Chlorine Dioxide

Incident Reports

Case 4023

Jonathan Chen, Ph.D.

Office of Pesticide Programs

Antimicrobials Division

U.S. Environmental Protection Agency

  SEQ CHAPTER \h \r 1 1200 Pennsylvania Avenue, NW

Washington, DC 20460

August 1, 2006

TABLE OF CONTENTS

  TOC \o "1-3" \u  0.0	INTRODUCTION	  PAGEREF _Toc122342428 \h  3 

1.0 	INCIDENT REPORT DATA ASSOCIATED WITH HEALTH EFFECTS	  PAGEREF
_Toc122342429 \h  3 

1.1 	OPP(s Incident Data System (IDS)	  PAGEREF _Toc122342430 \h  4 

1.2 	 Poison Control Center (1993 – 2003)	  PAGEREF _Toc122342431 \h 
4 

1.3 	California Data - 1982 through 2003	  PAGEREF _Toc122342432 \h  4 

1.4 	National Pesticide Telecommunications Network (NPTN)	  PAGEREF
_Toc122342433 \h  4 

1.5 	Incident Reports / Epidemiological Studies Published in Scientific
Literature.	  PAGEREF _Toc122342434 \h  4 

2.0	SUMMARY AND CONCLUSION	5

3.0	REFERENCE	12

 

0.0	INTRODUCTION tc \l1 "0.0	INTRODUCTION 

The chemical chlorine dioxide (ClO2) is used as a biocide in bleaching
cellulose, paper and pulp, flour, leather, fats and oils, textiles, and
beeswax; in purification of water; for taste and odor control of water;
in cleaning and detanning leather; in the manufacturing of chloride
salts; as an oxidizing agent; as a bactericide, antiseptic and
deodorizer (The Merck Index, 2001).  The purpose of this chapter is to
review the evidence of health effects in humans resulting from exposure
to chlorine dioxide.  

Two approaches are used in this section:

The potential health effects of chlorine dioxide in humans, reported as
incident reports from different sources, are summarized. 

A literature search of chronic health effects associated with chlorine
dioxide exposure, including results of epidemiological studies, is
summarized.

1.0 	INCIDENT REPORT DATA ASSOCIATED WITH HEALTH EFFECTS 

The following databases have been consulted for the poisoning incident
data

OPP Incident Data System (IDS) - The Incident Data System of The Office
of Pesticide Programs (OPP) of the Environmental Protection Agency (EPA)
contains reports of incidents from various sources, including
registrants, other federal and state health and environmental agencies,
and individual consumers, submitted to OPP since 1992.  Reports
submitted to the Incident Data System represent anecdotal reports or
allegations only, unless otherwise stated.  Typically no conclusions can
be drawn implicating the pesticide as a cause of any of the reported
health effects. Nevertheless, with enough cases and/or enough
documentation, risk mitigation measures may be suggested.

Poison Control Centers - as a result of a data purchase by EPA, OPP
received Poison Control Center data covering the years 1993 through 2003
for all pesticides.  Most of the national Poison Control Centers (PCCs)
participate in a national data collection system, the Toxic Exposure
Surveillance System, which obtains data from about 65-70 centers at
hospitals and universities.  PCCs provide telephone consultation for
individuals and health care providers on suspected poisonings, involving
drugs, household products, pesticides, etc.

California Department of Pesticide Regulation - California has collected
uniform data on suspected pesticide poisonings since 1982.  Physicians
are required, by statute, to report to their local health officer all
occurrences of illness suspected of being related to exposure to
pesticides.  The majority of the incidents involve workers.  Information
on exposure (worker activity), type of illness (systemic, eye, skin,
eye/skin and respiratory), likelihood of a causal relationship, and
number of days off work and in the hospital are provided.

National Pesticide Telecommunications Network (NPTN) - NPTN is a
toll-free information service supported by OPP.  A ranking of the top
200 active ingredients for which telephone calls were received during
calendar years 1984-1991, inclusive, has been prepared.  The total
number of calls was tabulated for the categories human incidents, animal
incidents, calls for information, and others.

