Air Pollution and Infant Mortality in Mexico City

Abstract

In a cohort of 4,563 nuclear workers followed retrospectively from 1950 to 1994, we found that age at exposure modified the effects of external radiation dose on cancer mortality. Analyses involved application of conditional logistic regression to risk sets of age- and calendar time-matched cancer deaths, with covariates treated as time dependent and with cumulative radiation doses divided according to the age intervals in which exposure occurred. After adjustment for confounding factors, we found that workers exposed to external radiation after the age of 50 years experienced exposure-related elevations in mortality from cancer at any site [rate ratio (RR) = 1.98; 95% confidence interval (CI) = 0.63-6.26], radiosensitive solid cancer (RR = 3.29; 95% CI = 1.10-9.89), and lung cancer (RR = 3.89; 95% CI = 1.23-12.3) substantially greater (1.6- to 3.5-fold greater) than were seen in coworkers exposed at all earlier ages. In contrast, all of the radiation doses contributing to mortality from cancers of the blood and lymph system were received before age 50 (for age <50, RR = 2.73 and 95% CI = 1.46-5.10; for age > or =50, RR = 0.24 and 95% CI = 0.00-687). Our results for cancer of any site are consistent with the results of previous studies examining the effects of exposure age in nuclear workers. Thus, effects of low-level radiation doses may depend on exposure age, and furthermore, patterns of effect modification by age may differ by type of cancer.

Estimating particle exposure in the Mexico City metropolitan area

“…The HI collects particles on a 41 -mm Teflon filter at a flow rate of 4 l/min, and weighed in a manner similar to the Hi -Vol filter. A more detailed description of the Pedregal dataset is given elsewhere (Loomis et al, 1999 ). For the TEOM data, 24-h averages were constructed from days on which 75% or more of the hourly observations were available; otherwise, the days were counted as missing.…”

Relationship between indoor, outdoor, and personal fine particle concentrations for individuals with COPD and predictors of indoor-outdoor ratio in Mexico city

“…A significant number of studies have found positive associations between increased daily morbidity and mortality and suspended particles in air pollution (Loomis et al, 1996(Loomis et al, , 1999Borja-Aburto et al, 1997Laden et al, 2000;Lippman et al, 2000;Sunyer et al, 2000;Sarnat et al, 2001;Vajanapoom et al, 2002). Increased rates of asthma exacerbation, respiratory symptoms, reduced lung function, increased hospitalization rates, and greater use of medications have also been found (Tellez-Rojo et al, 1997;Ilabaca et al, 1999;Romieu et al, 1999Romieu et al, , 2002Panella et al, 2000;Utell and Frampton, 2000;Anderson et al, 2001).…”

Estudios ecológicos

“…29 Loomis y colaboradores evaluaron también esta asociación en un estudio de series de tiempo en la ciudad de México, con resultados que apoyan las asociaciones iniciales del estudio de comparación de grupos múltiples. 9 Uno de los problemas de estos estudios ecológi-cos es la medición de la exposición a los contaminantes. Por un lado, estas series de tiempo se basan en mediciones de la calidad del aire hechas con monitores fijos, que no necesariamente reflejan las variaciones individuales en la exposición, derivadas del tipo de vivienda, tiempo dedicado a actividades extramuros o intensidad de las actividades y, por otro lado, la medición de las partículas suspendidas se basa en su peso más que en los componentes químicos de las mismas.…”