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25/09/2016

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Environmental Burden of Disease:

What do we really need to worry

about?

Ray Copes, MD

Chief, Environmental and Occupational Health, Public

Health Ontario

Associate Professor, University of Toronto

PublicHealthOntario.ca

Disclosure

• No conflicts to declare

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Learning objectives

• Describe the methods and findings of previous burden of

illness studies.

• Discuss uses of environmental burden of illness estimates.

• Apply burden of disease concepts to workplace populations to

help guide effective preventive efforts

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What is our ‘environment’?

• Macro, micro

• For a individual, workplace, patients in a medical practice,

population (provincial, national, global)

• Physical environment is one of many factors influencing health

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Why worry?

• Because we like to worry?

• Because we want to take action?

• But if we want to take action, informed action is likely to lead

to better results than uninformed action

• Good intentions are far more common than good outcomes

• How can we better understand the problem

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Risk Assessment

• A systematic process for describing and

quantifying the risk associated with hazardous

substances, processes, action, or events from Covello and

Merkhofer Risk Assessment Methods: Approaches for Assessing Health and Environmental Risks

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Risk Assessment

• Often described as 4 step process

• Scoping or problem formulation often receives little attention

• This has important implications for the final step of Risk

Characterization

• Although risk assessment are most frequently used in standard

setting and compliance; they are probably better suited to

comparing (or ranking) risks as a guide to setting priorities

• Can this be useful tool for setting priorities globally, nationally,

for workplaces, practices, individuals?

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Global burden of disease

1990 (WHO/World Bank Global Burden of Disease)

• Address lack of data on the contribution of disease, injuries

and risk factors to public health

• 10 risk factors (including air pollution), 107 diseases

• Concerns about comparability of burden estimates

• Reliability of measures of effect and exposure estimates from

epidemiologic studies used

• Varying definitions of risk factors between studies

• Limited data (exposures, outcomes, exposure-outcome relationships)

• Expert opinion-based weights for disability

• Lack of standardized methods for risk factor assessment

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Global burden of disease (2)

• Global Burden of Disease, WHO (2000)

• Comparative Risk Assessment module for 25 risk factors

• Burden from observed risk factor distribution compared to counterfactual

scenario

• 135 risk factors (including lead exposure, climate change, urban air

pollution and indoor smoke from solid fuels)

• Updates: 2001, 2002, 2004 (WHO)

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What is a disease burden?Mortality

Morbidity

Pathophysiologic Effects

Physiological Effects

Exposed

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Comparison of the magnitude of the ten leading diseases and injuries and the ten leading risk factors based on the percentage of global

deaths and the percentage of global DALYs, 2010The figure shows 25 total diseases, injuries, and risk factors because some of the largest

contributors to disability-adjusted life years (DALYs) were not in the top ten for deaths, and vice versa. DALYs=disability-adjusted life years.

IHD=ischaemic heart disease. LRI=lower respiratory infections. COPD=chronic obstructive pulmonary disease. HAP=household air pollution

from solid fuels. BMI=body-mass index. FPG=fasting plasma glucose. PM2.5 Amb=ambient particulate matter pollution. *Tobacco smoking,

including second-hand smoke. †Physical inacIvity and low physical acIvity.

Ten leading diseases and injuries

Source:

www.thelancet.com

Vol 380

December 15/22/29,

2012

Burden of disease attributable to 20 leading risk factors in 2010,

expressed percentage of global disability-adjusted life-years as a

percentage of global disability-adjusted life-years

Source: Lancet. Author manuscript; available in PMC 2014

September 05. NIH-PA

Both Sexes

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This is global assessment

• Helpful for WHO to set global priorities

• Not as helpful for national or local governments

• Need to apply at appropriate scale

• How would the previous Figure look if done for your work force or practice?

• Individual level tools have been developed and are available ( http://www.projectbiglife.ca/life/ )

• Can also limit burden of illness assessment to a specific set of factors (e.g. Environment or Workplace)


Why Do Environmental

Burden of Disease

Assessments?

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Human Health and the

Environment are inextricably

linked

But how?

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The beginning of EBD

1981 (Doll & Peto)

• One of the first attempts to quantify the relationship between

risk factors and preventable diseases

• Estimated preventable US cancer deaths from environmental

and lifestyle factors:

• Cigarette smoking: 30% of all cancer deaths

• Diet: 35% of cancers

• Occupational exposures: 4% of cancers

• Pollution: 2%

16Doll R, Peto R. The causes of cancer: quantitative estimates of avoidable risks of

cancer in the United States today. J Natl Cancer Inst. 1981 Jun; 66 (6):1191-308.