Published Incident Reports - Some incident reports associated with
chlorine dioxide related human health hazards are published in the
scientific literature.

1.1 	OPP’s Incident Data System (IDS) tc \l2 "1.1 	OPPs Incident Data
System (IDS) 

There are two minor incidents have been reported that are associated
with chlorine dioxide in the OPP incident data system.  Inhalation
exposure is the primary route of exposure.  Irritation type reactions
and headache are the primary concerns that have been reported.

1.2 	 Poison Control Center - 1993 through 2003 tc \l2 "1.2 	 Poison
Control Center 

There are no chlorine dioxide specific incidents that have been
reported.

1.3 	California Data - 1982 through 2003 tc \l2 "1.3 	California Data -
1982 through 2003 

There are 20 incidents that have been reported in the California
Pesticide Surveillance Program Database (1982-2003) as possibly or
probably chlorine dioxide related (summarized in Table 1).   Eleven of
these reported incidences are not agriculturally related. 
Lightheadedness, headache, nausea, coughing, throat irritation, sinus
tightness, difficulty breathing and chest tightness are the common
symptoms reported in these incidents.  Table 2 presents the types of
illnesses reported by year.  Table 3 gives the total number of workers
that took time off work as a result of their illness and how many were
hospitalized and for how long.

1.4 	National Pesticide Telecommunications Network (NPTN) tc \l2 "1.4 
National Pesticide Telecommunications Network (NPTN) 

There is no incident reported in the NPTN database related to chlorine
dioxide.

1.5 	Incident Reports / Epidemiological Studies Published in Scientific
Literature. tc \l2 "1.5 	Incident Reports Associated with Toxic Effects
of phenols Published in Scientific Literature. 

The health effects associated with chlorine dioxide are studied in
following epidemiological studies. 

A study was carried out in 9 Italian towns between October 1999 and
September 2000 that aimed to evaluate the association, if any, between
chlorite and chlorate in drinking water and both preterm delivery and
babies that are small for their gestational age at term (term-SGA). 
While controlling for numerous possible confounding factors, the study
showed that there is an association between babies that are small for
their gestational age at term and chlorite in drinking water when the
chlorite levels are greater than 200 µg/L and there is high exposure
from both ingestion and inhalation (from daily showering and bathing). 
Although as the authors point out, this association may be due to a
different disinfection byproduct produced by chlorine dioxide or to a
not yet identified confounding factor, there is no evidence indicate
chlorine dioxide exposure relate to term-SGA .  Chlorine dioxide
treatment is widely used in Italy. (Aggazzotti et al. 2003).  

A study was carried out to investigate the possible association between
maternal periconceptional exposure to public drinking water chlorination
byproducts and the incidence of congenital cardiac defects in a Swedish
county between January 1, 1982 and December 31, 1996.  Information in
Swedish health registers was linked with information on municipal
drinking water composition.  Individual data on drinking water
composition was obtained for 58,669 women.  Among the infants born to
these women, 753 had a cardiac defect.  Chlorine dioxide use in
disinfection was found to be an independent risk factor for cardiac
defect and so was increasing trihalomethane concentrations (THM
concentrations higher than 10 µg/L were statistically significantly
associated with cardiac defects).  The study concluded that the
individual risk for cardiac defect caused by chlorine dioxide is small,
but because a large population is exposed to public drinking water,
“the attributable risk for cardiac defects may not be negligible”
(Cedergren et al., 2002).

An epidemiologic study of 198 persons exposed for 12 weeks to drinking
water that had been disinfected with chlorine dioxide was conducted in a
rural village.  A control group of 118 nonexposed persons was also
studied.  Chlorite ions in the water averaged 5.28 ppm during the study
period.  Based on water consumption information, the mean chlorite dose
received was 10.3 mg/day and the range 0-39.4 mg/day.  Statistical
analysis of multiple hematologic and serum clinical chemistry
measurements failed to identify any significant adverse health effects
related to chlorine dioxide exposure (Michael et al., 1981).

