FINAL DRAFT 

ECAO-CIN-D002 

March, 1994 

DRINKING WATER CRITERIA DOCUMENT FOR 

CHLORAMINES 

HEALTH AND ECOLOGICAL CRITERIA DIVISION 

OFFICE OF SCIENCE AND TECHNOLOGY 

OFFICE OF WATER 
DISCLAIMER 

This report is an external draft for review purposes only and does not constitute 

Agency policy. Mention of trade names or commercial products does not constitute 

endorsement or recommendation for use. 

ii 
FOREWORD 

Section 1412 (b)(3)(A) of the Safe Drinking Water Act, as amended in 1986, requires 

the Administrator of the Environmental Protection Agency to publish maximum 

contaminant level goals (MCLGs) and promulgate National Primary Drinking Water 

Regulations for each contaminant, which, in the judgment of the Administrator, may have 

an adverse effect on public health and which is known or anticipated to occur in public 

water systems. The MCLG is nonenforceable and is set at a level at which no known or 

anticipated adverse health effects in humans occur and which allows for an adequate 

margin of safety. Factors considered in setting the MCLG include health effects data and 

sources of exposure other than drinking water. 

This document provides the health effects basis to be considered in establishing the 

MCLG. To achieve this objective, data on pharmacokinetics, human exposure, acute and 

chronic toxicity to animals and humans, epidemiology and mechanisms of toxicity are 

evaluated. Specific emphasis is placed on literature data providing dose-response 

information. Thus, while the literature search and evaluation performed in support of this 

document has been comprehensive, only the reports considered most pertinent in the 

derivation of the MCLG are cited in the document. The comprehensive literature data 

base in support of this document includes information published up to 1986; however, 

more recent data have been added during the review process, and final revisions updating 

this document were made. 

When adequate health effects data exist, Health Advisory values for less than lifetime 

exposures (1-day, 10-day and longer-term, 10% of an individual's lifetime) are included 

in this document. These values are not used in setting the MCLG, but serve as informal 

guidance to municipalities and other organizations when emergency spills or 

contamination situations occur. 

Tudor Davies, Director 

Office of Science and 

Technology 

James Elder, Director 

Office of Ground Water 

and Drinking Water 

iii 
DOCUMENT DEVELOPMENT 

Carolyn L. Smallwood, A.B., Document Manager 

Environmental Criteria and Assessment Office, Cincinnati 

U.S. Environmental Protection Agency 

Authors 

Carolyn L. Smallwood 

Environmental Criteria and Assessment
 


Office, Cincinnati
 


U.S. Environmental Protection Agency
 


Patricia A. Murphy
 


Environmental Criteria and Assessment
 


Office, Cincinnati
 


U.S. Environmental Protection Agency
 


Annette M. Gatchett
 


Environmental Criteria and Assessment
 


Office, Cincinnati
 


U.S. Environmental Protection Agency
 


Rita Schoeny
 


Environmental Criteria and Assessment
 


Office, Cincinnati
 


U.S. Environmental Protection Agency
 


Frank E. Scully, Jr.
 


Dept. of Chemical Sciences
 


Old Dominion University
 


Norfolk, VA 23508
 


Scientific Reviewers 

Randall F. Bruins 

Environmental Criteria and Assessment 

Office, Cincinnati 

U.S. Environmental Protection Agency 

W.B. Peirano 

Environmental Criteria and Assessment 

Office, Cincinnati 

U.S. Environmental Protection Agency 

iv 

David J. Reisman
 


Environmental Criteria and Assessment
 


Office, Cincinnati
 


U.S. Environmental Protection Agency
 


Cynthia Sonich-Mullin
 


Environmental Criteria and Assessment
 


Office, Cincinnati
 


U.S. Environmental Protection Agency
 


Joseph R. Bianchine
 


Medical Research and Development
 


American Critical Care
 


McGaw Park, IL
 


Joseph P. Gould
 


Environmental Chemistry
 


Georgia Institute of Technology
 


Atlanta, GA
 


Richard J. Bull
 


College of Pharmacy
 


Washington State University
 


Pullman, WA
 


Herbert H. Cornish
 


Professor Emeritus
 


University of Michigan
 


Ypsilanti, MI
 


Curtis D. Klaassen
 


University of Kansas Medical Center
 


Dept. of Pharmacology and Toxicology
 


Kansas City, KS
 


Loren K. Koller
 


College of Veterinary Medicine
 


Oregan State University
 


Corvallis, Oregan
 

DOCUMENT DEVELOPMENT (cont.) 

David Jollow
 


Medical University of South Carolina
 


Charleston, SC
 


Editorial Reviewers 

Erma Durden, B.S. 

Environmental Criteria and Assessment 

Office, Cincinnati 

U.S. Environmental Protection Agency 

Judith Olsen, B.A. 

Environmental Criteria and Assessment 

Office, Cincinnati 

U.S. Environmental Protection Agency 

Document Preparation 

Technical Support Services: Bette Zwayer, Environmental Criteria and Assessment 

Office, Cincinnati 

v 
TABLE OF CONTENTS
 


Page 

I. SUMMARY ................................................ I-1
 

II. PHYSICAL AND CHEMICAL PROPERTIES ....................... II-1
 

INTRODUCTION ............................................ II-1
 

PHYSICAL AND CHEMICAL PROPERTIES OF CHLORAMINES ...... II-2
 

USES OF CHLORAMINES .................................... II-11
 

ANALYTICAL METHODS ..................................... II-12
 

ENVIRONMENTAL FATE AND TRANSPORT ..................... II-16
 

SUMMARY ................................................ II-17
 

III. TOXICOKINETICS .......................................... III-1
 

INTRODUCTION ............................................ III-1
 

ABSORPTION .............................................. III-1
 

DISTRIBUTION ............................................. III-2
 

METABOLISM ............................................. . III-6
 

EXCRETION .............................................. . III-11
 

DISCUSSION ............................................. . III-14
 

SUMMARY ............................................... . III-16
 

IV. HUMAN EXPOSURE ......................................... IV-1
 

[To be provided by the Office of Water]
 

V. HEALTH EFFECTS IN ANIMALS ............................... V-1
 

INTRODUCTION ............................................ V-1
 

SHORT-TERM EXPOSURE ................................... V-1
 

OTHER SHORT-TERM EFFECTS .............................. V-15
 

LONG-TERM EXPOSURE .................................... V-16
 

DEVELOPMENTAL TOXICITY ................................. V-20
 

REPRODUCTIVE TOXICITY .................................. . V-21
 

MUTAGENECITY .......................................... . V-23
 

CARCINOGENICITY ......................................... V-26
 

SUMMARY AND DISCUSSION ................................. V-31
 

vi 
TABLE OF CONTENTS (cont.) 

Page 

VI. HEALTH EFFECTS IN HUMANS ............................... VI-1
 

INTRODUCTION ............................................ VI-1
 

CLINICAL REPORTS AND EXPERIMENTS ....................... VI-1
 

EPIDEMIOLOGY STUDIES .................................... VI-4
 

HIGH-RISK SUBPOPULATIONS ............................... VI-6
 

SUMMARY AND DISCUSSION ................................. VI-7
 

VII. MECHANISMS OF TOXICITY .................................. VII-1
 

GENERAL THEORIES ....................................... VII-1
 

SUMMARY ................................................ VII-3
 

VIII. QUANTIFICATION OF TOXICOLOGIC EFFECTS .................. VIII-1
 

INTRODUCTION ............................................ VIII-1
 

CURRENT LEVELS OF EXPOSURE ............................ VIII-7
 

NONCARCINOGENIC EFFECTS ............................... VIII-7
 

QUANTIFICATION OF NONCARCINOGENIC EFFECTS ............ VIII-14
 

Derivation of 1-Day Health Advisory ........................ VIII-14
 

Derivation of 10-Day Health Advisory ....................... VIII-15
 

Derivation of Longer-term HA ............................. VIII-16
 

Assessment of Lifetime Exposure and Derivation of a DWEL .... VIII-17
 

CARCINOGENIC EFFECTS ................................... VIII-19
 

EXISTING GUIDELINES, RECOMMENDATIONS AND STANDARDS . . VIII-21
 

SPECIAL GROUPS AT RISK .................................. VIII-21
 

RISK CHARACTERIZATION ................................... VIII-22
 

REFERENCES ............................................. IX-1
 

vii 
LIST OF TABLES
 


No. Title Page 

II-1	 	 Summry of Chemical and Physical Properties of Mono-
 

and Trichloramines ......................................... . II-3
 

II-2	 	 Proportions of Monochloramine (NH2Cl) and Dichloramine(NHCl2)
 

Formed in Water Chlorination with Equimolar Concentrations of
 

Ammonia and Chlorine ...................................... . II-5
 

III-1 Metabolism of NH2

36Cl in Rat Plasma ............................ III-7
 

III-2	 	Excretion of 36Cl in Rat 120 Hours After Single Oral Administration
 

of NH2

36Cl .................................................. III-11
 

III-3	 	Excretion of 36Cl in Rat 120 Hours After Single Oral Administration
 

of Na36Cl .................................................. III-12
 

V-1	 	 Summary of Studies on Acute and Subchronic Oral Exposure to
 

Monochloramine ............................................ V-2
 

V-2	 	 Summary of Studies on Chronic Oral Exposure to Monochloramine
 

in Drinking Water ............................................ V-5
 

VIII-1 Summary of HAs and Dwel for Noncarcinogenic Effects ............. VIII-20
 

viii 
LIST OF FIGURES
 


No. Title Page 

II-1 Graphic Description of Breakdown Phenomenon ................... II-7
 

III-1	 	NH2

36Cl Radioactivity Distribution in the Rat 120 Hours After the
 

Administration of NH2

36Cl (1.1 mg) Orally ......................... III-4
 

III-2 36Cl Distribution in the Rat ..................................... III-5
 

ix 
LIST OF ABBREVIATIONS
 


Alk-P Alkaline phosphatase
 


AST Aspartate aminotransferase
 


ATP Adenosine triphosphate
 


BUN Blood urea nitrogen
 


bw Body weight
 


CHO Chinese hamster ovary
 


CNS Central nervous system
 


CSF Cerebrospinal fluid
 


DNA Deoxyribonucleic acid
 


DPD Diethyl-p-phenylenediamine
 


DWEL Drinking water equivalent level
 


EAA Essential amino acid
 


EKG Electrocardiogram
 


FEV Forced expiratory volume
 


FVC Forced vital capacity
 


GGTP q-Glutamyltranspeptidase
 


GI Gastrointestinal
 


GSH Glutathione
 


HA Health advisory
 


HCT Hematocrit
 


HGB Hemoglobin percent
 


LIST OF ABBREVIATIONS (cont.) 

x 
i.p. Intraperitoneal
 


i.v. Intravenous
 


LOAEL Lowest-observed-adverse-effect level
 


MCH Mean corpuscular hemoglobin
 


MCHC Mean corpuscular hemoglobin concentration
 


MCV Mean corpuscular volume
 


NADH Nicotinamide-adenine dinucleotide dehydrogenase
 


NCP N-chloropiperidine
 


NOAEL No-observed-adverse-effect level
 


NOEL No-observed-effect level
 


PHA Phytohemagglutinin
 


RBC Red blood cell
 


RfD Reference dose
 


s.c. Subcutaneous
 


SCE Sister chromatid exchange
 


T4 Plasma thyroxine
 


TCA Trichloroacetic acid
 


TPA 12-o-Tetradecanoylphorbol-13-acetate
 


TrpC Tryptophan C
 


TWA Time-weighted average
 


xi 
xii
 
I. SUMMARY 

Inorganic chloramines are alternate disinfectants that are rapidly formed when free 

chlorine is added to water containing ammonia. To achieve the desired chloramine 

concentration, chlorine may also be intentionally added to the already naturally occurring 

ammonia in the water source. Under the usual conditions of water and wastewater 

chlorination, monochloramine is the principal chloramine encountered. In the event of 

excess hypochlorite or at lower pH, ammonia can be di- and trichlorinated and organic 

amines can be dichlorinated. Comparatively little is known about the physical properties 

of pure dichloramine because it is not stable and is difficult to synthesize. Trichloramine 

is formed in acidic solutions where chlorine concentrations are much greater than those 

of ammonia. This document will deal primarily with inorganic chloramines; however, 

where data are limited or not available various chlorinated amino compounds (including 

organic chloramines) will be provided as supplemental information. 

Inorganic dichloramine is unstable and decomposes to nitrogen, hypochlorous acid 

and other products. This reaction accounts to a large extent for the breakpoint reaction 

seen in water chlorination. Inorganic monochloramine is a much poorer disinfectant than 

hypochlorous acid, and it reacts slowly with organic amino nitrogen compounds to 

produce organic N-chloramines, which are even poorer disinfectants. 

Conventional methods of monochloramine analysis have led to confusion in the 

use of the term "chloramines." The term has been used to describe many compounds in 

CLORAMIN.1 I-1 03/08/94
 
complex mixtures that oxidize iodide to iodine, the amount of which is subsequently 

determined by colorimetric or amperiometric analysis. Organic N-chloramines and 

N-chloramides respond similarly to monochloramine; however, they are poor disinfectants 

compared with inorganic chloramine. From a public health viewpoint, these ambiguities 

can present serious problems since the disinfecting capabilities of waters that contain 

organic N-chloramines could be overestimated. Improved analytical methods are needed 

for the determination of organic and inorganic N-chloramines in chlorinated waters. For 

the purpose of this document, the term "chloramines" will refer to a combination of 

inorganic mono-, di- or trichloramines unless otherwise stated. 

Human exposure to chloramines is through ingestion of chlorinated water 

containing ammonia or chloraminated water. Chloramination is a technique that is being 

adopted by many communities to avoid formation of trihalomethanes on water 

disinfection. Organic chloramines have been shown to form upon chlorination of stomach 

fluid in vitro. However, the significance of their formation on ingestion of chlorinated water 

is not clear. 

Information on the absorption of inorganic chloramines is extremely limited. In one 

study an absorption rate constant was calculated for monochloramine at 0.278 mg/hour 

(after 8 hours) with an absorption half-life of 2.5 hours after a single oral dose of 4.6 

mg/kg/day was administered to Sprague-Dawley rats. After 48 hours, the rate constant 

was 0.018 mg/hour. Absorption rates with respect to various dosage media and different 

routes of exposure were not available. 

CLORAMIN.1 I-2 03/08/94
 
The distribution of radiolabeled chlorine in the subfractions of rat liver 

homogenates in organs, tissues, and fluids was similar (120 hours) after oral 

- administration of either 36Cl (200 mg/L as Na36Cl) or NH236Cl (370 mg/L NH236Cl). Plasma 

contained the highest concentrations of 36Cl radioactivity for NH2

36Cl followed by whole 

blood, skin, testes, packed cells, bone marrow, kidney, lung, stomach, thyroid, thymus, 

duodenum, spleen, carcass, liver, ileum and fat. The major metabolite of NH2

36Cl was 

36 - Cl . 

Information on the metabolism of chloramines is also extremely limited. One 

experiment indicated that chloramines are transformed to the chloride moiety and 

eliminated primarily in this form. 

Chloramines are eliminated primarily through the urine. During the first 24 hours 

after a single dose of NH2

36Cl (1.1 mg/animal) to Sprague-Dawley rats, only 0.40 and 

0.08% of the total dose was eliminated in the urine and feces, respectively. At the end 

of 120 hours, 25.15 and 1.98% of the dose was eliminated through the urine and feces, 

- respectively. By comparison 16.1 and 0.92% of 36Cl radiolabel (200 mg/L as Na36Cl) was 

eliminated in the urine and feces, respectively, in the first 24 hours. Over twice as much 

- of the 36Cl radiolabel was eliminated over a 120-hour period. The major difference 

- between the NH236

Cl and 36Cl studies was in the total amount of label excreted over the 

test period. 

CLORAMIN.1 I-3 03/08/94
 

Several short-term studies showed no observed adverse hematologic effects in 

mice, rats and monkeys. In A/J mice administered chloramine solutions between 2.5 and 

200 mg/L (pH 8.9) for 30 days, the only observable effect was a slight increase in 

hematocrit. In another study of similar duration (45 days) rats treated with 10, 50 or 100 

mg/L monochloramine experienced a decrease in the amount of methemoglobin present 

in the blood, the opposite of what was expected. Monochloramine in drinking water for 

6 weeks at 100 mg/L had no detectable effects on 18 hematologic tests of 12 African 

Green monkeys. 

In a 12-month study using Sprague-Dawley rats administered 1, 10 and 100 mg/L 

monochloramine, glutathione levels, red blood cell count and hematocrit were found to 

be decreased at sporadic intervals. However, there was a lack of dose- and 

time-dependent response in the results. Plasma thyroxine levels were significantly 

decreased and cholesterol elevated in pigeons administered 15 mg/L monochloramine 

for 3 months. 

Rats and mice were administered monochloramine in drinking water at 

concentrations of 0, 25, 50, 100, 200 or 400 ppm (0, 25, 50, 100, 200 or 400 mg/L) for 91 

days. Decreased body weight gain and liver damage were observed at 200 and 400 mg/L 

in rats and 100, 200 and 400 mg/L in mice. Histopathologic observation revealed mild 

to moderate cytologic alteration in the liver of male mice administered 200 and 400 mg/L 

chloramines. Chronic liver inflammatory changes occurred at 100, 200 and 400 mg/L in 

female mice and to a lesser extent in male mice at the 100 ppm level. Microscopic 

CLORAMIN.1 I-4 03/08/94
 
examination of rat tissues at the 400 mg/L level did not reveal any treatment-related 

lesions. The investigators suggested a NOEL of 50 mg/L or 8.3 mg/kg/day 

monochloramine based on chronic liver inflammatory changes in mice. 

In a 90-day study, male and female Sprague-Dawley rats were administered 

monochloramine in drinking water at concentrations of 0, 25, 50, 100 and 200 mg/L. At 

200 mg/L the average weight gain was 51% of controls. There were also reductions in 

organ weights (absolute, relative or both) at the high dose level. The authors identified 

the 100 mg/L dose as the NOAEL. 

B6C3F1 mice were administered monochloramine in their drinking water for 90 

days at 0, 12.5, 25, 50, 100 and 200 mg/L. There were weight gain reductions, and 

reductions in absolute and relative organ weights at the 100 and 200 mg/L dose levels. 

Based on these reductions the authors identified a NOAEL of 50 mg/L. 

In a 2-year study, F344/N rats and B6C3F1 mice were administered 0, 50, 100 and 

200 ppm monochloramine in their drinking water. There was a decrease in mean body 

weight in high-dose rats. The high-dose group had decreases in organ weights and 

increases in organ-to-body weight ratios at 14- or 66-week evaluations. There was also 

a dose-related decrease in mean body weights of dosed male and female mice 

throughout the study. There were decreases in organ weights and increases in 

organ-to-body weight ratios observed in high-dose mice at 15- or 66-week evaluations. 

CLORAMIN.1 I-5 03/08/94
 

Monochloramine was not teratogenic in mature female Sprague-Dawley rats 

exposed to 1, 10 or 100 mg/L in drinking water, nor did 40, 100 and 200 mg/L solutions 

induce sperm-head anomalies in B6C3F1 mice. In addition, no significant differences in 

fertility, viability, litter size, day of eye opening or day of vaginal patency were observed 

between control and exposed Long-Evans rats given >10 mg/kg chloramines. There were 

no alterations in sperm count, direct progressive sperm movement, percent mobility or 

sperm morphologic characteristics. 

Results on the mutagenicity of chloramines are inconclusive. Monochloramine has 

been found to be marginally mutagenic in Bacillus subtilis and in Vicia faba plant seeds. 

In Salmonella typhimurium (TA97, TA100 and TA102), chloramines (40 um) marginally 

increased the number of revertant colonies over untreated controls. It was responsible 

for cellular hypertrophy, increased mitotic figures and bizarre chromatin patterns in 

B6C3F1 mice exposed to 200 and 400 mg/L in drinking water. In another study, 

monochloramine at 40, 100 and 200 mg/L did not induce chromosomal aberrations or 

micronuclei in bone marrow of CD-1 mice. 

The organic chloramine, N-chloropiperidine, was found to be marginally mutagenic 

in the reverse mutation plate incorporation assay (Ames test). It was cytotoxic and 

cytostatic in CHO cells and produced chromosomal aberrations, the frequency of which 

was proportional to the concentration of the compound. It produced SCEs in CHO cells, 

but not in baby hamster kidney cells. The analogous chloramine, N-chlorodiethylamine, 

was more toxic but nonmutagenic. When the synthetic N-Cl compound chloramine T 

CLORAMIN.1 I-6 03/08/94
 
(sodium p-toluene-sulfonyl chloramide) was tested, SCEs were significantly increased in 

a dose-dependent manner in CHO cells. 

