Environmental Engineering Reference
In-Depth Information
The rapid growth of the world's population over the
past 100 years is not the result of a rise in the crude
birth rate. Instead, it largely reflects a decline in crude
death rates, especially in developing countries.
More people started living longer and fewer in-
fants died because of increased food supplies and dis-
tribution, better nutrition, medical advances such as
immunizations and antibiotics, improved sanitation,
and safer water supplies (which curtailed the spread
of many infectious diseases).
Tw o useful indicators of the overall health of peo-
ple in a country or region are
life expectancy
(the aver-
age number of years a newborn infant can expect to live)
and the
infant mortality rate
(the number of babies out
of every 1,000 born who die before their first birthday).
Great news.
The global life expectancy at birth in-
creased from 48 years to 67 years (76 years in devel-
oped countries and 65 years in developing countries)
between 1955 and 2005; it is projected to reach 74 by
2050. Between 1900 and 2005, life expectancy in the
United States increased from 47 to 78 years and is pro-
jected to reach 82 years by 2050.
Bad news.
In the world's poorest countries, life ex-
pectancy is 49 years or less. In many African countries,
life expectancy is expected to fall further because of
more deaths from AIDS.
Infant mortality is viewed as the best single
measure of a society's quality of life because it reflects
a country's general level of nutrition and health care. A
high infant mortality rate usually indicates insufficient
food (undernutrition), poor nutrition (malnutrition),
and a high incidence of infectious disease (usually
from contaminated drinking water and weakened dis-
ease resistance from undernutrition and malnutrition).
Good news.
Between 1965 and 2005, the world's in-
fant mortality rate dropped from 20 (per 1,000 live
births) to 6.5 in developed countries and from 118 to 61
in developing countries.
Bad news.
At least 7.6 million infants (most in de-
veloping countries) die of preventable causes during
their first year of life—an average of 21,000 mostly un-
necessary infant deaths per day. This is equivalent to
55 jumbo jets, each loaded with 400 infants younger
than age 1, crashing each day with no survivors!
The U.S. infant mortality rate declined from 165 in
1900 to 6.6 in 2005. This sharp decline was a major
factor in the marked increase in U.S. average life ex-
pectancy during this period.
Some 46 countries (most in Europe) had lower in-
fant mortality rates than the United States in 2005.
Three factors helped keep the U.S. infant mortality rate
relatively high:
inadequate health care for poor women
during pregnancy and for their babies after birth, drug ad-
diction among pregnant women,
and
a high birth rate
among teenagers.
Although the United States has the
highest teenage birth rate of any developed country,
the rate dropped by 40% between 1991 and 2002.
Extremely Effective
Total abstinence
100%
Sterilization
99.6%
Vaginal ring
98-99%
Highly Effective
IUD with slow-release
hormones
98%
IUD plus spermicide
98%
Vaginal pouch
(“female condom”)
97%
IUD
95%
Condom (good brand)
plus spermicide
95%
Oral contraceptive
93%
Effective
Cervical cap
89%
Condom (good brand)
86%
Diaphragm plus
spermicide
84%
Rhythm method (Billings,
Sympto-Thermal)
84%
Vaginal sponge impreg-
nated with spermicide
83%
Spermicide (foam)
82%
Moderately Effective
Spermicide (creams,
jellies, suppositories)
75%
Rhythm method (daily
temperature readings)
74%
Withdrawal
74%
Condom (cheap brand)
70%
Unreliable
Douche
40%
Chance (no method)
10%
Figure 7-6
Typical effectiveness rates of birth control methods
in the United States. Percentages are based on the number of
undesired pregnancies per 100 couples using a specific
method as their sole form of birth control for a year. For example,
an effectiveness rating of 93% for oral contraceptives means
that for every 100 women using the pill regularly for one year, 7
will get pregnant. Effectiveness rates tend to be lower in devel-
oping countries, primarily because of lack of education. Glob-
ally, 39% of the world's people using contraception rely on steril-
ization (32% of females and 7% of males), followed by intrauter-
ine devices (IUDs; 22%), the pill (14%), and male condoms
(7%). Preferences in the United States are female sterilization
(26%), the pill (25%), male condoms (19%), and male steriliza-
tion (10%). (Data from Alan Guttmacher Institute, Henry J. Kaiser
Family Foundation, and the United Nations Population Division)
