IP 724/ BMTRY789.05 Intro to Public Health 2/11/2015 Environmental Health Vena, John, PhD 1 Environmental Epidemiology in Developing Countries October 8, 2014 John E. Vena, Ph.D. Professor and Founding Chair Department of Public Health Sciences [email protected]1 Putting the ‘environmental’ in epidemiology? The study of health effects on populations of exposure to physical, chemical, & biologic agents external to the human body to which people are (generally) involuntarily exposed Frequently pertains to widespread risks affecting large populations 2 Porta “A Dictionary of Epidemiology, 5 th ed.” 2008; Steenland & Moe in Frumkin “Environmental Health: From Global to Local, 2 nd ed.” 2010 Unique challenges to environmental epidemiologic studies Difficulties in exposure assessment Widespread & homogeneous No ‘unexposed’ group Low levels of exposure Long latency periods Mild-moderate associations Rare endpoints Nonspecific effects Unmeasured variables & confounding 3 Bloom & Vena in Williams et al. “Principles of Toxicology, Environmental & Industrial Applications, 3 rd ed.” In press
Transcript
IP 724/ BMTRY789.05Intro to Public Health
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Environmental Epidemiology in Developing CountriesOctober 8, 2014
The study of health effects on populations of exposure to physical, chemical, & biologic agents external to the human body to which people are (generally) involuntarily exposed Frequently pertains to widespread risks
affecting large populations
2Porta “A Dictionary of Epidemiology, 5th ed.” 2008; Steenland & Moe in Frumkin “Environmental Health: From Global to Local, 2nd ed.” 2010
Unique challenges to environmental epidemiologic studies
Difficulties in exposure assessment Widespread & homogeneous No ‘unexposed’ group Low levels of exposure
Long latency periods Mild-moderate associations Rare endpoints Nonspecific effects
Unmeasured variables & confounding
3Bloom & Vena in Williams et al. “Principles of Toxicology, Environmental & Industrial Applications, 3rd ed.” In press
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Environmental epidemiology makes an important contribution to risk assessment
“Epidemiological studies…advantage is that they involve humans…weakness results from generally not having accurate exposure information & the difficulty of teasing out the effects of multiple stressors.”
“…data from human studies are unavailable, data from animal studies…are relied on to draw inference about the potential hazard to humans…but there are uncertainties associated with extrapolating…from animal…to humans.”
4http://www.epa.gov/risk/hazardous-identification.htm, accessed 9/17/2013; U.S. National Research Council (NRC) “Risk Assessment in the Federal Government: Managing the Process” 1983
Environmental epidemiology makes an important contribution to risk assessment
5http://www.epa.gov/risk/hazardous-identification.htm, accessed 9/17/2013; NRC “Risk Assessment in the Federal Government: Managing the Process” 1983
Environmental epidemiology works in conjunction with toxicology
6Bloom & Vena in Williams et al. “Principles of Toxicology, Environmental & Industrial Applications, 3rd ed.” In press
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Exposure assessment
Exposure The amount of a factor to which a group or
individual comes into contact
“…typically called the Achilles heel of environmental epidemiology”
A multifactorial & dynamic process Fate-transport processes (ex vivo)
The action of an exposure on a biologic target results from a highly complex process
8Bloom & Vena in Williams et al. “Principles of Toxicology, Environmental & Industrial Applications, 3rd ed.” In press; Sexton et al., 1992 Archives of Environmental Health 47:398-407
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Exposure to an agent is governed by the interplay of many abiotic & biotic factors
13Adapted from NRC “Environmental epidemiology. Vol. 1: Public health and hazardous wastes” 1991
Types of dataApproximation to actual exposure
Proximity to individual
1. Quantified personal Mx.'s Best Personal
2. Quantified area or ambient Mx.'s in the vicinity of the residence or other sites of activity
3. Quantified surrogates of exposure (e.g., estimates of drinking water use)
4. Distance from site & duration of residence
6. Residence or employment in geographic area in reasonableproximity to site of exposure
7. Residence or employment in defined geographic area of the site of exposure (e.g., county)
Poorest Ecologic
Various strategies are used to quantify exposure to an agent or agents
Magnitude (intensity) Average, cumulative, peak
Frequency
Duration Acute, sub-chronic, chronic
Route Ingestion, Inhalation, dermal absorption,
injection
14Bloom & Vena in Williams et al. “Principles of Toxicology, Environmental & Industrial Applications, 3rd ed.” In press; Ryan in Frumkin “Environmental Health: From Global to Local, 2nd ed.” 2010
Typical population distribution of environmental exposures
15Schettler et al. “Generations at Risk: Reproductive Health and the Environment” 1999
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Traditional epidemiologic approaches rely on indirect exposure assessment strategies
Imputing or modeling exposures Assignment of exposure as a function of
aggregate data
Environmental sampling Area or individual level environment
sampling
Personal exposure monitoring Use of portable monitors, records, etc.
