Brian Malig

State of California, California City, California, United States

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Publications (16)68.87 Total impact

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    ABSTRACT: Several cohort studies report associations between chronic exposure to ambient fine particles (PM2.5) and cardiovascular mortality. Uncertainty exists about biological mechanisms responsible for this observation, but systemic inflammation has been postulated. In addition, the subgroups susceptible to inflammation have not been fully elucidated. We investigated whether certain subgroups are susceptible to the effects of long-term exposure to PM2.5 on C-reactive protein (CRP), a marker of inflammation directly linked to subsequent cardiovascular disease. We used data from the SWAN cohort of 1923 mid-life women with up to five annual repeated measures of CRP. Linear mixed and GEE models accounting for repeated measurements within an individual were used to estimate the effects of prior-year PM2.5 exposure on CRP. We examined CRP as a continuous and as binary outcome for CRP greater than 3mg/l, a level of clinical significance. We found strong associations between PM2.5 and CRP among several subgroups. For example a 10µg/m(3) increase in annual PM2.5 more than doubled the risk of CRP greater than 3mg/l in older diabetics, smokers and the unmarried. Larger effects were also observed among those with low income, high blood pressure, or who were using hormone therapy, with indications of a protective effects for those using statins or consuming moderate amounts of alcohol. In this study, we observed significant associations between long-term exposure to PM2.5 and CRP in several susceptible subgroups. This suggests a plausible pathway by which exposure to particulate matter may be associated with increased risk of cardiovascular disease.
    Environmental Research 04/2014; 132C:168-175. · 3.24 Impact Factor
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    ABSTRACT: Background Several cohort studies report associations between chronic exposure to ambient fine particles (PM2.5) and cardiovascular mortality. Uncertainty exists about biological mechanisms responsible for this observation, but systemic inflammation has been postulated. In addition, the subgroups susceptible to inflammation have not been fully elucidated. Methods We investigated whether certain subgroups are susceptible to the effects of long-term exposure to PM2.5 on C-reactive protein (CRP), a marker of inflammation directly linked to subsequent cardiovascular disease. We used data from the SWAN cohort of 1923 mid-life women with up to five annual repeated measures of CRP. Linear mixed and GEE models accounting for repeated measurements within an individual were used to estimate the effects of prior-year PM2.5 exposure on CRP. We examined CRP as a continuous and as binary outcome for CRP greater than 3 mg/l, a level of clinical significance. Results We found strong associations between PM2.5 and CRP among several subgroups. For example a 10 µg/m3 increase in annual PM2.5 more than doubled the risk of CRP greater than 3 mg/l in older diabetics, smokers and the unmarried. Larger effects were also observed among those with low income, high blood pressure, or who were using hormone therapy, with indications of a protective effects for those using statins or consuming moderate amounts of alcohol. Conclusions In this study, we observed significant associations between long-term exposure to PM2.5 and CRP in several susceptible subgroups. This suggests a plausible pathway by which exposure to particulate matter may be associated with increased risk of cardiovascular disease.
    Environmental Research. 01/2014; 132:168–175.
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    ABSTRACT: Relationships between prenatal exposure to fine particles (PM2.5) and birth weight have been observed previously. Few studies have investigated specific constituents of PM2.5, which may identify sources and major contributors of risk. We examined the effects of trimester and full gestational prenatal exposures to PM2.5 mass and 23 PM2.5 constituents on birth weight among 646,296 term births in California between 2000 and 2006. We used linear and logistic regression models to assess associations between exposures and birth weight and risk of low birth weight (LBW; <2500g), respectively. Models were adjusted for individual demographic characteristics, apparent temperature, month and year of birth, region, and socioeconomic indicators. Higher full gestational exposures to PM2.5 mass and several PM2.5 constituents were significantly associated with reductions in term birth weight. The largest reductions in birth weight were associated with exposure to vanadium, sulfur, sulfate, iron, elemental carbon, titanium, manganese, bromine, ammonium, zinc, and copper. Several of these PM2.5 constituents were associated with increased risk of term LBW. Reductions in birth weight were generally larger among younger mothers and varied by race/ethnicity. Exposure to specific constituents of PM2.5, especially traffic-related particles, sulfur constituents, and metals, were associated with decreased birth weight in California.
