The September issue of the Bulletin
of the World Health Organization (WHO) focuses on current challenges for environmental
health. Among the main articles in this issue are:
Contamination of water supplies by arsenic in Bangladesh
Allan H Smith, professor of epidemiology at the University of
California at Berkeley, USA, et al report that a long-term epidemic of cancers and other
fatal diseases is facing Bangladesh because of contamination of water supplies by
naturally-occurring arsenic. The catastrophe is on a vast scale and needs to be declared a
public health emergency, the article's authors warn.
Arsenic contamination of ground water has been found in many other
countries, including Argentina, Chile, China, India, Mexico, Taiwan, Thailand and the
United States, and is a global problem. But Bangladesh's plight is unprecedented, the
article says - between 35 and 77 million people of the country's total population of
125 million are at risk of exposure to arsenic in their drinking water. At least 100 000
cases of debilitating skin lesions are believed to have already occurred.
"Bangladesh is grappling with the largest mass poisoning of a
population in history
the scale of this environmental disaster is greater than any
seen before. It is beyond the accidents at Bhopal, India, in 1984, and Chernobyl, Ukraine,
in 1986," says Smith.
Based on information from visits to Bangladesh by Professor Smith
between 1997 and 1998, this issue's lead article predicts a major increase in the
number of cases of diseases caused by arsenic if the population continues to drink
arsenic-contaminated water. These range from skin lesions to cancers of the bladder,
kidney, lung and skin, neurological effects, cardiovascular and pulmonary disease, and
diabetes. The diseases may develop slowly over many years.
"It is reasonable to expect marked increases in mortality from
internal cancers once sufficient latency has been reached," Professor Smith says.
Studies in other countries where the population has had long-term exposure to arsenic in
groundwater indicate that one in ten people who drink water containing high levels of the
poison may ultimately die from cancer. Dramatic increases in such deaths and cases have
been reported in Taiwan, Chile and Argentina.
The poisoning in Bangladesh stems from the creation during the last 20
years of millions of small tube-wells which are inserted into the ground at depths of
usually less than 200 metres and then capped with a metal hand pump. Ironically, many of
the first wells were constructed as part of a programme to provide "safe"
At the time, however, arsenic was not recognised as a problem in water
supplies and the standard water testing procedures did not include tests for it.
The alarm was first raised when doctors saw cases of arsenic-induced
skin lesions in West Bengal, India, in 1983. More than 1.5 million people were thought to
be exposed to arsenic there, with more than 200 000 cases of poisoning.
Similar cases then began to appear in neighbouring Bangladesh. Arsenic
contamination of water in the wells was first confirmed there in 1993 and in many studies
since then. Wells in several hundred villages have been scientifically surveyed as part of
a government programme, but Professor Smith says more urgent action is necessary.
"The discovery of arsenic contamination of ground-water in many
nations, including Argentina, Chile, China, India, Mexico, Taiwan, Thailand, the United
States and now Bangladesh, shows that this is a global problem," he writes.
Professor Smith believes that had a public health emergency been
declared, this "might have prompted a more rapid response to the
millions of wells and people remain to be examined."
"The response to arsenic contamination is clear-cut," he
notes. "Provide arsenic-free water
the health of the population is at risk and
relief cannot wait for further surveys."
Unlike other major health problems in Bangladesh, arsenic-caused
diseases can be eradicated at relatively low cost, according to Professor Smith. The core
activity of an emergency action plan should be rapid case ascertainment and immediate
provision of arsenic-free water, followed by treating and monitoring patients, the
education of communities about the risks and the provision of information about medical
The harm and good done by cities
Cities are the driving force of economic growth, but they are also
sources of poverty, inequality and environmental health hazards. For developing countries,
the problems of urban environmental health are considerable. On pages 1117-1126, McMichael
discusses the issues for low-income countries and argues that long-term solutions require
radical social and technological changes.
Understanding El Niño
Kovats (pp.1127-1135) explains how El Niño is directly linked to
weather changes all over the world, which in their turn cause floods, drought, famine,
forest fires and epidemics of vector-borne and hygiene-related diseases. El Niño causes
the occasional long warm periods occurring around the Equator in the Pacific. The deaths
caused by El Niño are estimated in thousands, and the disaster-related damage in billions
of dollars. But seasonal forecasting is becoming possible and early warning systems for
disasters and epidemics are gradually taking shape.
Indoor air pollution kills
Indoor air pollution may well account for nearly 2 million deaths a
year in developing countries and some 4% of the global burden of diseases. Bruce et al.
review evidence for the association between this common environmental defect and bad
health (pp. 1078-1092).
An environmental health movement is gathering strength in
industrialized countries. Opinions differ as to whether it is overriding the needs of
developing countries or helping to meet them. Some of the issues are discussed in the
Round Table (pp. 1156-1161).