A study of the blood chemistry parameters of 20 renal dialysis patients
was conducted after it was found out that a local water district had
introduced chlorine dioxide as a disinfectant for 12 months without
informing the renal dialysis clinic.  Renal dialysis patients are
considered to be more sensitive to chemicals in tap water than the
general population because not only are they in a compromised state of
health, but while the average population consumes 1-2 liters of tap
water per day, about 100-125 liters of tap water is used during the
process of renal dialysis.  However, the chlorination products measured
at the clinic after it had purified the water used in the preparation of
the dialysate consisted only of 0.02-0.08 mg/L chlorite.  No evidence of
chlorine dioxide induced anemia was found and no other clinically
significant effects were observed (Ames and Stratton, 1987).

2.0	SUMMARY AND CONCLUSION tc \l1 "3.0	SUMMARY AND CONCLUSION 

There are incidents associated with chlorine dioxide exposure reported
in both the OPP Incident Data System and the California Department of
Pesticide Regulation Database (1982-2003).  Among the reported incidents
in these databases, inhalation is the primary route of exposure. 
Irritation is the primary reported symptom.  There is no significant
health effects associated with chlorine dioxide exposure in published
scientific epidemiological studies.

Table 1.  Case Reports Received by the California Pesticide Illness
Surveillance Program, 1982 – 2003 in Which Health Effects Were
Definitely, Probably, or Possibly Attributed to Exposure to Chlorine
Dioxide

Year Case Identified	Case Number(a)	Relationship(b)	Days Lost from Work
/ Days Hospitalized (c)	Ag / Non-Ag (d)	Medical Description (e)
Narrative Description

1990	848	Probable	4 / 0	Non-Ag

SMELLED CHLORINE DEVELOPED BREATHING DIFICULTY, HEADACHE, COUGH,
DIZZINESS. DIAGNOSED BRONCHIAL IRRITATION. SAFETY EQUIPMENT NOT
REPORTED. CHLORINE DIOXIDE DELIVERY SYSTEM DID NOT WORK CORRECTLY THAT
DAY.

1990	1478	Probable	0 / 0	Non-Ag

WORKER APPLYING MATERIAL FROM SPRAY BOTTLE GOT FUMES IN EYES AND LUNGS
CAUSING BURNING. SHE ALSO SUFFERED FROM COUGHING AND SHORTNESS OF
BREATH. SHE WORE ONLY RUBBER GLOVES FOR PROTECTION. NOV ISSUED FOR USE
OF AN UNREGISTERED PRODUCT AND FOR NO TRAINING

1990	2474	Probable	0 / 0	Non-Ag

DISINFECTANT USED IN A MEAT PACKING FACILITY OVER A PERIOD OF TIME
CAUSED A FEMALE EMPLOYEE TO DEVELOP SOB, LIGHT HEADEDNESS AND THROAT
IRRITATION FROM CONSTANT EXPOSURE DUE TO INHALATION. EMPLOYEE WEARING
PROPER CLOTHING AND RUBBER GLOVES. DIAGNOSIS-CHE

1991	2230	Possible	UN / 0	Non-Ag	MODERATE CONJUNCTIVAL HYPEREMIA OF BOTH
EYES.	WORKER WAS SORTING TOMATOES ON A SORTING BELT.  WATER FROM THE
WATER BATH WAS SPLASHING ONTO THE SORTING BELT AND SOME SPLASHED UP INTO
HER EYES.  SHE IMMEDIATELY FLUSHED HER EYES OUT AND PUT EYE DROPS IN
THEM.  SHE THEN SOUGHT MEDICAL ATTENTION.

1991	2574	Probable	0 / 0	Ag	BRONCHOSPASM.	SEE 91-2573.

1991	2575	Probable	0 / 0	Ag	PNEUMONITIS, VOMITING, COUGHING.	SEE
91-2573.



