pollution. Moreover, the problems associated with water pollution are
worsening in many countries, particularly in some of the less-developed ones.
The main sources of water pollution include both inorganic and organic
wastes, heat from industries, petroleum compounds, municipal wastes,
agricultural wastes, pesticides, and acid mine drainage. Many industrial
processes have the potential to discharge various types of wastes that could
cause significant water pollution problems.
Human diseases and casualty arising from water pollution attracted
worldwide attention after ‘‘Minamata disease’’ and ‘‘itai-itai-byo’’ (‘‘ouchouch disease’’), which occurred in Japan during the 1940s and 1950s.
Minamata disease was caused by eating fish and shellfish laden with highly
toxic methylmercury, while itai-itai-byo was mainly attributed to ingestion of
rice contaminated with high levels of cadmium. (More-detailed information on
heavy metals is presented in Chapter 12.)
In addition to heavy metals, a variety of inorganic and organic compounds
can also contaminate streams, lakes, and rivers, threatening their water quality.
The recent observation that stream water, and also garden fertilizers, may be
contaminated with perchlorate is an example. Industrial and military
operations and fireworks manufacturers use perchlorate as an oxidizing
agent, and they appear to be the primary sources of contamination.
12
Perchlorate is potentially harmful to thyroid function, and could be widespread
in some American agricultural areas – earlier studies by the EPA research
laboratory indicated that common garden fertilizers contained perchlorate
concentrations up to 0.84% by weight. However, a subsequent study released
in June 2001 by the same agency showed that the majority of fertilizers used in
the U.S. are not contaminated with perchlorate salts.
12
Water pollution can not only influence human health directly, but also
threaten aquatic life, particularly fish. For instance, in the early 1960s, millions
of fish in the lower Mississippi River died from the effects of chlorinated
organic pesticides, particularly endrin. In the early 1970s, contamination of fish
by DDT and polychlorinated biphenyls (PCBs) caused an abrupt halt to
commercial salmon fishing in the upper Great Lakes.
Although much progress has been made since, and the public is encouraged
by the reports on the decreased levels of chlorinated hydrocarbons and other
toxicants in fish crops, problems of water pollution in Great Lakes appear to
persist, as seen in Case Study 2.1. Case Study 2.2, however, shows that
pollution problems can be reversed given the right conditions.
CASE STUDY 2.1
The Detroit News recently published an eye-opening report, under the title
‘‘Disappearing shrimp pose threat to Great Lakes whitefish.’’ According to the
report, one of the principal food sources for whitefish is disappearing rapidly
from the Great Lakes, a change that threatens to shake up the food chain and
impede the state of Michigan’s large commercial fishing industry. The report
shows that diporeia (Diporeia spp.), shrimp-like creatures about 12 mm in
18
Environmental Toxicology
[16:55 26/8/04 P:/CRC PRESS/4365 MING-HO.751 (1670)/4365-002.3d]
Ref: 4365 MING-HO YU Chap-002 Page: 18 13-30
worsening in many countries, particularly in some of the less-developed ones.
The main sources of water pollution include both inorganic and organic
wastes, heat from industries, petroleum compounds, municipal wastes,
agricultural wastes, pesticides, and acid mine drainage. Many industrial
processes have the potential to discharge various types of wastes that could
cause significant water pollution problems.
Human diseases and casualty arising from water pollution attracted
worldwide attention after ‘‘Minamata disease’’ and ‘‘itai-itai-byo’’ (‘‘ouchouch disease’’), which occurred in Japan during the 1940s and 1950s.
Minamata disease was caused by eating fish and shellfish laden with highly
toxic methylmercury, while itai-itai-byo was mainly attributed to ingestion of
rice contaminated with high levels of cadmium. (More-detailed information on
heavy metals is presented in Chapter 12.)
In addition to heavy metals, a variety of inorganic and organic compounds
can also contaminate streams, lakes, and rivers, threatening their water quality.
The recent observation that stream water, and also garden fertilizers, may be
contaminated with perchlorate is an example. Industrial and military
operations and fireworks manufacturers use perchlorate as an oxidizing
agent, and they appear to be the primary sources of contamination.
12
Perchlorate is potentially harmful to thyroid function, and could be widespread
in some American agricultural areas – earlier studies by the EPA research
laboratory indicated that common garden fertilizers contained perchlorate
concentrations up to 0.84% by weight. However, a subsequent study released
in June 2001 by the same agency showed that the majority of fertilizers used in
the U.S. are not contaminated with perchlorate salts.
12
Water pollution can not only influence human health directly, but also
threaten aquatic life, particularly fish. For instance, in the early 1960s, millions
of fish in the lower Mississippi River died from the effects of chlorinated
organic pesticides, particularly endrin. In the early 1970s, contamination of fish
by DDT and polychlorinated biphenyls (PCBs) caused an abrupt halt to
commercial salmon fishing in the upper Great Lakes.
Although much progress has been made since, and the public is encouraged
by the reports on the decreased levels of chlorinated hydrocarbons and other
toxicants in fish crops, problems of water pollution in Great Lakes appear to
persist, as seen in Case Study 2.1. Case Study 2.2, however, shows that
pollution problems can be reversed given the right conditions.
CASE STUDY 2.1
The Detroit News recently published an eye-opening report, under the title
‘‘Disappearing shrimp pose threat to Great Lakes whitefish.’’ According to the
report, one of the principal food sources for whitefish is disappearing rapidly
from the Great Lakes, a change that threatens to shake up the food chain and
impede the state of Michigan’s large commercial fishing industry. The report
shows that diporeia (Diporeia spp.), shrimp-like creatures about 12 mm in
18
Environmental Toxicology
[16:55 26/8/04 P:/CRC PRESS/4365 MING-HO.751 (1670)/4365-002.3d]
Ref: 4365 MING-HO YU Chap-002 Page: 18 13-30