likely to report fair/poor health (OR 0.50, 95% CI 0.28 to 0.90) or emotional distress (OR 0.45, 95% CI 0.26 to 0.80). CONCLUSIONS: These results demonstrate the importance of neighbourhood perceptions as a determinant of health, as well as conventional factors such as low income, lifestyle, and age. The dominance of physical environmental concerns may have arisen from the industrial nature of Hamilton, but this result merits further investigation.

Adolescent↗
PubMed2004

Do socioeconomic characteristics modify the short term association between air pollution and mortality? Evidence from a zonal time series in Hamilton, Canada.

STUDY OBJECTIVE: To assess the short term association between air pollution and mortality in different zones of an industrial city. An intra-urban study design is used to test the hypothesis that socioeconomic characteristics modify the acute health effects of ambient air pollution exposure. DESIGN: The City of Hamilton, Canada, was divided into five zones based on proximity to fixed site air pollution monitors. Within each zone, daily counts of non-trauma mortality and air pollution estimates were combined. Generalised linear models (GLMs) were used to test mortality associations with sulphur dioxide (SO(2)) and with particulate air pollution measured by the coefficient of haze (CoH). MAIN RESULTS: Increased mortality was associated with air pollution exposure in a citywide model and in intra-urban zones with lower socioeconomic characteristics. Low educational attainment and high manufacturing employment in the zones significantly and positively modified the acute mortality effects of air pollution exposure. DISCUSSION: Three possible explanations are proposed for the observed effect modification by education and manufacturing: (1) those in manufacturing receive higher workplace exposures that combine with ambient exposures to produce larger health effects; (2) persons with lower education are less mobile and experience less exposure measurement error, which reduces bias toward the null; or (3) manufacturing and education proxy for many social variables representing material deprivation, and poor material conditions increase susceptibility to health risks from air pollution.

Adult↗
PubMed2003

Environmental influences on healthcare expenditures: an exploratory analysis from Ontario, Canada.

STUDY OBJECTIVE: This paper explores the relation between healthcare expenditures (HCEs) and environmental variables in Ontario, Canada. DESIGN: The authors used a sequential two stage regression model to control for variables that may influence HCEs and for the possibility of endogenous relations. The analysis relies on cross sectional ecological data from the 49 counties of Ontario. MAIN RESULTS: The results show that, after control for other variables that may influence health expenditures, both total toxic pollution output and per capita municipal environmental expenditures have significant associations with health expenditures. Counties with higher pollution output tend to have higher per capita HCEs, while those that spend more on defending environmental quality have lower expenditures on health care. CONCLUSIONS: The implications of our findings are twofold. Firstly, sound investments in public health and environmental protection have external benefits in the form of reduced HCEs. Combined with the other benefits such as recreational values, investments in environmental protection probably yield net social benefits. Secondly, health policy that excludes consideration of environmental quality may eventually result in increased expenditures. These results suggest a need to broaden the cost containment debate to ensure environmental determinants of health receive attention as potential complements to conventional cost control policies.

Air Pollution↗
PubMed2001

The spatial association between community air pollution and mortality: a new method of analyzing correlated geographic cohort data.

We present a new statistical model for linking spatial variation in ambient air pollution to mortality. The model incorporates risk factors measured at the individual level, such as smoking, and at the spatial level, such as air pollution. We demonstrate that the spatial autocorrelation in community mortality rates, an indication of not fully characterizing potentially confounding risk factors to the air pollution-mortality association, can be accounted for through the inclusion of location in the model assessing the effects of air pollution on mortality. Our methods are illustrated with an analysis of the American Cancer Society cohort to determine whether all cause mortality is associated with concentrations of sulfate particles. The relative risk associated with a 4.2 microg/m(3) interquartile range of sulfate distribution for all causes of death was 1.051 (95% confidence interval 1.036-1.066) based on the Cox proportional hazards survival model, assuming subjects were statistically independent. Inclusion of community-based random effects yielded a relative risk of 1.055 (1.033, 1.077), which represented a doubling in the residual variance compared to that estimated by the Cox model. Residuals from the random-effects model displayed strong evidence of spatial autocorrelation (p = 0.0052). Further inclusion of a location surface reduced the sulfate relative risk and the evidence for autocorrelation as the complexity of the location surface increased, with a range in relative risks of 1.055-1.035. We conclude that these data display both extravariation and spatial autocorrelation, characteristics not captured by the Cox survival model. Failure to account for extravariation and spatial autocorrelation can lead to an understatement of the uncertainty of the air pollution association with mortality.

