Population and Public Health: Population and Public Health ENVRE 115
Oct. 9, 2007
Announcements: Announcements Send in student biographies
Assignment #2 due
Graduate Student Projects
Groups have been assigned
Encourage you to use discussion board to communicate with team mates
Require topic approval by Tues., Oct. 30th
Make appointment to meet with Molly
Agenda: Agenda Demographic Tools
Drivers of population growth
Development & Epidemiological Transition
Demographic Dividend
World population milestones : World population milestones
World Population Growth Through History: A.D. 2000 A.D. 1000 A.D. 1 1000 B.C. 2000 B.C. 3000 B.C. 4000 B.C. 5000 B.C. 6000 B.C. 7000 B.C. 1+ million years 8 7 6 5 2 1 4 3 Old Stone Age New Stone Age Bronze Age Iron Age Middle Ages Modern Age Black Death — The Plague 9 10 11 12 A.D. 3000 A.D. 4000 A.D. 5000 1800 1900 1950 1975 2000 2100 Future? Billions Source: Population Reference Bureau; and United Nations, World Population Projections to 2100 (1998). World Population Growth Through History
Trends in Worldwide Population Growth: Trends in Worldwide Population Growth Population Increase and Growth Rate, Five-Year Periods Millions Percent increase per year Source: United Nations, World Population Prospects: The 2004 Revision (medium scenario), 2005.
Projected Growth in World Population: Projected Growth in World Population UN Pop.Div(2004);WRI(2006)
Earthtrends.wri.org
Introduction to Demographics: Introduction to Demographics Terminology
Growth Rates
Population Pyramids
Terminology: Terminology Count: The absolute number of a population occurring in a specific area in a specified time period. Provides raw data.
Census data (number of people in the US)
Rate: The frequency of demographic events in a population divided by the population “at risk” during the same time period.
Birth rates (number of live births/number of women of childbearing age)
Ratio: The relation of one population sub-group to the total population or to another subgroup.
Sex ratios (number of males/number of females)
Dependency ratio (# of under 15 + # of 65 and over/# of 15 to 64)
Census Data: Population in US: Census Data: Population in US
Growth Rates Births/Total Population – Deaths/Total Population)*100 = Rate of Natural Increase : Growth Rates Births/Total Population – Deaths/Total Population)*100 = Rate of Natural Increase Examples of population growth rates (2003)
Belgium: 0.1% (10,318,000)
United Arab Emirates: 1.4% (3,800,000)
Uganda: 3% (25,632,794)
How long would take for these populations to double?
Belgium 700 years
United Arab Emirates 50 years
Uganda 23 years
The “Rule of 70” is used to calculate doubling time
Doubling Time = 70/rate expressed as a percentage
Assumption of constant growth rate during the time frame
Math Behind Exponential Growth: Math Behind Exponential Growth The basic differential equation for exponential growth: dN/dt = rN, over the period from t=0 to t = the time period in question, where N is the quantity growing and r is the growth rate
The integral of this equation is Nt = N0 x ert where N(t) is the size of a quantity after t intervals have elapsed, N(0) is the initial value of the quantity, e is the base of the natural logarithm, r is the average growth rate over the interval in question, and t is the number of intervals
If one knows the final and initial values of N and the average growth rate, one can find the time it takes at that average growth rate for the quantity to grow from its initial value to the final value
t = ln [ N(t)/N(0) ] / r
A special case is the doubling time, which is the time when N(t)/N(0) = 2. At that point rt = ln 2 = 0.69. If one knows the growth rate as a decimal fraction, then the Doubling Time = 0.69 / r.
This can be further simplified…if the growth rate is given in percent, then 0.69 must be multiplied by 100, and the doubling time = 69/r. This can then be rounded up to 70 (which is why it is called the rule of 70)
Examples: Examples Familiar example- compound interest on your bank account
1. How long would it take for your bank account to double when invested at 3.5%
Doubling Time Time = 70/3.5
= 20 years Time = 70/7
= 10 years 2. You invest $100 at 7% interest. How long will it
take to have $200?