Organic concentrates of water treated with monochloramine produced papillomas, 

squamous cell carcinomas and lung adenomas in SENCAR mice. These data are 

inadequate, however, to assess the carcinogenic potential of monochloramine. In a 

2-year study using male and female F344 rats and B6C3F1 mice, monochloramine was 

administered in drinking water at 0, 50, 100 and 200 ppm. Equivocal evidence of 

carcinogenic activity was found in female rats because of the slightly increased incidence 

of mononuclear cell leukemia. There was no evidence of carcinogenic activity in male 

rats or female or male mice, which was attributed to chloraminated drinking water. 

Information concerning human exposure to chloramines is extremely limited. In 

humans, acute exposure by inhalation of chloramine fumes has been observed after 

mixing 4-5% solutions of ammonia and sodium hypochlorite in a small room. Pneumonitis 

resulted, but no permanent pulmonary damage occurred. Very few experimental studies 

have been conducted. Individuals ingesting levels of chloramines between 0.01 and 24.0 

mg/L for 1 day or 5 mg/L for 12 weeks showed no hematologic or detrimental physiologic 

responses resulting from chloramine ingestion. 

There are no epidemiologic studies that have been designed to address 

specifically the potential adverse effects of exposure to chloramines on human health. 

One study was conducted to see if there was a difference in cancer mortality among 

CLORAMIN.1 I-7 03/08/94
 
communities using chlorine compared with communities using chloramine for disinfection. 

This study was not designed to assess adverse effects from exposure to chloramine but 

rather to consider the chloramine-exposed participants as controls. 

Chloramines appear to be produced by normal human neutrophils as part of their 

bactericidal action. Chloramines are believed to exert their effects by interfering with 

enzymatic reactions. Monochloramine oxidizes and denatures hemoglobin and inhibits 

the hexose monophosphate shunt. It also causes strand-breaks in DNA. 

Lack of sufficient data preclude the derivation of a 1-day HA for chloramines. It is 

recommended that the 10-day HA of 1 mg/L be adopted as the 1-day HA. The 10-day HA 

was derived from a drinking water study using African Green monkeys. The 10-day HA 

for a 10 kg child is 1 mg/L based on the absence of hematologic effects. The longer-term 

HAs for a 10 kg child and 70 kg adult are 1 and 4 mg/L, respectively. These HAs are 

based on a NOAEL for body and organ weight changes in rats exposed to chloramines 

in drinking water. The DWEL of 4 mg/L is derived from a proposed RfD of 0.1 mg/kg/day 

from a NOAEL in a chronic drinking water study using rats, based on absence of 

decreased organ weight changes. 

There was one 2-year bioassay with equivocal evidence of carcinogenic activity 

in female rats. The CRAVE Work Group verified (12/02/92) a classification for 

monochloramine of group D, not classifiable as to human carcinogenicity, meaning that 

there is inadequate human and animal evidence of carcinogenicity. 

CLORAMIN.1 I-8 03/08/94
 
CLORAMIN.1 I-9 03/08/94
 

II. PHYSICAL AND CHEMICAL PROPERTIES 

Introduction 

Inorganic chloramines are alternate disinfectants that are rapidly formed when free 

chlorine is added to water containing ammonia. This reaction is represented by the 

following equation with its respective reaction rate constant (at 25 C = 298 K) (Morris, 

1967): 

NH3 + HOCl = NH2Cl + H2O 

(k298 = 6.1x106 M-1 sec-1) 

Since ammonia has more than one hydrogen that can be replaced by a chlorine 

atom, it reacts with an excess of hypochlorous acid to form dichloramine (Morris, 1967; 

Gray et al., 1979): 

NH2Cl + HOCl = NHCl2 + H2O 

(k298 = 3.4x102 M-1 sec-1) 

or trichloramine (Morris and Isaac, 1983): 

NHCl2 + HOCl = NCl3 + H2O 

(k298 = 2.1 M-1 sec-1) 

CLORAMIN.2 II-1 03/08/94 
The distribution of mono-, di- and trichloramine is dependent on pH, temperature and 

relative concentrations of ammonia and hypochlorite as described in the following section 

on physical and chemical properties. 

Physical and Chemical Properties of Chloramines 

Under the usual conditions of water and wastewater chlorination, monochloramine 

is the principal chloramine encountered. Anhydrous monochloramine is a colorless, 

water-soluble liquid (Kirk-Othmer, 1979) that freezes at -66 C. The pure liquid

decomposes above -50 C with formation of nitrogen, chlorine and nitrogen trichloride 

(Colton and Jones, 1955; Kovacic et al., 1970). The known chemical and physical 

properties of pure monochloramine are summarized in Table II-1. The environmental 

significance of monochloramine, however, is generally restricted to its aqueous solutions, 

where it is useful in water treatment for destruction of pathogenic bacteria (Butterfield, 

1948; Wolfe et al., 1984). The rate of its formation is so rapid that determination of rates 

between pH 6.5 and 10 were impossible because of the rapidity of the reaction in this 

range (Weil and Morris, 1949). At pH 8.5 the rate of its formation reaction reaches a 

maximum (Weil and Morris, 1949). Monochloramine is the only chloramine formed when 

the pH of ammonia containing water is >8 and the molar ratio of hypochlorite to ammonia 

is <1 (Gray et al., 1979). 

CLORAMIN.2 II-2 03/08/94
 

CLORAMIN.2 II-3 03/08/94
 

At hypochlorite to ammonia ratios >1 or at lower pH values, dichloramine and 

trichloramine are formed. At pH values <5.5 monochloramine slowly converts to form 

dichloramine (Gray et al., 1979): 

2 NH2Cl + H+ = NHCl2 + NH4 

+ 

The relative proportions of monochloramine and dichloramine formed as a function of pH 

and temperature are listed in Table II-2. 

Comparatively little is known about the physical properties of pure dichloramine 

because of its instability and difficulty of preparation. Its odor, volatility from aqueous 

solution, and relative solubility in various solvents are intermediate between those of 

monochloramine and trichloramine (NRC, 1980). Under equilibrium conditions at pH 4 it 

is the only product of the reaction of equimolar concentrations of chlorine and ammonia. 

Under normal conditions, however, dichloramine solutions are unstable (Corbett et al., 

1953) and decompose by several mechanisms, not all of which have been elucidated 

(Chapin, 1931; Wei and Morris, 1974; Hand and Margerum, 1983). 

Trichloramine (nitrogen trichloride) is formed in acid solutions where chlorine 

concentrations are much greater than those of ammonia. At these high chlorine 

concentrations and at pH values <3, trichloramine is the only chloramine present. Nitrogen 

CLORAMIN.2 II-4 03/08/94
 

CLORAMIN.2 II-5 03/08/94
 

trichloride occurs in diminishing proportions at chlorine-to-ammonia mole ratios >2 and pH 

values of <7.5. At pH >7.5, no trichloramine is found, regardless of the ratio of chlorine 

to ammonia. Pure trichloramine is a bright yellow liquid that, because of its limited 

solubility, can be isolated from aqueous solution by solvent extraction (Dowell and Bray, 

1917). Its chemical and physical properties are summarized in Table II-1. It can be 

explosive in concentrated solutions and is an effective chlorinating agent, particularly in 

nonaqueous media (Dowell and Bray, 1917; Jander, 1955; Kovacic et al., 1970). In 

aqueous solutions at neutral pH it decomposes slowly to ammonia and hypochlorous acid 

(Ryan et al., 1980) by an autocatalytic pathway (Hand and Margerum, 1983). Aqueous 

solutions of trichloramine are stabilized by small amounts of acid (Corbett et al., 1953). 

When chlorine is added to waters containing ammonia, the breakpoint phenomenon 

becomes significant in the pH range of 6-9. The breakpoint is that dosage of chlorine that 

produces the first detectable amount of free chlorine residual. At chlorine-to-ammonia 

weight ratios of <5:1 pH 7, monochloramine is formed and the combined residual 

increases to a maximum. This is the case up to the hump in the curve as displayed in 

Figure II-1. At chlorine-to-ammonia weight ratios 5:1, dichloramine is formed. The 

residuals formed in this reaction occur between the top and the dip of the curve. With the 

addition of chlorine the previously formed dichloramine is oxidized to nitrous oxide (N2O), 

nitrogen trichloride (NCl3) and nitrogen (N2). The formation of these nitrogen compounds 

oxidize chlorine which in turn results in a decrease of ammonia nitrogen. As the 

chlorine-to-ammonia nitrogen weight ratio reaches 10:1 at pH 7, the breakpoint 

CLORAMIN.2 II-6 03/08/94
 

phenomenon occurs (NRC, 1980; White, 1972). At the breakpoint dosage, some resistant 

chloramines are present (primarily di- and trichloramine); however, they are not of any 

importance (NRC, 1980). 

Chlorine that is added after the breakpoint exists as free chlorine [that is, elemental 

chlorine, hypochlorous acid (HOCl) and the hypochlorite ion (OCl )] (Pressley et al., 1973; 

Wei and Morris, 1974). When natural waters and wastewater are chlorinated, there is a 

residual oxidant formed, which remains stable at the breakpoint and in the presence of 

hypochlorite beyond the breakpoint. This residual oxidant responds to conventional 

methods of analysis in the same way monochloramine does. It can be shown that some 

organic amino nitrogen compounds form very stable organic N-chloramines that, unlike 

inorganic chloramines, do not decompose in the presence of excess hypochlorite. This 

residual oxidant is, therefore, believed to be due to organic N-chloramines. 

Monochloramine is less effective as a chlorinating agent than hypochlorous acid by 

a factor of 104 (Morris, 1967). However, when chloramines (mostly monochloramine) 

were used to treat raw water, Stevens et al. (1978) determined that trihalomethane (THM) 

formation was minimized. Thus, during the chlorination of water, when the ammonia 

breakpoint is not achieved, THM production may be significantly reduced. Rickabaugh 

and Kinman (1978) determined that chloramination of Ohio River water with 

monochloramine at 10 mg/L, pH 7-9 and 25 C resulted in 90.7-99.9% less THM formation, 

as compared with THM production from chlorination with 10 mg/L chlorine as hypochlorous 

CLORAMIN.2 II-8 03/08/94
 
acid or hypochlorite. Presumably many of the reaction products of water treated with free 

chlorine (Cl, OCl and HOCl) are produced by the reaction of combined chlorine residual 

(chlorinated waters that contain chloramines) with free chlorine. This is a result of the slow 

hydrolysis of chloramines to hypochlorous acid. The products should occur in low 

concentrations because of the low equilibrium concentration of the hypochlorous acid 

formed (Margerum et al., 1979). 

Margerum et al. (1979) indicated that the formation of hydroxylamine (NH2OH) 

NH2Cl + OH = NH2OH + Cl 

at pH 8 has a reaction half-time of 350 years. Therefore, it probably does not occur in 

water treatment. 

When low concentrations (mg/L range) of monochloramine and phenol are mixed, 

chlorophenols appear after a reaction time of several days (Burttschell et al., 1959). This 

probably results from the hydrolysis of NH2Cl and subsequent reaction of HOCl with 

phenols. 

Organic amines and amino acids in natural waters also react rapidly with hypochlorite 

to form organic N-chloramines (Calvert, 1940; Wright, 1926, 1936; Taras, 1950; Crane et 

al., 1946; Ellis and Soper, 1954; Mauger and Soper, 1946; Sandford et al., 1971; Edmond 

CLORAMIN.2 II-9 03/08/94
 
and Soper, 1949; Ingols et al., 1953; Wajon and Morris, 1980). Morris (1967) concluded 

that the reaction rates of free chlorine with amino nitrogen compounds increases with the 

basicity of the compound. As with ammonia, organic amines can also form dichloramines, 

but the reaction rates are considerably slower for the addition of the second chlorine atom 

than the addition of the first chlorine atom. Formation of N,N-dichloromethylamine from 

N-chloromethylamine occurs with a second order reaction rate constant at 25 C of 1.1x103 

M-1 sec-1 which is faster for organic than inorganic dichloramine (Morris, 1967): 

CH3NHCl + HOCl = CH3NCl2 + H2O 

Both inorganic chloramines and organic N-chloramines are formed when wastewater 

effluents are chlorinated. The relative amounts depend on the concentration ratios of 

ammonia to organic amino-N, the temperature, pH and the relative reaction rates (Isaac 

and Morris, 1980). 

Organic N-chloramines can also form slowly by the reaction of inorganic chloramine 

with organic amines (Snyder and Margerum, 1982; Isaac and Morris, 1983, 1985): 

NH2Cl + RNH2 = NH3 + RNHCl 

The transfer of chlorine from monochloramine to organic amines has been shown to 

involve two mechanisms: hydrolysis of the monochloramine to ammonia and hypochlorous 

CLORAMIN.2 II-10 03/08/94
 
acid and direct chlorine transfer from a protonated monochloramine NH3Cl+ to the organic 

amine (Snyder and Margerum, 1982; Isaac and Morris, 1983, 1985). Because the chlorine 

transfer reaction is slow, its significance may be limited to large water distribution systems 

using inorganic chloramine as the disinfectant where retention time in the system becomes 

considerable. 

From a water treatment standpoint organic N-chloramines are undesirable, since they 

are not effective disinfectants (Feng, 1966; Marks and Styandskov, 1950; Wolfe et al., 

1984; Wolfe and Olson, 1985). 

Uses of Chloramines 

The combining of ammonia with chlorine for the purpose of forming chloramines to 

treat drinking water has been called combined residual chlorination, chloramination or the 

chloramine process (NRC, 1979). This process has been employed to provide a more 

persistent disinfecting residual than free chlorine. It also generally reduces the unpleasant 

taste and odors resulting from the formation of chlorophenolic compounds (Symons et al., 

1978). 

Inorganic chloramines have been considered poorer disinfectants than hypochlorous 

acid, since nearly 25 times as much chloramine as free chlorine was required to obtain a 

100% kill with equivalent contact times (Butterfield, 1948). Brodtmann and Russo (1979) 

refuted the idea that chloramine was a poor biocide for use in the treatment of drinking 

CLORAMIN.2 II-11 03/08/94 
water. They found that chloramine treatment of drinking water was effective in destroying 

60% of the total bacterial population remaining after clarification, with a contact time of 

<10 minutes. Furthermore, the chloramine treatment was effective in destroying 88% of 

the remaining coliform bacteria before sand filtration. Thus, the authors concluded that 

chloramine properly applied at effective dosages (1.5-1.8 mg/L) produced 100% kills of 

pathogenic bacterial species and reduced the total population of bacteria to an acceptable 

range. 

Analytical Methods 

Methods deemed acceptable for the determination of chlorine residuals in natural and 

treated waters include the following: colorometric methods, amperometric titration, 

stabilized neutral orthotolidine (SNORT) method, ferrous diethyl-p-phenylenediamine 

(DPD) method, and the leucocrystal violet (LCV) method. 

The most common methods of analysis of monochloramine and most monochlorinated 

organic N-chloramines use the ability of these compounds to oxidize iodide to iodine 

followed by determination of the amount of iodine formed (APHA, 1980). The iodine 

formed can be titrated with a standardized solution of sodium thiosulfate and the endpoint 

detected visually with the aid of a starch solution. It can also be detected colorimetrically 

by addition of DPD (diethyl-p-phenylenediamine), which is converted to a red oxidized 

form. The intensity of the red color is measured with a spectrophotometer at 515 nm or 

with a filter photometer equipped with a filter having maximum transmission in the 

CLORAMIN.2 II-12 03/08/94
 
wavelength range 490-530 nm. The oxidized DPD can also be titrated with standardized 

ferrous ammonium sulfate. This method is known as the FAS-DPD titrimetric method. 

Another method of measuring the iodine formed involves amperometric titration using a 

standardized solution of phenylarsine oxide. Leucocrystal violet is a colorless form of a 

dye that is converted by iodine to its colored form and measured with a spectrophotometer 

(592 nm), using a filter photometer or Nessler tubes. 

Organic amines and albumenoid nitrogen compounds interfere with the analysis of 

monochloramine in chlorinated natural waters because they respond in a similar manner. 

In addition, as described below, the use of iodometric methods for analysis of chloramines 

has contributed a considerable amount of confusion to the meaning of the term 

"chloramines" (Johnson, 1978; Jolley and Carpenter, 1983; Wajon and Morris, 1980; 

Cooper et al., 1982). There is a need for new methods for distinguishing the various 

chemical compounds that respond to conventional analyses as "free residual chlorine" and 

"combined residual chlorine." 

Most kinetic measurements of the formation, reactions and decomposition of inorganic 

mono-, di- and trichloramine have employed a direct spectrophotometric determination of 

their concentrations. Each has characteristic absorption spectra (Hand and Margerum, 

1983). However, because of their low molar extinction coefficients the method is only good 

for measurements of solutions with concentrations >10-4 M. 

CLORAMIN.2 II-13 03/08/94
 

Evans (1982) reported a voltammetric method for analysis of inorganic chloramines 

in aqueous solution from pH 4-12. However, the method has approximately the same 

sensitivity as the spectrophotometric method. 

Scully et al. (1984a) studied solutions of organic and inorganic N-chloramines in acid 

solution (pH 2) by cyclic voltammetry. Monochloramines can be distinguished from 

dichloramines and hypochlorous acid, but the method also lacks the sensitivity needed to 

measure concentrations <10-4 M. 

Scully et al. (1984b) developed a method for the analysis of organic and inorganic 

chloramines in dilute aqueous solution. The method involves derivatization of the 

chloramines with the sodium salt of 5-dimethylaminonaphthylene-1-sulfinic acid in 

bicarbonate buffer to form highly fluorescent sulfonamide derivatives. These derivatives 

can be separated by high pressure liquid chromatography so that organic chloramines can 

be measured in the presence of inorganic chloramine. The method has not yet been used 

successfully to identify organic N-chloramines in chlorinated natural waters. This will be 

necessary before the importance of organic N-chloramines in drinking water can be 

determined. 

From a strictly chemical standpoint only ammonia and organic amines (R = alkyl or 

aryl) can form chloramines. Considerable confusion, however, has been introduced into 

the nomenclature of chloramines because of the methods used in the analysis of these 

CLORAMIN.2 II-14 03/08/94
 
compounds in chlorinated natural waters and wastewaters (Johnson, 1978; Jolley and 

Carpenter, 1983; Wajon and Morris, 1980; Cooper et al., 1982). The term "combined 

residual chlorine" has been used to describe compounds in chlorinated waters that can be 

analyzed by amperometric and colorimetric methods only after addition of iodide, and the 

term "free residual chlorine" has been used to describe compounds that are generally 

analyzed by the same methods before the addition of iodide (APHA, 1980). Because 

solutions of organic and inorganic chloramines respond to these analyses as "combined 

residual chlorine" and because natural waters that contain high concentrations of ammonia 

form correspondingly high concentrations of combined residual chlorine, the terms 

combined residual chlorine and chloramines have become almost synonymous. 

Consequently, chlorinated waters that contain combined residual chlorine are said to 

contain chloramines. While the major fraction of combined residual chlorine is probably 

inorganic chloramines, other compounds including organic amines that are likely to 

contaminate natural waters and wastewaters react with chlorine to form compounds that 

respond to analyses as combined residual chlorine. For instance, proteinaceous or 

albumenoid nitrogen compounds contain amide linkages that react slowly with hypochlorite 

to form chloramides, R(C=O)NClR, which respond to analyses as combined residual 

chlorine. 

In addition, because solutions of hypochlorite are most commonly associated with free 

residual chlorine, hypochlorite and free residual chlorine also have become almost 

synonymous. Nevertheless, N-chlorosuccinimide, which is a chlorimide, and 

CLORAMIN.2 II-15 03/08/94
 
trichloroisocyanuric acid respond at least partially to conventional analyses as free 

residual chlorine (Morris et al., 1980). The term free residual chlorine most accurately 

refers to elemental chlorine, hypochlorus acid (HOCl) and hypochlorite ion (OCl ). From 

a public health viewpoint these ambiguities can present serious problems; for instance, 

organic chloramines are poor disinfectants compared with inorganic chloramine (NH2Cl) 

(Johnson, 1978). Jolley and Carpenter (1983) suggested the terms "combined oxidant" 

and "free oxidant" to avoid the ambiguities that have become associated with the residual 

chlorine term. 

Further ambiguity exists in the term chloramine because it implies simply that a 

compound, organic or inorganic, contains both a chlorine atom and an amino nitrogen 

functional group. This would then include the highly carcinogenic nitrogen mustards that 

are not formed when water containing ammonia or organic amines is chlorinated. For the 

purposes of this document, only the toxicology and health effects data of organic and 

inorganic N-chlorinated amino nitrogen compounds will be reviewed. 

