02/24/2009 US EPA
CHLORAMINES-RELATED RESEARCH
16) Why does EPA believe monochloramine is safe and appropriate to use?
Research and experience indicate that monochloramine use at regulated levels is a
safe means for disinfecting drinking water.
•	Research indicates that monochloramine produces lower levels of regulated
disinfection byproducts compared to chlorine.
•	Decades of use in the U.S., Canada, and Great Britain shows monochloramine is a
safe and effective secondary drinking water disinfectant.
•	EPA continues researching the safety of monochloramine and other drinking water
disinfectants.
EPA used accepted risk assessment methods to evaluate the safety of
monochloramine.
•	EPA's risk assessment process included a review of available research and
historical data.
•	EPA's Drinking Water Criteria Document for Chloramines1 provides the detailed
risk assessment process that the Agency followed in setting the standard for
monochloramine.2
•	EPA's risk assessment process focused on health outcomes that scientists
considered most critical.
EPA's regulatory standard for chloramines provides a wide margin of safety* to
offset uncertainties in risk assessments.
•	Risk assessments of monochloramine contain uncertainties, including information
regarding potentially harmful disinfection byproducts.
•	Federal laws require EPA to take action to protect human health even when there
is incomplete information4.
•	EPA regulatory officials must weigh the public health benefits of disinfection
against the uncertain risks of the harmful disinfection byproducts5.
Additional Supporting Information:
1.	The Drinking Water Criteria Document for Chloramines can be found at
http://www.epa.gov/ncea/pdfs/water/chloramine/dwchloramine.pdf, ECAO-CIN-D002, March,
1994.
2.	The chloramine limit was set in the Stage 1 DBP Rule. This rule is available at
http://www.epa.gov/safewater/disinfection/index.html. In addition, EPA has enforceable
regulations to limit occurrence of disinfection byproducts in drinking water for a group of four total
trihalomethanes (TTHMs) (chloroform, bromodichloromethane (BDCM), dibromochloromethane
(DBCM), and bromoform), a group of five haloacetic acids (HAA5) (monochloroacetic acid (MCA),
dichloroacetic acid (DCA), trichloroacetic acid (TCA), monobromoacetic acid (MBA), and
dibromoacetic acid (DBA)), and the individual byproducts chlorite and bromate. The maximum
contaminant levels for these disinfection byproducts are: TTHMs (0.080 mg/L), HAA5 (0.060
mg/L), chlorite (1.0 mg/L), bromate (0.010 mg/L). See Stage 2 Disinfection Byproducts Rule (71
FR 388, January 4, 2006) for more information on disinfection byproducts and discussion of
uncertainties, http://www.epa.gov/fedrgstr/EPA-WATER/2006/Januarv/Dav-04/w03.pdf.
3.	For additional information regarding how uncertainty factors are applied to risk assessments to
provide a wide margin of safety see: http://epa.gov/risk/dose-response.htm.
4.	For example, See the Safe Drinking Water Act section 1412(b).
5.	See the Safe Drinking Water Act section 1412(b)(6) for more information.

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