Air Pollution fromHousehold Fuel Use

Kirk R. SmithProfessor of Global Environmental Health

University of California, Berkeley

Expert Group• UC Berkeley: Kirk R. Smith,

Heather Adair• UC San Francisco: John Balmes• Stanford: Sara Stern-Nezer• Harvard: John McCracken, Joel

Schwartz• World Bank: Doug Barnes• Macro International: Vinod

Mishra• Health Effects Institute: Sumi

Mehta

• NCI: Qing Lan

• Liverpool University: Nigel Bruce, Dan Pope, Mukesh Dherani

• WHO: Eva Rehfuess• Sri Ramakrishna University:

Kalpana Balakrishnan• Peking University: Jinliang

Zhang, Xiaoli Duan• Universidad Peruana de

Ciencias Aplicadas: Claudio Lanata

• Univ Maryland: Amir Sapkota

Smith et al, CRA-2000

Toxic Pollutants in Biomass Fuel Smokefrom Simple (poor) Combustion

• Small particles, CO, NO2

• Hydrocarbons– 25+ saturated hydrocarbons such as n-hexane– 40+ unsaturated hydrocarbons such as 1,3 butadiene– 28+ mono-aromatics such as benzene & styrene– 20+ polycyclic aromatics such as benzo()pyrene

• Oxygenated organics– 20+ aldehydes including formaldehyde & acrolein– 25+ alcohols and acids such as methanol– 33+ phenols such as catechol & cresol– Many quinones such as hydroquinone – Semi-quinone-type and other radicals

• Chlorinated organics such as methylene chloride and dioxin

Source: Naeher et al,J Inhal Tox, 2007

First person in human history to have her exposuremeasured doing one of the oldest tasks in human history

Kheda District,Gujarat, India1981

Location Region Number of households

Range

(24 hour average of

PM 10 )

Mean

(24 hr average of Kitchen & Living Concentrations of PM10)

Other Determinants

Tamil Nadu South 437 110-410 223 Fuel/

Kitchen/Stove

Andhra Pradesh

South 342 115-980 485 Fuel/

Kitchen

Karnataka South 36 608-1443 898 Fuel/

Stove

Madhya Pradesh

West/Central 78 280-3300 690 Fuel/

Kitchen

Gujarat West 64 489-1530 780 Fuel/

Kitchen

Goa West 121 450-978 635 Fuel/

Kitchen

West Bengal East/North East 94 290-3870 795 Fuel/

Kitchen

Haryana North 150 443- 4590 850 Fuel/

Kitchen

Uttaranchal North/Mountain 76 270-2240 620 Fuel/

Kitchen

Three Briefings

• Progress in updating/expanding outcome assessments

• Progress in updating/upgrading exposure assessments

• Framing issues needing resolution

Evidence for Outcomes• CRA-2000: ALRI in children, COPD, lung cancer from

coal• Potential additions for CRA-2005

– Cataracts– Low birthweight– TB– Pneumonia in adults– Lung cancer from biomass– Upper aerodigestive cancers– Burns and scalds

• Special case of heart disease

CRA-2000 Outcomes

• ALRI in children – New SR/MA published (Bruce et al., Bull WHO, 2008)– Guatemala RCT analyses completed

• ITT and exposure-response analyses

• COPD– New SR/MA completed and being prepared for publication

• Lung cancer in coal– IARC review and monograph completed and in press– Formal MA underway (with biomass as well)

Study design N* OR 95% CI

Intervention 2 1.28 1.06, 1.54

Cohort 7 2.12 1.06, 4.25

Case-control 15 1.97 1.47, 2.64

Cross-sectional

3 1.49 1.21, 1.85

All 26 1.78 1.45, 2.18

*Number of estimates available

RESPIRE (Randomized Exposure Study of Pollution Indoors and Respiratory Effects)

Traditional open 3-stone fire: kitchen 48-hour PM2.5 levels of

more than 1000 μg/m3

The plancha chimney wood stove, shown to reduce 48-hour kitchen

PM2.5 by 80 - 90%

RESPIRERandomizedControl TrialGuatemala

Child Exposures

0 1 2 3 4 5 6 7

CO Exposure (ppm)

ALR

I Rat

e (p

er 1

00 C

hild

-Yr)

2030

4060

80

(A)