16Ryan in Frumkin “Environmental Health: From Global to Local, 2nd ed.” 2010
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Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.
The correct bibliographic citation for the definition is: Preamble to the Constitution of the World Health Organization as adopted by the International Health Conference, New York, 19-22 June, 1946; signed on 22 July 1946 by the representatives of 61 States (Official Records of the World Health Organization, no. 2, p. 100) and entered into force on 7 April 1948.
The Definition has not been amended since 1948.
International Comparisons of Disease Frequency
• World Health Organization (WHO) tracks international variations in rates of disease.
• Infectious and chronic diseases show great variation across countries.
• Variations are attributable to climate, cultural factors, dietary habits, and health care access.
• Of 37 countries, the U.S. was 26th in male life expectancy and 25th in female life expectancy.
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Child Mortality Rate
• Number of children dying before the age of five has fallen below nine million for first time on record
• 90 per 1,000 in 1990
• 65 per 1,000 in 2008
• 8.8 million in 2008, lowest since 1960 since records were first kept
Downward trend due to:
• Successful programs
• Wide distribution of inexpensive technologies
• Vaccinations
• Anti‐malaria mosquito nets
• More mothers breast‐feeding
• Progress is great, but still unacceptable that 8.8 million children are dying…
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Leading cause of child mortality:
• About 2 million children die from pneumonia
• Diarrhea
• Malaria
• HIV/AIDS
• measles
• malnutrition
Millennium Development Goal (MDG)
• Set by leaders of 189 nations in 2000
• Goal #4: cut child mortality rate by two‐thirds by 2015
• Avg. rate in industrialized countries: 6 per 1,000
• Avg. rate in developing world: 87 per 1,000
• Avg. rate in least developed places: 155 per 1,000
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Aging populations: trends in number of persons (millions) aged 60
• Shift in the pattern of morbidity and mortality from infectious and communicable diseases to chronic, degenerative diseases.
Stages of the Epidemiological Transition
Source: Disease Control Priorities in Developing Countries, second edition, 2006, Table 33.1
Stage
Life Expectancy (years)
Deaths Due to Cardio-vascular Disease (%)
World Population at this Stage (%) Regions Affected
Pestilence and famine 35 5-10 11
Sub-Saharan Africa, parts of all regions except high-income regions
Receding pandemics 50 15-35 38
South Asia, southern East Asia and the Pacific, parts of Latin America and the Caribbean
Degenerative and human-created diseases 60 >50 35
Europe and Central Asia, northern East Asia and the Pacific, Latin America and the Caribbean, Middle East and North Africa, and urban parts of most low-income regions (especially India)
Delayed degenerative diseases >70 <50 15
High-income countries, parts of Latin America and the Caribbean
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•Infectious diseases are emerging and spreading geographically at the fastest pace in history.
• Chronic diseases are the leading cause of mortality worldwide, representing 60% of deaths.
•The World Bank estimates that a global flu pandemiccould cost $1.5 trillion.
• More than 25 million people have died from AIDS globally, 33 million are living with HIV/AIDS and 15 million children have been orphaned by the epidemic.