What does the public and policy making

community see about the ‘link’?

• Wide array of standards set by multiple jurisdictions and

sectors -(e.g. air, water, food, soil) ostensibly set on the basis

of protecting human health from environmental exposures.

• Media coverage of health and environment issues – can be

informative but often coverage of what’s novel rather than

normal (the exception rather than the rule)

• Problem: ad hoc, fragmented, little context.

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Burden of disease for environmental risk factors

• Global EBD assessment, WHO (2006)

• Comparative risk assessment

• 6 risk factors:

Outdoor air pollution

Indoor air pollution from solid fuel

Lead

Water, sanitation and hygiene

Climate change

Selected occupational risk factors

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Outcomes assessedRisk factors Related diseases

Outdoor air pollution Cardiovascular mortality, respiratory mortality, mortality

from acute respiratory infections in children, lung cancer

Indoor air pollution from

solid fuel use

Lower acute respiratory infections in children, lung

cancer, chronic obstructive lung disease (COPD)

Lead Intellectual impairment, cardiovascular disease

Water, sanitation and

hygiene

Diarrhoeal diseases, trachoma, schistosomiasis,

ascariasis, trichuriasis, hookworm disease

Climate change Diarrhoeal diseases, malaria, selected unintentional

injuries (example from floods), protein-energy

malnutrition

Selected occupational

factors: injuries, noise,

carcinogens, airborne

particulates

Unintended injuries, hearing loss, cancers, asthma, COPD,

low back pain

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Canada Afghanistan

Population 32.3 mil 29.9 mil

GNI/capita 35 310 US$ NA

% urbanization 80% 49%

% people living in cities greater than 100,000

inhabitants79% 16%

Population below the poverty line (national) NA NA

Population below the poverty line

(international, <$1/day)NA NA

Under age 5 mortality rate 6/1000 live births (2006)

257/1000 live births(2006)

Life expectancy 81 years (2006) 42 years (2006)

Country profile of Environmental Burden of Disease


Canada

Afghanistan

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Environmental burden by disease category [DALYs/1000 capita], per year

Canada Afghanistan

No (2008)

NA

NA


How well are we doing?

• In many developed countries there has been progress in reducing risks and environmental burden of disease through current approach

• But……. are we directing our efforts to the largest sources of risk?

• Are our policies and practices effective? Cost-effective?

• Can we do better?

• Not without better information?

• Previous work has been done at the national or local level

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Previous studies

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Reference Region Approach Results

Cohen et

al (2005)

Global Exposure-

based

PM2.5: 3% of cardiopulmonary deaths, 5% of

trachea, bronchus and lung cancer deaths,

total 0.8 million premature deaths annually

Elliott and

Copes

(2011)

BC Exposure-

based

PM2.5: 0.2% all-cause mortality among adults

Anthropogenic PM2.5: 0.93% all-cause mortality

among adults

Lucas et al

(2008)

Global Exposure-

based

UV radiation: 1.6 million DALYs annually

Stassen et

al (2008)

Belgium Exposure-

based

Transportation noise: 20,517 DALYs in Flanders

in 2004

Boyd and

Genuis

(2008)

Canada Outcome-

based

Total environmental burden of disease:

10,000-25,000 deaths

78,000-194,000 hospitalizations

8,000-24,000 incident cancers

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A modest startEnvironmental Burden of Cancer

for Ontario

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https://www.publichealthontario.ca/en/eRepository/Environmental_Burden_of_Cancer_in_Ontario_2016.pdf


Environmental burden of disease (EBD)

• How do we define environment?

• What would be most useful for policy makers, public,

researchers?

• Information or information for action

• Attributing current outcomes to past exposures or predicting

future outcomes from today’s exposures

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Environmental Burden of Disease

• Shifts focus from ‘risk’ to ‘outcomes’

• Does it work? WHO

• Ontario experience

Local issues – expected outcomes in a neighbourhood

with soil contamination

Province wide estimate of BoD - Radon

What if we tried to estimate BoD for all (many?) environmental hazards as a guide to identifying ‘big’ versus ‘small’ contributors to adverse health outcomes?

