been implicated in impaired reproductive success in fish populations of the
Baltic Sea
25 and the North Sea.
26 These compounds also have detrimental
effects on the health and reproduction of seals.
27,28,29
More recently, reproductive anomalies in wildlife have sparked concern
about the ability of a number of chemicals to cause ill effects by disrupting the
body’s normal hormonal system. An increasing number of chemicals are now
known to have such action. Examples include organochlorines, such as PCBs,
dioxins, as well as DDT; pesticides such as carbamates (e.g., aldicarb,
carbofuran), triazines (e.g., atrazine and simazine), and pyrethroids, (see
Chapters 3 and 12); heavy metals such as cadmium, lead, and mercury; and
organobrominate compounds.
The reproductive toxicity of the pesticide 2,2-dibromo-3-chloropropane
(DBCP) became clear in the late 1970s and early 1980s when male farm
workers in the banana-growing region of Costa Rica were found to be sterile.
By the mid-1990s, nearly 1500 male workers had been diagnosed with sterility
from exposure to DBCP.
30
There has been a steady rise in the number of premature births in the U.S.
According to U.S. government statistics, 11.8% of all babies (about 440,000
infants), were born prematurely in 1999 À that is, before the end of the 37th
week of gestation (the normal length of gestation is 40 weeks). According to
data from the National Center for Health Statistics, in 1981 9.4% of live births
were premature. Although strong evidence is still lacking, some researchers
presented data at a meeting in October 2001, sponsored by the Institute of
Medicine, suggesting that industrial chemicals, pesticides, and air pollutants
could have contributed to the 23% rise in premature births in the U.S. since the
early 1980s. One of the strongest associations was found in a study that
measured the levels of DDE (a metabolite of DDT) in stored sera of mothers
who gave birth between 1929 and 1966, when DDT was heavily used in the
U.S. In a sample group of 2380 babies born to these women, 361 were preterm
and 221 were small for gestational age. The greater the level of DDE in the
mother’s blood, the higher was the risk for the infant.
31
Shortened gestation times were also reported to be associated with benzene
exposure. A Chinese scientist studied 542 births to women working at a
petrochemical plant in Beijing, and found that benzene shortened the
pregnancies of those women who had a genetic profile that prevented them
from detoxifying benzene easily.
32 The health effects of benzene are discussed
in more detail in Chapter 11.
2.3.5 RESPIRATORY DISEASES
Many epidemiological and animal studies have shown that airborne pollutants
are commonly found in the urban environment in concentrations high enough
to adversely affect the lungs.
33 During the past five decades, chronic bronchitis,
emphysema, and lung cancer have become major public-health problems in the
U.S. and other major industrialized countries. In the U.S., although heart
diseases have been known as the number one killer for several decades, death
Environmental Change and Health
25
[16:55 26/8/04 P:/CRC PRESS/4365 MING-HO.751 (1670)/4365-002.3d]
Ref: 4365 MING-HO YU Chap-002 Page: 25 13-30
Baltic Sea
25 and the North Sea.
26 These compounds also have detrimental
effects on the health and reproduction of seals.
27,28,29
More recently, reproductive anomalies in wildlife have sparked concern
about the ability of a number of chemicals to cause ill effects by disrupting the
body’s normal hormonal system. An increasing number of chemicals are now
known to have such action. Examples include organochlorines, such as PCBs,
dioxins, as well as DDT; pesticides such as carbamates (e.g., aldicarb,
carbofuran), triazines (e.g., atrazine and simazine), and pyrethroids, (see
Chapters 3 and 12); heavy metals such as cadmium, lead, and mercury; and
organobrominate compounds.
The reproductive toxicity of the pesticide 2,2-dibromo-3-chloropropane
(DBCP) became clear in the late 1970s and early 1980s when male farm
workers in the banana-growing region of Costa Rica were found to be sterile.
By the mid-1990s, nearly 1500 male workers had been diagnosed with sterility
from exposure to DBCP.
30
There has been a steady rise in the number of premature births in the U.S.
According to U.S. government statistics, 11.8% of all babies (about 440,000
infants), were born prematurely in 1999 À that is, before the end of the 37th
week of gestation (the normal length of gestation is 40 weeks). According to
data from the National Center for Health Statistics, in 1981 9.4% of live births
were premature. Although strong evidence is still lacking, some researchers
presented data at a meeting in October 2001, sponsored by the Institute of
Medicine, suggesting that industrial chemicals, pesticides, and air pollutants
could have contributed to the 23% rise in premature births in the U.S. since the
early 1980s. One of the strongest associations was found in a study that
measured the levels of DDE (a metabolite of DDT) in stored sera of mothers
who gave birth between 1929 and 1966, when DDT was heavily used in the
U.S. In a sample group of 2380 babies born to these women, 361 were preterm
and 221 were small for gestational age. The greater the level of DDE in the
mother’s blood, the higher was the risk for the infant.
31
Shortened gestation times were also reported to be associated with benzene
exposure. A Chinese scientist studied 542 births to women working at a
petrochemical plant in Beijing, and found that benzene shortened the
pregnancies of those women who had a genetic profile that prevented them
from detoxifying benzene easily.
32 The health effects of benzene are discussed
in more detail in Chapter 11.
2.3.5 RESPIRATORY DISEASES
Many epidemiological and animal studies have shown that airborne pollutants
are commonly found in the urban environment in concentrations high enough
to adversely affect the lungs.
33 During the past five decades, chronic bronchitis,
emphysema, and lung cancer have become major public-health problems in the
U.S. and other major industrialized countries. In the U.S., although heart
diseases have been known as the number one killer for several decades, death
Environmental Change and Health
25
[16:55 26/8/04 P:/CRC PRESS/4365 MING-HO.751 (1670)/4365-002.3d]
Ref: 4365 MING-HO YU Chap-002 Page: 25 13-30