Does monochloramine cause cancer?


23) Does monochloramine cause cancer?
EPA believes that water disinfected with monochloramine that meets regulatory
standards poses no known or anticipated adverse health effects, including cancer.
Most of the research on the cancer risk of monochloramine comes from animal
studies using mice and rats.1 SO DO THE STUDIES ON CHLORINE – THEY USED
THE SAME PROTOCAL. In fact, the Drinking Water Criteria Document for
Chloramine, published in 1994 which EPA authored and continues to cite for
justification for using chloramines was based upon studies of rats and mice.
EPA believes that available data support the use of monochloramine to protect
public health. Only in terms of reducing chlorine byproducts, where is the data on
the safety of chlormaine byproducts?
EPA’s regulatory standard for chloramines provides a wide margin of safety2 to offset
any uncertainties in risk assessments. These are speaking of standards for the
compound chloramines not the byproducts of NDMA, hydrazine, iodo acids or
Monochloramine use may reduce bladder cancer risk compared to chlorine use.
Several studies have shown lower rates of bladder cancer in communities served by
systems that use monochloramine as a secondary disinfectant compared to systems that
use chlorine.1
Compared to chlorine, water treated with monochloramine may contain higher
concentrations of unregulated disinfection byproducts but the cancer risk is unknown.3
EPA continues to support research3 on the safety of monochloramine use. EPA
sponsored studies have reported highly toxic byproducts associated with
monochloramine that have been found to be genotoxic, cytotoxic and
carcinogenic. EPA has classified two of these byproducts (NDMA and Hydrazine)
to be ‘probable human cancinogens”. EPA and WHO studies have determined
that monochloramine is the least effective alternative for bacteria and virus
Monochloramine use produces lower levels of regulated disinfection byproducts that
are linked to cancer.
Regulated disinfection byproducts are produced in lower amounts when
monochloramine is used.
Regulated disinfection byproducts serve as indicators4 of other types of byproducts
that may also be reduced as a result of using monochloramine.
Compared to chlorine, water treated with monochloramine may contain higher
concentrations of unregulated disinfection byproducts.3
Additional Supporting Information:
3. EPA is currently researching unregulated disinfectant byproducts that can form from monochloramine
use. Compared to chlorine, water treated with monochloramine may contain different unregulated
disinfection byproducts than chlorinated water. There are few studies on health effects of unregulated
disinfection byproducts. However, additional information on NDMA, an unregulated byproduct, can be
found at: . Also see question 9 and
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02/24/2009 US EPA
25) Do chloramines cause breathing problems?
EPA believes that water disinfected with monochloramine that meets regulatory
standards has no known or anticipated adverse health effects, including breathing
Monochloramine does not enter the air easily and therefore would be difficult to
inhale. This statement completely ignores the fact that monochloramine speciates
into di and tri chloramines with the slightest change in pH and temperature.
PAWC chemist stated that all chloraminated water contains all three species of
chloramines. It is widely known that tri-chloramine is the culprit for respiratory
irritation. Tri chloramines is created when chloraminated water is heated and
vaporized as in heated pools or showers.
CDC’s investigation1 of reports of monochloramine-related breathing problems
associated with drinking water use was unable to draw any conclusions about
monochloramine use and health effects. See above
Breathing problems associated with trichloramine and indoor swimming pools have
been reported.2 In a study by Dr. Richard Bull to determine dermal affects of
chloramines on mice, Dr. Bull emerced mice in chloraminated water. One
hundred percent of his test mice died from inhalation of chloramines before he
could complete his testing. Special harnesses had to be made for the mice in
order to conduct the dermal study. Dr. Bull indicated that no such problem
occurred with chlorinated water.
Trichloramine3, a chemical related to monochloramine and often found in swimming
pools, has been linked to breathing problems.
Trichloramine forms in swimming pools when chlorine reacts with ammonia from
bodily fluids.
Breathing problems traceable to disinfected water are typically related to swimming
pool use.4
EPA continues to review research related to the use of disinfectants used in
swimming pools. The findings in this area are unanimous. Dr. David Reckhow
indicates that the respiratory issues associated with swimming pool chloramines
is analogous to chloraminated drinking water that is heated or where pH is similar
to that of swimming pool conditions. Where are the studies in progress???
People who believe their breathing problems are related to monochloramine should
consult with their doctors.
The causes of breathing problems are often difficult to determine.
People who have breathing problems should inform their doctors if they have spent
time in or around a swimming pool recently.
CDC’s investigation1 of reports of monochloramine-related breathing problems
associated with drinking water use was unable to draw any conclusions about
monochloramine and health effects. This is how they keep changing the subject of
the discussion. They acknowledge that tri-chloramine is caused by ammonia and
chlorine and a respiratory problem in swimming pools. Connecting the dots – trichloramine
is a respiratory irritant…tri-chloramine is created with temperature
and pH change in monochloramine…. Trichloramine is created in showers, spas,
dishwasher vapor, etc. ……Yet they say MONO chloramines does not pose
breathing related problems. this is not rocket science it is simple is not
the mono chloramines – it is the TRI chloramines…but the trichloramine is an
unintended and unavoidable result of monochloramine use in a treatment
system…and, by their own admission, has not been studied by EPA.
Additional Supporting Information:
1. CDC and EPA conducted a preliminary investigation of reports of monochloramine-related
respiratory problems associated with drinking water. The investigation consisted of a
questionnaire filled out by complainants. The information collected could be used to help design
future epidemiologic studies.
CDC’s trip report can be found at:
2. Reported breathing problems due to chloramines are primarily related to inhalation of
household chemicals (mixing ammonia and bleach cleaning products), indoor swimming pool
air, or industrial exposure. See question 1 for further information about different types of
3. Trichloramine formation does not usually occur under normal drinking water treatment
conditions. However, if the pH is lowered below 4.4 or the chlorine to ammonia-nitrogen ratio
becomes greater than 7.6:1, then trichloramine can form. Trichloramine formation can occur at a
pH between 7 and 8 if the chloramine to ammonia-nitrogen ratio is increased to 15:1. Source:
Optimizing Chloramine Treatment, 2nd Edition, AwwaRF, 2004. It may not occur in the
treatment process but it does occur in the water use. They will only talk about
the conditions of treatment and the water quality as it leaves the plant…..not the
end point use.
4. Improper pool maintenance can often lead to trichloramine formation: Some examples
include: and


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