Health Effects of Air Pollution PPT


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1 : Health Effects of Air Pollution Michael Lipsett, M.D. California Office of Environmental Health Hazard Assessment, Oakland, California and Department of Epidemiology & Biostatistics UCSF School of Medicine San Francisco, California
2 : Breaking News: Air Pollution and New-onset Asthma 3,535 children in 12 communities in Southern California Over a 4-year period, playing 3 or more outdoor team sports increased risk of new asthma by 1.8 (95% CI=1.2-2.8) ? Asthma risk observed in high ozone (4-yr mean = 59.6 ppb) communities (RR=3.3, 95% CI=1.9-5.8), but not low ozone (4-yr mean = 40 ppb) communities (McConnell R et al. Lancet 2002;359:386-91)
3 : Ozone and new asthma – Plausibility? Overall risk of asthma in high ozone communities was not increased Increased time spent outdoors in high ozone communities was associated with a 1.4-fold increase in risk of asthma High activity sports can increase breathing rates by up to 17 times Risk increased linearly with the number of sports played
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5 : Overview Criteria pollutant exposures ? focus on particulate matter Particulate matter deposition and retention Effects of acute exposure Chronic effects in adults and children
6 : Ultra Fine Particulate Matter Sizes and Composition
7 : PM in the Cross-hair Human Hair (60 mm diameter) Hair cross section (60 mm)
8 : Diesel Particles and Human Hair: One Perspective
9 : Particles – Does Size Matter?Or Mass? Or Number? Or What? Mass Diameter Number Surface Area (?g/m3) (?) (per ml) (? 2/ml) 10 2 1.2 24 10 0.5 153 120 10 0.02 2,400,000 3016 Adapted from Donaldson K et al. Occup Environ Med 2001;58:211-216
10 : Particle Deposition Larger particles (greater than 1 ?) tend to deposit higher in the respiratory tract Smaller particles tend to penetrate more deeply in the lung However, some of each deposit throughout the respiratory tract Chronic lung disease ? up to 3X deposition as in healthy people
11 : Particle Retention Large numbers of particles retained in airways (@107/g dry lung tissue) Increasing concentrations deeper in lung : 25 - 100X more at airway branches and in respiratory bronchioles than along mainstem bronchus Marked inter-individual variability in particle retention (several hundred-fold) (Source: Churg A, Brauer M. Ultrastruct Pathol 2000; 24:353-61)
12 : PM Ambient Air Quality Standards are Based on Epidemiological Studies Use real-world exposures and health responses Can examine different segments of the population (e.g., elderly, asthmatics, children) Use statistical associations to infer effects of air pollution
13 : PM Epidemiological Studies – Associations with Short-term Exposures Studies of PM10 and mortality conducted in over 200 cities world-wide Examine associations between daily concentrations of PM and daily death counts. Studies account for weather extremes, seasonal effects, day of week, co-pollutants, and other factors.
14 : Consistent associations between daily averages of PM10 and mortality Associations also reported between daily PM10 and many measures of illness cardiorespiratory hospitalizations emergency room visits school absenteeism asthma attacks bronchitis & other respiratory symptoms in children decreased lung function PM Epidemiology Studies – Short-term Exposure Results
15 : Low-Level Particulate Matter and Cardiovascular Effects - Are these Studies Believable? Numerous time-series studies link low-level ambient particulate matter (PM) with increased cardiac morbidity and mortality No good mechanistic explanations for this phenomenon until recently
16 : PM & Effects on the Circulatory System Pulmonary inflammation and/or particles absorbed into the blood may: Blood viscosity Blood coagulability Blood clot formation Cardiac ischemic events (First proposed by Seaton A et al. Lancet 1995; 345:176-178)
17 : PM and Plasma Viscosity In German study of cardiovascular risk factors, analysis of blood drawn during 13-day air pollution episode in 1985 showed risk of having blood viscosity >95th percentile for the whole study (Peters A, Lancet 1997;349:1582- 1587): Men -- OR = 3.62, 95% CI = 1.61-8.13 Women -- OR = 2.26, 95% CI = 0.97-5.26 Plasma viscosity is associated with increased severity of cardiovascular disease.
18 : PM and Myocardial Infarction Boston study of 772 patients interviewed about onset of myocardial infarction symptoms PM10 and PM2.5 measured 2 and 24 hours before symptom onset both showed elevated odds ratios Source Peters A et al. Circulation 2001:103 Odds ratio Exposure quintile
19 : PM and Heart Rate Variability 3 studies in Utah (n=7) , Boston (n =21) , and Baltimore (n=26) Results not entirely consistent, but all found at least one measure of HRV decreased in relation to PM10 or PM2.5 Of note, changes in HRV occurred within hours of exposure (Pope CA et al., Am Heart J 1999;138: 890-899; Gold DR, et al. Circulation 2000;101: 1267-1273; Liao, D et al. Environ Health Perspect 1999;107: 521-525)