MD-diagnosed ALRI

RESPIRE-Guatemala

Approximate Mean PM2.5 exposure in 100s of ug/m3

SR/MA COPD• 4,027 studies identified

through Medline, Cochrane, DARE, LILAC, CINAHL and EMBASE for all studies published between 1950 and 2008

• Exclusion criteria applied in 3 rounds to those articles matching search terms

• 28 articles published in peer-reviewed journals were selected for final inclusion in the analysis (22 cross-sectional, 2 cohorts, 4 case-control)

Exclusion/Inclusion Criteria1) Population - individuals <15

years excluded, studies on non-human populations

2) Exposure not indoor air pollution

3) Outcome not defined as COPD using clinical or spirometrical definitions

4) Effect measure not risk ratio; unable to combine with other studies (9 studies met inclusion criteria in final round of selection but could not be included in analysis)

Method - SRMA COPD (con’t)

• Summary RR estimates calculated using both fixed effects and random effects models

• Heterogeneity among studies assessed using general variance-based methods

• Publication bias assessed using funnel plot, Eggers and Begg’s tests

Exposure Assessment Used for Analysis

# final studies

Fuel Type 19

Coal only 7

Wood only 6

Stove type 2

Years exposed 5

Urban vs. rural 2

Outcome Assessment Used for Analysis

# final studies

Chronic Bronchitis, clinical definition

20

COPD, FEV1/FVC<.70 4

Previous physician diagnosis

4

Forest Plot for all studies included in meta-analysis• Random effects model was used to account for

significant heterogeneity between studies; 2=150.329, df=29 (p=0.000)

• Overall effect measure for all studies 2.140 (1.777, 2.577)

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are needed to see this picture.

Subanalysis by fuel type• Studies vary significantly

based on exposure assessment and design

• Despite this variation, 19/28 studies included in final analysis showed an association between outcome and exposure that was statistically significant

• Wood smoke was more strongly associated with COPD than coal, although confidence intervals for both effect estimates overlap

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are needed to see this picture.

Coal only

1.413 (1.180, 1.692)

QuickTime™ and a decompressor

are needed to see this picture.

Wood only

2.276 (1.172, 4.419)

Conclusions - IAP & COPD• Despite variation between studies, significant

evidence exists to support an association between IAP and COPD

• Many studies compare biomass fuels to “cleaner fuels”, such as LPG and paraffin but evidence exists that these fuels themselves may be associated with disease; thus the measured effect may underestimate the relationship between IAP and COPD

• Presence or absence of ventilation is another factor which may account for heterogeneity across studies, but too few studies adjusted for ventilation to perform a subanalysis

New Outcomes

• TB: SR/MA done by others and three new case-control studies near finalized – combine?

• LBW/SB: SR/MA completed • Cataracts: SR done and new exp-resp study in

analysis• Adult pneumonia and upper aerodigestive

cancers: SR/MAs underway• Burns and scalds: not yet determined how to

include or whether they can be quantified

IAP & TB Biological Mechanism

• Smoke/particles generates inflammatory response- impairs the function of normal clearance of secretions on the tracheobronchial mucosal surface

• This may allow TB bacteria to escape the first level of host defenses, which prevent bacilli from reaching the alveoli

• Smoke also impairs the antibacterial properties of alveolar macrophages- such as ability to phagocytize bacteria and intracellular bactericidal processes

• Alveolar macrophages isolated from the lungs of smokers have reduced phagocytotic ability and secrete a lower level of pro-inflammatory cytokines

Ref: Bates et al. Arch Intern Med. 2007;167:335-342

Ex-smokers

Current smokers

Ever-smokers

21

Association between solid fuel use relative to cleaner burning fuel or electricity and risk of Tuberculosis

Authors Study type & location

Outcome Exposure tool & metric used

Sample size(cases, controls)

Adjusted Variables

RR (95%CI)

Gupta et al (1997)

Case-control, North India

Pulmonary TB Q. Type of fuel mainly used for cooking

n = 707(543 rural, 164 urban)

Age 2.54 (1.07-6.04)

Mishra et al (1999)

National Family Health Survey, India

Self -Reported TB

S. Type of fuel used mainly for cooking

n = 260,162 Sep. kitchen, house type, crowding, educ., age, gender, residence, religion, caste/tribe, geographic region

2.58 (1.98-3.37)

Padilla et al (2001)