Slide14: Consider a country with 100 people, growing at 7% per year. In 10 years, the population will double to 200 people, in another 10 years it will double again to 400 people, etc (see graph) 3. How long will it take this country to
reach 1 million? t = ln [N(t)/N(0)] / r t = ln (1,000,000/100)/0.07
t = ln (10,000)/0.07
t = 9.2103/0.07
t = 131.5 years Doubling Time
Slide15: 4. In a country where the GDP is growing at 4.5% per annum and the population is growing at 1.0 % per annum, how long will it take for the per capita GDP to double?
Doubling time = 70/(4.5%-1% )
= 70/3.5
= 20 years 5. In 1971, global population was 3.8 million and it is currently 6.8 million. What was the global population growth rate during this time frame?
Doubling Time Time= 70/rate(%)
36 years = 70/rate
rate = 70/36
rate= 1.9%
Crude and adjusted rates: Crude and adjusted rates Crude rates are affected by population characteristics, particularly age structure
Adjusted rates allow for valid comparisons
In 2002 Sweden’s crude death rate was 11 per 1,000 compared to Panama’s crude death rate of 5 per 1,000.
Does this mean Panama has a lower mortality rate?
No. Sweden has 18% of its population in the 65-year or older category
where deaths are more likely to occur compared to Panama where 6%
of its population are 65+.
Population Pyramids What can they tell us?: Population Pyramids What can they tell us? Graphically displays a population’s age and sex composition
Horizontal bars present the numbers or proportions of males and females in each age group.
The sum of all the age-sex groups in the population pyramid equals 100 percent of the population
What can we infer from this data?: What can we infer from this data?
Japan 1995 Census: Japan 1995 Census
Drivers of Population Growth: Drivers of Population Growth Birth Rate/Fertility
Age structure of population
Mortality
1. Birth Rate: 1. Birth Rate Birth rate is defined as the number of live births per 1,000 women aged 15-49 in a given year
Replacement level fertility
Net reproduction rate of 1
Every woman of childbearing age has 1 daughter
Total fertility rate of 2.1
Every woman of childbearing age has 2.1 children
Fertility Rates Are Declining: Fertility Rates Are Declining Average number of children per woman Source: United Nations, World Population Prospects: The 2004 Revision, 2005.
Four factors that influence fertility: Four factors that influence fertility The proportion of women of childbearing age who are married or in a sexual union
The percent of women using contraception and the level of abortion
The proportion of women of childbearing age who currently are unable to conceive a child (usually from postpartum infecundity from breastfeeding)
Educational attainment of girls and women
Age at Marriage: Age at Marriage Median Age at First Marriage, Women 20 to 24 at Time of Survey
Years Source: Measure DHS STATcompiler: accessed online at www.statcompiler.com on June 2, 2006.
Trends in Contraceptive Prevalence % of women in union aged 15-49 who are using contraception: Trends in Contraceptive Prevalence % of women in union aged 15-49 who are using contraception Sources: UN Population Division database, data available as of 1 March 2001.
Association Between Fertility and Education of Girls: Association Between Fertility and Education of Girls Percent of Girls Enrolled in Secondary School Source: Population Reference Bureau, Population & Economic Development Linkages 2007 Data Sheet. Total Fertility Rate
Association Between Fertility and Female Labor Force Participation: Association Between Fertility and Female Labor Force Participation Female Labor Force Participation Rate 2004 Source: United Nations, World Population Prospects: The 2004 Revision, 2005; International Labor Organization, Yearbook of Labor Statistics 2006. Total Fertility Rate 2000-2004
Association between fertility and wealth: Association between fertility and wealth Average Number of Children Born to a Woman During Her Lifetime Source: ORC Macro, Demographic and Health Surveys.
Complex associations between female education, economy, and fertility: Complex associations between female education, economy, and fertility
2. Age Structure of a Population: 2. Age Structure of a Population A large proportion of young people guarantees that population will continue to grow even with declining fertility
Takes two or three generations (70-100 years) before each new birth is offset by a death
Referred to as population momentum
Women of Childbearing Age There is a growing population of women in their childbearing years that will contribute to future world population growth even if fertility continues to decline: Women of Childbearing Age There is a growing population of women in their childbearing years that will contribute to future world population growth even if fertility continues to decline Source: United Nations, World Population Prospects: The 2004 Revision (medium scenario), 2005.