    Environmental Research 12/2013; · 3.24 Impact Factor
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    ABSTRACT: Although respiratory disease has been strongly connected to fine particulate air pollution (particulate matter <2.5 μm in diameter (PM2.5)), evidence has been mixed regarding the effects of coarse particles (particulate matter from 2.5 to 10 μm in diameter), possibly because of the greater spatial heterogeneity of coarse particles. In this study, we evaluated the relationship between coarse particles and respiratory emergency department visits, including common subdiagnoses, from 2005 to 2008 in 35 California counties. A time-stratified case-crossover design was used to help control for time-invariant confounders and seasonal influences, and the study population was limited to those residing within 20 km of pollution monitors to mitigate the influence of spatial heterogeneity. Significant associations between respiratory emergency department visits and coarse particle levels were observed. Asthma visits showed associations (for 2-day lag, excess risk per 10 μg/m(3) = 3.3%, 95% confidence interval: 2.0, 4.6) that were robust to adjustment by other common air pollutants (particles <2.5 μm in diameter, ozone, nitrogen dioxide, carbon monoxide, and sulfur dioxide). Pneumonia and acute respiratory infection visits were not associated, although some suggestion of a relationship with chronic obstructive pulmonary disease visits was present. Our results indicate that coarse particle exposure may trigger asthma exacerbations requiring emergency care, and reducing exposures among asthmatic persons may provide benefits.
    American journal of epidemiology 05/2013; · 5.59 Impact Factor
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    ABSTRACT: Though respiratory disease has been strongly connected to fine particulate air pollution (particles less than 2.5 microns in diameter), evidence has been mixed regarding the effects of coarse particles (particles between 2.5 and 10 microns) on respiratory health. In this study, we used air monitoring data and emergency room visit data for 2005-2008 to evaluate the relationship between coarse particle levels and respiratory emergency room visits in 35 California counties. We utilized a time-stratified case-crossover design to control for seasonal influences and time-invariant confounders, and limited the study population to those residing within 20km of available coarse particle monitoring to improve exposure assessment. Controlling for daily temperature and day of week, we found significant associations between respiratory admissions and coarse particle levels 1 and 2 days prior. More specifically, asthma visits demonstrated similar but stronger associations (excess risk per 10 micrograms/m^3 = 3.3%; 95% CI: 2.0, 4.6 for 2-day lag) that were robust to further adjustment by other air pollutants. No significant associations were observed for visits for chronic obstructive pulmonary disease, pneumonia, or acute respiratory infections. Coarse particle exposure may lead to asthma exacerbation, and efforts should be made to reduce exposures in asthmatics.
    140st APHA Annual Meeting and Exposition 2012; 10/2012
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    ABSTRACT: Background: The association between temperature and mortality has been widely researched, although the association between temperature and morbidity has been less studied. We examined the association between mean daily apparent temperature and emergency room (ER) visits in California. Methods: We used a time-stratified case-crossover design, restricting our data to the warm seasons of 2005-2008 in 16 climate zones. The study population included cases residing within 10 km of meteorologie monitors. Conditional logistic regression models with apparent temperature were applied by climate zone; these models were then combined in meta-analyses to estimate overall effects. Our analyses considered the effects by disease subgroup, race/ethnic group, age group, and potential confounding by air pollutants. Results: More than 1.2 million ER visits were included. Positive associations were found for same-day apparent temperature and ischemie heart disease (% excess risk per 10°F = 1.7 [95% confidence interval = 0.2 to 3.3]), ischemie stroke (2.8 [0.9 to 4.7]), cardiac dysrhythmia (2.8 [0.9 to 4.9]), hypotension (12.7 [8.3 to 17.4]), diabetes (4.3 [2.8 to 5.9]), intestinal infection (6.1 [3.3 to 9.0]), dehydration (25.6 [21.9 to 29.4]), acute renal failure (15.9 [12.7 to 19.3]), and heat illness (393.3 [331.2 to 464.5]). Negative associations were found for aneurysm, hemorrhagic stroke, and hypertension. Most of these estimates remained relatively unchanged after adjusting for air pollutants. Risks often varied by age or racial/ethnic group. Conclusions: Increased temperatures were found to have same-day effects on ER admission for several outcomes. Age and race/ethnicity seemed to modify some of these impacts.
