Water Quality and Health Council
August 28, 2005


Detractors Continue to Challenge Chlorination as a Safe Water Solution
for Developing Nations

By Fred Reiff

[Originally published in early June, 2005.]

Despite data supporting chlorine's highly beneficial impact on clean
water supplies and public health, claims persist that the potential
risks of chlorination outweigh the public health value of water
disinfection. To me this is comparable to watching the third sequel of
a grade Z science fiction movie about a monster that won't die.

A case in point is a Greenpeace report currently posted on the
organization's website asserting that DBP concerns had no bearing on
the spread of disease during the 1991 cholera epidemic that began in
Peru and was propagated to almost all countries of Latin America. From
personal experience I can confirm that these claims are utter
nonsense. I am concerned that such disinformation and half truths
might be accepted as fact, resulting in otherwise avoidable disease,
suffering, death, and economic impact on the poor people of developing

Why am I qualified to respond? From 1981 through most of 1995, I was
an official in the Pan American Health Organization/World Health
Organization (PAHO) in a position that offered a very unique vantage
point. During this period I was responsible for disseminating the WHO
drinking water quality guidelines and fomenting the adoption or
updating of national drinking water quality standards. I also was
responsible for managing the United Nations Global Environmental
Monitoring Programs for Water (for the Americas), the development and
promulgation of environmental interventions in disaster preparedness
and relief, and the development of appropriate technology for
treatment of both potable and waste water. I also served on PAHO's
management task force that was formed for the prevention and control
of cholera. This level of involvement provided many opportunities for
both overall and close-up monitoring of the status of water supply
disinfection and its effectiveness as a public health measure in
prevention and control of waterborne diseases in all Latin American
and the Caribbean countries before, during, and after the introduction
of cholera in Peru in 1991.

For many years prior to the cholera outbreak, PAHO had been promoting
the disinfection of community water distribution systems and other
delivery systems for water for human consumption. Primarily through
its Center for Sanitary Engineering and Environmental Science (CEPIS)
in Lima, Peru, PAHO collaborated in pilot and demonstration projects
for virtually all disinfection methodologies in various countries to
ascertain their relative disinfection efficiency, cost effectiveness,
and practicality for various cultural and economic situations. Some of
them worked well and others were failures. Everything considered,
chlorination was almost always found to the most reliable and cost

Until the cholera outbreak erupted in Peru in January-February of
1991, the acute and deadly diarrheal disease had not been prevalent in
the Americas since the early 1900's. Immediately upon verification of
its presence, PAHO began organizing workshops to inform the
appropriate officials of the countries of Latin America (and later
Caribbean countries) of the seriousness of this disease and its
potential to become an epidemic. We shared the most effective and
advanced technologies to detect the pathogen, how to diagnose and
treat the disease, the tried and proven methodologies that have been
used to prevent cholera, public education strategies, and the
epidemiological efforts and methodologies to track and understand the
propagation of the disease.

Simultaneously, PAHO headquarters directed each of the PAHO Country
Offices to advise health and water agencies to take measures to
continuously chlorinate all water distribution and delivery systems.
For the population not connected to public water systems, special
programs were developed to promote the disinfection of water at the
household level. In addition, treatment of the waste products of
cholera victims with lime was recommended before its discharge to the
sewer systems or the environment, and a list of all preventive
measures to be taken by officials and individuals were provided to all
appropriate officials. Chlorination was recommended, not only because
all of the countries were familiar with this technology, but also
because chlorine products were readily available and chlorination was
the least costly of the disinfection methodologies. And, most
importantly, chlorine is very effective in killing or inactivating
Vibrio cholerae, the pathogen of this disease as well as pathogens
associated with almost all other waterborne diseases.

Shortly after this directive was issued, I was surprised to learn that
some local PAHO officials were encountering pockets of resistance to
chlorination from a number of health officials, both in Peru and in
other countries. I was specifically told that the reason was their
concern for chlorination by-products, especially trihalomethanes. This
concern had its origin in press releases and published scientific
studies widely disseminated by environmental agencies in the developed
countries. I traveled to Peru and other countries and personally met
with the health officials and even heads of water agencies who
expressed their concern directly to me; some even believed that they
might be subjected to a lawsuit if they chlorinated or raised the
level of chlorine in their water supplies. I also met other concerned
health officials in various cholera workshops and symposiums sponsored
by PAHO. Most surprising of all was the discovery that even officials
in small towns were aware of disinfection by-products and their
alleged negative health effects. It was pointed out to all that when
the cholera pathogen is present in a water supply, the risk of
contracting the disease is immediate, and that a resulting epidemic
could cause thousands of deaths. In contrast, the hypothetical health
risk posed by trihalomethanes in levels in excess of those recommended
by WHO (and EPA) was one extra death per 100,000 persons exposed for a
period of 70 years. Unfortunately, some of these well-meaning, but
ill-informed officials had to experience the immense proportional
difference in risk before accepting this reality.