Table 1.  Case Reports Received by the California Pesticide Illness
Surveillance Program, 1982 – 2003 in Which Health Effects Were
Definitely, Probably, or Possibly Attributed to Exposure to Chlorine
Dioxide (Continued)

Year Case Identified	Case Number (a)	Relationship (b)	Days Lost from
Work / Days Hospitalized (c)	Ag / Non-Ag (d)	Medical Description (e)
Narrative Description

1994	847	Possible	0 / 0	Ag	RESPIRATORY IRRITATION, COUGHING, DIZZINESS,
SLIGHT BACK AND CHEST DISCOMFORT.	FOUR WORKERS NOTICED AN ODOR WHILE
INSPECTING ONIONS ON A CONVEYOR BELT AND BECAME ILL.  THE ONIONS ARE
PRESSURE WASHED WITH CHLORINATED WATER UNDER A SHIELDED HOOD.  SEE ALSO
94-848 TO 850.

1994	848	Possible	0 / 0	Ag	THROAT IRRITATION, DRY COUGH.	SEE 94-847.

1994	849	Possible	0 / 0	Ag	COUGHING, THROAT IRRITATION, NAUSEA.	SEE
94-847.

1994	850	Possible	0 / 0	Ag	COUGHING, MILD RHINORRHEA, NAUSEA.	SEE
94-847.

1994	930	Possible	0 / 0	Non-Ag	COUGHING, THROAT IRRITATION, SHORTNESS OF
BREATH, WATERING EYES.	WORKER SUFFERED RESPIRATORY AND EYE PROBLEMS
WHILE INSPECTING ONIONS ON A CONVEYOR BELT.  THE ONIONS HAD BEEN WASHED
IN A CHLORINATED SOLUTION.  SHE SOUGHT MEDICAL ATTENTION FOUR DAYS
LATER.

1994	1030	Possible	0 / 0	Non-Ag	BURNING EYES, COUGHING, NAUSEA,
HEADACHE.	WORKER WAS INSPECTING ONIONS AND WAS EXPOSED TO FUMES FROM THE
CHLORINE WASH.



Table 1.  Case Reports Received by the California Pesticide Illness
Surveillance Program, 1982 – 2003 in Which Health Effects Were
Definitely, Probably, or Possibly Attributed to Exposure to Chlorine
Dioxide (Continued)

Year Case Identified	Case Number (a)	Relationship (b)	Days Lost from
Work / Days Hospitalized (c)	Ag / Non-Ag (d)	Medical Description (e)
Narrative Description

1997	237	Probable	UN / 0	Ag	CHEST TIGHTNESS.	A CHLORINE DIOXIDE PIPE
EXPLODED IN A CARROT PACKING PLANT.  FIFTEEN FEET AWAY, A WORKER
CLEANING A TANK SMELLED CHLORINE AND JUMPED FROM THE TANK.  THE JUMP
INJURED HIS LEG AND BROKE HIS FOOT.  HE ALSO COMPLAINED OF TRANSITORY
CHEST TIGHTNESS.

1997	1040	Possible	4 / 0	Non-Ag	RESPIRATORY IRRITATION, COUGHING, EYE
IRRITATION.	CHLORINE DIOXIDE WAS BEING ADDED TO WATER IN A TANK WHILE AN
EMPLOYEE WAS OPERATING A CANNING MACHINE.  SHE WAS EXPOSED TO THE FUMES
AND DEVELOPED SYMPTOMS.  SHE SOUGHT MEDICAL ATTENTION 4 DAYS LATER.

1997	1096	Probable	0 / 0	Non-Ag	SORE THROAT, STOMACH ACHE, CONSTIPATION,
PAIN AND TIGHTNESS IN THE CHEST, COUGHING.	CHLORINE DIOXIDE WAS BEING
USED AS A SANITIZING RINSE ON PACKING PLANT EQUIPMENT, WHEN A POWER LOSS
OCCURRED.  THIS SHUT OFF A VENTING FAN SO THE CHLORINE DIOXIDE VENTED
INTO A ROOM OF WORKERS.  SEE 97-1103 AND 1104.

1997	1103	Probable	0 / 0	Non-Ag	WHEEZING, COUGHING.	SEE 97-1096.  THREE
WORKERS DEVELOPED SYMPTOMS AND SOUGHT MEDICAL ATTENTION.