Environmental Fate and Transport 

The major source of chloramines in waters is the reaction of ammonia compounds with 

added chlorine. This occurs as a by-product of chlorination (i.e., in drinking water 

processing and sewage effluents) and from use of the chlorine-ammonia process 

(chloramination). An inventory of municipal water supplies undertaken in 1963 indicated 

that 308/11,590 surveyed used an ammonia-chlorine process (chloramination) (Moore and 

CLORAMIN.2 II-16 03/08/94
 
Calabrese, 1980). For a discussion of rates of formation and breakdown of chloramines 

see the Physical and Chemical Properties Section and the Uses of Chloramines Section 

of this chapter. A 1984 survey of some U.S. utilities using chloramines (Trussell and Kreft, 

1984) showed a possible distribution of chloramine residuals. A typical range of 

chloramine concentrations in drinking water supplies where it is used as a primary 

disinfectant or to provide a residual in the distribution system is 1.5-2.5 mg/L. 

Summary 

The alternate disinfectant inorganic chloramines are formed when water containing 

ammonia is chlorinated. The type and extent of each is dependent on pH, temperature 

and relative concentrations of ammonia and hypochlorite. Under the usual concentrations 

and conditions of water and wastewater treatment, monochloramine is the principal 

chloramine formed. Ammonia reacts with an excess of hypochlorous acid to form 

dichloramine or trichloramine. Dichloramine solutions, however, are unstable and readily 

decompose. When chlorine concentrations are much greater than ammonia and the 

solutions are acidic (pH<3), trichloramine is formed. Monochloramine at standard 

temperature and pressure is a liquid, whereas trichloramine at standard temperature and 

pressure is a solid. 

Organic amines or amino acids react rapidly with hypochlorite in natural waters to form 

organic N-chloramines. Organic N-chloramines are also formed by the slow reaction of 

CLORAMIN.2 II-17 03/08/94
 

inorganic chloramines with organic amines. Information on organic chloramines and their 

reactions is very limited. 

Chloramines are used primarily as disinfectants since they are a more persistent 

disinfecting residual than free chlorine. They also reduce the unpleasant taste and odors 

in drinking water resulting from chlorophenolic compound formation. 

There are several acceptable methods for determining chlorine residuals in natural 

and treated waters. They are as follows: colorimetric methods, amperometric titration, 

stabilized neutral orthotolidine (SNORT) method, ferrous diethyl-p-phenylenediamine 

(DPD) method, and the leucocrystal violet (LCV) method. New methods with greater 

sensitivity and the ability to distinguish various chemical compounds are needed. 

The reaction of ammonia compounds with added chlorine is the major source of 

chloramine release to the environment. This is due to processes and by-products of 

chlorination. 

CLORAMIN.2 II-18 03/08/94
 

TABLE II-1 

Summary of Chemical and Physical Properties of Mono- and Trichloramines 

Properties Monochloraminea Trichloromineb,c 

Chemical structure NH Cl 2 NCl3 

Molecular weight 51.48 120.38 

Chemical Abstracts 

Registry Number 

10599-90-3 10025-85-1 

Registry of Toxic Effects of Chemical 

Substances (RTECS) Number 

FN0275000 ­

Synonyms ­ Nitrogen trichloride 

Nitrogen chloride 

Chlorine nitride 

Trichlorine nitride 

Color Yellow (liquid) Yellow oil (liquid) 

Colorless crystals 

(solid) 

Rhombic crystals 

(solid) 

Physical state 

(25 C, 1 atm) 

Liquid Thick oil or rhombic 

crystals 

Melting point, C -66 <-40 

Boiling point, C ­ <71 

Explodes at 93 

Density ­ 1.653 

Solubility in water Soluble Insoluble in cold, 

decomposes in hot 

Other solubilities ETOH, ether, 

CCl 4 , benzene

CS , PCl , 

benzene, CCl , 2 3 

4 

CHCl3 

a

RTECS, 1984
 b

Merck Index, 1983 
 c

Weast, 1983
 
TABLE II-2 

Proportions of Monochloramine (NH Cl) and Dichloramine (NHCl ) 2 2 

Formed in Water Chlorination with Equimolar Concentrations 

of Ammonia and Chlorinea,b 

pH Proportion (%) at 0 C Proportion (%) at 10 C Proportion (%) at 25 C 

NH Cl 2 NHCl2 NH Cl 2 NHCl2 NH Cl 2 NHCl2 

4 0 100 0 100 0 100 

5 34 66 20 80 13 87 

6 77 23 67 33 57 43 

7 94 6 81 9 88 12 

8 99 1 98 2 97 3 

9 100 0 100 0 100 0 

a

Source: NRC, 1980 

b

Consideration of kinetic effects leads to calculated values with lower proportions of NHCl2 
III. TOXICOKINETICS 

Introduction 

Studies relevant to the toxicokinetics of inorganic chloramines are severely 

limited. However, studies done with various chlorinated amino compounds (including 

organic chloramines) give information on the pharmacokinetics of chloramines. 

Absorption 

Scully et al. (1985) have shown that solutions of hypochlorite can react with 

amines and amino acids in stomach fluid to form the corresponding N-chloramines. In 

separate experiments piperidine (0.2 M solution) and glycine (0.5 M solution) were 

administered to Sprague-Dawley rats followed by a solution (either 200 or 1000 mg/L) 

of aqueous hypochlorite. Stomach fluid was recovered from these animals and shown 

to contain the corresponding N-chloramino derivatives. The "chlorine demand" of 

stomach fluid was determined by chlorinating the stomach fluid to various levels, 

incubating the chlorinated fluid in the dark for 1 hour and measuring the residual chlorine 

­ in essence developing a breakpoint curve for the fluid. The chlorine dosage at which 

a breakpoint was found was taken as the chlorine demand. The shape of the breakpoint 

curve was very similar to that of wastewater, exhibiting a significant irreducible minimum 

at the breakpoint and a high chlorine demand (400-800 mg/L) (Scully et al., 1986). 

Scully et al. (1985) also found that when N-chloropiperidine (1.3 mL of 1700 mg/L as 

chlorine containing 100 Ci tritium labeled N-chloropiperidine) was administered to 

CLORAMIN.3 III-1 03/04/94
 

Sprague-Dawley rats, small amounts (1-3 
 Ci) of the added chloramine appeared in the 

plasma at 30, 60 and 120 minutes after the exposure.
 

Abdel-Rahman et al. (1983) administered single oral doses of 3 mL NH2

36Cl (370 

mg/L) to four male Sprague-Dawley rats that had been fasted overnight. Each rat 

received 1.1 mg of test material ( 4.6 mg/kg/day). A peak 36Cl plasma level (10.3 g/L) 

was reached 8 hours after administration, and the absorption rate constant was 0.278 

mg/hour with an absorption half-life of 2.5 hours. The 36Cl plasma level remained at a 

plateau from 8 to 48 hours after administration. After 48 hours the radiolabel was 

eliminated from the plasma with a half-life of 38.8 hours and a rate constant of 0.018 

mg/hour. 

Toxicokinetics data on other absorption rates with respect to various dosage 

media and different routes of exposure were not available. 

Distribution 

At 24 hours following the single oral treatment to rats of NH2

36Cl as described 

above, Abdel-Rahman et al. (1983) found the level of 36Cl radioactivity in the plasma to 

be 0.87%/mL of the administered dose. During the first 24 hours the portion of the 

administered NH2

36Cl dose eliminated through the urine was 0.40% and 0.08% by the 

feces. After the addition of TCA, 0.14%/mL was precipitated from 1 mL of plasma, 

possibly indicating binding to the protein fraction. Packed cells had an activity of 

0.20%/mL that decreased to 0.06%/mL after washing twice with saline, indicating that 

CLORAMIN.3 III-2 03/04/94
 
most of the 36Cl radioactivity in the packed cells was loosely bound to the erythrocyte 

membrane or was exchangeable with the chloride in saline. 

Abdel-Rahman et al. (1983) also characterized the subcellular distribution of 36Cl 

radioactivity in rat liver preparations 24 hours following NH2

36Cl administration. The 

major portion of the activity (75%) in the whole liver homogenate was recovered in the 

cytosol, 2.5% was recovered in the microsomal, 1.5% in the nuclear and <0.1% in the 

mitochondrial fractions. Only 4.0% of the total 36Cl radioactivity of the whole homogenate 

- was precipitated by TCA. In the control experiment using 36Cl Suh and Abdel-Rahman 

(1983) found a similar liver subcellular distribution of 36Cl radioactivity: 0.82 g/g in the 

whole homogenate, 0.66 g/g in the cytosol, 0.03 g/g in the microsomes, 0.01 g/g in 

nuclei, and 0.001 g/g in mitochondria. 36Cl was administered as 200 mg/L Na36Cl (0.6 

mg/animal) solution orally. 

The distribution of 36Cl in various tissues was determined 120 hours following 

NH2

36Cl administration (Abdel-Rahman et al., 1983). Plasma contained the highest 

concentration of 36Cl radioactivity (3.15 g/g), followed by whole blood (2.66 g/g), skin 

(2.13 g/g), testes (2.09 g/g), packed cells (1.90 g/g), bone marrow (1.82 g/g), 

kidney (1.62 g/g), lung (1.58 g/g), stomach (1.53 g/g), thyroid (1.36 g/g), thymus 

(1.36 g/g), duodenum (1.20 g/g), spleen (1.11 g/g), carcass (0.77 g/g), liver (0.74 

g/g), ileum (0.59 g/g) and fat (0.18 g/g) (Figure III-1). In the control experiment with 

36Cl-labeled chloride Suh and Abdel-Rahman (1983) using 47% as much labeled 

CLORAMIN.3 III-3 03/04/94
 

material as in the NH2

36Cl study found an approximately proportional amount of 36Cl 

distributed similarly 

CLORAMIN.3 III-4 03/04/94
 


throughout the same organs, fluid and tissues (Figure III-2). The 36Cl radioactivity was 

highest in plasma (1.4 g/g) followed by whole blood (1.3 g/g), testes (1.2 g/g), 

packed cells (1.1 g/g), skin (0.9 g/g), kidney (0.8 g/g), lung (0.8 g), bone marrow 

(0.8 g/g), stomach (0.7 g/g), thymus (0.7 g/g), spleen (0.6 g/g), duodenum (0.5 

g/g), carcass (0.3 g/g), liver (0.3 g/g), ileum (0.4 g/g) and fat (0.2 g/g). 

Metabolism 

Abdel-Rahman et al. (1983) measured chloride, chlorite and chlorate in plasma 

120 hours after administration of NH2

36Cl in rats for determination of its metabolites. 

Neither 36Cl-labeled chlorite nor chlorate was detected in rat plasma. Most of the total 

36Cl was identified as 36Cl-chloride, which (according to the investigators) indicated that 

the chlorine moiety was eliminated primarily in this form (Table III-1). 

Scully et al. (1986) identified three organic N-chloramines (N-chloroglycine, 

N-chloroalanine and N-chlorophenylalanine) formed in vitro when stomach fluid from 

Sprague-Dawley rats was chlorinated with a concentration of 400 mg/L hypochlorite. 

After in vitro chlorination of stomach fluid from rats fasted for 8, 24 and 48 hours, Scully 

et al. (1990) identified and quantified N-chloroleucine or N-chloroisoleucine, 

N-chloroglycine and N-chlorophenylalanine by GC/MS. Scully et al. (1986) also found 

that because stomach fluid already contains high concentrations of amino nitrogen, the 

percent conversion of a single exogenous amine to its chloramino compound is low. 

They determined the actual yield of chloramine by administration of tritium-labeled 

piperidine followed by aqueous hypochlorite. The quantity of N-chloropiperidine formed 

CLORAMIN.3 III-6 03/04/94
 
FIGURE III-2 
 

36

Cl distribution in the rat. Four fasted rats were each administered 200 mg/L 

Na36Cl in a 3 mL solution orally. The rats were sacrificed 120 hours after administration, 

and 36Cl was determined in different organs. Values represent the mean ± SE as g 

36Cl /mL (or per gram tissue) from four rats. 

Source: Suh and Abdel-Rahman, 1983 

CLORAMIN.3 III-7 03/04/94
 

CLORAMIN.3 III-8 03/04/94
 

was determined by direct liquid chromatography of the compound. This quantity 

combined with the average chlorine demand determined for stomach fluid was used to 

calculate the yield of chloramine formed. For concentrations of hypochlorite ranging 

from 200-1000 mg/L, yields of organic chloramines varied from 50-75% of the theoretical 

amount expected for these compounds. However, Scully et al. (1986) showed that 

administration of hypochlorite to animals at low (<40 mg/L), medium (40-800 mg/L) and 

high (>800 mg/L) dosages can produce very different results. This may be due to 

different chemical reactions taking place at varying hypochlorite concentrations below 

the minimum chlorine demand. They cautioned that toxicologic studies conducted at 

high oxidant concentrations may not reflect chloramine reactions that would account for 

any toxicologic effects observed at lower oxidant concentrations or at actual drinking 

water concentrations. 

Under conditions designed to simulate the GI tract, Bercz and Bawa (1986) found 

that monochloramine caused covalent binding of radioiodide to nutrient biochemicals. 

Saliva and gastric juice were obtained from rhesus monkeys under mild anesthesia. 

Depending on their solubilities, nutrient substrates were dissolved in solvents and added 

to a mixture of 600 ppm monochloramine, 0.02 N HCl and 0.1 M KI. Monochloramine 

was believed to oxidize iodide to iodine, which subsequently reacted with nutrient 

chemicals to form iodinated organic compounds. Tyrosine, 4-aminobenzoic acid, 

arachidonic acid, and folic acid were among the compounds that became iodinated 

under the conditions of the experiment. Some of the reactions occurred under basic pH 

conditions. The observed percent binding was generally lower for reactions occurring 

CLORAMIN.3 III-9 03/04/94
 
at lower pHs. While complex mixtures of nutrients such as gastric juice and saliva 

appeared to bind iodine in dilute aqueous solution, it is important that these results be 

correctly extrapolated to physiologic pH before their significance is fully understood. 

The biologic effects of chloramine, its persistence in biologic fluids and its 

possible conversion to more toxic products were examined by the U.S. EPA (1990). The 

persistence of monochloramine in saliva and gastric fluid was examined to determine the 

extent of formation of the products dichloramine, trichloramine and molecular chlorine. 

Pooled human saliva and gastric fluid samples were treated with monochloramine to 

produce samples with initial concentrations of monochloramine between 1.0 and 20 ppm. 

These samples were continuously analyzed by membrane introduction mass 

spectrometry and tandem mass spectrometry for monochloramine, dichloramine, 

trichloramine and chlorine. The continuous monitoring experiments for the saliva 

monochloramine mixtures were done using the technique of selected ion monitoring. 

Because of constituents present in the gastric fluid samples, selected ion monitoring 

experiments were shown not to give reliable results and the multiple reaction monitoring 

procedure was used. 

Monochloramine was completely depleted in saliva in 5 minutes at the 1 ppm 

level, the 5 ppm solution was incompletely depleted in 2 hours and the monochloramine 

in the higher concentration solutions was largely unaffected. Dichloramine, trichloramine 

and molecular chlorine were not produced in detectable levels from the 

chloramine-treated saliva samples. 

CLORAMIN.3 III-10 03/04/94
 
Gastric fluid monochloramine disappeared completely in <30 seconds at all 

concentrations, and dichloramine, trichloramine and molecular chlorine were not 

observed. 

Excretion 

Abdel-Rahman et al. (1983) collected the urine, feces and expired air of 

Sprague-Dawley rats over a 5-day period after the administration of 370 mg/L (1.1 

mg/animal or 4.6 mg/kg/day) NH2

36Cl to four Sprague-Dawley rats. The amount of 

36Cl-radiolabeled material excreted by urinary and intestinal routes are summarized in 

Table III-2. During the first 24 hours after administration of NH2

36Cl, only 0.40 and 0.08% 

of the total dose administered was eliminated in the urine and feces, respectively. The 

proportion of the dose eliminated through the urine and feces at the end of the 120-hour 

study period was 25.15 and 1.98%, respectively. By comparison, Suh and 

Abdel-Rahman (1983) found that over twice as much of the 36Cl-radiolabel was 

eliminated over the 120-hour study period when 36Cl-radiolabeled chloride ion (200 mg/L 

as Na36Cl) was administered (Table III-3). They found that 57.2% of the administered 

36Cl-radiolabel was eliminated in urine and 3.0% was eliminated in feces. Unlike 

NH2

36Cl, more of the 36Cl-label was eliminated in the first 24 hours, 16.1% in urine and 

0.92% in feces. After 48 hours 36Cl was eliminated with a half-life similar to that found 

after 24 hours in the NH2

36Cl study (t1/2 = 24 hours). 

CLORAMIN.3 III-11 03/04/94
 

CLORAMIN.3 III-12 03/04/94
 

CLORAMIN.3 III-13 03/04/94
 

Discussion 

In order to interpret the results of the toxicokinetics correctly, it is necessary to 

understand the complications of the synthesis of NH2

36Cl and possible interferences. 

36Cl-radiolabeled chloride ion is available commercially. HO36Cl is synthesized 

- by acidic permanganate oxidation of the 36Cl to 36Cl2: 

2KMnO4 + 16H36Cl = 2KCl + 2MnCl2 + 536Cl2 + 8H2O. 

The 36Cl-labeled Cl2 gas is passed from the generation flask to a receiving flask where 

it is dissolved in deionized water: 

36Cl2 + H2O = HO36Cl + H36Cl 

The resulting hydrolysis converts half the labeled chlorine to HO36Cl, the desired 

compound, and half to 36Cl . 

Chlorine-36 radiolabeled inorganic chloramine is synthesized by reaction of the 

solution of HO36Cl (containing an equivalent amount of 36Cl ) with aqueous ammonia in 

bicarbonate buffer: 

NH3 + 36ClO = NH2

36Cl + HO 

CLORAMIN.3 III-14 03/04/94
 

However, the observed kinetics of NH2

36Cl absorption and elimination are necessarily 

affected by the presence of an equivalent amount of 36Cl formed during the preparation 

of the HO36Cl. 

In addition, the stomach contains high concentrations of Cl . There is a lack of 

information on the rate of chloramine-chloride exchange 

NH2

36Cl + Cl = NH2Cl + 36Cl 

in solutions of high chloride concentration. If this exchange rate is significant, the 

toxicokinetics of NH2

36Cl could appear to resemble chloride when, in fact, the compound 

has simply lost its radiolabel through exchange. This is the case for HO36Cl (Anbar et 

al., 1959) where the exchange reaction is so fast that at 25 C in the presence of 0.1 M 

chloride the exchange is 99% complete in <0.1 sec at any pH <10.8. In the absence of 

specific information on the isotopic exchange rates for NH2

36Cl, the rate of hydrolysis of 

NH2Cl as reported by Margerum et al. (1979) (k = 1.9x10-5 sec-1) and by Anbar and Yagil 

(1962) (k = 6.3x10-5 M-1 sec-1) would suggest that the rate of exchange is slow and that 

it would require between 4 and 10 hours for half the radiolabel to be lost at 25 C. 

Nevertheless, monochloramine exchanges its chlorine with organic amino nitrogen 

compounds at a rate faster than hydrolysis (Snyder and Margerum, 1982; Isaac and 

Morris, 1983, 1985). Since the stomach contains high concentrations of organic amino 

nitrogen, the chlorine from the NH2

36Cl can be transferred to these organic amino 

nitrogen compounds. How this affects the rate of isotope exchange is unknown. 

CLORAMIN.3 III-15 03/04/94 
The control reagent used in the above toxicokinetic study (Anbar et al., 1959) of 

NH2

36Cl was 36Cl . It is not likely that an oxidant as strong as NH2Cl will survive intact 

absorption, distribution, and excretion from an animal. If the chloramine is rapidly 

detoxified in the stomach to 36Cl-radiolabeled chloride and ammonia, the observed 

toxicokinetics will be identical to the control kinetics. However, if the chloramine acts as 

a chlorinating agent, other more stable chlorinated organic compounds may form. The 

observed kinetics may then be due to exposure to these chlorinated compounds. 

Summary 

Information on the absorption of inorganic chloramines is extremely limited. In one 

study Abdel-Rahman et al. (1983) calculated an absorption rate constant for 36Cl at 0.278 

mg/hour (after 8 hours) with an absorption half-life of 2.5 hours after male 

Sprague-Dawley rats were administered a single oral dose of 4.6 mg/kg/day. After 48 

hours the radiolabel was eliminated from the plasma with a half-life of 38.8 hours and a 

rate constant of 0.018 mg/hour. Absorption rates with respect to various dosage media 

and different routes of exposure were not available. However, studies done with various 

chlorinated amino compounds (including organic chloramines) give information on the 

pharmacokinetics of chloramines. Scully et al. (1985) found that when the organic 

chloramine, N-chloropiperidine, was administered to Sprague-Dawley rats, 1-3 Ci of the 

chloramine appeared in the plasma at 30, 60 and 120 minutes after the exposure. 