Debates over the relative significance of the drinking water pathway
for cholera in comparison to other pathways also impeded the rapid
implementation of drinking water chlorination. Routes that can be
taken by cholera include food, beverage, and ice that have been
processed or prepared with contaminated water, unhygienic food
handlers, produce that is eaten raw but which has been irrigated with
cholera contaminated water, filter feeding shellfish harvested in
sewage contaminated water, and casual person-to-person contact. Both
practical experience and studies have proven that even if cholera is
initially introduced through a pathway other than drinking water, the
waterborne pathway will soon be activated unless drinking water is
disinfected continuously with an adequate level of disinfectant and
measures are taken to prevent recontamination before its consumption.
A cholera contaminated distribution system is without doubt the most
efficient way to transmit this disease.

It should be noted that throughout the first four years of this
epidemic the countries with the highest percentage of continuously and
adequately chlorinated water systems had no secondary transmission of
cholera, even though the disease was introduced into these countries.
Also countries that quickly implemented chlorination were able to
bring the epidemic under control. There was also an obvious inverse
correlation between the percentage of the population receiving
chlorinated water and the incidence of new cases of cholera. In one
country with excellent long-term epidemiological surveillance in
place, it was found that after implementation of measures to prevent
cholera, there was also a significant reduction in typhoid fever and
infectious hepatitis.

Conversely, those countries that were not able (for whatever reason)
to implement chlorination of water supplies on a timely basis,
suffered recurring annual epidemics until a sufficient percentage of
the population had developed immunity, preventing further epidemic
propagation of the disease. Typically there were a number of reasons
for delay in implementing widespread chlorination of drinking water
supplies. However, no obstacle was harder to overcome than the
incorrect perception of risks posed by disinfection by-products
relative to the very real and deadly threat of cholera.

To reduce the spread of cholera in areas of abject poverty where
household were not connected to water distribution systems PAHO worked
in concert with the U.S. Centers for Disease Control and Prevention
(CDC) and the University of North Carolina to develop, test, and
microbiologically and epidemiologically monitor the results of a
methodology to purify the available water at the household level. The
end result was chlorination of the household water in containers that
were specifically designed to preclude subsequent contamination during
storage and use. The annual cost of this intervention was found to be
less than $2.00 per family, the major cost being the container. The
annual cost of the calcium hypochlorite was less than fifty cents per
family. Not only did this prove effective for Latin America but it
also led to global health organizations adopting this or similar
programs as a viable interim health measure for developing countries
in Africa and Asia.

Since the cholera outbreak of 1991, many nations have embraced what is
known as the "Precautionary Principle", a protocol acknowledging that
uncertainty is inherent in managing emerging risks. The thrust of
public health management in the principle is to take steps to reduce
potential harm, even when uncertainties remain. Yet a true
precautionary approach also means that you do not do away with a
proven health intervention. This concept was clearly stated by Dr.
Carlyle Macedo, Director of PAHO in his address to the 1992
International Conference on the Safety of Water Disinfection,
Balancing the Chemical & Microbiological Risks sponsored by the
International Life Sciences Institute.

"In developing countries, the primary public health concern for water
supplies should remain preventing them from becoming an efficient
vehicle for the widespread transmission of enteric diseases. This
concern should not be overshadowed in any way in our efforts to also
address the tertiary concern of minimizing the relatively small risk
stemming from disinfection by-products...

"The high incidence of diseases that are related to water supply and
sanitation are primarily a reflection of the social and economic
inequities and marginalization that unfortunately still exist in our
hemisphere. Basically the people that suffer the most from these
diseases have so few economic resources that all but the simplest and
least expensive of interventions to reduce their risk of exposure to
the many waterborne pathogens are beyond their means. Under such
circumstances the disinfection of drinking water with chlorine at the
household level, is usually the most viable and cost-effective public
health intervention available. To cause these people to abandon
chlorination is not only unwise, but cruel, if the alternative is
beyond their economic and technical means. Unless there is a simple
alternative at an affordable cost, these people should not be
frightened away from chlorinating their water. This will only increase
their suffering and decrease their life expectancy."

To protect public health, particularly in developing regions, applying
the precautionary principle requires use of practical, affordable
technologies and a realistic balancing of known and uncertain risks.

Fred M. Reiff, an engineer, is a former official of the Pan American
Health Organization/ World Health Organization. He retired from that
organization in 1995 but continues to serve as an independent
international consultant.

To read the Greenpeace report "Cholera and Chlorine" please look

Copyright 2005 Water Quality and Health Council