3. Mortality: 3. Mortality Death is the ultimate determinant of population growth
Falling mortality precedes a decline in fertility Death rate Time Rate
Development and public health Epidemiological Transition: Development and public health Epidemiological Transition
Systematic Shift in Disease Patterns : Systematic Shift in Disease Patterns Mortality Rates Infectious diseases Development Trauma Type 2
Diabetes CHD Cancers
Slide35: Global Burden of Disease – Mortality
Global Burden of Disease – DALYs: Global Burden of Disease – DALYs
How To Shift Causes of Mortality: How To Shift Causes of Mortality Improved sanitation and drinking water supplies
Medical advances (vaccination, antibiotics)
Social advances (improved nutrition, access to health care)
Occupational Health & Safety (injury prevention, chemical safety)
Infrastructure Improvements (roadways, housing, energy)
Consumer Safety (injury prevention, chemical safety)
Economic growth
Demographic Transition: Demographic Transition
Public Health : Public Health Where disease, demographics and development meet
Premise: Premise Fertility has a fixed upper limit but not mortality so mortality is the fundamental factor that controls population dynamics
Diseases and injuries control mortality
Investment in public health shifts the causes of death (Epidemiological Transition) and this will influence population structure where women and children benefit the most
During the late phase of the demographic transition when fertility and dependency rates fall countries can harness the demographic dividend when output per capita rises
Great Sanitary Awakening Cornerstone of Public Health: Great Sanitary Awakening Cornerstone of Public Health Increased immigration to cities during the Industrial Revolution
Analysis of 19th century England revealed urban mortality rates were much higher than rural rates dubbed the “Urban Penalty”
The concept that a government had the moral and ethical responsibility to protect the general welfare of its citizens
“Scourge of the Poor”
Improved Sanitation and Municipal Water Supply Virtually eliminated typhoid fever and cholera: Improved Sanitation and Municipal Water Supply Virtually eliminated typhoid fever and cholera Redirected sewage discharges away from drinking water intake and
water filtration went online in 1906 Philadelphia, USA Typhoid
Deaths
Public Health Benefits From Municipal Water Supply: Public Health Benefits From Municipal Water Supply In the United States from 1900-1940
Mortality from diarrheal disease decreases from 140 to 20 per 100,000
Child mortality rates decrease from 130 to 60 per 1,000 live births
Life expectancy at birth increased by 16 years
Typhoid fever – one of the top 5 causes of death – virtually eliminated
Cost-benefit analysis conducted by Cutler & Miller, 2005
1:23 cost-benefit ratio
Every life saved cost $500* resulting in $11,500 gain * 2002 US$
Factors contributing to diarrheal disease: Factors contributing to diarrheal disease Access To Safe Water
The source is less than 1 kilometer away from its place of use and reliably produces at least 20 liter per member of a household per day
1.1 billion people in developing countries have inadequate access to water
Access To Sanitation
An excreta disposal system is considered adequate if it is private or shared (but not public) and if it can effectively prevent human, animal, and insect contact with excreta
2.6 billion people in developing countries lack basic sanitation
Hygiene Practices
Increase water quantity allows for more frequent washing practices (hand, food, bathing) which blocks transmission of disease causing pathogens
Municipal water supplies are the cheapest source of water for the consumer: Municipal water supplies are the cheapest source of water for the consumer UNDP, 2006
Slide46: Advanced sanitation is the most expensive for the consumer but has the most health benefits Data from Peru:
Having a pit latrine in the home lowers
the incidence of diarrhea by 50% while
having a flush toilet lowers the risk by 70% UNDP, 2006 Sanitary Ladder
Slide47: Method of disposing of human excreta is one of the strongest predictors of child survival UNDP, 2006
Slide48: Access to improved water source Access to improved sanitation WHO Global water supply and sanitation assessment 2000
Current Burden of Waterborne Disease: Current Burden of Waterborne Disease 2nd largest cause of global child mortality
1.8 million children die from diarrhea each year
4931 children a day
3.4 children a minute
410 children died during this lecture
Over half of the hospital beds in the developing world are occupied by people suffering from preventable waterborne disease
Inequalities in the Use of Health Services: Inequalities in the Use of Health Services Surveys 1992-2001
Average rich/poor ratio The average of the ratios of the richest quintile to poorest quintile
Not weighted for population size and excluding countries with use less than 1% 42 countries 50 countries 53 countries 47 countries 53 countries Source: D.R. Gwatkin, S. Rutstein, K. Johnson, E.A. Suliman, and A. Wagstaff, Initial Country-Level Information about Socioeconomic Differences in Health, Nutrition, and Population, Volumes I and II (Washington, DC: The World Bank, November 2003).