Changes in cigarettes consumption (sales) in developing and developed countries, 1974-1992
IUMSP-GCT
0
50
100
150
200
19
74
19
76
19
78
19
80
19
82
19
84
19
86
19
88
19
90
Pe
rce
nt
ch
an
ge
(%
)
China
South Korea
India
Thailand
USA
UK
Canada
China: 390%
UK
Thailand
India
Global Climate Change:Emerging & Re-Emerging Diseases
http://www.ipcc.ch/
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Global CO2 Changes
Source: www.ipcc-wg2.org
The Greenhouse Effect
Source: www.ipcc-wg2.org
Global Temperature Changes
Source: www.ipcc-wg2.org
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Environmental Effects of Climate Change
Source: www.ipcc-wg2.org
• The Earth’s climate is warming - human activities are primarily responsible -further climate change is inevitable without actions to reduce emissions
• Most socio-economic sectors, ecological systems and human health will be adversely affected by climate change, with developing countries being the most vulnerable
Sources: FAO 2005; WHO 2006; UNICEF 2005
Global Hunger Index (%)
Global Hunger Map, 2005-06
Not included No data
Most hunger
Least hunger
> 30% 20-29%10-19%<10%
FAO estimates of food insecurity, under-nutrition:
c.2000: 820 million2007: 923 million2008: 963 million
Climate change will impair farm production in many poor countries and regions
Modelled % change in agricultural production due to climate change, 2080
Source: Cline WR, 2007: Global warming and agriculture: Impact estimates by country. Washington, D.C.: Center for Global Development, Peterson Institute for International Economics (cited in von Braun J (IFPRI), 2007
< - 25%
> + 25%
0 to 5%
NA
-15 to -5%LESS
MORE
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World -0.6 to -0.9
Developed countries +2.7 to +9.0
Developing countries -3.3 to -7.2
Southeast Asia -2.5 to -7.8South Asia -18.2 to -22.1Sub-Saharan Africa -3.9 to -7.5Latin America +5.2 to +12.5
From: Tubiello & Fischer, 2007
% Change (range)
Modelled impact of climate change on global cereal grain production:
Percent change, 1990-to-2080
CLIMATE
CHANGE
• Temperature Rise• Sea Level Rise• Hydrologic Extremes
• Weather Extremes
Urban Heat Island Effect
Air Pollution
Vector-borne Diseases
Water-borne Diseases
Water resources
Heat StressCardiorespiratory failure
Respiratory diseases, e.g., COPD & Asthma
MalariaDengueEncephalitisHantavirusRift Valley Fever
• Malaria is one of the deadiest communicable diseases globally and the deadliest tropical parasitic disease today
• Each year, 350-500 million cases of malaria occur worldwide, and over one million people die, most of them young children in sub-Saharan Africa
• ~40% of the globe has endemic malaria, which could increase to 60% w/ a few degree increase in global temperatures
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Above. Relationship between temperature and malaria parasite development time inside mosquito (extrinsic incubation period or EIP). EIP shortens at higher temps, so mosquitoes become infectious sooner.
Right. Malaria shift to higher elevations due to change in altitude where freezing occurs
EMERGING VIRUSES: Recent Examples, 1993-2009
2009 *INFLUENZA (H1N1) ‘Swine flu’ *LUJO VIRUS (South Africa/Zambia)*EV104 ENTEROVIRUS
White = human, no animal reservoirYellow = initial zoonotic event Orange = zoonosis.* novel virus not previously seen.
Air Pollution and Health
Acute exposures Early studies
Time series
Susceptible subpopulations
Chronic exposures Harvard Six Cities Study
American Cancer Society Study
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Research Needs and Issues
Chronic exposure information limited
Longitudinal data costly
Recall bias for potential confounders/effect modifiers
Use of existing datasets
Major Contributions to the Unhealthy Air Environment
US Prior to Clean Air Act, now in developing countries
Smoke from domestic coal-burning stoves and boilers
Uncontrolled fossil-fueled power plants Open combustion of wastes, leaves, garbage,
etc. Uncontrolled combustion by factories,
schools, domestic and municipal incinerators Uncontrolled automobile emissions
Well Established Morbidity Effects of AP Higher prevalence of chronic obstructive lung
disease (probably additive to the effect of tobacco smoking)
Exacerbation of disease status in persons with chronic obstructive lung disease, heart disease
Increased incidence of acute respiratory disease in children
Impaired ventilatory function of school children
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Lethal Effects of Air Pollution
Severe recurrent air pollution episodes occurred, 1930-1960’s
Episodes were result of uncontrolled combustion of fossil fuels
Concentrations of pollutants during these episodes exceeded present air standards by 3-fold or more
Air pollution also produced variations in day-to-day mortality
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There is overwhelming evidence that air pollution has long term effects on cardiorespiratory disease and lung cancer Likely due to the mixture of air pollutants and
not just one specific pollutant
There is overwhelming evidence that air pollution has long term effects on lung cancer
– Likely due to the mixture of air pollutants and not just one specific pollutant
– Recent cohort studies estimate an 8‐10% increase in risk for each 10 microgram per cubic meter of particulate air pollution exposure (17).