The distribution of radiolabeled chlorine in the subfractions of rat liver homogenates, 

in organs, tissues and fluids was similar (120 hours) after oral administration of either 

CLORAMIN.3 III-16 03/04/94
 
36 36 Cl (200 mg/L as Na36Cl) or NH2

36 Cl (370 mg/L NH 2 Cl) (Abdel-Rahman et al. 1983; Suh 

and Abdel-Rahman (1983). Plasma contained the highest concentrations of 36Cl 

radioactivity for NH36Cl followed by whole blood skin, testes, packed cells, bone marrow, 

kidney, lung, stomach, thyroid, thymus, duodenum, spleen, carcass, liver, ileum and fat 

(Abdel-Rahman et al., 1983). 

Information on the metabolism of chloramines is also extremely limited. 

Abdel-Rahman et al. (1983) indicated that chloramine (NH2

36Cl) administered to rats was 

metabolized primarily to 36Cl-chloride, which indicated that the chlorine moiety was 

eliminated in this form. 

When pooled saliva and gastric fluid were treated with monochloramine (U.S. EPA, 

1990), saliva monochloramine was depleted in 5 minutes at 1 ppm, and in higher 

concentrations was not affected, while gastric monochloramine disappeared in <30 

seconds at all concentrations tested. Dichloramine, trichloramine and molecular chlorine 

were not produced in detectable levels from the chloramine-treated saliva or gastric 

samples. 

Chloramines or their metabolites (principally chloride) are eliminated primarily 

through the urine. Abdel-Rahman et al. (1983) found that during the first 24 hours after 

a single administration of NH2

36Cl (1.1 mg/animal) to Sprague-Dawley rats, only 

0.40-0.08% of the total dose was eliminated in the urine and feces, respectively. At the 

end of 120 hours 25.15 and 1.98% of the dose was eliminated in the urine and feces, 

CLORAMIN.3 III-17 03/04/94
 
respectively. By comparison, Suh and Abdel-Rahman (1983) found that over twice as 

much of the 36Cl-radiolabel was eliminated over a 120-hour period when 200 mg/L of 

Na36Cl was administered orally to rats. Unlike NH2

36Cl, more of the 36Cl-label was 

eliminated in the first 24 hours, 16.1% in urine and 0.92% in feces. The major difference 

between the NH2

36Cl and Na36Cl studies (Abdel-Rahman et al., 1983; Suh and 

Abdel-Rahman 1983) was in the total amount of label excreted over the test period. Only 

half as much label was eliminated in the chloramine study as in the chloride study. 

Interpretation of the toxicokinetics of inorganic chloramines is difficult since 

synthesis of NH2

36Cl is complicated by possible interferences. There is a lack of 

information on the rate of chloramine/chloride exchange in solutions of high chloride 

concentrations. 

NH2

36Cl + Cl = NH2Cl + 36Cl 

If this exchange rate is significant the toxicokinetics of NH2

36Cl could appear to 

resemble chloride when, in fact, the compound has simply lost its radiolabel through 

exchange. Since the stomach contains high dose concentrations of organic amino 

nitrogen, the chlorine from the NH2

36Cl can be transferred to these organic amino 

nitrogen compounds (Snyder and Margerum, 1982; Issac and Morris, 1983, 1985). How 

this affects the rate of exchange is unknown. 

CLORAMIN.3 III-18 03/04/94
 

TABLE III-1 

Metabolism of NH 2 Cl in Rat Plasma 36 a 

Treatment 

Analyte (%/mL)b,c 

Total Cl 36 Cl 36 

NH Cl (1.1 mg) 2 

36 0.41 ± 0.08 0.35 ± 0.08 

a

Source: Abdel-Rahman et al., 1983 

b

Neither 36ClO2 nor 36ClO3 was detected in rat plasma at the time period studied. 

Values represent mean ± SE from seven (fasted) rats after 120 hours following 

NH2

36Cl treatment expressed as percentage of total administered dose per mL of 

plasma. 

c 
TABLE III-2 

Excretion of Cl in Rat 120 Hours After 36 

Single Oral Administration of NH Cl 2 

36 a 

Collection 

Period 

(hours) 

Proportion of NH Cl Excreted (%) 2 

36 b 

Urine Feces Total 

0-8 0.07 ± 0.07 

8-16 0.13 ± 0.02 

16-24 0.21 ± 0.08 

0-24 0.40 ± 0.02 0.08 ± 0.05 0.48 ± 0.02 

24-48 6.28 ± 2.87 0.48 ± 0.24 6.75 ± 3.10 

48-72 6.30 ± 5.52 0.31 ± 0.29 6.60 ± 5.80 

72-96 5.03 ± 3.03 0.26 ± 0.21 5.29 ± 3.24 

96-120 7.16 ± 1.93 0.87 ± 0.49 8.02 ± 1.44 

0-120 25.15 ± 13.32 1.98 ± 0.29 27.13 ± 13.61 

a

Source: Abdel-Rahman et al., 1983 

b

Values represent the mean ± SE from four treated (fasted) rats expressed as the 

proportion of administered dose. 36Cl was not detected in expired air throughout the 

120 hours studied. 
TABLE III-3 

Excretion of Cl in Rat 120 Hours After 36 

Single Oral Administration of Na Cl 36 a 

Collection 

Period 

(hours) 

Proportion of Na Cl Excreted (%) 36 b 

Urine Feces Total 

0-12 8.2 ± 1.9 

12-24 9.7 ± 1.9 

0-24 16.1 ± 3.8 0.92 ± 0.43 17.0 ± 3.4 

24-48 8.2 ± 1.8 0.43 ± 0.12 8.6 ± 1.8 

48-72 14.8 ± 3.2 0.55 ± 0.50 15.4 ± 2.8 

72-96 9.5 ± 1.9 0.93 ± 0.17 10.4 ± 2.0 

96-120 8.6 ± 1.6 0.17 ± 0.07 8.8 ± 1.6 

0-120 57.2 ± 10.6 3.0 ± 0.91 60.2 ± 9.7 

a

Source: Suh and Abdel-Rahman, 1983 

b

Values represent the mean ± SE from four treated rats, expressed as percentage of 

administered dose. 36Cl was not detected in expired air through the 120-hour study. 
V. HEALTH EFFECTS IN ANIMALS 

Introduction 

Animal studies on chloramines are limited. Few health-related studies have been 

conducted on chloramines in drinking water. Since chloramines may be used as an 

alternate means of disinfection, more studies are being conducted. Summaries of the 

acute, subchronic and chronic oral studies are presented in Tables V-1 and V-2. 

Short-Term Exposure 

Because individuals undergoing long-term hemodialysis have been shown to 

develop hemolytic anemia when water containing monochloramine (NH2Cl) has been 

inadvertently used in the dialysis treatment, hematologic parameters have been examined 

in several studies. Moore et al. (1980) exposed 12 male A/J mice per group for 30 days 

to a bicarbonate buffered solution (pH 8.9) of monochloramine in drinking water at 

concentrations of 2.5-200 mg/L. They found no statistically significant (two-way analysis 

and Kruskal-Wallis one-way analysis of variance) changes in nine measured blood 

parameters; however, hematocrit did rise slightly with increasing levels of monochloramine. The authors concluded that monochloramine ingested by A/J strain mice did not 

appear to produce hemolysis even at very high dose levels. 

Abdel-Rahman et al. (1984) investigated the toxicity of NH2Cl in male 

Sprague-Dawley rats. Acute exposure to a single dose at 10, 20 or 40 mg/L NH2Cl 

induced a statistically significant (p<0.05) increase in blood glutathione levels within 30 

CLORAMIN.5 V-1 03/08/94
 






minutes after administration of a 3 mL aqueous solution by gavage. On the other hand, 

chronic administration at 1, 10 or 100 mg/L doses in drinking water induced a statistically 

significant (p<0.05) decrease in glutathione after 4 months of exposure at the 1 and 100 

mg/L dose levels. The difference in glutathione blood levels following subchronic versus 

chronic exposures may be due to different physiologic responses such as 1) an increase 

in reduced glutathione levels resulting in increased RBC glutathione reductase activity 

in subchronically exposed animals, and 2) a decrease in reduced glutathione levels in 

chronically exposed animals, which is due to depletion of glutathione body stores. 

Bercz et al. (1982) studied the toxicity of monochloramine administered in drinking 

water to 5 adult males and 7 adult female African Green monkeys with body weights 

ranging from 3.0-5.7 kg. Monochloramine was administered for 6 weeks at 100 mg/L. 

The authors estimated the mean daily dose to be 10 mg/kg/day. Such ingestion of 

monochloramine had no detectable effect in 18 hematologic tests on the 12 monkeys, 

including red cell GSH levels. No evidence of thyroid suppression was detected in 

serum. Maziarka et al. (1976) also found that rats exposed for 9 months to 9.0 mg/L 

chloramines showed no observable hematologic effects. However, the study was not a 

dose-response type and many of the blood parameters reflecting oxidant stress were not 

measured. 

In a review of alternate disinfectants Bull (1980) reported the results of a 45-day 

study in which 10, 50 or 100 mg/L (1.4, 7.0 and 14.0 mg/kg assuming rats consume 0.14 

L/day) monochloramine in drinking water was administered to laboratory rats. Body 

CLORAMIN.5 V-7 03/08/94
 
weight gain and hematologic parameters in exposed animals did not differ significantly 

from control animals. The only significant finding was a decrease in the amount of 

methemoglobin present in the blood at 100 mg/L monochloramine. This is the opposite 

of what was expected. There were no signs of overt toxicity (Bull, 1980). Details of this 

study were not reported. 

A subchronic 30-day toxicity test was performed on groups of 10 male and 10 

female CD-1 mice using concentrated drinking water samples collected at a pilot scale 

drinking water treatment plant using monochloramine for disinfection purposes (Miller et 

al., 1986). The residual monochloramine level was 2.1 mg/L before concentration of 

organics by reverse osmosis. Samples were concentrated (100x or 400x) before 

toxicologic testing. Post exposure, the mice were examined for gross pathologic changes. 

Body weights were not significantly different from controls. There was a statistically 

significant increase (p<0.05) in liver-to-body weight ratios of females and a statistically 

significant decrease (p<0.05) in the lung weights of males and females at 100x. The 

brain and kidney weights were significantly decreased (p<0.05) in males at 100x. At 400x 

the kidney and liver weights of males were significantly decreased (p<0.05) and the ovary 

weights of females were significantly increased (p<0.05). The authors conclude that 

these data did not reveal any overt toxicity; therefore, histopathologic examinations of 

major organs was not performed. 

A draft report by GSRI (1981) investigated the effects following exposure to 

monochloramine in Fischer 344 rats and B6C3F1 mice. Rats (10/sex/group) were 

CLORAMIN.5 V-8 03/08/94
 
administered concentrations of 0, 25, 50, 100, 200 and 400 ppm (25, 50, 100, 200 and 

400 mg/L) monochloramine in drinking water ad libitum for 91 days. Using water and food 

consumption data provided in the report, corresponding doses were calculated to be 2.5, 

4.9, 10.2, 18.8 and 40.7 mg/kg/day for males and 3.8, 6.5, 13.8, 26.6 and 53.9 mg/kg/day 

for females. No animals died during the course of the study. After 25 days the buffer 

system for monochloramines was changed because of a palatability problem at the 

high-dose levels. Terminal body weight gains in male rats decreased at the 200 and 400 

ppm levels by 13 and 24%, respectively, when compared with their controls. Female rats 

gained 8 and 14% less weight than their controls at the 200 and 400 ppm levels, 

respectively. The decrease in the percentage of body weight gain was most marked at 

0-4 weeks and appeared to be related to the palatability of the 200 and 400 ppm 

solutions. Absolute liver weights showed a trend toward reduced liver size; however, 

when liver weights were expressed as a percentage of total body weight no significant 

differences were observed. Protein excretion increased in male rats when 200 and 400 

ppm monochloramine was administered. Microscopic examination of tissues at the 400 

ppm level did not reveal any treatment-related lesions. This study identified a NOAEL for 

rats of 100 ppm (10.2 mg/kg/day). (Confidence in this study is low because of questions 

regarding the conduct of this study, the histopathologic evaluations and lack of 

corroboration of its findings.) 

Similarly, mice (10/sex/group) were administered concentrations of 0, 25, 50, 100, 

200 and 400 ppm (25, 50, 100, 200 and 400 mg/L) monochloramines in drinking water ad 

libitum for 91 days. Using water and food consumption data provided in the report 

CLORAMIN.5 V-9 03/08/94
 
corresponding doses were 4.9, 8.3, 14.5, 31.3 and 50.7 mg/kg/day for males and 7.7, 

12.1, 21.9, 34.6 and 88.5 mg/kg/day for females. During the course of the study no 

animals died. The buffer system for monochloramines was changed after 25 days since 

palatability was a problem at the high dose levels. Male and female mice gained less 

weight than the controls at the 200 and 400 ppm levels. There was a reduction in 

absolute liver weights and liver-to-body weight ratios in male mice at the 400 ppm levels 

and in female mice at >100 ppm. Histopathologic observations revealed necrotic 

changes at the low doses and mild to moderate cytologic alteration in the livers of male 

mice administered 200 and 400 ppm. Chronic liver inflammatory changes occurred at 

100, 200 and 400 ppm in female mice and to a lesser extent in male mice at the 100 ppm 

level. At concentrations of 100, 200 and 400 ppm increased frequency of mitotic figures, 

hypertrophy and bizarre chromatin patterns occurred in males and in one female at 200 

ppm. This study identified a NOAEL for mice of 50 ppm (8.4 mg/kg/day). 

In a more recent study, Daniel et al. (1990) administered 0, 25, 50, 100 and 200 

mg/L monochloramine to male and female Sprague-Dawley rats (10/sex/dose) in their 

drinking water for 90 consecutive days. Using food and water consumption data provided 

in the report, corresponding doses were calculated to be 0, 1.8, 3.4, 5.8 and 9.0 

mg/kg/day for males and 0, 2.6, 4.3, 7.7 and 12.1 mg/kg/day for females. A control group 

received distilled water buffered with sodium bicarbonate to a pH of 8.0-8.5. Mortality, 

clinical signs, body weight, organ weights, food consumption, hematology, clinical 

chemistry, gross pathology, and histopathology were examined. Water consumption was 

significantly decreased at all monochloramine doses. At 200 mg in males water 

CLORAMIN.5 V-10 03/08/94
 
consumption was 31% of controls and in females at 200 mg water consumption was 

34% of controls. 

Food consumption was significantly reduced in males at the highest dose tested. 

In males there was a significant reduction in body weight gain at doses of 50 mg/L and 

higher. The reduced body weight gain in females was significant only at 200 mg/L. For 

males and females the average weight gain at 200 mg/L was 51% of controls. At the 

200 mg/L dose, reductions in the absolute weight of liver and spleen were observed in 

both sexes. In females, the absolute weight of the thymus was also decreased as was 

the weight of the lung and heart of the males. Also at 200 mg/L, females had increased 

relative kidney and decreased relative liver weights while males had increased relative 

brain, testes and kidney weights. 

At 100 mg/L males had significantly decreased absolute liver weights and at 50 

mg/L males had decreased absolute lung weights. At the 25 mg/L dose, there was no 

significant effect on absolute organ weights in either sex. The authors concluded that the 

100 mg/L dose is considered the NOAEL. Although reductions in organ weights 

appeared to be dose-related in males, subsequent histopathologic examination did not 

reveal any target organ or treatment-related changes. Although reduced RBC count (200 

mg/L) and decreased calcium levels in males were significant, the authors did not 

consider them biologically significant, dosage-related or within the normal range for rats 

of this age and strain. 

CLORAMIN.5 V-11 03/08/94
 

Daniel et al. (1991) administered monochloramine in drinking water for 90 days to 

male and female B6C3F1 mice (10/sex/dose) at 0, 12.5, 25, 50, 100 and 200 mg/L. Using 

food and water consumption data provided in the report, corresponding doses were 

calculated to be 0, 2.5, 5.0, 8.6, 11.1 and 15.6 mg/kg/day for males and 0, 2.8, 5.3, 9.2, 

12.9 and 15.8 mg/kg/day for females. Mortality, clinical signs, body weight, organ 

weights, food consumption, hematology, clinical chemistry, gross pathology and 

histopathology were examined. Food consumption was decreased in males and females 

at the two highest dose levels with a statistically significant decrease in females. Water 

consumption was decreased in all treated groups with statistically significant decreases 

in female mice at all treatment levels and male mice at the two highest levels. 

In males there was an increase in lymphocytes at 100 and 200 mg/L and in 

females there was a decrease in neutrophils at 100 mg/L and a decrease in MCV in all 

dose levels. None of the hematology results were considered to be dose related. Alk-P 

was decreased in males at all concentrations, statistically significant at 25, 50 and 100 

mg/L, while AST was increased in females at all dose levels, and statistically significant 

at 50 and 200 mg/L. 

There were significant reductions in body weight gain in males at the three highest 

dose levels, and at the two highest dose levels in females. Significant decreases in water 

consumption occurred in all doses in female mice and at the two highest dose levels in 

males. Significant reductions in absolute organ weights were evident in males and 

females drinking 200 mg/L monochloramine. In male and female mice, liver and heart 

CLORAMIN.5 V-12 03/08/94
 
weights were decreased at the two highest dose levels, and relative and absolute spleen 

weights were decresed in the two highest doses for females. At the highest dose, the 

kidney and lung weights were decreased in males and females; also at the highest dose, 

absolute testes and spleen weights were decreased in males. When analyzed relative 

to body weight, brain, kidney, lung and testes in males and brain and kidney in females 

were significantly increased at the highest dose compared with the control value. Based 

on relatively minor changes at 100 mg/L of monochloramine, including <10% depression 

of body weight and the greater changes at 200 mg/L (19-25% decreased body weight), 

the 100 mg/L dose (12.9 mg/kg/day) can be identified as a NOAEL in this study. 

No compound-related gross or microscopic lesions were observed, and no target 

tissues were identified in the monochloramine-treated animals. 

Exon et al. (1987) administered monochloramine at 0, 9, 19 and 38 ppm (mg/L) in 

the drinking water of male Sprague-Dawley rats (12/sex/dose) from weaning to 12 weeks 

of age (9 weeks of exposure). Based on reference body weight and water consumption 

values for subchronic exposure (U.S. EPA, 1986), the corresponding intake of 

monochloramine was 0, 1.3, 2.6 and 5.3 mg/kg/day. Following treatment, the test animals 

were assessed for immune competence. Parameters of immunity measured were spleen 

and thymus weights, antibody production, delayed-type hypersensitivity (DTH) reactions, 

natural killer cell (NKC) cytotoxicity, oxidative metabolism response and phagocytosis by 

macrophages and production of two immunoregulatory cytokines, interleukin 2 (I12) and 

prostaglandin E2 (PGE2). Significant (p<0.05) reduction of spleen weights (38 ppm), 

CLORAMIN.5 V-13 03/08/94
 
decreased antibody synthesis (9 and 19 ppm) and augmented PGE2 production (19 and 

38 ppm) were reported. The authors state that these results indicate that B lymphocyte, 

as well as macrophage function may be adversely affected. While monochloramine 

appears to exert immunotoxic effects, the biologic importance of effects on the immune 

system as a factor in the toxicity of monochloramines is not clear. In addition, there is a 

lack of correlation among various endpoints examined, as well as deficiencies in some 

of the methodologies (i.e., the use of the ELISA test for antibody analysis). Based on 

these considerations, a NOAEL or LOAEL cannot be determined from this study. 

Since pigeons may be susceptible to cardiovascular disease, Revis et al. (1986) 

investigated the relationship of monochloramine to plasma cholesterol and thyroid levels. 

Groups of 12 male white carneau pigeons (age 3-4 months) were fed altered diets and 

drinking water containing either 0 (deionized water), 2 or 15 ppm monochloramine ad 

libitum for 3 months. The treatment diets consisted of either (A) a diet reduced to 0.35% 

calcium (80% of the minimal daily requirement for a pigeon) i.e., a normal diet, or (B) a 

diet reduced to 0.35% calcium with the addition of 10% lard and 0.5% cholesterol, i.e., 

a high cholesterol diet. The controls were given either diet and deionized water ad 

libitum. Treated drinking water was prepared and changed daily. At 1-month intervals 

blood samples were collected and plasma levels of cholesterol and T4 were determined. 

The study reported that plasma T4 levels were significantly decreased in pigeons fed a 

normal diet (A) or high cholesterol diet (B) and drinking water containing 15 ppm 

monochloramine. Following a 3-month exposure to diet B and receiving either deionized 

water or water containing 15 ppm monochloramine, plasma cholesterol levels were 

CLORAMIN.5 V-14 03/08/94
 
1266±172 and 2049±212 mg/dL, respectively, a difference of 783 mg/dL. Significant 

increases in plasma cholesterol were also observed in pigeons at the 2 ppm level 

compared with deionized water and when both groups were fed only the calcium-deficient 

diet (A). No significant changes were observed in the comparative 15 ppm diet (A) group. 