Case-control, Mexico

Pulmonary TB Q. Types of fuel used in the past and present for cooking

n = 833(288, 545)

Age, sex, overcrowding, educ., smoking, SES, residence, state of birth

2.20(1.10-4.20)

Crampin et al (2004)

Case-control, Malawi

Pulmonary TB Q. Cooking fire exposuresNever or rare; rare and indoors, or only indoors; indoors but hot all year; always indoors

n = 1590(598, 992)

Age, sex, HIV, area 0.60 (0.30-1.10)

Shetty et al (2006)

Matched case-control, South India

Pulmonary TB Q. Cooking fuel use: biomass fuels and gas/electric

n = 378 (189, 189)

Educ., income, sep. kitchen, alcohol, smoking, person/rm, chronic disease

0.90 (0.46-1.76)

TB and Solid Fuel: Case Control Study(Results from Pokhara, Nepal)

Independent variable Odds ratio

P value 95% CI

Biomass stoveKerosene stove

2.572.73

0.0090.042

1.26-5.251.04-7.17

>8 pack-year smoker 3.43 0.021 1.20-9.79

Locality 1.60 0.213 0.76-3.36

Kero lamp in the house 7.11 0.008 1.69-29.96

Ever Alcohol 1.98 0.221 0.66-5.89

Any family TB 8.47 0.000 4.38-16.35

IAP &Cataract Mechanism

•The incomplete combustion of biomass fuels produces naphthalene. Naphthalene's intermediate, 1,2 napthaquinone, is a reactive species capable of producing reactive oxygen species (ROS)

• ROS produce superoxides (O2- ) who stimulate the production of H2O2 and OH- radicals and induce oxygen toxicity and oxidative reactions

• To reduce the damaging effect of ROS, different enzymes, vitamin E, vitamin C and NADPH are consumed

• The lack of NADPH, imbalances the ratio of protective enzymes and metabolites needed to maintain the supply of antioxidants available to protect the eye

•Some of the resulting oxidative damage within the eye includes:

Lipid damage

Protein aggregation thru cross-linking

Hyperplasia, hypertrophy and multi-layering of epithelial cells

Len discoloration & opacity

•All of the cellular damage listed above, and reduction of antioxidants for cell protection can lead to the formation of cataracts.

Nuclear Cataract

Association between solid fuel (SF)) use relative to cleaner burning fuel or electricity and risk of cataracts

Authors Study Type & Location

Exposure Metric

Sample Size(cases,

controls)

Adjusted Variables

RR (95% CI)

Mohan et al. (1989)

India-USControl Study

Main cooking fuel used?

n = 1990 (1441, 549)

Age, sex, education, yrs. of examination (D1, D2), age x D interaction,

1.61 (1.02 – 2.50)

Ughade et al. (1998)

Case-Control, India

Use of cheaper cooking fuels?

n = 524(262, 262)

Matched on age & sex 4.13 (2.64 – 6.45)APR: 76% in exposed & 37% in all cases

Zodpey et al. (1999)

Case-control, India

Main cooking fuel used?

n = 446 women (223, 223)

Socioeconom. status (SES)

2.37 (1.44 – 4.13)APR: 58% in all exposed & 29% in all cases

Pokhrel et al. (2005)

Case-control, Nepal-India

Type of stove used: clean fuel stove, SF improved stove, SF unimproved stove

Duration of stove use: (# of yrs)

n = 409 (206, 203)

Illiteracy, urban/rural residency,lighting type, use of incense, and lack of ventilation*Matched on age

1.23 (0.44-3.42)(improved SF stove)1.90 (1.00-3.16)(un-improved SF stove)

Saha et al.(2005)

Cross-sectional,India

Type of fuel used (biomass alone or in combination w/ cleaner fuels )

n = 469 Age, sex, per capita income, smoking, diabetes, hypertension & house type

Wood: 2.12 (1.03 – 4.34)Gas : 1.13 (0.78-1.65)Kerosene: 1.25 (0.90-1.73)Coal: 0.59 (0.20-1.68)Cattle Dung: 0.79 (0.45-1.16)

Biological PlausibilityRole of Carbon Monoxide (CO)

--Biomass combustion similar to tobacco smoke (COHb 2.5-13%; covering range for passive to heavy active smoking). Boy et al. 2002.--CO crosses placental barrier (haemoglobin in fetal blood has 10x more affinity for binding CO than for adults). Ritz et al. 1999.--Fetal elimination of CO slower than in the mother. Hill et al. 1977.