    Epidemiology 01/2012; 23(6):813-820. · 5.74 Impact Factor
  • Rupa Basu, Brian Malig
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    ABSTRACT: Investigators have consistently demonstrated associations between elevated temperatures and mortality worldwide. Few have recently focused on identifying vulnerable subgroups, and far fewer have determined whether at least some of the observed effect may be a manifestation of mortality displacement. We examined mean daily apparent temperature and mortality in 13 counties in California during the warm season from 1999 to 2006 to identify age and disease subgroups that are at increased risk, and to evaluate the potential effect of mortality displacement. The time-series method using the Poisson regression was applied for data analysis for single lag days of 0-20 days, and for cumulative average lag days of five and ten days. Significant associations were observed for the same-day (excess risk=4.3% per 5.6 °C increase in apparent temperature, 95% confidence interval: 3.4, 5.2) continuing up to a maximum of three days following apparent temperature exposure for non-accidental mortality. Similar risks were found for mortality from cardiovascular diseases, respiratory diseases, and among children zero to 18 years of age, and adults and the elderly 50 years and older. Since no significant negative effects were observed in the following single or cumulative days, evidence of mortality displacement was not found. Thus, the effect of temperature on mortality appears to be an event that occurs within three days following exposure, and requires immediate attention for prevention.
    Environmental Research 11/2011; 111(8):1286-92. · 3.24 Impact Factor
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    ABSTRACT: Several investigators have documented the effect of temperature on mortality, although fewer have studied its impact on morbidity. In addition, little is known about the effectiveness of mitigation strategies such as use of air conditioners (ACs). The authors investigated the association between temperature and hospital admissions in California from 1999 to 2005. They also determined whether AC ownership and usage, assessed at the zip-code level, mitigated this association. Because of the unique spatial pattern of income and climate in California, confounding of AC effects by other local factors is less likely. The authors included only persons who had a temperature monitor within 25 km of their residential zip code. Using a time-stratified case-crossover approach, the authors observed a significantly increased risk of hospitalization for multiple diseases, including cardiovascular disease, ischemic heart disease, ischemic stroke, respiratory disease, pneumonia, dehydration, heat stroke, diabetes, and acute renal failure, with a 10°F increase in same-day apparent temperature. They also found that ownership and usage of ACs significantly reduced the effects of temperature on these health outcomes, after controlling for potential confounding by family income and other socioeconomic factors. These results demonstrate important effects of temperature on public health and the potential for mitigation.
    American journal of epidemiology 11/2010; 172(9):1053-61. · 5.59 Impact Factor
  • Rupa Basu, Brian Malig
    American journal of epidemiology 10/2010; · 5.59 Impact Factor
  • Rupa Basu, Brian Malig, Bart Ostro
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    ABSTRACT: With temperatures expected to increase because of climate change, it is essential to study the health outcomes of elevated temperature in vulnerable populations, such as expectant mothers. In this study, the authors estimated the association between heat and humidity, as measured by apparent temperature, and preterm delivery. They conducted a case-crossover analysis of almost 60,000 births spanning 16 counties in California that occurred from 1999 to 2006 between May and September. The authors identified cases of preterm birth from a state registry of births, which were combined with meteorologic and air pollution monitoring data based on residential zip code. High ambient temperature was significantly associated with preterm birth for all mothers, regardless of maternal racial/ethnic group, maternal age, maternal education, or sex of the infant. Results indicated that an 8.6% increase (95% confidence interval: 6.0, 11.3) in preterm delivery was associated with a 10°F (5.6°C) increase in weekly average (lag06) apparent temperature. Greater associations were observed for younger mothers, blacks, and Asians. These associations were independent of air pollutants. Given the significant associations for apparent temperature and preterm delivery found in this study, more large-scale studies of temperature and preterm delivery are warranted.