T4 levels were not significantly altered when 2 ppm monochloramine and diet (A) were 

administered. There was no clear dose-response effect for plasma cholesterol observed 

in any of the treatment groups. Thus, factors associated with the effects of 

monochloramine on plasma cholesterol are not known. The authors suggested that the 

changes in plasma cholesterol may be mediated by products formed when 

monochloramine reacts with organic matter in the upper GI tract. Pigeons may or may 

not mimic humans in thyroid function, so the significance of effects in the pigeons 

relationship to humans is unknown. Also, pigeons were maintained on a calcium deficient 

diet in order to depict an average human diet. It is not known if pigeons metabolize 

calcium in the same manner as humans. 

Other Short-term Effects 

Robinson et al. (1986) treated female Sencar mice (5/dose) with aqueous solutions 

of monochloramine by whole-body exposure (except head) for a 10-minute period for 4 

days to assess hyperplastic effects. The backs of the animals were shaved 3 days before 

treatment of 1, 10, 100 and 1000 mg/L of monochloramine. Animals were sacrificed the 

day following the last treatment and skin thickness measured. TPA 

(12-o-tetradecanoylphorbol13-acetate) was applied at a dose of 1.0 g in 0.2 mL 

acetone/mouse to the positive control mice. Epidermal thickness on the fifth experimental 

CLORAMIN.5 V-15 03/08/94
 
day measured 

given water measured 15.4 

32.8 
 m in the positive controls. The epidermal layer in control animals 

m. Exposure to 1, 10, 100 and 1000 mg/L monochloramine 
 

decreased epidermal thickness ( 14.0, 14.4, 13.1 and 13.6, respectively); however, this 

was not significant when compared with controls. In addition, cell counts were not 

increased at any of the doses when compared with controls. 

Flour bleached with trichloramine administered in the diet has been shown to 

produce "canine hysteria" or "running fits" in dogs. However, one study suggests that this 

is a species-specific phenomenon for dogs (Mellanby, 1946; Silver et al., 1947a,b,c; 

Newell et al., 1947) and does not affect humans (Pollock, 1949). Trichloramine is formed 

in waters at high chlorine-to-ammonia ratio concentrations and at lower pHs than normally 

found in drinking water. 

Long-Term Exposure 

Abdel-Rahman et al. (1984) conducted a study to investigate the toxicity of NH2Cl 

in drinking water (see Table V-2). Groups of four male Sprague-Dawley rats drank either 

0, 1, 10 or 100 mg/L NH2Cl in deionized water daily for 12 months. The levels of 

chlorine, dichloramine and trichloramine in the NH2Cl solution were <1%, <1% and 0%, 

respectively, of the total NH2Cl added. Food was available ad libitum and body weight 

was measured during the treatment. Cardiac puncture and collection of heparinized 

blood was performed at 2, 4, 6, 8, 10 and 12 months after treatment. Hematologic 

parameters, blood glutathione (GSH) levels and osmotic fragility were monitored 

throughout the treatment period. 3

H-Thymidine incorporation was studied in liver, kidney, 

CLORAMIN.5 V-16 03/08/94
 
testes, intestinal mucosa and spleen after 3 months of treatment. Increased incorporation 

of 3H-thymidine was observed in the kidney and spleen at 1 and 10 mg/L and in testes at 

100 mg/L at 3 months; other time periods were not examined. Body weights were 

significatnly reduced after 3 months of treatment at 100 mg/L and remained lower than 

controls throughout the experiment. Blood levels of chloroform monitored during the 

study were no different than in untreated rats. Results varied over the 12-month study 

period, but at 6 and 12 months after initiation of the study statistically lower GSH levels 

were observed at all doses. After 3 months of treatment significant decreases in RBC 

count and hematocrit were observed at the higher dose levels. A reduction in hemoglobin 

concentration and mean corpuscular hemoglobin occurred at 100 mg/L after 10 months 

of treatment. The decrease in blood GSH could be due to a protective role by GSH 

against damage caused by oxidants. The health significance of these types of changes 

is uncertain. Furthermore, results were analyzed by inappropriate statistical methods and 

a number of "significant" changes in hematologic parameters relative to control values 

were identified that had no consistent relationship with dose and were not observed 

consistently throughout the period of exposure. 

The NTP (1990) conducted two studies to determine the potential chronic toxicity 

or carcinogenic activity of chloraminated drinking water. In the first study F344/N 

(70/sex/dose) rats were administered chloramine for 2 years at doses of 0, 50, 100 and 

200 ppm in pH 9 buffered charcoal filtered deionized drinking water. These doses were 

calculated on the basis of a time-weighted average to be 0, 2.1, 4.8 and 8.7 mg/kg/day 

for male rats and 0, 2.8, 5.3 and 9.5 mg/kg/day for female rats. There was a dose-related 

CLORAMIN.5 V-17 03/08/94
 
decrease in the amount of water consumed by both sexes; this decrease was noted 

during the first week and continued throughout the study. Food consumption of treated 

rats was the same as the controls with males consuming more. Mean body weights of 

200 ppm dosed rats were lower than their control groups. However, mean body weights 

of rats receiving chloraminated drinking water were within 10% of controls until week 97 

for females and week 101 for males. At the end of the study all animals were given a 

complete histopathologic examination. The authors determined that no clinical changes 

were attributable to chloraminated drinking water. Survival of rats receiving 

chloraminated drinking water was not significantly different than controls except that, for 

the 50 ppm dose groups, survival was greater than that of controls. 

Groups of rats (10/sex/group) were predestined for incremental sacrifice and 

evaluation at 14 and 66 weeks. At these times a complete hematologic examination and 

necropsy were performed on all animals and histopathologic examinations were 

performed on all control and high-dose rats. In F344/N rats at the 14-week evaluation the 

mean body weight at necropsy of 200 ppm dosed males was significantly lower (p<0.01) 

than that of controls while mean body weights of low- and mid-dose males was similar to 

that of controls. At the 66-week evaluation, there was a dose-related decrease in body 

weights of chloraminated treated male rats. The mean body weights of high-dose male 

and female rats were 94 and 92% of controls, respectively. Slight decreases (p<0.05) in 

the liver and kidney weight in high-dose males and kidney-to-body weight ratios in male 

and female high-dose rats were related to the lower body weights in these groups. 

CLORAMIN.5 V-18 03/08/94
 

The second NTP (1990) study was a 2-year study to determine the potential 

chronic toxicity or carcinogenic activity of chloraminated drinking water. B6C3F1 mice 

(70/sex/dose) were administered chloramine at doses of 0, 50, 100 and 200 ppm in pH 

9 buffered charcoal filtered deionized drinking water. These doses were calculated based 

on a time-weighted average to be 0, 5.0, 8.9 and 15.9 mg/kg/day for male mice and 0, 

4.9, 9.0 and 17.2 mg/kg/day for female mice. There was a dose-related decrease in the 

amount of water consumed by both sexes; this decrease was noted during the first week 

and continued throughout the study. Male and female mice had similar food 

consumptions as controls except the 200 ppm dose females that were slightly lower than 

controls. There was a dose-related decrease in mean body weights of dosed male and 

female mice throughout the study. Mean body weights of high-dose male mice were 

10-22% lower than their control group after week 37 and the body weights of high-dose 

female mice were 10-35% lower after week 8. Survival of mice receiving chloraminated 

drinking water was not significantly different than controls. All animals were given a 

complete histopathologic examination at the end of the study. The authors did not 

attribute any clinical findings to the consumption of chloraminated drinking water. 

Groups of mice (10/sex/group) were predestined for incremental sacrifice and 

evaluation at 15 and 66 weeks. A complete hematologic examination and necropsy were 

performed on all animals and a histologic examination was performed on all controls and 

high-dose rats at the incremental sacrifices. At 15 weeks the group mean body weights 

of high-dose male and female mice were 91 and 84% of controls, respectively. At the 

66-week evaluation, the differences in body weight between the high-dose mice and 

CLORAMIN.5 V-19 03/08/94
 
controls was 87% for females but 91% of controls for mid- and high-dose males. 

Decreases in liver weights and increases in brain- or kidney-to-body weight ratios 

observed in high-dose mice at 15 or 66 weeks were attributable, according to NTP, to the 

lower body weights in these groups. 

Because specific organic N-chloramines have not yet been identified in chlorinated 

water or in vivo on ingestion of chlorinated water, Bempong and Scully (1980a) studied 

N-chloropiperidine (NCP), a model for the health effects of organic chloramines as a class 

of compounds. They found it was toxic to C57Bl/J6 mice after i.p. injection. Groups of 

10 female and 10 male mice were injected with either 50, 100, 200, 300 or 400 mg/kg bw 

of NCP. The animals were observed daily for toxic effects, food intake and body weight. 

The LD50 for NCP was slightly greater than 300 mg/kg as presented by the available data. 

However, the toxicity of NCP was increased when allowed to stand at room temperature 

in an aqueous solution, indicating that the degradation products are more toxic. The 

toxicity of the chloramine was less than that of the parent amine, but the toxicity of 

aqueous solutions of the chloramine increased on standing at room temperature for 24 

hours or more. 

Developmental Toxicity 

Abdel-Rahman et al. (1982) investigated the effects of monochloramine 

administered in drinking water to adult female Sprague-Dawley rats. Six animals/group 

were administered 0, 1, 10 or 100 mg/L NH2Cl daily in the drinking water both 2.5 months 

before and throughout gestation. Sacrifice of rats on the 20th day of gestation was 

CLORAMIN.5 V-20 03/08/94
 
performed for soft-tissue and skeletal examination of the progeny. Monochloramine did 

not produce any significant changes in rat fetuses at any dose level; in fact, there was a 

slight increase in fetal weight in all NH2Cl groups compared with controls. 

Reproductive Toxicity 

Eight- to 10-week-old hybrid male mice (C57Bl/J6 x DBA2) and 10-week-old inbred 

male golden Syrian hamsters (numbers not specified) were given daily exposures (ad 

libitum) to 400 mg/kg/day NCP in 0.001% ethanol for 100 days. Significant increases of 

abnormal sperm (either tail or head anomalies) were observed in both hamsters and mice 

after 5 weeks of exposure (Bempong and Scully, 1983). Another significant result among 

NCP-treated hamsters was reduced sperm count after 70 days of daily exposure. Greater 

than 80% of the hamster population was classified as sterile based on their reproductive 

performance. A few (number not provided) were reported as having testicular atrophy 

after 16 weeks of daily exposure. Gradual reductions in percent abnormal sperm were 

observed after the 75th day of treatment in hamsters; however, sperm counts did not 

increase. In mice the level of sperm abnormalities remained the same for more than 5 

weeks except there was a reduction in sperm tail damage with concomitant increased 

anomalous sperm heads. Sperm count was also reduced in mice but did not affect 

percent anomalous sperm. The data support the concept that species and strain 

differences in sperm abnormalities are suggestive of genotoxic control of sperm 

development. In addition, the investigators propose that since increased levels of sperm 

abnormalities were observed >5 weeks after treatment, the most sensitive cells were early 

CLORAMIN.5 V-21 03/08/94
 

spermatocytes > differentiating spermatogonia > premeiotic cells (Bempong and Scully, 

1983). 

Fertility studies were also undertaken wherein male mice and male hamsters were 

caged with two respective females after 1 week of continuous exposure as described 

previously (Bempong and Scully, 1983). The duration of each mating period was 7 days. 

Six treatment groups of 15-25 females were constituted in the following manner: 

1) untreated (UT) female x UT male; 2) UT female x ethylmethane sulfonate (EMS)­

treated male; 3) NCP-treated female x NCP-treated male; 4) UT female x NCP male; 

5) NCP female x UT male; and 6) piperidine-treated female x piperidine-treated male. 

EMS served as a positive control and piperidine was included to ascertain the extent to 

which effects could be ascribed to the monochloramine group. Reduced fertility indices 

were observed on week 5 and subsequently for all matings of NCP-treated animals, 

except when females only were exposed (group 5). To obtain data on potential 

embryotoxic effects of NCP, five pregnant animals/group were allowed to reach term and 

the offspring were counted. Numbers of offspring/pregnancy were variable for the 

NCP-treated animals, but was lowest for the group (3) wherein both males and females 

received NCP. Treatment with NCP increased the number of uterine moles, particularly 

when the female was exposed. Implant frequency was reduced in all NCP treatment 

groups; exposure of both males and females resulted in a significantly greater reduction 

than treatment of either single parent (Bempong and Scully, 1983). 

CLORAMIN.5 V-22 03/08/94
 

In a more recent study, Carlton et al. (1986) administered monochloramine by 

gavage at doses of 0, 2.5, 5.0 and 10 mg/kg bw/day to male (12/dose) and female 

(24/dose) Long-Evans rats for 66-76 days. Males were treated for 56 days and females 

for 14 days before mating. The administration was continued during the 10-day mating 

trial period, and thereafter females were gavaged with monochloramine daily throughout 

gestation and lactation. Males were necropsied at the end of the mating period and bled 

for complete blood counts and thyroid hormone levels. Their sperm was examined for 

normalcy and histologic examinations were performed on the reproductive tract including 

the testis, epididymus, prostate and seminal vesicles. Dams and some offspring were 

necropsied at weaning 21 days after birth of the pups. At necropsy dams were bled for 

complete blood counts and thyroid hormone levels. In addition, the reproductive tract was 

removed for histopathologic examination. Other offspring were administered chloramines 

after weaning until they were 28-40 days old; these pups were evaluated for vaginal 

patency and thyroid hormone levels. The authors reported no significant (statistical 

analysis not provided) differences between control and exposed rats in fertility, viability, 

litter size, day of eye opening, or average day of vaginal patency (day 31.8-32.6). There 

were no alterations in sperm count, direct progressive sperm movement, percent mobility, 

or sperm morphologic characteristics in adult males. Weights of male and female 

reproductive organs were not significantly different among test and control groups, and 

there were no significant morbid anatomic changes evident on tissue examination. There 

were no signs of toxicity, changes in hematologic parameters, or body weight suppression 

in adult rats of either sex at any dose level. The mean weight of the pups was unchanged 

from that of control litters. Based on these data, a NOAEL of 10 mg/kg/day is identified. 

CLORAMIN.5 V-23 03/08/94
 
Mutagenicity 

Lu Shih and Lederberg (1976) showed chloramine to be weakly mutagenic at the 

trpC locus of Bacillus subtilis. They further investigated the biologic and physical effects 

of chloramine on B. subtilis after treatment of the bacterial cells or the bacterial DNA. 

Both resulted in single-strand breaks and a few double-strand scissions at higher 

chloramine doses, with loss of DNA-transforming activity. Since some DNA 

repair-defective mutants seem to be more sensitive to chloramine, it would appear that 

chloramine's bacteriotoxic effect may be due in part to its ability to damage DNA. 

Thomas et al. (1987) reported that monochloramine (40 m) slightly increased the 

number of revertant colonies over untreated control levels in assays employing 

Salmonella typhimurium (TA97, TA100 and TA102). Positive controls were run 

concurrently. Lipophilic dichloramines were the most active mutagens in this study. 

Fetner (1962) found that distilled water containing monochloramine produced 

chromosome breakage when used for soaking Vicia faba seeds. A 1-hour exposure to 

10-4 M monochloramine produced 24% abnormal anaphases (including chromosomal 

bridges and fragments) in the embryonic Vicia roots. As there was no visible browning 

of the plant embryos, Fetner concluded that monochloramine produced chromosome 

breakage at a concentration that exhibited little evidence of tissue damage. 

Meier et al. (1985) evaluated the ability of monochloramine and other oxidants to 

induce chromosomal aberrations (5/sex/dose) and micronuclei in the bone marrow of 

CLORAMIN.5 V-24 03/08/94
 
CD-1 mice (4/sex/dose), and sperm-head abnormalities in male B6C3F1 mice (10/dose). 

Monochloramine administered by gavage at concentrations of 40, 100 and 200 mg/L 

showed no evidence of any significant effects in any of the tests. 

Bempong and Scully (1980a) found that the organic chloramine, NCP, was weakly 

mutagenic in a preincubation Salmonella reverse mutation assay (Ames test). Mutagenic 

activity was detected in the absence of exogenous S9 activation in strains TA1535 and 

TA100. The toxicity of the chloramine appeared to overshadow its mutagenic property 

at doses >64 g/plate with a concomitant reduction in the number of revertants/plate. 

N-Chlorodiethylamine, on the other hand, was highly toxic but nonmutagenic (Scully et 

al., 1983). 

The effect of increasing concentrations of NCP on the toxicity, mitotic indices and 

chromosomal aberrations were studied in Chinese hamster cells (CHO). CHO cells 

exposed to NCP (0.4-2.4 g/L) for 3 hours and analyzed during a 96-hour period 

proliferate less rapidly than control cells and as the concentration of NCP increased, 

mitotic indices were reduced and the peaks of mitotic activity shifted resulting in 

chromosome separation and nuclear distribution. CHO cells were exposed to increasing 

concentrations of NCP (0, 0.4, 0.8 and 1.2 

after treatment and analyzed for chromatid aberrations (breaks, exchanges, fragments, 

ring and centric errors). The increases in the frequency of aberrations were proportional 

to the increase in NCP concentration with breaks accounting for the major proportion of 

aberrations. Chromosomal aberrations were further investigated after a 3-hour incubation 

g/mL) for a 3-hour period, harvested 48 hours 

CLORAMIN.5 V-25 03/08/94
 

and a 60-hour recovery period to allow for delayed mitotic activities, and increased 

populations of metaphases. A nonlinear dose-dependent increase in bridges, dicentrics, 

exchanges, fragments and ring configurations occurred (Bempong and Scully, 1980b; 

Bempong et al., 1981, 1986; Scully and Bempong, 1982). 

Chloramine T (sodium p-toluenesulfonylchloramide) tested negative in a 

Salmonella reverse mutation assay (Ames test) in the presence of S-9 in strains TA98, 

TA100, TA1535 and TA1538 (Anderson and Styles, 1978), and negative in strains TA98, 

TA100, TA1535, TA1537 and TA1538 with and without S-9 fractions (Gocke et al., 1981). 

Weitberg (1987) tested the ability of chloramine T (sodium p-toluenesulfonylchloramide) to produce SCEs in cultured CHO cells. A significant 

dose-dependent increase was observed at 10-5 to 10-7 M and at 10-8 M when compared 

with controls. This effect was significantly diminished when cells were treated with 

methionine, a thioether, which reduces N-Cl back to the parent amine. 

Süssmuth (1982) examined the mutagenicity of chlorinated solutions of several 

amino acids using several strains of bacteria including the recombination-deficient strain 

of B. M45 (rec), Es. coli P3478 (polA1), and three histidine auxotrophic strains of S. 

himurium. Chlorinated solutions of methionine, tyrosine, phenylalanine and glycine were 

mutagenic in more than one strain of bacteria. The active mutagens in Süssmuth's 

solutions were not defined clearly. Since the amino acids react rapidly in chlorinated 

water to form N-chloramino acids, the first group of compounds to form would be the 

CLORAMIN.5 V-26 03/08/94
 
chloramine acids. These may be the active mutagens; however, because some of the 

chloramine acids are labile, their degradation by-products may be the active mutagens. 

An Ames Salmonella assay was performed using concentrated drinking water 

samples collected at a pilot scale drinking water treatment plant disinfected with 

monochloramine (Miller et al., 1986). The reverse osmosis concentrates ranged from 

0.025-1.0 mL. The mutagenic response was negative for strains TA98 or TA100 when 

tested with or without the metabolic activation system S9. 

Carcinogenicity 

Several initiation-promotion studies have been conducted. Although these studies 

are not useful for quantitative risk assessment, they may support findings in bioassay 

studies. 

Settled, coagulated and sand-filtered Ohio River water was treated with 

monochloramine at 3 mg/L (Bull, 1980; Bull et al., 1982). The residual disinfectant was 

dissipated within 48 hours. The water was then concentrated by reverse osmosis and the 

concentrate subjected to a mouse skin initiation-promotion assay in SENCAR mice. A 

total of 1.5 mL of the reverse osmosis concentrate was applied to the backs of the mice 

in six doses (0.25 mL each) over a 2-week period. This was followed by thrice weekly 

applications of 2.5 ug of the promoting agent phorbol myristate acetate in acetone for 18 

weeks. Nondisinfected water concentrates produced no tumors, while concentrated 

monochloramine-treated water samples induced neoplasms in 5/25 animals. Lesions 

CLORAMIN.5 V-27 03/08/94
 
included papillomas (1/25), squamous cell carcinomas (2/25) and lung adenomas (5/25). 

Overall chi-square analysis comparing numbers of animals with systemic tumors indicated 

that the increase was not significant. Subsequent to the results published by Bull (1980), 

five additional experiments were undertaken using new samples of disinfected waters. 

Results of two of these were published by Bull et al. (1982). In initiation-promotion 

assays of concentrated monochloramine-treated water samples at a dose of 1.0 g for 

20 weeks, 23% and 15% of animals developed papillomas respective to the two studies. 

