represented a sharp departure from previous years, when amphibian populations had crashed only from habitat destruction or the introduction of exotic
predator species. Scientists fear that many species of amphibians that have
been around for 350 million years will not survive the 21st century. They view
these population losses as an indication that there may be something seriously
wrong with the environment. Some scientists suspect that infections, and the
effects of synthetic organic compounds (such as pesticides), metallic contaminants, acid precipitation, UV radiation, and increased temperatures may
be responsible for the phenomenon. So far, however, there is no conclusive
evidence that any of these is responsible for the mysterious declines. Some
scientists believe that several factors may be acting synergistically to produce
the rapid die-offs.
2
3.6 INJURIES TO HUMANS
Many individuals in numerous countries have suffered injuries resulting from
exposure to high levels of airborne or waterborne pollutants. Exposure to high
levels of air pollutants results in various physiological changes, leading to
health problems. Air pollutants, such as SO 2 , O 3 and other oxidants, and
particulate matter, have been regarded as being responsible, solely or in
combination, for causing coughing, degeneration of the lining of the throat,
pulmonary disease, and heart failure. Some of the injuries result in permanent
disability, while others are fatal. Historically, such human injuries occurred
only in certain occupations, but in recent years, injuries or deaths have
occurred as results of non-occupation-related factors.
Studies show that over the past two decades there has been a startling rise
in the prevalence of asthma among children and young adults. This trend
persists, mostly in affluent countries.
3 In many of the countries where asthma is
common, its prevalence has jumped nearly 50% in 10 years. Rates of
hospitalization for asthma are also rising in these countries. For example,
asthma mortality among persons of the age group 5 to 34 years rose more than
40% between the mid-1970s and mid-1980s in most countries studied.
4
Although the reason for this trend is not known, many scientists consider it
to be associated with environmental factors.
Individuals exposed to toxicants may suffer from various signs and
symptoms without knowing the cause at the time of exposure. Furthermore,
symptoms may not be manifested immediately following exposure. With
cancer, it often takes 15 years or more for symptoms to appear. For example,
many of New York’s shipyard workers who developed diseases after exposure
during the 1940s to asbestos were not diagnosed until 15 to 30 years later.
Other examples include Minamata disease and itai-itai-byo, described in
Chapter 2. A further example is ‘‘yu-sho’’ or ‘‘oil disease,’’ which occurred in
Japan as a result of consuming rice oil that was highly contaminated by
polychlorinated biphenyls (PCBs).
Occurrence of Toxicants
35
[16:54 26/8/04 P:/CRC PRESS/4365 MING-HO.751 (1670)/4365-003.3d]
Ref: 4365 MING-HO YU Chap-003 Page: 35 31-44
predator species. Scientists fear that many species of amphibians that have
been around for 350 million years will not survive the 21st century. They view
these population losses as an indication that there may be something seriously
wrong with the environment. Some scientists suspect that infections, and the
effects of synthetic organic compounds (such as pesticides), metallic contaminants, acid precipitation, UV radiation, and increased temperatures may
be responsible for the phenomenon. So far, however, there is no conclusive
evidence that any of these is responsible for the mysterious declines. Some
scientists believe that several factors may be acting synergistically to produce
the rapid die-offs.
2
3.6 INJURIES TO HUMANS
Many individuals in numerous countries have suffered injuries resulting from
exposure to high levels of airborne or waterborne pollutants. Exposure to high
levels of air pollutants results in various physiological changes, leading to
health problems. Air pollutants, such as SO 2 , O 3 and other oxidants, and
particulate matter, have been regarded as being responsible, solely or in
combination, for causing coughing, degeneration of the lining of the throat,
pulmonary disease, and heart failure. Some of the injuries result in permanent
disability, while others are fatal. Historically, such human injuries occurred
only in certain occupations, but in recent years, injuries or deaths have
occurred as results of non-occupation-related factors.
Studies show that over the past two decades there has been a startling rise
in the prevalence of asthma among children and young adults. This trend
persists, mostly in affluent countries.
3 In many of the countries where asthma is
common, its prevalence has jumped nearly 50% in 10 years. Rates of
hospitalization for asthma are also rising in these countries. For example,
asthma mortality among persons of the age group 5 to 34 years rose more than
40% between the mid-1970s and mid-1980s in most countries studied.
4
Although the reason for this trend is not known, many scientists consider it
to be associated with environmental factors.
Individuals exposed to toxicants may suffer from various signs and
symptoms without knowing the cause at the time of exposure. Furthermore,
symptoms may not be manifested immediately following exposure. With
cancer, it often takes 15 years or more for symptoms to appear. For example,
many of New York’s shipyard workers who developed diseases after exposure
during the 1940s to asbestos were not diagnosed until 15 to 30 years later.
Other examples include Minamata disease and itai-itai-byo, described in
Chapter 2. A further example is ‘‘yu-sho’’ or ‘‘oil disease,’’ which occurred in
Japan as a result of consuming rice oil that was highly contaminated by
polychlorinated biphenyls (PCBs).
Occurrence of Toxicants
35
[16:54 26/8/04 P:/CRC PRESS/4365 MING-HO.751 (1670)/4365-003.3d]
Ref: 4365 MING-HO YU Chap-003 Page: 35 31-44