Adolescent↗
PubMed2001

Testing relationships among determinants of health, health policy, and self-assessed health status in Quebec.

By removing financial barriers, the Canada Health Act (1984) equalized access to health care services in Canada. Yet class, educational, and geographical disparities in individual and population health status persist. Recent health reform policies in Quebec assert that health and well-being are a function of income, educational level, housing conditions, employment, and other socioeconomic factors. They suggest that health policy should encompass social policies that influence individual and community socioeconomic factors which in turn affect health. Against the backdrop of these reforms, this study tests the importance of socioeconomic factors as a determinant of health--while controlling for other known determinants through a logistic regression model--with data from the Santé Quebec health surveys 1987 and 1992-93. The results confirm the importance of economic security as a determinant of individual health. This effect appears to operate through an individual income variable and through the community-level variable of regional unemployment. The importance of the income effect declined between 1987 and 1992-93. This may indicate that an increased focus on the socioeconomic determinants of health has reduced inequalities in health. It may also mean that health inequalities appear inevitable until health care policy merges completely with broader health and social policies. But such integration may well conflict with economic (and political) imperatives of the post-Fordist capitalist system.

Adolescent↗
PubMed2000

Heterogeneity in the determinants of health and illness: the example of socioeconomic status and smoking.

Systematic variations in health and illness among social groups have persisted and, in some cases increased, in many countries in spite of improvements in the availability of, and access to, health care services. Health policy makers have responded by showing increasing interest in non-clinical determinants of health as a way of explaining the observed systematic variations in health and illness. Yet health care and non-health care "factors" are often seen as competing for society's scarce resources in the production of health. The purpose of this paper is to augment this traditional approach to understanding the determinants of health in populations by exploring heterogeneity in the smoking-health relationship between social groups. Logistic regression analyses were performed using data from the 1992-93 Santé Quebéc survey, a weighted random sample of the non-institutionalized population of the province of Québec, Canada (N = 23,564). The findings suggest that the likelihood of reporting health as poor or fair was greater for smokers than non-smokers. However, the difference between smokers and non-smokers was significantly greater among groups of the population with low incomes and without employment, but significantly less among sub-groups with lower levels of education. These findings suggest that the identification, evaluation and implementation of health care programmes need to pay greater attention to the interface between social, behavioural and clinical determinants of health.

Adult↗
PubMed1998

Socioeconomic and environmental covariates of premature mortality in Ontario.

This paper contributes to debates on the broad determinants of health and on the policy shift from curative to preventive and protective interventions. It addresses empirically the relative importance of influences on health with a multiple regression analysis of ecologic data from the 49 counties of Ontario. One model achieved high predictive power (that is, Adj R2 > 75%, p < 0.0001). Educational levels were a strong predictor of population health, showing a consistent inverse relationship with premature mortality ratios for both sexes and it was the strongest predictor for females. A low income variable supplied the strongest prediction for male mortality. This variable displayed a positive association with male mortality. Municipal expenditures on environmental protection exerted a negative effect on male mortality. These findings raise questions about the current directions of health policy in Ontario where the provincial government has reduced funding to social and environmental programs, while promising to maintain health care funding.

Adolescent↗
PubMed1986

Children's pain vocabulary.

This paper will address children's pain vocabulary, that is, the self-reported words provided by the children, in a descriptive study carried out to examine how a group of school-age children view their pain. This was an initial step to demonstrate that children can describe pain and do possess a pain vocabulary. Our aim was to determine the feasibility of achieving a meaningful grouping of children's pain words and the pain intensity implied by the words. A sample of 40 school-age children were the subjects for this study. All the pain word descriptors used by the children in response to the question 'Can you think of words to describe what pain feels like?' were categorized on the basis of the Melzack classification.

Child↗