For these assays, however, papillomas were also observed in 15 and 13% of mice treated 

with saline and in 20% of mice exposed to nondisinfected water concentrates. The 

authors pointed out that the average tumor incidence of all the monochloramine 

concentrated water-exposed animals is almost twice that of the simultaneous controls and 

is more than double the historical control response. It is likely that the initiating activity 

of the water concentrates is not due to the monochloramine per se, but rather to organic 

chloramines or other materials formed as by-products of the disinfection process. The 

authors noted that as the reverse osmosis process used to produce the water 

concentrates does not concentrate low molecular weight organics, trihalomethanes were 

not included in these test samples. 

Herren-Freund and Pereira (1986) tested chloramines for initiation-promotion 

activity in rat liver by using the rat liver foci bioassay. The endpoint of the assay is the 

occurrence of altered foci of hepatocytes. This assay uses an increased incidence of 

-glutamyltranspeptidase positive foci (GGT foci) as an indicator of carcinogenicity since 

initiation-promotion bioassays using GGT foci have detected both hepatic and nonhepatic 

CLORAMIN.5 V-28 03/08/94
 
carcinogens. Male rats (authors do not clarify if Fischer 344 or Sprague-Dawley or both 

were used) were administered chloramine (route not specified) 14.75 mg/kg bw 24 hours 

following a 2/3 partial hepatectomy. Seven days after initiation, promotion by 500 ppm 

phenobarbital in drinking water was begun. After 10 weeks of exposure to phenobarbital, 

the rats were removed from the exposure to the promoter for 1 week and then sacrificed. 

Positive and negative controls were run concurrently. The authors reported that under 

conditions of this study chloramine did not initiate GGT foci. 

Similar results were reported by Miller et al. (1986) when rats (10/group) were 

administered concentrated drinking water samples collected at a pilot scale drinking water 

treatment plant using monochloramine for disinfection purposes, which were concentrated 

(4000x or 2000x the residual concentration of 2.1 mg/L) by the macroreticular resin 

process. Rats were partially (2/3) hepatectomized on day 0 and treated 24 hours later 

with chloramines for 1 week. On day 7 the rats received 500 ppm sodium phenobarbital 

in their drinking water for 56 days. Chloramine-treated water did not initiate the incidence 

of GGT foci above that of the vehicle control group. 

One of the toxicologic tests used for determining tumor-initiating potential of 

concentrated drinking water samples is the mouse lung adenoma assay. Concentrated 

drinking water samples from a pilot treatment plant using monochloramine for disinfectant 

purposes was administered to 6-week-old strain A mice in drinking water samples 

concentrated (4000x and 2000x) by the macroreticular resin process (Miller et al., 1986). 

The residual chloramine level before concentration was 2.1 mg/L. Both positive and 

CLORAMIN.5 V-29 03/08/94
 
negative controls were run concurrently. The vehicle controls had 0.1 adenoma/animal 

and the treated animals had 0.20 adenoma/animal, indicating there was no 

treatment-related effect. 

The National Toxicology Program (NTP, 1990) conducted a 2-year study of 

chloraminated drinking water in F344/N rats at doses of 0, 50, 100 and 200 ppm. This 

dose was calculated to be 0, 2.1, 4.8 and 8.7 mg/kg/day for males and 0, 2.8, 5.3 and 9.5 

mg/kg/day for females. The purpose of this study was to determine the potential chronic 

toxicity or carcinogenic activity of chloraminated water. The water from all treatment 

groups was charcoal filtered and deionized to remove organic substances and other 

residues. 

According to the authors there were no neoplasms or nonneoplastic lesions in rats 

of the 2-year study that were attributable to the consumption of chloraminated drinking 

water. The incidence of mononuclear cell leukemia was slightly increased relative to that 

of controls in the mid- and high-dose range. Although female rats receiving 

chloraminated water had significantly greater leukemia incidence in the high-dose group 

than the controls, there was no clear dose response and the incidence of leukemia in the 

female control group (16%) was less than the untreated historical controls (25%). There 

was also no evidence of a reduced latency in the occurrence of leukemia in female rats 

consuming chloraminated water. However, because of the marginal statistical 

significance the increased incidence of leukemia was considered equivocal evidence of 

CLORAMIN.5 V-30 03/08/94
 

carcinogenic activity in female rats. There was no evidence of carcinogenic activity of 

chloraminated drinking water for male rats. 

The National Toxicology Program (NTP, 1990) conducted another 2-year study of 

chloraminated drinking water in B6C3F1 mice at doses of 0, 50, 100 and 200 ppm. These 

doses were calculated to be 0, 5.0, 8.9 and 15.9 mg/kg/day for males and 0, 4.9, 9.0 and 

17.2 mg/kg/day for females. The purpose of this study, as with the rat study, was to 

determine the potential chronic toxicity or carcinogenic activity of chloraminated water. 

The water from all treatment groups was charcoal filtered and deionized to remove 

organic substances and other residues. 

Renal tubular cell adenomas occurred in two high-dose and one low-dose male 

mice; focal tubule hyperplasia was seen in one low-dose, three mid-dose and one 

high-dose male. Hyperplasia was also observed in male control animals. There were no 

other lesions in the kidneys of male or female mice receiving chloraminated water. 

Histopathology evaluation of the kidneys failed to identify any difference in the incidence 

or severity of renal tubular atrophy, dilation, regeneration, focal mineralization, or protein 

casts. Step sections of the kidneys of male mice did not provide supportive evidence of 

a chemical effect. There were no neoplasms or nonneoplastic lesions in mice in the 

2-year study that were attributable to the consumption of chloraminated drinking water, 

according to the authors. There was no evidence of carcinogenic activity of 

chloraminated drinking water for male or female mice. 

CLORAMIN.5 V-31 03/08/94
 

Summary and Discussion 

Several short-term studies showed no observed adverse hematologic effects in 

mice, rats and monkeys (Moore et al., 1980; Bercz et al., 1982; Bull, 1980). In A/J mice 

administered chloramine solutions between 2.5 and 200 mg/L (pH 8.9) for 30 days, the 

only observable effect was a slight increase in hematocrit (Moore et al., 1980). In another 

study of similar duration (45 days) rats treated with 10, 50 or 100 mg/L monochloramines 

experienced a decrease in the amount of methemoglobin present in the blood, the 

opposite of what was expected (Bull, 1980). Monochloramine in drinking water for 6 

weeks at 100 mg/L resulted in no detectable effects on 18 hematologic tests of 12 African 

Green monkeys (Bercz et al., 1982). The results from the three studies described above 

are somewhat conflicting in that similar dose levels and duration produced different 

changes in hematologic parameters (i.e., increased hematocrit, decreased 

methemoglobin in blood) while others produced no detectable effects. In one longer-term 

study in which blood glutathione levels were decreased after 12 months of exposure to 

monochloramine, there was a lack of dose- and time-dependency in the observed effects 

(Abdel-Rahman et al., 1984). 

One possible reason for the varying observations between laboratories may be the 

conditions under which the solutions of monochloramine are generated. It is understood 

that, as the pH of a solution of monochloramine is lowered, some of the monochloramine 

is converted to dichloramine. To avoid this, solutions are frequently buffered to pH 8 to 

avoid dichloramine formation. However, in doing this, buffer concentrations may be 

exerting an unusually strong effect on the reactions of disinfectants in the stomach where 

CLORAMIN.5 V-32 03/08/94
 
enzyme activity is usually greatest (lower pH). The pH and buffer concentrations of the 

monochloramine solutions used in toxicity studies may vary widely from laboratory to 

laboratory. 

A draft report by GSRI (1981) investigated the effects in rats and mice 

administered drinking water containing 0, 25, 50, 100, 200 or 400 mg/L monochloramine 

for 91 days. Using water and food consumption data provided in the report, 

corresponding respective doses were 2.5, 4.9, 10.2, 18.8 and 40.7 mg/kg/day for male 

rats; 3.8, 6.5, 13.8, 26.6 and 53.9 mg/kg/day for female rats; 4.9, 8.3, 14.5, 31.3 and 50.7 

mg/kg/day for male mice; and 7.7, 12.1, 21.9, 34.6 and 88.5 mg/kg/day for female mice. 

Animals experienced decreased body weight gain and liver damage at 200 and 400 mg/L 

monochloramine in rats and 100, 200 and 400 mg/L monochloramine in mice. Based on 

these observations, the investigators suggested a NOEL of 50 mg/L or 8.3 mg/kg/day 

monochloramine. 

In addition monochloramine at 9, 19 and 38 ppm in drinking water may exert 

immunotoxic effects to male Sprague-Dawley rats. Significant (p<0.05) reduction of 

spleen weight (38 ppm), decreased antibody synthesis (9 and 19 ppm) and augmented 

PGE2 production (19 and 38 ppm) were reported (Exon et al., 1987). The biologic 

importance of effects on the immune system as a factor in the toxicity of monochloramines 

is not clear. 

CLORAMIN.5 V-33 03/08/94
 

Daniel et al. (1990) investigated the effects of monochloramine administered for 

90 days in the drinking water of Sprague-Dawley rats at 0, 25, 50, 100 and 200 mg/L. 

Based on food and water consumption data, doses were calculated to be 0, 1.8, 3.4, 5.8 

and 9.0 mg/kg/day for males and 0, 2.6, 4.3, 7.7 and 12.1 mg/kg/day for females. For 

males and females the average weight gain at 200 mg/L dose was 51% of controls. 

Reductions in absolute and relative organ weights occurred at 200 mg/L. The authors 

concluded that 100 mg/L is considered the NOAEL. 

Daniel et al. (1991) also investigated the effects of monochloramine administered 

for 90 days in the drinking water of B6C3F1 mice at 0, 12.5, 25, 50, 100 and 200 mg/L. 

Based on food and water consumption data, doses were calculated to be 0, 2.5, 5.0, 8.6, 

11.1 and 15.6 mg/kg/day for males and 0, 2.8, 5.3, 9.2, 12.9 and 15.8 mg/kg/day for 

females. Based on decreases in liver, heart and lung weights in males and liver, heart 

and spleen weights in females at 100 mg/L and decreased weight gain and food 

consumption in both sexes and reduced water consumption in females, the 50 mg/L 

concentration is considered the NOAEL. 

NTP (1990) conducted two studies for 2 years (F344/N rats and B6C3F1 mice) to 

determine the potential chronic toxicity for chloraminated drinking water. Chloramine was 

administered at doses of 0, 50, 100 and 200 ppm. These doses were calculated to be 0, 

2.1, 4.8 and 8.7 mg/kg/day for male rats and 0, 2.8, 5.3 and 9.5 mg/kg/day for female rats, 

and 0, 5.0, 8.9 and 15.9 mg/kg/day for male mice and 0, 4.9, 9.0 and 17.2 mg/kg/day for 

female mice. Mean body weights of 200 ppm dosed rats were lower than controls. Slight 

CLORAMIN.5 V-34 03/08/94
 
decreases in organ-to-body weight ratios in high-dose rats were related to the lower body 

weights. There was a dose-related decrease in mean body weights of dosed male and 

female mice throughout the study. No clinical changes were attributable to chloraminated 

drinking water in the rat or mouse study. 

Studies suggest that flour treated with trichloramine may cause "canine hysteria" 

but one study suggests that this is a species-specific phenomenon in dogs (Mellanby, 

1946; Silver et al., 1947a,b,c; Newell et al., 1947) and does not affect humans (Pollock, 

1949). 

Few studies have been conducted on organic N-chloramines. Studies conducted 

with N-chloropiperidine suggest that organic chloramines may be toxic, but determination 

of their environmental significance will rely on identification of specific organic 

N-chloramines actually formed on chlorination of natural waters (Bempong and Scully, 

1980a). 

Monochloramine was not teratogenic in mature female Sprague-Dawley rats 

exposed to 1, 10 or 100 mg/L in drinking water nor did 40, 100 and 200 mg/L solutions 

induce sperm-head anomalies in B6C3F1 mice (Abdel-Rahman et al., 1982). 

In a more recent study there were no significant differences in fertility, viability, 

litter size, day of eye opening or day of vaginal potency between control and exposed 

Long-Evans rats given 10 mg/kg chloramines. There were no alterations in sperm 

CLORAMIN.5 V-35 03/08/94
 
count, direct progressive sperm movement, percent mobility or sperm morphologic 

characteristics in adult males. Weights of male and female reproductive organs were not 

significantly different among test and control groups. 

Data on the mutagenicity of chloramines are inconclusive. A number of studies 

suggest that monochloramine and some organic N-chloramines and N-chloramino acids 

may be weakly mutagenic. Monochloramine has been found to be marginally mutagenic 

in Bacillus subtilis bacteria (Lu Shih and Lederberg, 1976) and in Vicia faba plant seeds 

(Fetner, 1962). It was responsible for cellular hypertrophy, increased mitotic figures and 

bizarre chromatin patterns in B6C3F1 mice exposed to 200 and 400 mg/L in drinking 

water (Wolfe et al., 1984). Thomas et al. (1987) reported monochloramine (40 um) 

slightly increased the number of revertant colonies over untreated control levels in assays 

employing Salmonella typhimurium (TA97, TA100 and TA102). In addition, 

monochloramine showed no evidence of producing spermhead abnormalities in B6C3F1 

mice or inducing chromosomal aberrations and micronuclei in bone marrow of CD-1 mice 

(Meier et al., 1985). 

The organic chloramine, N-chloropiperidine, was found to be marginally mutagenic 

in the reverse mutation plate incorporation assay (Ames test). It was cytotoxic and 

cytostatic in CHO cells and produced chromosomal aberrations, the frequency of which 

was proportional to the concentration of the compound (Bempong and Scully, 1980b; 

Bempong et al., 1981, 1986; Scully and Bempong, 1982). It produced SCEs in CHO 

cells, but not in baby hamster kidney cells (Scully et al., 1983). The analogous 

CLORAMIN.5 V-36 03/08/94
 
chloramine, N-chlorodiethylamine, was more toxic but nonmutagenic (Scully et al., 1983). 

When the synthetic N-Cl compound chloramine T (sodium p-toluenesulfonylchloramide) 

was tested, SCEs were significantly increased in a dose-dependent manner in CHO cells 

(Weitberg, 1987). 

Data indicate that chloramine per se is not an initiator (Bull et al., 1982; Bull, 1980; 

Herren-Freund and Pereira, 1986). Two-year studies by the National Toxicology Program 

(NTP, 1990) have shown equivocal evidence of carcinogenic activity in female rats that 

is due to the slightly increased incidence of mononuclear cell leukemia compared with 

that of concurrent controls, although incidence in historical controls was higher. There 

was no evidence of carcinogenic activity that isdue to chloraminated drinking water in 

male rats or in male or female mice. Until the carcinogenicity of chloramines is further 

delineated, it is categorized in group D, not classifiable as to human carcinogenicity, 

meaning that there is inadequate human and animal evidence of carcinogenicity (U.S. 

EPA, 1986). 

CLORAMIN.5 V-37 03/08/94
 

VI. HEALTH EFFECTS IN HUMANS 

Introduction 

Data on the human health effects observed following exposure to chloramines are 

limited to a few clinical reports and epidemiologic studies. Several cases have been 

reported where chloramine-T has caused allergic contact dermatitis. Clinical reports 

indicate that acute chloramine exposure either by inhalation or ingestion results in 

burning eyes and throat, dyspnea, coughing, nausea, reversible pulmonary damage and 

allergic responses. One epidemiologic study looked at a population exposed to 

chloramine in its drinking water and used the disease risk as a baseline for comparing 

the risk in a population exposed to chlorine in its drinking water. These findings will be 

addressed only briefly as they are not directly relevant to this document. Damage to red 

blood cells has been observed in high risk subpopulations such as hemodialyzed 

individuals. 

Clinical Reports and Experiments 

Lombardi et al. (1989) reported the work related case of a 38-year-old nurse who 

developed subacute eczema that appeared to be caused by the use of chloramine-T as 

an antiseptic disinfectant in the cleansing of burns. Only a few cases of sensitization to 

chloramine-T have been reported and usually from nonoccupational contact even though 

it has widespread use in Italy as an antiseptic, disinfectant and chemical reagent. 

CLORAMIN.6 VI-1 03/08/94
 

Laakso et al. (1982) reported the case of a 27-year-old woman who mixed 500 

mL of 4-5% household ammonia with the same amount of 5% sodium hypochlorite 

bleach in a small, poorly ventilated bathroom. The vapors from the mixture caused 

burning in the eyes and throat, dyspnea, coughing, nausea and vomiting. Inhalation of 

the chloramine fumes resulted in pneumonitis, which did not result in permanent 

pulmonary damage. 

Beck (1983) reported the case of a 28-year-old nurse who suffered from rhinitis 

when she was in contact with a chloramine solution. Chloramine is often used as an 

antiseptic in the treatment of infected ulcers, and when the nurse was treated with a 2% 

chloramine solution for a dental abscess, a severe angioneurotic edema developed. 

Since this Type I reaction to chloramine was reported only once before, the authors 

recommended that a prick test with chloramine be used before treatment of patients with 

previous exposures. 

A clinical study was conducted by Lubbers et al. (1981) to assess the safety of 

chronically administered chlorine water disinfectants in humans. This study was 

conducted in three parts over a 12-week period. Phase I and Phase II subjects were 

male college students between the ages of 21 and 35 years of age, of normal body 

weight and free of any history of disease or any medical or surgical condition that might 

interfere with the absorption, excretion or metabolism of substances by the body. Phase 

III subjects were glucose-6-phosphate dehydrogenase deficient, but were normal in all 

other respects. 

CLORAMIN.6 VI-2 03/08/94
 
Phase I consisted of an increasing dose tolerance analysis in which progressive 

doses of chlorine were administered in water as chlorate, chlorine dioxide, chlorite, 

chlorine and chloramine to six groups, 10 subjects/compound with 10 subjects in the 

control group that received untreated water. Chloramine was given every 3 days for a 

total of 15 days, at concentrations of 0.01, 1.0, 8.0, 18.0 and 24.0 mg/L (corresponding 

doses of 0.14, 14, 110, 260 and 340 ug/kg/day assuming a body weight of 70 kg) in a 

total volume of 1000 mL. 

Phase II consisted of 60 subjects randomly assigned into six treatment groups of 

10 subjects/group with one group receiving untreated water. A daily concentration of 5 

mg/L chloramines in a volume of 500 mL of water was administered for 12 consecutive 

weeks. Physicals and collection of blood and urine were conducted on a weekly basis 

during the treatment period and for 8 weeks following. 

Phase III was conducted on male students who were deficient in 

glucose-6-phosphate dehydrogenase and were considered to be more susceptible to 

oxidative stress. These students were given 5 mg/L of sodium chlorite daily in a volume 

of 500 mL for 12 consecutive weeks. 

Blood and urine samples were collected and physical exams were given, including 

blood pressure measurements and taste tests. During all three phases of this study a 

massive volume of raw data was acquired. No definitive finding of detrimental 

physiologic impact was made in any of the three phases of this human investigation of 

CLORAMIN.6 VI-3 03/08/94
 
the relative safety and tolerance of oral chlorine disinfectant ingestion. Other possible 

confounders such as diet and other sources of drinking water were not addressed. The 

fact that there were no overt adverse health effects within the limitations of this study 

suggests that ingestion of chloramine at these levels over a relatively short period of time 

produces no toxicity in healthy adult males, but does not rule out the possibility that 

longer treatment periods would result in any detectable adverse outcomes of biologic 

significance. 

Epidemiology Studies 

There are no epidemiologic studies that have been designed to address 

specifically the potential adverse effects of exposure to chloramines on human health. 

The study of Zierler et al. (1986, 1988) was designed in response to earlier ecologic 

studies that indicated that areas using chlorinated surface waters for drinking water were 

associated with higher cancer mortality than areas using other sources of drinking water 

and disinfectant practices. The addition of chlorine to surface water is known to form 

organic micropollutants (Murphy and Craun, 1990). Specifically, the reaction of free 

chlorine with naturally occurring precursor substances, primarily humic and fulvic acids, 

produces a group of halogen-substituted single-carbon compounds known as 

trihalomethanes (THMs) (Craun, 1988). The predominant THMs formed are chloroform 

and bromodichloromethane. The process of chloramination produces only small 

amounts of THMs. It was originally thought that the early findings of increased cancer 

mortality associated with chlorinated drinking water might be due to exposure to the 

THMs themselves. Zierler's study in Massachusetts was conducted to see if there was 

CLORAMIN.6 VI-4 03/08/94
 
a difference in cancer mortality among communities using chlorine compared with 

communities using chloramine for disinfection. In this sense, the persons who were 

exposed to chloraminated drinking water were used as controls with the assumption 

being they would be much less exposed to chlorination by-products. 

