Mercury Contamination of Minamata Bay: Historical
Overview and Progress Towards Recovery 1
A. KUDO and R.R. TURNER
The contamination of Minamata Bay with mercury compounds and the subsequent effects of this
contamination on humans and animals who ate seafood from the bay have been described repeatedly
elsewhere, but there are few publications which have focused on the physicochemical aspects of the
situation and the nature and effectiveness of the work undertaken to restore the bay. This chapter
briefly reviews the available English language literature on these subjects and is intended to allow for
easier comparison with other similar sites which have not progressed as far in restoration work.
Minamata Bay was severely contaminated with mercury from acetaldehyde and vinyl chloride plants
between 1950 and 1968. While the predominant form of mercury discharged to the bay was inorganic,
some may have been methylated and the origin of highly elevated concentrations in seafood.
Somewhat lower but still unacceptably elevated levels of mercury in seafood persisted even after use of
mercury at the plants was discontinued. Sediment contamination was mapped in detail in the early
1970s and led to a major dredging and containment project, which began in 1980, to restore the bay.
All restoration was completed by 1990. Limited available data from monitoring of mercury in
commercially important fish species appear to demonstrate a successful restoration.
1
Introduction
Perhaps no other legacy of man's early ignorance of the price of releasing toxic
compounds into the environment is better known than that of Minamata Bay, a
small bay on the southwestern shore of Kyushu Island in southern Japan.
Characterized as a sleepy fishing community which shared the shores of the bay
with a chemical company, Minamata first brought global attention to the perils of
consumption of fish and shellfish contaminated with mercury, and gave its name
to the disease caused by eating foods containing alkyl mercury (D'Itri 1994).
Although acetaldehyde production using inorganic mercury as a catalyst
occurred outside of Japan (e.g., Germany, cf. Wilken and Wallschlaeger 1996)
there are apparently no comparable situations where releases from this type of
industry contaminated food which was the main staple for a community. Much
of the published literature on Minamata Bay has rightly focused on the human
tragedy which occurred there (e.g., D'Itri and D'Itri 1977; Harada 1982; Ellis 1989;
Mishima 1992) and less on the physicochemical characteristics of the contam'This chapter was prepared while the second author held a Senior Research Associateship under the
auspices of the National Research Council - US Environmental Protection Agency National Health
and Environmental Effects Research Laboratory
Environmental Science
Mercury Contaminated Sites (ed. by R. Ebinghaus et al.)
Overview and Progress Towards Recovery 1
A. KUDO and R.R. TURNER
The contamination of Minamata Bay with mercury compounds and the subsequent effects of this
contamination on humans and animals who ate seafood from the bay have been described repeatedly
elsewhere, but there are few publications which have focused on the physicochemical aspects of the
situation and the nature and effectiveness of the work undertaken to restore the bay. This chapter
briefly reviews the available English language literature on these subjects and is intended to allow for
easier comparison with other similar sites which have not progressed as far in restoration work.
Minamata Bay was severely contaminated with mercury from acetaldehyde and vinyl chloride plants
between 1950 and 1968. While the predominant form of mercury discharged to the bay was inorganic,
some may have been methylated and the origin of highly elevated concentrations in seafood.
Somewhat lower but still unacceptably elevated levels of mercury in seafood persisted even after use of
mercury at the plants was discontinued. Sediment contamination was mapped in detail in the early
1970s and led to a major dredging and containment project, which began in 1980, to restore the bay.
All restoration was completed by 1990. Limited available data from monitoring of mercury in
commercially important fish species appear to demonstrate a successful restoration.
1
Introduction
Perhaps no other legacy of man's early ignorance of the price of releasing toxic
compounds into the environment is better known than that of Minamata Bay, a
small bay on the southwestern shore of Kyushu Island in southern Japan.
Characterized as a sleepy fishing community which shared the shores of the bay
with a chemical company, Minamata first brought global attention to the perils of
consumption of fish and shellfish contaminated with mercury, and gave its name
to the disease caused by eating foods containing alkyl mercury (D'Itri 1994).
Although acetaldehyde production using inorganic mercury as a catalyst
occurred outside of Japan (e.g., Germany, cf. Wilken and Wallschlaeger 1996)
there are apparently no comparable situations where releases from this type of
industry contaminated food which was the main staple for a community. Much
of the published literature on Minamata Bay has rightly focused on the human
tragedy which occurred there (e.g., D'Itri and D'Itri 1977; Harada 1982; Ellis 1989;
Mishima 1992) and less on the physicochemical characteristics of the contam'This chapter was prepared while the second author held a Senior Research Associateship under the
auspices of the National Research Council - US Environmental Protection Agency National Health
and Environmental Effects Research Laboratory
Environmental Science
Mercury Contaminated Sites (ed. by R. Ebinghaus et al.)