– A recent prospective study in Europe (1998‐2005) estimated exposure to air pollution and environmental tobacco smoke (ETS) in 10 countries (18). Among never and ex‐smokers the proportion of lung cancers attributed to air pollution was 5‐7% and the proportion attributed to ETS was 16‐24%(18).
• To combat this substantial and growing burden of disease, WHO has developed a comprehensive programme to support developing countries. WHO's Programme on Household Air Pollution focuses on:
• Research and evaluation
• Capacity building
• Evidence for policy‐makers
• Databases
Water, Sanitation and Health & Health Risk Management
Water, Sanitation and Health
Water, Sanitation and Health & Health Risk Management
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Sources of Diseases
• Pathogenic microorganisms in contaminated water
• Lack of access to adequate (safe) water sources or water point-of-use water treatments
• But also lack of sanitation and poor hygiene are responsible for the transmission of diseases
• Water often contaminated due to inadequate sanitation and waste water treatment: faeces of an infected person enters the water untreated
• Some estimated 884 million people worldwide lack access to improved water supply and 2.6 billion people lack access to improved sanitation (WHO/UNICEF 2010)
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1. Water-Borne Diseases
Poor sanitation leads to discharge of sewage directly into the environment.Source: WaterAid (2013)
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Water, Sanitation and Health & Health Risk Management
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Diseases
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1. Water-Borne Diseases
Dirty water causes more deaths per year than armed conflicts.
Source: WSSCC (2007)
Diarrhoea (multiple liquid bowl movements per day; this loss of fluid can lead to death)
Cholera (infection in the small intestine leading to diarrhoea and vomiting and thus to dehydration)
Typhoid (fever, headache, pain and diarrhoea)
And several other parasitic infections (e.g. schistosomiasis, guinea worm, ...)
Most significant is the persistence and wide distribution of diarrhoea throughout the developing world – an effect of inadequate water supply and sanitation.
Water, Sanitation and Health & Health Risk Management
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School Absence
Absence of 443 Mio school days each year (BORKOWSKY 2006) due to water-borne diseases
• Strong negative impact on nutrition, health and learning capacities especially of children
• Hurts prospects for future earnings and makes continuing poverty more likely
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2. Effects of Water-Borne Diseases
Adequate sanitation can reduce water-borne diseases of children.
Source: WHO (2012)
Water, Sanitation and Health & Health Risk Management
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Severe Sickness and Death
• Parasitic helminthes infections: severe consequences e.g. cognitive impairment, massive dysentery, anaemia and death of around 9400 people every year
• In Sub-Saharan Africa, schistosomiasis kills more than 200,000 people every year
• Acute diarrhoea, as occurs in cholera, if left untreated can cause death within a day or less
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2. Effects of Water-Borne Diseases
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Water, Sanitation and Health & Health Risk Management
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Breaking Economic Development
• Large-scale death and poor health also act as a brake on economic development
• Unsafe water and inadequate sanitation especially impacts the poor (About 2/3 of people without access to a protected water source live on less than US$2 a day )
• Adequate water supplies and sanitation are often key step out of poverty
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2. Effects of Water-Borne Diseases
Water, Sanitation and Health & Health Risk Management
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Clean Water and Sanitation are intertwined with more than health!
Due to the interconnectedness between water, sanitation, health and poverty, lack of safe water supply and proper sanitation has not only an impact on health, but consequently on education, ability to work and thus economic development.
Thus both adequate drinking water and sanitation are crucial for the health of human and thus their physical and economical development (school visits and escaping the poverty trap).
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3. Conclusion
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Studying Human Health and the Environment
• The International Society for Environmental Epidemiology (ISEE) provides a forum for the discussion of problems unique to the study of health and the environment. With membership open to environmental epidemiologists and other scientists worldwide, ISEE provides a variety of forums for discussions, critical reviews, collaborations and education on issues of environmental exposures and their human health effects.
http://www.iseepi.org/
• Students and New Researchers Network The SNRN is open to students, postdoctoral trainees and
new researchers in environmental epidemiology or related disciplines.