The first phase of this study (Zierler et al., 1986) looked at the patterns of cancer 

mortality among 43 communities using either chlorine or chloramine since 1938. All 

resident Massachusetts deaths among those 45 years and older and occurring during 

1969-1983 were eligible for the study. Deaths were selected for inclusion if the last 

residence listed on the death certificate was in a community using chlorine or chloramine 

for disinfection. Cancers of the bladder, colon, kidney, pancreas, rectum, stomach, lung 

and female breast were thought to be related to chlorinated by-products of disinfection 

and were therefore treated as cases for a mortality odds ratio (MOR) analysis. Deaths 

from cardiovascular and cerebravascular disease, chronic obstructive lung disease and 

lymphatic cancer (N=214,988), considered to be unrelated to chlorinated by-products, 

were used for comparison. In general, cancer mortality was not associated with type of 

disinfectant in the MOR analysis. There was a slight association (MOR=1.05) for 

chlorine use noted only with bladder cancer that increased slightly (MOR=1.15, 95% 

confidence interval = 1.06-1.26) when lung cancer deaths were used for controls. 

Standardized mortality ratio analysis of the data set were generally unremarkable. There 

was a small increase in mortality (SMR=118, 95% confidence interval = 116-120) from 

influenza and pneumonia in the chloraminated communities. 

CLORAMIN.6 VI-5 03/08/94
 

The second phase of this mortality study (Zierler et al., 1988) was designed to 

further pursue the bladder cancer findings in a more refined case-control analysis, which 

included decedent next-of-kin interviews. Information on cigarette smoking, occupation 

and residential history was obtained. The relationship with bladder cancer and 

residence in communities using chlorine for disinfection again persisted. The crude 

association was highest for lifetime residents of chlorinated drinking water communities 

relative to lifetime residents of chloraminated drinking water communities (MOR=1.5, 

95% confidence interval = 1.1-2.2) when lymphatic cancers were used for controls. The 

MOR increased to 2.7 after controlling for the joint effects of age, gender, occupation and 

pack-years of cigarette smoking. Although the exposure estimates in these analyses are 

relatively crude, there is a consistent relationship, albeit small, with bladder cancer 

mortality and years of exposure to chlorinated drinking water when compared with years 

of exposure to chloraminated drinking water. The study was not designed to assess 

adverse effects from exposure to chloramine, but rather considers the 

chloramine-exposed participants as controls. At this time there are no epidemiologic 

studies that have evaluated chloraminated drinking water as the exposure of interest and 

not the control exposure. 

High-Risk Subpopulations 

Eaton et al. (1973) studied hemodialyzed patients (number of subjects not 

reported) from three University of Minnesota hospitals. They observed significant 

methemoglobinemia (>5% statistical analysis not provided) and Heinz body inclusions 

in the red cells of the patients in two hospitals, which used unpurified tap water and 

CLORAMIN.6 VI-6 03/08/94
 
water purified with the reverse osmosis (RO) technique during dialysis. The RO 

technique removes particulate matter and trace metals from the dialysis water. 

Charcoal-filtered RO water that did not contain chloramines was used in the third 

hospital, and did not result in significant methemoglobinemia. Serial observation of 

several patients exposed to chloramines through dialysis suggested that the RBC 

oxidant damage was cumulative. In addition to oxidant damage to the RBC, chloramines 

inhibit the metabolic pathway used by these cells to prevent and repair such damage. 

Thus, chloramine-containing dialysis water presented a severe threat of acute hemolytic 

anemia to uremic patients undergoing dialysis. 

Kjellstrand et al. (1974) also observed similar effects in patients undergoing 

hemodialysis. The authors concluded that chloramines induced their deleterious effects 

through the formation of methemoglobin from the direct oxidation of hemoglobin, and 

through damage of the hexosemonophosphate shunt (HMPS), with which red cells 

defend themselves against oxidant damage. The authors suggested that 

chloramine-induced hemolysis may be reduced by the addition of ascorbic acid to the 

treatment water. 

Summary and Discussion 

Few acute exposures to chloramines have been reported in the literature. Laakso 

et al. (1982) reported pneumonitis as a result of inhalation of chloramine fumes from a 

mixture of household ammonia and sodium hypochlorite. Permanent pulmonary damage 

CLORAMIN.6 VI-7 03/08/94
 

was not sustained. Beck (1983) reported a Type I allergic response after treatment with 

a 2% chloramine solution for a dental abscess. 

One experimental study on chloramines was located in the available literature. 

Lubbers et al. (1981) reported no hematologic or abnormal effects following routine 

clinical tests in individuals ingesting 0.01, 1.0, 8.0, 18.0 and 24.0 mg/L (0.14, 14, 110, 

260 and 340 mg/kg/day, respectively) chloramines for 1 day in drinking water or 5 mg/L 

chloramines for 12 weeks in drinking water. It is unknown, however, whether exposure 

beyond this time would have any impact. 

Although mentioned here for the sake of completeness, the work of Zierler et al. 

(1986, 1988) should not be used as definitive evidence that chloramine exposure is not 

associated with adverse health effects in humans. Although statistically stable because 

they are based on large numbers of deaths, the community based SMR analyses 

represent a relatively crude means of assessing the relationship of a specific cause of 

death with a specific drinking water disinfection practice. If there is a positive 

relationship between these variables, it may go undetected because of the attenuating 

effects of random misclassification of the observed deaths into exposure categories. The 

case-control study of bladder cancer was designed to use the chloramine exposure as 

the comparison group and does not address the potential adverse effects from 

chloramine, although often misinterpreted in this way. 

CLORAMIN.6 VI-8 03/08/94
 

Hemodialyzed patients are a high-risk subpopulation for chloramine exposure 

through chloraminated dialysis water. Chloramines cause oxidant damage to red blood 

cells and inhibition of the hexose-monophosphate shunt with which red blood cells 

defend themselves against oxidant damage (Eaton et al., 1973; Kjellstrand et al., 1974). 

Thus, this high-risk group must also be considered when using monochloramine for 

disinfection of water used in dialysis. 

CLORAMIN.6 VI-9 03/08/94
 

VII. MECHANISMS OF TOXICITY 

General Theories 

The literature on the mechanism of inactivation of microorganisms by chloramines 

is limited. Since low levels of inorganic chloramines are effective in inactivating bacteria, 

Nusbaum (1952) proposed that the mechanism of action must essentially be the same as 

that of hypochlorous acid on enzymes; that is, the chloramine molecules enter the 

cytoplasm and interfere with enzymatic reations. Ingols et al. (1953) studied bactericidal 

mechanisms of chlorine compounds on unspecified bacterial suspensions. They noted 

that monochloroamine bacteriotoxicity was not completely reversed by the addition of 

sulfhydryl radicals; and thus, conclude that sulfhydryl radical oxidation was not the 

exclusive mechanism of toxicity. They proposed that the sulfhydryl group of critical 

enzymes may be the point of vulnerability to a strong oxidant (for example, chlorine 

dioxide) but that changes in other functional groups may also be involved in cell death. 

Thus, a weak oxidant like monochloramine may lead to microbial inactivation by changes 

in groups other than sulfhydryls. 

Lu Shih and Lederberg (1976) showed that chloramine applied to both intact 

Bacillus subtilis cells or to the extracted bacterial DNA resulted in double and single strand 

breaks. Some microbial toxicity may, therefore, be attributable to DNA damage. 

Monochloramine produced chromosome breaks in Vicia faba (Fetner, 1962), and organic 

chloramines have been shown to produce chromosomal abnormalities in rodent cells 

(NIEHS, 1982). 

CLORAMIN.7 VII-1 07/27/93
 

Through observation of patients undergoing long-term hemodialysis and 

concomitant analysis of the water used for this process, Eaton et al. (1973) ascertained 

that chloramines were probably the oxidants responsible for hemolytic anemia in the 

patients. In vitro studies using human RBCs indicated that chloramine produced 

denaturation of hemoglobin through direct oxidant damage to erythrocytes. It also 

inhibited the hexose monophosphate shunt, which generates NADPH that in turn protects 

RBCs from oxidant damage. 

A study by Grisham et al. (1984) demonstrated that organic N-chloramines formed 

in vivo play an important role in ameliorating oxidant effects but can also contribute to 

monochloramine formation. These workers stimulated isolated human neutrophilic 

leukocytes to produce hydrogen peroxide (H2O2) and secrete cytoplasmic granule 

components such as myeloperoxidase into the medium. Myeloperoxidase catalyzed the 

- oxidation of chloride (Cl ) by H2O2 to yield hypochlorous acid (HOCl). The HOCl, in turn, 

reacted with endogenous nitrogen compounds to yield derivatives containing 

nitrogen-chlorine (N-Cl) bonds, such as hydrophilic, low molecular weight, 

mono-N-chloramine (RNHCl) derivatives. The RNHCl derivatives were of low toxicity, but 

reacted with ammonium ion (NH4

+

) to yield monochloramine (NH2Cl). The bactericidal, 

cytotoxic and cytolytic activities of the organic N-chloramines (RNHCl) result from reaction 

of RNHCl derivatives and the ammonium ion. This indicates that neutrophil amines act as 

a trap for HOCl, and by competing with endogenous NH4

+ for reaction with HOCl, protect 

neutrophils and other cells from oxidative attack. The RNHCl derivatives remain as a 

CLORAMIN.7 VII-2 07/27/93
 

reserve of oxidizing equivalents that convert to a toxic form when an increase in NH4

+ 

concentration favors formation of monochloramine. 

Nusbaum (1952) proposed that the mechanism of action of dichloramine was similar 

to monochloramine, but there are insufficient data to support this contention. Silver et al. 

(1947c) demonstrated that trichloramine reacted with cystine and cysteine residues to 

produce a reagent that was responsible for causing canine hysteria. 

Summary 

Bactericidal, cytotoxic and cytolytic activities of organic N-chloramines (RNHCl) 

result from the reaction of RNHCl derivatives and the ammonium ion to yield 

monochloramine (NH2Cl). The RNHCl derivatives remain as a reserve of oxidizing 

equivalents, which convert to a toxic form when the ammonium ion concentration increases 

favoring monochloramine formation (Grisham et al., 1984). 

It has been suggested that the chloramine molecules enter the cytoplasm and 

interfere with enzymatic reactions (Nusbaum, 1952). Ingols et al. (1953) found 

monochloramine required higher concentrations and longer contact times to destroy 

bacteria than hypochlorous acid, suggesting that monochloramine led to microbial 

inactivation through enzyme changes that may not have been involved in bacterial 

inactivation by hypochlorous acid. Chloramines are also capable of causing DNA damage 

in bacterial plant and mammalian cells, which may contribute to cytotoxicity. Eaton et al. 

(1973) found that chloramines produced denaturation of hemoglobin through both direct 

oxidant damage to RBCs and inhibition of the hexose monophosphate shunt. 

CLORAMIN.7 VII-3 07/27/93
 
CLORAMIN.7 VII-4 07/27/93
 

RfD (NOAEL or LOAEL ) 

[Uncertainty Factor (s) x Modifying Factor ] mg /kg /day 

VIII. 

Introduction 

The quantification of toxicologic effects of a chemical consists of separate 

assessments of noncarcinogenic and carcinogenic health effects. 

produce carcinogenic effects are believed to have a threshold dose below which no 

adverse, noncarcinogenic health effects occur, while carcinogens are assumed to act 

without a threshold. 

In the quantification of noncarcinogenic effects, a Reference Dose (RfD), [formerly 

termed the Acceptable Daily Intake (ADI)] is calculated. h 

uncertainty spanning perhaps an order magnitude) of a daily exposure to the human 

population (including sensitive subgroups) that is likely to be without an appreciable risk 

of deleterious health effects during a lifetime. -

adverse-effect level (NOAEL), or lowest-observed-adverse-effect level (LOAEL), identified 

from a subchronic or chronic study, and divided by an uncertainty factor(s) times a 

modifying factor. 

Selection of the uncertainty factor to be employed in the calculation of the RfD is 

based upon professional judgment, while considering the entire data base of toxicologic 

effects for the chemical. d 

QUANTIFICATION OF TOXICOLOGIC EFFECTS 

Chemicals that do not 

The RfD is an estimate (wit 

The RfD is derived from a no-observed 

The RfD is calculated as follows: 

In order to ensure that uncertainty factors are selected an 

CLORAMIN.VIII VIII-1 03/08/94
 

applied in a consistent manner, the U.S. EPA (1994) employs a modification to the 

guidelines proposed by the National Academy of Sciences (NAS, 1977, 1980) as follows: 

Standard Uncertainty Factors (UFs) 

Use a 10-fold factor when extrapolating from valid 

experimental results from studies using prolonged exposure to 

average healthy humans. This factor is intended to account 

for the variation in sensitivity among the members of the 

human population. [10H] 

Use an additional 10-fold factor when extrapolating from valid 

results of long-term studies on experimental animals when 

results of studies of human exposure are not available or are 

inadequate. This factor is intended to account for the uncertainty in extrapolating animal data to the case of humans. 

[10A] 

Use an additional 10-fold factor when extrapolating from less 

than chronic results on experimental animals when there is no 

useful long-term human data. This factor is intended to 

account for the uncertainty in extrapolating from less than 

chronic NOAELs to chronic NOAELs. [10S] 

Use an additional 10-fold factor when deriving an RfD from a 

LOAEL instead of a NOAEL. This factor is intended to account 

for the uncertainty in extrapolating from LOAELs to NOAELs. 

[10L] 

Modifying Factor (MF) 

Use professional judgment to determine another uncertainty 

factor (MF) that is greater than zero and less than or equal to 

10. The magnitude of the MF depends upon the professional 

assessment of scientific uncertainties of the study and data 

base not explicitly treated above, e.g., the completeness of the 

overall data base and the number of species tested. The 

default value for the MF is 1. 

The uncertainty factor used for a specific risk assessment is based principally upon 

scientific judgment rather than scientific fact and accounts for possible intra- and 

CLORAMIN.VIII VIII-2 03/08/94
 
DWEL (RfD ) x (Body weight in kg ) 

Drinking Water Volume in L/day mg /L 

interspecies differences. W 

guidelines for selection of an uncertainty factor include the use of a less than lifetime study 

for deriving an RfD, the significance of the adverse health effects and the counterbalancing 

of beneficial effects. 

From the RfD, a Drinking Water Equivalent Level (DWEL) can be calculated. 

DWEL represents a medium specific (i.e., drinking water) lifetime exposure at which 

adverse, noncarcinogenic health effects are not anticipated to occur. 

100% exposure from drinking water. h 

effects basis for establishing a drinking water standard. 

derived as follows: 

where: 

Body weight = assumed to be 70 kg for an adult 

Drinking water volume = assumed to be 2 L/day for an adult 

In addition to the RfD and the DWEL, Health Advisories (HAs) for exposures of shorter 

duration (1-day, 10-day and longer-term) are determined. s 

informal guidance to municipalities and other organizations when emergency spills or 

contamination situations occur. milar to the RfD 

and DWEL; however, the NOAELs or LOAELs are identified from acute or subchronic 

studies. 

Additional considerations not incorporated in the NAS/OD 

The 

The DWEL assumes 

The DWEL provides the noncarcinogenic healt 

For ingestion data, the DWEL is 

The HA values are used a 

The HAs are calculated using an equation si 

The HAs are derived as follows: 

CLORAMIN.VIII VIII-3 03/08/94
 

HA (NOAEL or LOAEL ) x (bw ) 

(UF ) x ( L /day ) mg /L 

Using the above equation, the following drinking water HAs are developed for 

noncarcinogenic effects: 

1. 1-day HA for a 10 kg child ingesting 1 L water per day. 

2. 10-day HA for a 10 kg child ingesting 1 L water per day. 

3. Longer-term HA for a 10 kg child ingesting 1 L water per day. 

4. Longer-term HA for a 70 kg adult ingesting 2 L water per day. 

The 1-day HA calculated for a 10 kg child assumes a single acute exposure to the 

chemical and is generally derived from a study of <7 days duration. The 10-day HA 

assumes a limited exposure period of 1-2 weeks and is generally derived from a study of 

<30 days duration. The longer-term HA is derived for both the 10 kg child and a 70 kg 

adult and assumes an exposure period of 7 years (or 10% of an individual's lifetime). The 

longer-term HA is generally derived from a study of subchronic duration (exposure for 10% 

of animal's lifetime). 

The U.S. EPA categorizes the carcinogenic potential of a chemical, based on the 

overall weight-of-evidence, according to the following scheme: 

Group A: Human Carcinogen. Sufficient evidence exists from epidemiology 

studies to support a causal association between exposure to the chemical and 

human cancer. 

Group B: Probable Human Carcinogen. Sufficient evidence of carcinogenicity in 

animals with limited (Group B1) or inadequate (Group B2) evidence in humans. 

Group C: Possible Human Carcinogen. Limited evidence of carcinogenicity in 

animals in the absence of human data. 

CLORAMIN.VIII VIII-4 03/08/94
 
Group D: Not Classified as to Human Carcinogenicity. Inadequate human and 

animal evidence of carcinogenicity or for which no data are available. 

Group E: Evidence of Noncarcinogenicity for Humans. No evidence of 

carcinogenicity in at least two adequate animal tests in different species or in both 

adequate epidemiologic and animal studies. 

If toxicologic evidence leads to the classification of the contaminant as a known, 

probable or possible human carcinogen, mathematical models are used to calculate the 

estimated excess cancer risk associated with the ingestion of the contaminant in drinking 

water. The data used in these estimates usually come from lifetime exposure studies 

using animals. In order to predict the risk for humans from animal data, animal doses must 

be converted to equivalent human doses. This conversion includes correction for 

noncontinuous exposure, less than lifetime studies and for differences in size. The factor 

that compensates for the size difference is the cube root of the ratio of the animal and 

human body weights. It is assumed that the average adult human body weight is 70 kg 

and that the average water consumption of an adult human is 2 L of water per day. 

For contaminants with a carcinogenic potential, chemical levels are correlated with a 

carcinogenic risk estimate by employing a cancer potency (unit risk) value together with 

the assumption for lifetime exposure from ingestion of water. The cancer unit risk is 

usually derived from a linearized multistage model with a 95% upper confidence limit 

providing a low dose estimate; that is, the true risk to humans, while not identifiable, is not 

likely to exceed the upper limit estimate and, in fact, may be lower. Excess cancer risk 

estimates may also be calculated using other models such as the one-hit, Weibull, logit 

and probit. There is little basis in the current understanding of the biologic mechanisms 

CLORAMIN.VIII VIII-5 03/08/94
 
involved in cancer to suggest that any one of these models is able to predict risk more 

accurately than any other. Because each model is based upon differing assumptions, the 

estimates derived for each model can differ by several orders of magnitude. 

The scientific data base used to calculate and support the setting of cancer risk rate 

levels has an inherent uncertainty that is due to the systematic and random errors in 

scientific measurement. In most cases, only studies using experimental animals have 

been performed. Thus, there is uncertainty when the data are extrapolated to humans. 

When developing cancer risk rate levels, several other areas of uncertainty exist, such as 

the incomplete knowledge concerning the health effects of contaminants in drinking water, 

the impact of the experimental animal's age, sex and species, the nature of the target 

organ system(s) examined and the actual rate of exposure of the internal targets in 

experimental animals or humans. Dose-response data usually are available only for high 

levels of exposure and not for the lower levels of exposure closer to where a standard may 

be set. When there is exposure to more than one contaminant, additional uncertainty 

results from a lack of information about possible synergistic or antagonistic effects. 

Current Levels of Exposure 

Monochloramine has been used as a disinfectant of drinking water. An inventory of 

municipal water supplies done in the early 1960s revealed that 308 of 11,590 supplies 

surveyed used an ammonia chlorine process (Moore and Calabrese, 1980). 

CLORAMIN.VIII VIII-6 03/08/94
 

According to Morris et al. (1980), the extent of knowledge of natural water 

contamination by N-containing aromatic compounds or the degree to which these 

compounds react with aqueous chlorine is very limited. It is known that both inorganic 

chloramines and organic N-chloramines are found upon chlorination of wastewater 

effluents (Isaac and Morris, 1980). One survey reported the presence of monochloramine 

ranging from 0.0321-0.9979 mg/L and dichloramine ranging from 0.0020-0.6950 mg/L in 

secondary sewage effluents and cooling water samples (Jolley et al., 1978). Because 

inorganic and organic chloramines cannot be identified separately, the levels are based 

on the mixture. 

Noncarcinogenic Effects 

The chlorination of water containing ammonia or organic amines may result in the 

formation of monochloramine, dichloramine, and trichloramine (nitrogen trichloride) through 

the reaction between ammonia and hypochlorous acid. The amount of chloramines 

produced depends upon the levels of chlorine and ammonia, and the pH of the water being 

treated. Some studies on the oral effects of chloramines were presented in Tables V-1 

and V-2. 