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WHO exposure- and scenario-based methods

ExposureExposure-response

relationshipOutcomes

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Scenario-based approach

- Identify outcomes associated with risk factor

- Defined exposure scenarios for population

- Exposure-response relationship

- Calculate distribution of health impacts

Exposure-based approach


- Distribution of exposure in population

- Exposure-response relationship

- Calculate distribution of health impacts


WHO outcome-based method

ExposureExposure-response

relationshipOutcomes

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Outcome-based approach


- Distribution of outcomes in population

- Determination and definition of attributable fraction for risk factor

- Calculate attributable fraction

Environmental Burden of

Cancer in OntarioPHO Grand Rounds – August 9, 2016Ray Copes, Sue Greco – Public Health OntarioStephanie Young – Cancer Care Ontario

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a. Selected environmental carcinogens

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cancercare.on.ca/environmentreport publichealthontario.ca/environmentalcancer

Results reflect:

1. EXPOSURE

• Current (2010) levels of exposure

• Exposure across a lifetime

• Population-, not individual-, level exposures

• “No threshold” assumption

2. POTENCY

• Underlying studies to develop potency estimates

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→ 23 environmental carcinogens relevant to

Ontario population

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COMBUSTION BY�

PRODUCTS

• Fine particulate matter (PM2.5)

• Diesel engine exhaust

• Polycyclic aromatic hydrocarbons

(PAHs)

• Second-hand smoke (SHS)

• 2,3,7,8-Tetrachlorodibenzo-dioxin

(dioxin)

METALS

• Arsenic

• Cadmium

• Chromium

• Nickel

OTHER

• Acrylamide

• Asbestos

• Polychlorinated

biphenyls (PCBs)

VOLATILE ORGANIC

COMPOUNDS (VOCs)

• 1,2-Dichloropropane

• 1,3-Butadiene

• Chlorinated toluenes

• Benzene

• Dichloromethane

• Formaldehyde

• Tetrachloroethylene (PCE)

• Trichloroethylene (TCE)

• Vinyl chloride

RADIATION

• Radon

• Solar ultraviolet (UV) radiation

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b. Considered multiple routes of exposure

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c. Developed exposure estimates from a variety

of data sources

• Exposures based on carcinogen

concentrations in indoor air,

outdoor air, food, drinking water,

and dust

• Data sources ranged from

provincial monitoring campaigns

to population-based surveys and

individual studies

• Current exposure estimates

applied across a lifetime

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d. Used two models to estimate the

environmental burden of cancer

Model Risk Assessment Population Attributable

Fraction (PAF)

Estimates: Excess cases Fraction of cases

Function of: • Exposure

• Potency

• Number exposed

• Attributable fraction

(influenced by exposure

and potency/relative

risk)

• Number of cancer cases

(site specific)

Number 18 536

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Environmental burden of cancer dominated by 3

Heat map for each carcinogen and route of exposure


Reducing the Environmental Burden of Cancer

• Exposure can be reduced through legislation and public policy

• Requires coordinated efforts among complex technical,

environmental, health and social systems

• Solutions demand an integrated whole-of-government

approach and cooperation by the private sector, non-

governmental organizations and individual citizens

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Take-home messages

• There have been some past successes in reducing exposures

(e.g. second hand smoke)

• Opportunity to tackle current exposures of public health

significance

• Three carcinogens contributed to over 90% of the

environmental burden of cancer in Ontario

• UV (from sunlight)

• Radon (from indoor air)

• PM2.5 (from outdoor air)

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Take-home messages

• There have been some past successes in reducing

exposures (e.g. second hand smoke)

• Opportunity to tackle current exposures of public health

significance

• Three carcinogens contributed to over 90% of the

environmental burden of cancer in Ontario

• UV (from sunlight)

• Radon (from indoor air)

• PM2.5 (from outdoor air)

• But need to distinguish between attributable and preventable!

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Environmental burden of cancer falls between

burdens of alcohol and smoking

• Overall burden is 4,800 (range: 3,540 to 6,510) new cancer

cases each year in Ontario from exposure to these 23

carcinogens

• 6% (range: 4 to 8%) of all new cases in Ontario (2011)

• Results dominated by a few carcinogens, with burden for half

of carcinogens over 10 cancers per year

• Generally consistent with but more detailed than past

estimates

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Thank You

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