20 : PM and Cardiac Arrhythmias Among 100 patients with implantable cardioverter defibrillators, risks of >10 events (1995-1997), for 5th-95th percentile change: Pollutant metric OR (95% CI) PM10 (lag 2) 1.68 (0.98-2.86) PM2.5 (lag 2) 1.64 (1.03-2.62) Black carbon (5-day avg) 2.16 (0.96-4.86) CO (5-day avg) 1.94 (1.01-3.75) NO2 (5-day avg) 2.13 (1.76-5.56) (Peters A et al. Epidemiology 2000;11:11-17) Associations with black carbon, CO, and NO2 suggest link with traffic generally, not just PM
21 : PM Epidemiology Studies – Long-term Exposures Several studies report associations between mortality and long-term exposure to PM10 and/or PM2.5. Analysis accounts for relevant individual-level factors (e.g., smoking, weight, alcohol, occupational exposure, gender, age, and others).
22 : PM Epidemiology Studies – Long-term Exposure Results Harvard 6-cities study - RR (cardiorespiratory mortality) = 1.37 (95%CI=1.11-1.68) American Cancer Society study - RR (cardiorespiratory) = 1.31 (95%CI=1.17-1.46) Chronic exposure to air pollution corresponding a difference of 24 ?g/m3 (PM2.5), might decrease average life expectancy by about 1.5 years.
23 : Adjusted Mortality Rate Ratios in Six Cities Study (Dockery DW et al., N Engl J Med 1993;329:1753-1759)
24 : HEI Re-analysis of Cohort Mortality Studies Many sensitivity analyses confirmed basic results Effects seen mainly in less educated: tend to be nonsignificant for those with > high school education
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26 : Children’s Health Study Largest recent prospective study of air pollution’s chronic effects in children 3,676 schoolchildren in 12 communities followed for up to 10 years Avg PM10 (1994) = 34.8 ?g/m3 (13 Lompoc – 71 Mira Loma)
27 : Children’s Health Study: Results At study inception, no relation of PM10 or PM2.5 with respiratory illness (current asthma, bronchitis, cough or wheeze) 40% greater risk of bronchitis in asthmatics per 19 ?g/m3 change in PM10, but high correlation with other pollutants (McConnell R et al. Environ Health Perspect 1999;107:757-60) Over a 4-year period, PM10, PM2.5, coarse particles, acid vapors, and NO2 were associated with ? lung growth, more pronounced with more time outdoors (Gauderman WJ et al. Am J Respir Crit Care Med 2000;162;1383-90)
28 : Some unresolved issues in PM epidemiology Which subfraction(s) [size/composition] most important in health effects? Do early-life exposures have a life-long impact? How do educational differences affect susceptibility to mortality? Common underlying mechanisms for acute health impacts? Are there thresholds for any of the observed effects?
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31 : Ambient Particles and Mortality in the Coachella Valley Desert area @ 60 miles east of L.A., where most PM10 variability (>90%) is due to the coarse fraction Time-series of daily mortality (8/89-10/92) found a relationship with PM10 similar to urban areas -- ??4.6% increase in daily mortality/50 ?g/m3 PM10, with 7.3% increase in cardiovascular mortality.
32 : Mortality Time-Series Studies Method to test hypothesis about an association between dose (exposure) and response Attempts to explain variation in some health endpoint due to variation in some pollution exposure, controlling for other factors that may also influence endpoint Daily mortality = f(air pollution, age, weather, DOW, season) Concern for confounders: A factor that is related to both air pollution and health
33 : PM and fibrinogen In a large cross-sectional U.S. study, OR = 1.77 (95% CI = 1.26-2.49) for having fibrinogen > 95th percentile for PM10 (IQR) of 26 ?g/m3 (Schwartz J. Environ Health Perspect 2001;109(suppl 3):405-409.). In a 12-month cohort study (n=112) in the U.K., suggested possibly fibrinogen in relation to PM10 (Seaton A et al. Thorax 1999; 54: 1027-1032) Increased blood fibrinogen levels also reported in a human controlled exposure study and in one very high-dose animal study using ROFA particles (Ghio et al. AJRCC 2000;981-988; Gardner SY et al. Toxicol Sci 2000;56:175-180)
34 : PM and C-reactive protein German MONICA study found increased odds of high CRP levels associated with TSP (Peters A et al. Eur. Heart J 2001;22:1198-1204) Odds ratio TSP Metric 12-month U.K. cohort study also found CRP in relation to ambient PM10 (Seaton A et al. Thorax 1999; 54: 1027-1032)
35 : Harvard 6-cities study 8111 adults followed for 14-16 yr Used annual average of PM in each city Results adjusted for age, sex, smoking, occupational exposure to dust, gases or fumes, education, BMI RR (all cause) = 1.26 (95%CI=1.08-1.47) RR (cardiorespiratory) = 1.37 (95%CI=1.11-1.68) RR (lung cancer) = 1.37 (95% CI=0.81-2.31)
36 : ACS II Cohort Study 550,000 people from 151 cities followed for 7 years starting in 1982 Controlled for age, sex, occupational exposure, obesity, alcohol and cigarette use, socioeconomic status RR (all cause) = 1.17 (95%CI=1.09-1.26) RR (cardiorespiratory) = 1.31 (95%CI=1.17-1.46) RR (lung cancer) = 1.03 (95% CI=0.80-1.33) RRSO4 (lung cancer) = 1.36 (95% CI=1.11-1.66)

 

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(Source: Churg A, Brauer M. Ultrastruct Pathol 2000; 24:353-61). PM Ambient Air Quality Standards    more
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