2/24/2009 US EPA
CHLORAMINES-RELATED RESEARCH
15) Why does EPA believe that sufficient research has been conducted to approve
the use of monochloramine as a drinking water disinfectant?
EPA uses risk assessment methods to evaluate the safety of drinking water
disinfectants.
•	EPA's Drinking Water Criteria Document for Chloramines1 provides the detailed risk
assessment process followed in setting the standard for monochloramine.2
•	EPA's risk assessment process included a review of available research and
historical data.
•	EPA's risk assessment process focused on health outcomes that scientists
considered most critical.
EPA's regulations account for uncertainties in the risk assessment by applying
uncertainty factors.3
•	Risk assessments of monochloramine contain substantial uncertainties regarding
potentially harmful disinfection byproducts.
•	Federal laws require EPA to act to protect human health even when there is
incomplete information4.
•	Regulators must weigh the public health benefits of disinfection against the risks of
the harmful disinfection byproducts5.
Research and experience indicate that monochloramine is safe at levels that are
typically used to treat drinking water.
•	Research indicates that monochloramine produces lower levels of regulated
disinfection byproducts that may be harmful.
•	Monochloramine use may reduce the potential cancer risk from chlorinated
byproducts.
•	EPA continues to encourage research6 on the safety of monochloramine as a
drinking water disinfectant.
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 (also known as safety 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.
6.	See question 19 for more information on research.

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