Animal studies:--Retarded fetal growth from cigarette smoke (inc. CO). Bosley et al. 1981.--Inhaled CO in pregnant rabbits (90ppm) reduced birth weight by 11%. Astrup et al. 1972.

Biological Plausibility

Role of particulate matter (PM)

Maternal PM exposure associated with decreased efficiency of transplacental function (restricted fetal development). Gliniania et al. 2004.

Transplacental transfer of polyaromatic hydrocarbons (PAH) of ETS from mother to fetus. Perera et al. 1999.

Increased PHA-DNA adduct levels from exposure to PAH from ambient air pollution (increase the potential for genetic fetal damage) reported in maternal and newborn white blood cells. Perera et al. 1999.

Systematic review and meta-analyses of risk of low birth weight and stillbirth associated with indoor air pollution in developing countries

Pope DP, Mishra V, Thompson L, Siddiqui AR, Rehfuess E, Weber M, Woodruff T, Bruce, NG

Inclusion criteria

Outcomes

Exposure:

(1) Low birth weight (<2500g) or mean birth weight

(2) Stillbirth or perinatal/ early neonatal deaths (first 7 days)

Direct/ indirect measurement of IAP exposure from solidfuel use

982 papers identified and screened by titles

29 papers screened by abstract

4 papers selectedfor inclusion

953 papers excluded- not relevant

22 papers excludedoutdoor pollution,

not low birth weight

1 unpublished study selected for inclusion

5 studies included in the review

7 papers reviewed 3 papers excludedoutdoor pollution,tobacco smoke,

not low birth weight

Indoor air pollution and birth weight

171 papers identified and screened by titles

12 papers screened by abstract

2 papers selectedfor inclusion

159 papers excluded- not relevant

9 papers excludedoutdoor pollution,

not stillbirth

1 unpublished study selected for inclusion

3 studies included in the review

3 papers reviewed1 papers excludedneonatal mortality

Indoor air pollution and stillbirth

Effect on low birth weight (odds ratio) of exposure to IAP from solid fuel use compared to cleaner fuels, or users of improved

chimney stoves

Details of studies for IAP and birth weight review

Study and Setting Outcome Exposure Covariates

Boy et al. 2002Cross-sectional survey.Guatemala.

Singleton home (delivery within 72 hrs) and hospital births. Salter spring scales.

Interview: cook with wood/ coal vs electricity/gas.

Parity, GA, SES, area, vitamins, maternal nutrition.

Mavalankar et al. 1992Case-control study.India.

LBW cases (<2500g) and controls (until discharge or up to 7 days) from 3 teaching hospitals.

“Exposure to cooking fire smoke” during pregnancy.

Maternal education, weight, parity, GA, blood pressure, religion…

Mishra et al. 2004Cross-sectional survey.Zimbabwe.

Representative sample. Singleton births. Birth weight from health card (53%) and maternal recall.

Interview: Main cooking fuel. High (wood/ dung/ straw). Low (electricity/ gas).

Maternal age, BMI, education, religion, region, vitamins, birth order…

Siddiqui et al. 2008Cohort study.Pakistan.

Singleton births. Infant scales used within 48 hours.

Interview: Wood vs gas for cooking.

Kitchen and house structure, literacy, income, BMI, gravidity…

Thompson et al. 2005RCT.Guatemala.

Singleton births. Infant scales used – majority (66%) within 48 hours.

Plancha (chimney stove) vs open fire.

Maternal age, SES, primiparity, >5 births, passive smoking

Covariates: GA = Gestational age

Details of studies for IAP and stillbirth review

Study and Setting Outcome Exposure Covariates

Mavalankar et al. 1991Case-control study.India.

3 teaching hospitals. Cases: stillbirths/ early neonatal deaths. Controls: surviving until discharge.

Interview: “Exposure to cooking fire smoke” during pregnancy.

Maternal education, age, weight, anaemia, antenatal factors, previous stillbirth, parity…

Mishra et al. 2005Cross-sectional survey.India.

Representative sample.“Delivery of dead baby after 28th week of pregnancy”

Interview: Main cooking fuel. High (wood/ dung/ straw). Low (electricity/ gas).