    American journal of epidemiology 10/2010; 172(10):1108-17. · 5.59 Impact Factor
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    ABSTRACT: Studies have shown associations between air pollution or traffic exposure and adverse birth outcomes, such as low birth weight. However, very few studies have examined the effect of traffic emissions on spontaneous abortion (SAB). The goal of this study was to determine whether residential exposure to vehicular traffic was associated with SAB. Pregnant women from a prepaid health plan in California were recruited into a prospective cohort study in 1990-1991. Three measures of traffic exposure were constructed for the 4,979 participants using annual average daily traffic (AADT) counts near each residence and distance from residence to major roads. SAB was examined in relation to the traffic exposure measures using logistic regression adjusting for a number of demographic and lifestyle variables. Of the traffic measures, maximum annual average traffic within 50 m showed the strongest association with SAB, although it was not statistically significant. The adjusted odds ratio (AOR) for the top 90th percentile (AADT greater than 15,199) versus the bottom 75th percentile (AADT = 0-1,089) was 1.18 [95% confidence interval (CI), 0.87-1.60]. However, subgroup analyses showed statistically significant associations for traffic with SAB among African Americans (AOR = 3.11; 95% CI, 1.26-7.66) and nonsmokers (AOR = 1.47; 95% CI, 1.07-2.04). In this cohort, living within 50 m of a road with AADT of 15,200 or more was significantly associated with SAB among African Americans and nonsmokers. Further research is needed to confirm these results and possibly elucidate the mechanisms responsible for the findings.
    Environmental Health Perspectives 12/2009; 117(12):1939-44. · 7.26 Impact Factor
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    ABSTRACT: This study examined the association between mean daily apparent temperature and hospital admissions for several diseases in nine California counties from May to September, 1999 to 2005. We conducted a time-stratified case-crossover study limited to cases with residential zip codes located within 10 km of a temperature monitor. County-specific estimates were combined, using a random effects meta-analysis. The analyses also considered the effects of ozone and particulate matter (PM(2.5)). We found that a 10 degrees F increase in mean apparent temperature was associated with a 3.5% [95% confidence interval (CI) 1.5-5.6] increase in ischemic stroke and increases in several other disease-specific outcomes including all respiratory diseases (2.0%, 95% CI 0.7-3.2), pneumonia (3.7%, 95% CI 1.7-3.7), dehydration (10.8%, 95% CI 8.3-13.6), diabetes (3.1%, 95% CI 0.4-5.9), and acute renal failure (7.4%, 95% CI 4.0-10.9). There was little evidence that the temperature effects we found were due to confounding by either PM(2.5) or ozone. Our results indicate that increases in ambient temperature have important public health impacts on morbidity.
    International Journal of Public Health 09/2009; 55(2):113-21. · 1.99 Impact Factor
  • B J Malig, B D Ostro
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    ABSTRACT: To examine the risk of all-cause and cardiovascular mortality associated with short-term coarse particle exposure in California while addressing issues of exposure misclassification by limiting the study to those residing near a pollution monitor. Deaths in 15 California counties from 1999 to 2005 were linked to coarse particulate monitoring data. Case deaths were limited to those residing in a zip code within 20 km of a pollution monitor. We used conditional logistic regression with a case-crossover design to estimate county-specific effects of coarse particles. County estimates were then pooled using random-effects meta-analysis to create overall study estimates. Effects specific to race and educational status were also analysed. We observed an increased excess risk (ER) of both all-cause mortality (ER per 10 microg/m(3) = 0.7%, 95% CI -0.1 to 1.5) and cardiovascular mortality (ER per 10 microg/m(3) = 1.3%, 95% CI 0.1 to 2.5) from a 2-day lag in coarse particles. Greater effects were observed among Hispanics and non-high school graduates. Adjustment for fine particles and decreasing the inclusion buffer to 10 km did not substantively alter the results. Our study provides further evidence of an association between acute exposure to coarse particles and mortality, and supports the hypothesis that lower socioeconomic status groups may be more susceptible to its effects.