Childhood Vaccination Coverage: Childhood Vaccination Coverage Children 12-23 Months Receiving Full Basic Coverage
Percent Source: ORC Macro, Demographic and Health Surveys.
Annual Cost per Fully Immunized Child for the Traditional Childhood Vaccines By Immunization Strategy, 2001 BCG (TB), Diptheria, Tetanus, Pertussis, Polio, & Measles: Annual Cost per Fully Immunized Child for the Traditional Childhood Vaccines By Immunization Strategy, 2001 BCG (TB), Diptheria, Tetanus, Pertussis, Polio, & Measles Cost ($) Mean Cost of all strategies $17 Note: Numbers are rounded. Mean values are used. Costs are weighted by population.
Source: Disease Control Priorities in Developing Countries, second edition, 2006, Table 20.4
People’s Republic of China: People’s Republic of China China began investing in social development projects including education and health care under Maoist Government
1952-1982: Invested in rural health through network of clinics and ‘barefoot’ doctors
Infant mortality decreased from 200 to 34/1000 live births
Life expectancy rose from 35 years to 68 years
Fertility rates declined from 6 births/woman (1970) to 3 birth/woman(1979) to “one child” policy in 1980
Universal primary education
1980s saw major economic reform characterized by deregulation and liberalization opened up their economies to international trade and attracted foreign investment.
Slide54: People born in the 1965 cohort with improved health care and education are now in their 40’s and in their productivity peak
Harnessed demographic dividend due to low ratio of dependents
2005 GDP growth was 9%
1/3 of income growth per capita in SE Asia (about 2 percentage points) during 1965-90 is attributable to the independent influence of changes in age structure
Cover from the book by David Cork and Susan Lightstone:
The Pig and the Python, How to Prosper from the Aging Baby Boom http://www.iiasa.ac.at/Research/LUC/ChinaFood/data/anim/pop_ani.htm
Period of Potential Demographic Bonus: Period of Potential Demographic Bonus Countries with increasing numbers of working-age adults relative to dependent elderly and children have an opportunity to increase employment, investment, and savings
Whether or not the demographic bonus is realized depends on economic policies and economic opportunities
Source: Population Reference Bureau, Population & Economic Development Linkages 2007 Data Sheet.
Resources: Resources “Improving the health of the world's poor” BMJ No 7107 Volume 315
http://www.bmj.com/archive/7107/7107e1.htm
Population health in transition by John Caldwell
http://whqlibdoc.who.int/bulletin/2001/issue2/79(2)159-170.pdf
World Health Reports
http://www.who.int/whr/en/
Preventing disease through healthy environments: Towards an estimate of the environmental burden of disease
http://www.who.int/quantifying_ehimpacts/publications/preventingdisease.pdf
Health and Economic Growth: Findings and Policy Implications. Edited by G. López-Casasnovas, B. Rivera and L. Currais. MIT Press
http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=10711
Why Has China’s Economy Taken Off Faster than India’s? David E. Bloom, David Canning, Linlin Hu, Yuanli Liu, Ajay Mahal, and Winnie Yip
http://www.hsph.harvard.edu/pgda/Bloom_Canning_China_India.pdf