Results on the mutagenicity of chloramines are inconclusive. Chloramine is weakly 

mutagenic for Bacillis subtilis and causes DNA breaks in this bacterial species (Lu Shih 

and Lederberg, 1976). Thomas et al. (1987) reported that monochloramine (40 um) 

marginally increased the numbers of revertant colonies over untreated control levels in 

assays employing Salmonella typhimurium (TA97, TA100 and TA102). Monochloramines 

CLORAMIN.VIII VIII-7 03/08/94
 
produce chromosome abnormalities in both Vicia faba and rodent cells (Fetner, 1962; 

NIEHS, 1982). It was responsible for cellular hypertrophy, increased mitotic figures and 

bizarre chromatin patterns in B6C3F1 mice exposed to 200 and 400 mg/L in drinking water 

(Wolfe et al., 1984), while Meier et al. (1985) found that monochloramine at 0, 40, 100 and 

200 mg/L did not induce chromosomal aberrations or micronuclei in bone marrow of CD-1 

mice or spermhead abnormalities in B6C3F1 mice. Organic chloramines are mutagenic 

or bacteriotoxic in S. typhimurium and have been reported to produce SCEs and other 

chromosomal changes in mammalian cells (Scully et al., 1983; Bempong and Scully, 

1980b; Bempong et al., 1981, 1986; Scully and Bempong, 1982). Tests for teratogenic, 

reproductive and carcinogenic effects have been negative or inconclusive. 

Abdel-Rahman et al. (1984) investigated the toxicity of monochloramine (NH2Cl) in 

groups of four male Sprague-Dawley rats/treatment weighing 160 g. Acute exposure to 

a single dose at 10 (0.19 mg/kg/day), 20 (0.38 mg/kg/day) or 40 (0.75 mg/kg/day) mg/L 

NH2Cl induced a significant increase in blood glutathione levels within 30 minutes after 

administration of 3 mL aqueous solution by gavage. As part of the same study, the longterm toxicity of NH2Cl in drinking water was also investigated. Groups of four male 

Sprague-Dawley rats drank either 0, 1 (0.067 mg/kg/day), 10 (0.67 mg/kg/day) or 100 (6.7 

mg/kg/day) mg/L NH2Cl in deionized water daily for <12 months. The levels of chlorine, 

dichloramine and trichloramine in the NH2Cl solution were <1%, <1% and 0% respectively 

of the total NH2Cl added. Food was available ad libitum and body weight was measured 

during the treatment. Heparinized blood was collected by cardiac puncture at 2, 4, 6, 8, 

10 and 12 months after treatment, and blood GSH and osmotic fragility were determined 

CLORAMIN.VIII VIII-8 03/08/94
 
at each of these intervals. Results varied over the 12-month study period, but at 6 and 12 

months after initiation of the study, statistically lower GSH levels were observed in all 

treated rats. After 3 months of treatment significant decreases in RBC count and 

hematocrit were observed at the higher dosage levels. Hemoglobin concentration and 

MCH decreased significantly in the 100 mg/L group after 10 months of treatment. The 

health significance of these types of changes is uncertain. Furthermore, results of 

treatment effects were analyzed by inappropriate statistical methods (ANOVA). The 

multiple comparison test used for paired comparisons (Duncan's) is a nonconservative 

appproach. A more conservative approach would have taken into account correlations or 

nonindependences. In addition, the control variability was greater than variability between 

dose groups. A number of "significant" changes in hematologic parameters relative to 

control values were identified that had no consistent relationship with dose and were not 

observed consistently throughout the period of exposure. This could be due to the use of 

a multiple comparison procedure, which is liberal such as the Duncan's. 

Several short-term studies showed no observed adverse hematologic effects in mice, 

rats and monkeys (Moore et al., 1980; Bercz et al., 1982; Bull, 1980). In A/J mice 

administered chloramine solutions between 2.5 and 200 mg/L (pH 8.9) for 30 days, the 

only observable effect was a slight increase in hematocrit (Moore et al., 1980). In another 

study of similar duration (45 days) rats treated with 10, 50 or 100 mg/L monochloramine 

experienced a decrease in the amount of methemoglobin present in the blood, the 

opposite of what was expected (Bull, 1980). Bercz et al. (1982) studied the toxicity of 

monochloramine administered in drinking water to 5 adult male and 7 adult female African 

CLORAMIN.VIII VIII-9 03/08/94
 
Green monkeys (3.0-5.7 kg). Monochloramine was administered for 6 weeks at 0 and 100 

mg/L. The authors estimated the mean daily dose at 10 mg/kg/day. Treatment with 

monochloramine had no detectable effect in 18 hematologic tests on the 12 monkeys, 

including red cell GSH levels. No evidence of thyroid suppression was detected from 

measurements of serum T4. The results of these data are somewhat conflicting in that 

similar dose levels and duration produced different changes, if any, in hematologic 

parameters. One explanation for the varying observations between laboratories may be 

the conditions under which the solutions of monochloroamine were generated. 

In 1981 a draft report investigated the effects of monochloramine in Fischer 344 rats 

and B6C3F1 mice (GSRI, 1981). Rats and mice (10 animals/sex/group) were administered 

concentrations of 0, 25, 50, 100, 200 and 400 ppm monochloramine in drinking water for 

91 days. Using food and water consumption data provided in the report, corresponding 

dose levels are as follows: 2.5, 4.9, 10.2, 18.8, 40.7 mg/kg/day for male rats; 3.8, 6.5, 

13.8, 26.6, 53.9 mg/kg/day for female rats; 4.9, 8.3, 14.5, 31.3, 50.7 mg/kg/day for male 

mice; 7.7, 12.1, 21.9, 34.6, 88.5 mg/kg/day for female mice. After 25 days the buffer 

system for monochloramine was changed because of a palatibility problem at the higher 

dose levels. Decreased body weight gain and decreased relative liver weight were 

observed in male and female rats at concentrations of 200 and 400 mg/L. A statistical 

analysis was not provided. Protein excretion increased in male rats only when 200 and 

400 mg/L monochloramine was administered. Microscopic examination of rat tissues at 

the 400 ppm level did not reveal any treatment-related lesions. 

CLORAMIN.VIII VIII-10 03/08/94
 

As with rats, male and female mice gained less weight than the controls at the 200 

and 400 ppm levels. There was a reduction in absolute liver weights and liver-to-body 

weight ratios in male mice at the 400 ppm level and in female mice at 100 ppm. 

Histopathologic observations revealed mild to moderate cytologic alteration in male mice 

administered 200 and 400 ppm levels. Chronic liver inflammatory changes occurred at 

100, 200 and 400 ppm in female mice and to a lesser extent in male mice at the 100 ppm 

level. At concentrations of 100, 200 and 400 ppm increased frequency of mitotic figures, 

hypertrophy and unusual chromatin patterns occurred in males and in a female at 200 

ppm. The results suggest a LOAEL for liver toxicity of 100 ppm and a NOEL of 50 ppm 

based on chronic liver inflammatory changes in mice. 

Daniel et al. (1990) administered 0, 25, 50, 100 and 200 mg/L monochloramine to 

male and female Sprague-Dawley rats (10/sex/dose) in their drinking water for 90 

consecutive days. These doses correspond to 0, 1.8, 3.4, 5.8 and 9.0 mg/kg/day for males 

and 0, 2.6, 4.3, 7.7 and 12.1 mg/kg/day for females. At 50 mg/L in males there were 

reductions in body weight gain with significant reductions only at the highest dose (200 

mg/L). For males and females in the 200 mg/L dose group the average weight gain was 

51% of that of the controls; however, water consumption for the 200 mg/L dose was 31 

and 33% of controls for males and females, respectively. At the 200 mg/L dose level there 

were also reductions in organ weights (absolute, relative or both) and liver and spleen 

weight reductions in both sexes. Although authors concluded that 100 mg/L dose is 

considered the NOAEL, they suggest that a matched watering and feeding study would be 

CLORAMIN.VIII VIII-11 03/08/94
 

useful for distinguishing between systemic toxic effects and weight loss from taste aversion 

to more clearly identify the NOAEL. 

Daniel et al. (1991) administered 0, 12.5, 25, 50, 100 and 200 mg/L monochloramine 

to male and female B6C3F1 mice (10/sex/dose). These doses correspond to 0, 2.5, 5.0, 

8.6, 11.1 and 15.6 mg/kg/day for males and 0, 2.8, 5.3, 9.2, 12.9 and 15.8 mg/kg/day for 

females. Water consumption was decreased in all treated groups. There were significant 

water and food consumption decreases and weight gain reductions at the two highest dose 

groups. There were reductions in absolute and relative organ weights in male and female 

mice in the two highest dose groups. Based on relatively minor changes at 100 mg/L) 

including <10% decrease in body weight gain at 100 mg/L, and 19-25% decrease in body 

weight gain at 200 mg/L, a NOAEL of 100 mg/L (12.9 mg/kg/day) was identified based on 

a decrease in body weight gain and decreased organ weights in B6C3F1 mice consuming 

200 mg/L monochloramine in the drinking water for 90 days. The authors state that the 

lower levels of serum enzyme and reduced organ weights were considered consistent with 

decreased water and nutrient consumption and altered electrolyte balance rather than 

disinfectant-induced toxicity. The authors conclude that the absence of histopathology or 

observable clinical signs of toxicity suggest that these monochloramine exposures induce 

a relatively mild, nonspecific toxicity by an indirect mechanism (nutritional and electrolyte 

deficiencies) rather than a direct toxicologic effect on specific organs or tissues. 

NTP (1990) conducted 2-year studies using monochloramine administered in the 

drinking water. In the first study monochloramine was administered to male and female 

CLORAMIN.VIII VIII-12 03/08/94
 
F344/N rats at 0, 50, 100 and 200 ppm. These doses were calculated on a time-weighted 

average to be 0, 2.1, 4.8 and 8.7 mg/kg/day for males and 0, 2.8, 5.3 and 9.5 mg/kg/day 

for females. Mean body weights of high-dose rats were lower than their respective 

controls. However, mean body weights of rats receiving chloraminated drinking water were 

within 10% of controls until week 97 for females and week 101 for males. Interim 

evaluations made at 14 weeks revealed that body weights of high-dose males were lower 

than controls. At the 66-week evaluation, there was a dose-related decrease in body 

weight in male chloraminated-treated rats and the mean body weights of high-dose rats 

were 94% and 92% of controls for males and females, respectively. Decreases in liver and 

kidney weight in the high-dose males and increases in brain and kidney-to-body weight 

ratios in high-dose male and female rats were observed in the 14- and 66-week 

evaluations. 

The NTP (1990) second study was a 2-year study of momochloramine administered 

in drinking water to male and female B6C3F1 mice at 0, 50, 100 and 200 ppm. These 

doses were calculated on a time-weighted average to be 0, 5.0, 8.9 and 15.9 mg/kg/day 

for males and 0, 4.9, 9.0 and 17.2 mg/kg/day for females. Mean body weights of 

high-dose male mice were 10-22% lower than controls after week 37 and the body weights 

of high-dose female mice were 10-35% lower after week 8. At the 15-week interim 

sacrifice the mean body weights of high-dose mice were 91% and 84% of controls for 

males and females, respectively. At the 66-week evaluation the differences in body weight 

between the high-dose and controls was 87% for females but 91% of controls for the midand high-dose males. Decreases in liver weights and increases in brain and 

CLORAMIN.VIII VIII-13 03/08/94
 
kidney-to-body weight ratios were observed in high-dose male and female mice at 15 and 

66 weeks. 

Quantification of Noncarcinogenic Effects 

Derivation of 1-Day Health Advisory. The only report of an acute exposure to 

monochloramine in the literature is the study by Abdel-Rahman et al. (1984) wherein the 

authors observed a drop in blood GSH levels at the lowest dose administered by gavage 

(3 mL of 10 mg/L solution). As the health implications of these effects are uncertain, they 

were transitory and were not corroborated by other investigations, it would seem 

inappropriate to use this study as the basis for a 1-day HA. Therefore, no suitable study 

is available for the derivation of a 1-day HA. It is recommended that the 10-day HA of 1.0 

mg/L be adopted as the 1-day HA. 

Derivation of 10-Day Health Advisory. Similar NOAELs or NOELs for 

monochloramine of 200, 100 and 100 ug/L for hematologic parameters were identified by 

Bercz et al. (1982), Moore et al. (1980) and Bull (1980), respectively. Both Moore et al. 

(1980) and Bull (1980) did observe some changes in hematologic parameters. Moore et 

al. (1980) found a slight increase in hematocrit in A/J mice after 30 days of exposure 

whereas after 45 days of exposure to rats there was a decrease in the amount of 

methemoglobin present in the blood, the opposite of what was expected (Bull, 1980). 

Bercz et al. (1982) reported a NOEL in monkeys after treatment with 100 mg/L 

chloramines in drinking water. There were no detectable effects in 18 hematologic tests. 

The authors calculated that by the termination of the study the test animals were 

CLORAMIN.VIII VIII-14 03/08/94
 
10 day HA 10 mg /kg /day x 10 kg 

100 x 1 L/day 

1 mg /L 

consuming 10 mg chloramine/kg/day. s 

between laboratories may be the conditions under which the solutions of monochloramine 

were generated. . 

(1982) study be used to derive the 10-day HA for two reasons: Bull (1980) study 

provides an incomplete description of methods concerning study design and clinical 

analysis, and 2) monkeys may be a better animal model since the A/J strain of mice used 

in the Moore et al. (1980) study maintain an erythrocyte glucose-6-phosphate 

dehydrogenase activity 3 times that of human cells and may be more resistant to oxidant 

stress (Kiese, 1974). s 

determined to be the rate of consumption of chloramine at the 6-week termination of the 

study. 

A provisional 10-day HA is calculated as follows: 

For a 10 kg child: 

where: 

10 mg/kg/day = NOAEL based on the absence of hematologic effects in 

monkeys (Bercz et al., 1982) 

10 kg = assumed body weight of a child 

10 = uncertainty factor for use of an animal NOAEL and to protect 

sensitive members of the human population 

1 L/day = assumed water consumption of a child 

One explanation for the varying observation 

It is recommended that the NOEL of 100 mg/L from the Bercz et al 

1) the 

A NOEL is, therefore, set at 10 mg/kg/day, which the author 

CLORAMIN.VIII VIII-15 03/08/94
 

Thus, the proposed 10-day HA is 1 mg/L for a 10 kg child. The small number of animals 

used by Bercz et al. (1982) and the lack of other shorter- term studies for supporting data 

should be considered when evaluating this HA. 

Derivation of Longer-Term HA. Several longer-term studies were considered for 

serving as the basis for the longer-term HA. The 1981 draft report by GSRI had 

methodology and data inconsistencies that make it unsuitable for a longer-term HA. In the 

Daniel et al. (1990) study, male and female rats in the 200 mg/L dose group (highest dose 

tested) had an average weight gain of 51% of controls and drinking water consumption 

was decreased 31-34%, which may suggest that the effect of weight loss may be due to 

a taste aversion rather than a systemic toxic effect. Although the authors identified a 

NOAEL of 100 mg/L (5.8 and 7.7 mg/kg/day) they also suggested that the NOAEL could 

be more clearly identified by a matched feeding and water study to more clearly distinguish 

between systemic toxic effects and weight loss from taste aversion. In the Daniel et al. 

(1991) study a NOAEL of 50 mg/L (8.6-9.2 mg/kg/day) was identified for B6C3F1 mice. 

At the two higher dose levels tested, the lower levels of serum enzymes and reduced 

organ weights were considered by the authors to be consistent with decreased water and 

nutrient consumption and altered electrolyte balance rather than chemical-induced toxicity. 

The studies by Daniel et al. are supportive of the NTP (1990) study, which is used as the 

basis for the DWEL. Using the data from either of the two studies by Daniel et al. would 

result in a longer-term HA of 3 mg/L, slightly less than the DWEL of 4 mg/L. The DWEL 

is based on a well conducted chronic NTP (1990) study with a NOAEL of 9.5 mg/kg/day. 

Because of the problems in interpreting the subchronic studies, it is recommended that the 

CLORAMIN.VIII VIII-16 03/08/94
 
RfD 9.5 mg/kg/day 

100 

0.095 mg/kg/day (rounded to 0.1 mg/kg/day) 

DWEL of 4 mg/L be adopted for the longer-term HA for adults. r the 10 kg child drinking 

1 L/day, the DWEL is modified resulting in a longer-term HA of 1 mg/L. 

Assessment of Lifetime Exposure and Derivation of a DWEL. It is recommended 

that the study by NTP (1990) be used as a basis for a DWEL because it is a chronic 2-year 

study using rats and mice with chloramine in the drinking water. 

was administered to rats and mice in their drinking water there were statistically significant 

changes in body and several organ weights (as previously described) at the high-dose 

level. However, the significance of these changes is unclear because test animals 

consumed a reduced amount of water, which was perhaps due to palatability, and NTP 

does not consider these changes in body and organ weight biologically significant. s 

recommended that the highest dose tested be used as the NOAEL. 

in the rat study was chosen over the NOAEL in the mouse study to calculate the proposed 

RfD because data from acute and shorter term studies indicate that the rat is the more 

sensitive species. 

where: 

9.5 mg/kg/day = NOAEL based on an absence of biologically significant 

adverse effects in rats (NTP, 1990) 

100 = uncertainty factor for protection of sensitive members of the 

human population and for use of an animal NOAEL 

Fo 

When monochloramine 

It i 

The NOAEL identified 

The calculation of the RfD is as follows: 

CLORAMIN.VIII VIII-17 03/08/94
 

DWEL 0.1 mg /kg /day x 70 kg 

2 L/day 

3.5 mg /L (rounded to 4 mg /L) 

where: 

0.1 mg/kg/day = RfD 

2 L/day = assumed water consumption by an adult 

70 kg = assumed body weight of an adult 

The RfD of 0.1 mg/kg/day was verified (06/23/92) by the RfD/RfC Work Group of the 

U.S. EPA (1994). 

study. Although ideally higher doses should have been tested, this was not possible due 

to the taste aversion. The study by NTP (1990) examined relevant endpoints in two animal 

species exposed to chloramine by a relevant route of exposure for a prolonged period of 

time. Several dosage levels were included, the number of animals per dose group was 

adequate, and the statistical analyses were used. 

level of confidence in the data base. lable on mice, rat and monkeys for 

the noncarcinogenic toxicity of oral exposure to monochloramine for subchronic periods. 

The developmental toxicity and reproductive toxicity of monochloramine have been 

examined in rats but a developmental toxicity study in a second species and a 

2-generation reproductive study are not available. (Information available for chlorine can 

be used to satisfy data gaps for monochloramine.) Confidence in the data base is limited 

The Work Group expressed a high degree of confidence in the critical 

The Work Group expressed a medium 

Information is avai 

CLORAMIN.VIII VIII-18 03/08/94
 

by the lack of information on health effects in humans. Overall confidence in the RfD is 

considered to be medium. A summary of the HAs and DWEL is presented in Table VIII-1. 

Carcinogenic Effects 

In a 2-year study by NTP (1990), there was equivocal evidence of carcinogenic activity 

of chloraminated drinking water in female rats, which was due to the slightly increased 

incidence of mononuclear cell leukemia compared with that of controls. There was no 

CLORAMIN.VIII VIII-19 03/08/94


evidence of carcinogenic activity because of chloraminated drinking water in male rats or 

in male or female mice. Monochloramine was verified by the CRAVE Work Group 

(12/02/92) and is classified in group D, not classifiable as to human carcinogenicity, 

meaning that there is inadequate human and animal evidence of carcinogenicity (U.S. 

EPA, 1986). 

Existing Guidelines, Recommendations and Standards 

The NAS (1987) calculated a suggested no-adverse-response level (SNARL) of 0.581 

mg/L. This was based on a NOEL of 50 ppm (estimated by NAS to be 8.3 mg/kg bw/day) 

from a 90-day study in mice, which showed reduced body weight and liver toxicity (GSRI, 

1981). It was assumed that a 70 kg human consumes 2 L of water daily, which contributes 

20% of total intake. This value should be viewed cautiously since the data in this study 

were not verified. 

Special Groups at Risk 

Long-term hemodialysis patients have displayed higher risks of hemolytic anemia 

caused by chloramines present in dialysis baths. These chloramines denature hemoglobin 

through oxidation and inhibit the hexose monophosphate shunt (Eaton et al., 1973). This 

problem can be eliminated by using charcoal-filtered water in the dialysis bath; therefore, 

this group should not be given special consideration in the development of water quality 

criteria (U.S. EPA, 1981). 

Risk Characterization 

CLORAMIN.VIII VIII-21 03/08/94
 
In characterizing the risk that chloramines pose in drinking water, the health effects 

must be considered in light of the widespread use of the chloramine-ammonia process 

(chloramination) for disinfection purposes. As stated earlier in this document, the range of 

residual in the distribution system (1.5-2.5 mg/L) is well below the DWEL of 4 mg/L. In 

humans, health effects do not appear to be associated with levels of residual chloramine 

typically found in drinking water. 

CLORAMIN.VIII VIII-22 03/08/94
 

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