changes are made, it is estimated that within the next two decades the use of water
by humans will increase by about 40% and demand will outstrip available supplies.
Water-related political and public health crises loom in several regions within
decades, including the Middle East, northern Africa and parts of South Asia.
India, which had a supply of 5500 m per person per year in 1950, currently has
around 1800 m per person (close to the recognized minimum requirement), and
this will fall by a further quarter over the coming 25 years. Environmental
conflict and security over scarce resources has implications for human health,
and this is discussed further in Section 3.
Chemical Contamination of Air, Water, Food and Soil
Soil plays an important part in the regulation of the climatic system, and provides
food, which is essential for human health. The existence of a sufficient global stock
of fertile soil is essential to ensure adequate food production for an indefinite
period. However, soil is a finite resource and has been depleted on a global
scale. In fact, we have entered the 21st century with an estimated one-third of
the world’s productive land moderately or severely damaged, by erosion,
compaction, salination and waterlogging. Soil has also been damaged by
chemicalization. For instance, the use of chemicals has reduced the organic
content of soils and resulted in contamination with heavy metals and
persistent pollutants.
Chemicals are in common use in many industrial and manufacturing processes
and have provided numerous benefits to society by, for example, ensuring food
security and protecting health. Many of these chemicals have accumulated in
air, water and soil. This chemicalization of soil and waterways is likely to increase
as the use of nitrogenous fertilizer increases, particularly in Latin America and
Africa. Already the past half-century’s combination of huge increases in
nitrogenous fertilizer use, in livestock production, and in the combustion of fossil
fuels, has added greatly to the level of biologically active (‘fixed’) nitrogen within
the biosphere. Humankind now produces more fixed nitrogen annually than do
the world’s natural processes (vulcanism, lightning, naturally-occurring rhizomes,
etc.). This has contributed to the acidification of soils and has resulted in
increasingly high nitrate levels in ground water. In China, for example, nitrate
levels are already well above the WHO standard, set in relation to public health
risks, and these may well double over the coming half-century.
Exposure to these chemicals is also proving to have detrimental consequences
R. Cassen and P. Visario, Br. Med. J., 1999, 319, 995.
D. Pimentel, Ecosystem Health, 2000, 6, 221.
D. J. Greenland, P. J. Gregory and P. H. Nye, in Feeding a World Population of More than Eight
Billion, ed. J. C. Waterlow, D. G. Armstrong, L. Fowden and R. Riley, Oxford University Press, 1998.
C. Lok, Nature, 2001, 409, 969.
European Environment Agency and United Nations Environment Programme, Down to Earth:
Soil Degradation and Sustainable Development in Europe. A Challenge for the 21st Century,
http://themes.eea.eu.int/binary/e/envissue16.pdf (27.12.00), 2000.
B. E. Fisher, Environ. Health Perspect., 1999, 107, A18.
P. M. Vitousek, H. A. Mooney, J. Lubchenco, and J. M. Melillo, Science, 1997, 277, 494.
K. Strzepek, EMF Conference, Snowmass, Colorado, 2000.
M. J. Ahern and A. J. McMichael
144
by humans will increase by about 40% and demand will outstrip available supplies.
Water-related political and public health crises loom in several regions within
decades, including the Middle East, northern Africa and parts of South Asia.
India, which had a supply of 5500 m per person per year in 1950, currently has
around 1800 m per person (close to the recognized minimum requirement), and
this will fall by a further quarter over the coming 25 years. Environmental
conflict and security over scarce resources has implications for human health,
and this is discussed further in Section 3.
Chemical Contamination of Air, Water, Food and Soil
Soil plays an important part in the regulation of the climatic system, and provides
food, which is essential for human health. The existence of a sufficient global stock
of fertile soil is essential to ensure adequate food production for an indefinite
period. However, soil is a finite resource and has been depleted on a global
scale. In fact, we have entered the 21st century with an estimated one-third of
the world’s productive land moderately or severely damaged, by erosion,
compaction, salination and waterlogging. Soil has also been damaged by
chemicalization. For instance, the use of chemicals has reduced the organic
content of soils and resulted in contamination with heavy metals and
persistent pollutants.
Chemicals are in common use in many industrial and manufacturing processes
and have provided numerous benefits to society by, for example, ensuring food
security and protecting health. Many of these chemicals have accumulated in
air, water and soil. This chemicalization of soil and waterways is likely to increase
as the use of nitrogenous fertilizer increases, particularly in Latin America and
Africa. Already the past half-century’s combination of huge increases in
nitrogenous fertilizer use, in livestock production, and in the combustion of fossil
fuels, has added greatly to the level of biologically active (‘fixed’) nitrogen within
the biosphere. Humankind now produces more fixed nitrogen annually than do
the world’s natural processes (vulcanism, lightning, naturally-occurring rhizomes,
etc.). This has contributed to the acidification of soils and has resulted in
increasingly high nitrate levels in ground water. In China, for example, nitrate
levels are already well above the WHO standard, set in relation to public health
risks, and these may well double over the coming half-century.
Exposure to these chemicals is also proving to have detrimental consequences
R. Cassen and P. Visario, Br. Med. J., 1999, 319, 995.
D. Pimentel, Ecosystem Health, 2000, 6, 221.
D. J. Greenland, P. J. Gregory and P. H. Nye, in Feeding a World Population of More than Eight
Billion, ed. J. C. Waterlow, D. G. Armstrong, L. Fowden and R. Riley, Oxford University Press, 1998.
C. Lok, Nature, 2001, 409, 969.
European Environment Agency and United Nations Environment Programme, Down to Earth:
Soil Degradation and Sustainable Development in Europe. A Challenge for the 21st Century,
http://themes.eea.eu.int/binary/e/envissue16.pdf (27.12.00), 2000.
B. E. Fisher, Environ. Health Perspect., 1999, 107, A18.
P. M. Vitousek, H. A. Mooney, J. Lubchenco, and J. M. Melillo, Science, 1997, 277, 494.
K. Strzepek, EMF Conference, Snowmass, Colorado, 2000.
M. J. Ahern and A. J. McMichael
144