    Occupational and environmental medicine 08/2009; 66(12):832-9. · 3.64 Impact Factor
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    ABSTRACT: Epidemiologic studies have demonstrated an association between acute exposure to ambient fine particles and both mortality and morbidity. Less is known about the relative impacts of the specific chemical constituents of particulate matter<2.5 microm in aerodynamic diameter (PM2.5) on hospital admissions. This study was designed to estimate the risks of exposure to PM2.5 and several species on hospital admissions for respiratory diseases among children. We obtained data on daily counts of hospitalizations for children<19 and <5 years of age for total respiratory diseases and several subcategories including pneumonia, acute bronchitis, and asthma for six California counties from 2000 through 2003, as well as ambient concentrations of PM2.5 and its constituents, including elemental carbon (EC), organic carbon (OC), and nitrates (NO3). We used Poisson regression to estimate risks while controlling for important covariates. We observed associations between several components of PM2.5 and hospitalization for all of the respiratory outcomes examined. For example, for total respiratory admissions for children<19 years of age, the interquartile range for a 3-day lag of PM2.5, EC, OC, NO3, and sulfates was associated with an excess risk of 4.1% [95% confidence interval (CI), 1.8-6.4], 5.4% (95% CI, 0.8-10.3), 3.4% (95% CI, 1.1-5.7), 3.3% (95% CI, 1.1-5.5), and 3.0% (95% CI, 0.4-5.7), respectively. We also observed associations for several metals. Additional associations with several of the species, including potassium, were observed in the cool season. Components of PM2.5 were associated with hospitalization for several childhood respiratory diseases including pneumonia, bronchitis, and asthma. Because exposure to components (e.g., EC, OC, NO3, and K) and their related sources, including diesel and gasoline exhaust, wood smoke, and other combustion sources, are ubiquitous in the urban environment, it likely represents an identifiable and preventable risk factor for hospitalization for children.
    Environmental Health Perspectives 03/2009; 117(3):475-80. · 7.26 Impact Factor
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    ABSTRACT: Living near traffic has been associated with asthma and other respiratory symptoms. Most studies, however, have been conducted in areas with high background levels of ambient air pollution, making it challenging to isolate an independent effect of traffic. Additionally, most investigations have used surrogates of exposure, and few have measured traffic pollutants directly as part of the study. We conducted a cross-sectional study of current asthma and other respiratory symptoms in children (n = 1,080) living at varying distances from high-traffic roads in the San Francisco Bay Area, California, a highly urbanized region characterized by good regional air quality due to coastal breezes. We obtained health information and home environmental factors by parental questionnaire. We assessed exposure with several measures of residential proximity to traffic calculated using geographic information systems, including traffic within a given radius and distance to major roads. We also measured traffic-related pollutants (nitrogen oxides and nitrogen dioxide) for a subset of households to determine how well traffic metrics correlated with measured traffic pollutants. Using multivariate logistic regression analyses, we found associations between current asthma and residential proximity to traffic. For several traffic metrics, children whose residences were in the highest quintile of exposure had approximately twice the adjusted odds of current asthma (i.e., asthma episode in the preceeding 12 months) compared with children whose residences were within the lowest quintile. The highest risks were among those living within 75 m of a freeway/highway. Most traffic metrics correlated moderately well with actual pollutant measurements. Our findings provide evidence that even in an area with good regional air quality, proximity to traffic is associated with adverse respiratory health effects in children.
    Environmental Health Perspectives 10/2008; 116(9):1274-9. · 7.26 Impact Factor
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    ABSTRACT: Several studies have demonstrated associations between daily mortality and ambient particulate matter less than 2.5 microns in diameter (fine particles or PM2.5). Few, however, have examined the relative toxicities of PM2.5 constituents, including elemental carbon and organic carbon (EC and OC, respectively), nitrates and transition metals. There is also little information about whether associations between PM2.5 constituents and mortality are modified by socioeconomic and demographic factors. To examine associations of daily cardiovascular mortality with PM2.5 and its constituents after stratification by gender, race/ethnicity and education, using data from six California counties during 2000 to 2003. The association of daily counts of cardiovascular mortality with PM2.5 components was analysed using time-series regression analyses. Poisson models with natural splines were used to control for time-varying covariates such as season and weather. Separate models were run after stratification by gender, race/ethnicity (White, Hispanic, Black) and education (high school graduation or not). Models were run for each county and results were combined using random effects meta-analysis. Daily counts of cardiovascular mortality were associated with PM2.5 and several of its species including EC, OC, nitrates, sulphates, potassium, copper and iron. For many of these species, there were significantly higher effect estimates among those with lower educational attainment and Hispanic individuals. For example, while essentially no association was observed for individuals who graduated from high school, an interquartile change in several of the components of PM2.5 was associated with a 3-5% increase in daily mortality among non-high school graduates. There is evidence that several PM2.5 constituents may represent important contributors to cardiovascular mortality. Many of these constituents are generated by motor vehicles, especially those with diesel engines, and by residential wood combustion. In addition, factors associated with low educational attainment may increase susceptibility to PM2.5 and its components.
    Occupational and environmental medicine 05/2008; 65(11):750-6. · 3.64 Impact Factor