Mortality time-series studies

Stieb DM, Judek S, Burnett RT (2002) Meta-analysis of time-series studies of air pollution and mortality Effects of gases and particles and the influence of causes of death, age, and season. J Air Waste Manage Assoc, 52 470-484. 

Burnett RT, Goldberg MS (2003) Size fractionated particulate mass and daily mortality in 8 Canadian cities. In Health Effects Institute, special report. Revised analyses of time-series studies of air pollution and health, pp 85-89... 

Villeneuve PJ, Burnett RT, Shi Y, Krewski D, Goldberg MS, Heitzman C, Chen Y, Brook J (2003) A time-series study of air pollution, socioeconomic status, and mortality in Vancouver, Canada. J Expo Anal Environ Epidemiol 13 427-435 Violante FS, Barbieri A, Curti S, Sanguinetti G, Graziosi F, Matdoli S (2006) Urban atmospheric pollution personal exposure versus fixed monitoring station measurements. Chemosphete 64 1722-1729... 

Various health effects have been reported from short-term studies. Increased mortality associated with short-term exposure is the most important health outcome in these studies. A multiplicity of studies from various settings in the US, Canada and Europe attest the association of different metrics of particular matter (PMio, PM2.5, PMio 2.5 or ultrafine particles) with general and cause specific human mortality. In the first line are daily time series studies from single cities (e.g. Schwartz 1991). More relevant are analyses that pool data from several locations, using a common protocol for analysis of the within-city data and then combining estimates from various locations in order to gain precision and to evaluate the heterogeneity of the effect of particulate matter across the cities. 

Zeger SL, Thomas D, Dominici F et al (2000) Exposure measurement citot in time-series studies of air pollution concepts and consequences. Environ Health Perspect 108 419-426 Zeka A, Zanobetti A, Schwartz J (2005) Short term effects of particulate matter on cause specific mortality effects of lags and modification by city characteristics. Occup Environ Med 62 718-725... 

Many time-series studies have addressed the associations between daily mortality counts and pollutant levels, after taking into account weather and temporal trends in mortality. These studies have considered total mortality, exclusive of external causes, and also cause-specific mortality, with focus on cardiac and respiratory causes of death. Total mortality counts are a relatively nonspecific outcome category, because a priori considerations of pathogenesis indicate that effects of particulate air pollution would be anticipated primarily on deaths from chronic cardiac and respiratory conditions and from respiratory infections, inclnd-ing pneumonia and influenza. To date, two studies have linked air pollntion exposure with mortality on a longer time frame (4,5). These stndies are viewed as pivotal because they indicate possible longer-term effects from particnlate polln-... 

Epidemiological studies suffer from the weakness that observed associations with a specific exposure may result from an unmeasured association with an unknown or uncontrolled factor correlated with both exposure and disease that is, from a confounder. Time-series studies have the advantage that many major causes of increased mortality (such as smoking, hypertension, or even age) cannot confound the observed associations with particulate air pollution because these fac-... 

A weakness of time-series studies is that those individuals who die as a result of pollution exposure cannot be identified. The associations of mortality with particle air pollution are stronger in the elderly (21,22,37,38), and deaths are associated with chronic respiratory or cardiovascular problems (43). But it is not clear who is dying. Are they people who would have died within the next couple of days anyway Is air pollution harvesting those who were on the verge of mortality If so, the few days loss of life expectancy may not have major pubhc health significance. 

Saldiva PHN, Pope CA m, Schwartz J, Dockery DW, Lichtenfels AJ, Salge JM, Barone I, Bohm GM. Air pollution and mortality in elderly people a time series study in Sao Paulo, Brazil. Arch Environ Health 1995 50 159-163. 

Hepatic Effects. Chromium(VI) has been reported to cause severe liver effects in four of five workers exposed to chromium trioxide in the chrome plating industry. Derangement of the cells in the liver, necrosis, lymphocytic and histiocytic infiltration, and increases in Kupffer cells were reported. Abnormalities in tests for hepatic dysfunction included increases in sulfobromophthalein retention, gamma globulin, icterus, cephalin cholesterol flocculation, and thymol turbidity (Pascale et al. 1952). In a cohort of 4,227 workers involved in production of stainless steel from 1968 to 1984, excess deaths were observed from cirrhosis of the liver compared to expected deaths (0/E=55/31.6) based on national rates and matched for age, sex, and calender time having an SMR of 174 with confidence limits of 131-226 (Moulin et al. 1993). No measurements of exposure were provided. Based on limited information, however, the production of chromium compounds does not appear to be associated with liver effects. As part of a mortality and morbidity study of workers engaged in the manufacture of chromium(VI) compounds (84%) and chromium(III) compounds (16%) derived from chromium(VI) in Japan, 94 workers who had been exposed for 1-28 years were given a complete series of liver function... 

The APHEA (Air Pollution and Health—An European Approach) project studied air-pollution effects in 15 and later with the APHEA 2 project in 34 European cities (Katsouyanni et al. 1995, 1997, 2001). The NMMAPS (National Morbidity, Mortality, and Air Pollution Study) project in the United States focused on time-series analyses of PMio effects on mortality during 1987-1994 in the 90 largest US cities (Samet et al. 2000a, b, c), and in the 20 largest US cities in more detail (Dominici et al. 2000a, b). These data have been summarized in the US-EPA s particulate matter criteria document (US-EPA 2004) and in a met analysis carried out by a WHO-Europe task group (Anderson et al. 2004). 

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