September 11, 2009 1

Environmental Epidemiology

Mark GoldbergProfessor, Dept. of Medicine (Division of Clinical

Epidemiology, RVH)McGill School of the Environment

Dept. of Epidemiology and BiostatisticsDept. of Oncology

September 11, 2009 2

The Most Important Epidemiological Study Ever

John Snow: The Cholera Epidemic in London in the Mid-

1880s

September 11, 2009 3

Geographical Analysis: London, September 23, 1848-August 25, 1849

7.24

3.70

2.44

1.61

1

Relative death rate

1.10375,971415North

7.96

4.07

2.46

1.77

Deaths/1,000

502,5484,001South

392,4441,597East

373,605920Central

300,711533West

Population in 1841

No. deaths (1848-

49)

District

September 11, 2009 4

Deaths from Cholera per 10,000 Homes, by Source of Water Supply, London, 1854

+259.9

-18.0

0

Difference

5.7315.41,26340,046Southwark & Vauxhall

0.737.59826,107Lambeth

155.51,422256,423Rest of London

RatioDeaths/10,000 homes

Deaths from cholera

Number of homes served

Company

Estimate of average no. of deaths per home ratio=8.4

September 11, 2009 5

Geographic Distribution of Cases Around the Broad Street Pump, Summer, 1854

Broad St. Pump

September 11, 2009 6

Public Health Actions

• No specific cause identified at that time, yet…– 1857: legislation mandating that all water

companies in London filter their water– Germ theory supported– Clean up the environment….?

• NB: it has only been 20 years since Montreal has had a sewage treatment facility

• Sydney, NS, still sends its untreated sewage directly to the Atlantic

• 1883: Vibrio cholerae identified

September 11, 2009 7

My Work

• Occupational and environmental risk factors for cancer

• Acute effects of air pollution on health• Chronic effects of air pollution on health• Climate change: Acute effects of

weather on health• Funding: CIHR, NIH, Health Effects

Institute, US EPA, Health Canada

September 11, 2009 8ISEE August 2009 8

ExamplePostmenopausal Breast Cancer

and Traffic-related Air Pollution

Students: Dan L. Crouse, Hong Chen,Collaborators: Nancy Ross, France

Labrèche, Rick Burnett, Michael Jerrett

September 11, 2009 9ISEE August 2009 9

Context

• Postmenopausal breast cancer case-control study, Montreal, 1996-7

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Pictures (1)

Anjou, Boul. Metropolitain Park-Extension

September 11, 2009 12ISEE August 2009 12

Land Use Regression Map Averaged over three Seasons

September 11, 2009 13ISEE August 2009 13

Back Estimation of the LUR Map for NO2

regional spat. variation (1985: NOregional spat. variation (1985: NO22))

regional spat. variation (2006: NOregional spat. variation (2006: NO22))

SmallSmall--area surface map (2006: NOarea surface map (2006: NO22))

XX

Montreal Montreal IslandIsland

÷÷÷

September 11, 2009 14ISEE August 2009 14

Results (OR per increase of 5ppb)

Year of estimate of exposure

Age adjusted OR 95%CI

Fully adjustedOR 95%CI

2006-LUR 1.15 0.89-1.48 1.31 0.96-1.79

1996-weighted by ratio of IDWs

1.10 0.91-1.32 1.24 0.98-1.56

1985-weighted by ratio of IDWs

1.05 0.91-1.22 1.14 0.95-1.37

September 11, 2009 15ISEE August 2009 15

Comparing Worst Exposed to Least Exposed Areas

Year of estimate of exposure

Fully adjustedOR 95%CI

2006-LUR 1.86 1.09-3.18

1996-weighted by ratio of IDWs

1.90 1.14-3.16

1985-weighted by ratio of IDWs

1.65 1.00-2.72

September 11, 2009 16