Smoking, anaemia, BMI, education, SES, religion, region, crowding…

Siddiqui et al. 2005Cohort study.Pakistan.

“Reproductive loss through stillbirth after 28th week of pregnancy”

Interview: Wood vs gas for cooking.

Location (urban vs rural).

FUNNEL PLOT – ASSESSMENTOF PUBLICATION BIASEffect on low birth weight of exposure to IAP from solid fuel use compared to cleaner fuels, or

users of improved chimney stoves (Begg’s and Eggar’s tests NS – no evidence)

0.1

.2.3

s.e

. o

f lo

go

r

.5 1 1.5 2 2.5exp(logor), log scale

Funnel plot with pseudo 95% confidence limits

Effect on mean birth weight (in gm.) of exposure to IAP from solid fuel use compared to cleaner fuels, or users of improved

chimney stoves

Effect on stillbirth (odds ratio) of exposure to IAP from solid fuel use compared to cleaner fuels

Summary of pooled effects

Outcome Estimate 95% CI

% LBW OR = 1.34 1.19, 1.56

% LBW (sensitivity analysis)1 OR = 1.37 1.21, 1.55

Mean birth weight (low minus high exposure) Mean = 85.0g 40.1, 129.9

Mean birth weight (low minus high exposure)(sensitivity analysis)2 Mean = 75.0g 28.4, 121.4

Stillbirth OR = 1.53 1.23, 1.91

1 Sensitivity analysis excludes one study based on methodological quality 2 Sensitivity analysis excludes one estimate using mother’s recall of birth weight

Environmental Tobacco Smoke and birth weight

Outcome Estimate 95% CI

% LBW(9 prospective cohort studies)

OR = 1.32 1.07, 1.63

% LBW (17 retrospective cohort studies) OR = 1.22 1.08, 1.37

Mean birth weight (low minus high exposure)(17 prospective cohort studies) Mean = 33.0g 15.7, 51.3

Mean birth weight (low minus high exposure)(27 retrospective cohort studies) Mean = 41.0g 21.1, 60.6

Source: Leonardi-Bee et al. 2008

Ambient Air Pollution and % LBW

Study Exposure Relative Risk

95% CI

Wang et al 1997Beijing, China

100µg/m3 increase in SO2

100µg/m3 increase in TSP*1.111.10

1.06, 1.161.05, 1.14

Bobak 2000Czech Republic

50µg/m3 increase in SO2

50µg/m3 increase in TSP*1.201.15

1.11, 1.301.07, 1.24

Ha et al 2001South Korea

‘increased concentration’ of SO2

‘increased concentration’ of TSP*1.061.05

1.02, 1.101.00, 1.08

* Total Suspended Particles (TSP)

Reviews in progress

Lung cancer:NCI/UoL/UoM

Systematic review and meta-analyses for risk of lung cancer associated with domestic use of coal and biomass fuel.

-Qing Lan and colleagues, at the NCI, have already been working on a review on coal use and lung cancer for the update of the IARC 100th monograph. This review will produce estimates of risk for lung cancer in China (ready for internal review) and the rest of the World. UoL/ UoM will share their protocol developed for the CRA work with the NCI team to explore opportunities for collaboration and also to help ensure a standardised systematic approach to producing risk estimates for the CRA review.

-Work on the review of biomass use and lung cancer is less advanced and NCI has agreed to collaborate with UoL/ UoM on this as per the latter’s protocol.

- A pooled analysis of studies contributing data (Europe, China, Asia) has been carried out by Qing Lan and colleagues, and is ready for submission. Five of the constituent studies (published) will contribute data points to the global review (coal).

Reviews in progress,cont.Adverse pregnancy outcomes (Low birth weight & stillbirth):UoLDraft paper ready for peer review[see later slides in this set for summary]

Systematic review and meta-analysis completed.

Relatively few studies, but consistent effects. Insufficient material to distinguish IUGR from general low birth weight.

Upper aerodigestive tract cancers :UoL/UoMDatabase searches nearing completion

Systematic review and meta-analyses for risk associated with domestic use of coal and biomass fuel.

Adult pneumonia:UoLDatabase searches nearing completion

Systematic review and meta-analyses for risk associated with domestic use of coal and biomass fuel.

Burns and scalds:UoL

The exact scope of this systematic review is being developed.

[go to Exposure Slides]