1997	1104	Probable	0 / 0	Non-Ag	SORE THROAT, COUGHING, EYE IRRITATION,
NAUSEA.	SEE 97-1096.

2001	354	Possible	0 / 0	Ag	COUGHING, HEADACHE, VOMITING.	TWO PROCESSING
PLANT EMPLOYEES DEVELOPED SYMPTOMS WHILE WORKING ON THE STRAWBERRY
PROCESSING LINE. THIS EMPLOYEE SORTED STRAWBERRIES ON A CONVEYOR BELT.
LAB REPORTS SHOWED THE WASH WATER CHLORINE LEVELS A LITTLE HIGH 5 TIMES
THAT DAY. SEE 2001-355.

Table 1.  Case Reports Received by the California Pesticide Illness
Surveillance Program, 1982 – 2003 in Which Health Effects Were
Definitely, Probably, or Possibly Attributed to Exposure to Chlorine
Dioxide (Continued)

Year Case Identified	Case Number (a)	Relationship (b)	Days Lost from
Work / Days Hospitalized (c)	Ag / Non-Ag (d)	Medical Description (e)
Narrative Description

2001	355	Probable	0 / 0	Ag	COUGHING, CHEST PAIN, SORE THROAT, HEADACHE.
SEE 2001-354. THIS EMPLOYEE DUMPED CRATES OF STRAWBERRIES INTO THE
CHLORINATED WASH TANK WATER.

2001	937	Possible	UN / 0	Non-Ag	SORE THROAT, DRY AND IRRITATED NOSE,
COUGHING, NAUSEA, LIGHTHEADEDNESS.	A MAILROOM CLERK DEVELOPED SYMPTOMS
WHEN A TECHNICIAN DISINFECTED THE VENTILATION SYSTEM. THE NEXT DAY, SHE
REPORTED HER SYMPTOMS TO THE SUPERVISOR WHO SENT HER FOR A MEDICAL
EVALUATION. SHE NO LONGER WORKS AT THE COMPANY AND COULD NOT BE LOCATED.

Note:		

(a) Case numbers are assigned sequentially from 1 each year. 		

(b) A relationship of ‘Definite’ indicates that both physical and
medical evidence document exposure and consequent health effects. 
‘Probable’ relationship indicates that limited or circumstantial
evidence supports a relationship to pesticide exposure.	

      ‘Possible’ relationship indicates that evidence neither
supports nor contradicts a relationship		.

(c) Counts full days only. An entry of ‘Indefinite’ indicates the
event occurred, but the time period is not known.	UN = unkown.	

(d) The abbreviation 'Ag' stands for 'Agricultural' and indicates
pesticide use intended to contribute to production of an agricultural   
 commodity. All other situations are designated 'Non-Ag'.		

(e) The medical description field was added to the database in 1991.
Table 2: Cases Due to Chlorine Dioxide Exposure in California Reported
by Type of Illness and Year, 1982-2003

Year	

Illness Type

	

Systemic	

Mouth	

Eye	

Skin	

Respiratory	

Combinationa	

Total



1990	-	-	-	-	

3	

-	

3



1991	

1	

-	

1	

-	

2	

1	

3



1994	2	-	-	-	

4	

2	

4



1997	-	-	-	-	

4	

-	

4



2001	

1	

1	

2	

2	

-	

1	

5



Total	

4	

1	

3	

2	

13	

4	

19



a Category includes combined effects to eye, skin, mouth and respiratory
systems.

Table 3: Number of Persons Disabled (taking time off work) or
Hospitalized for Indicated Number of Days after Chlorine Dioxide
Exposure in California, 1982-2003.

	

Number of Persons Disabled	

Number of Persons Hospitalized



One day	

-	

-



Two days	

-	

-



3-5 days	

2	

-



Unknown	

3	

-



 tc \l1 " 

3.0	REFERENCES

Aggazzotti,G; Fabiani, L.;  Triassi, M,; Sciacca,  S.;  Ravera, G.; 
Kanitz, S.;  Barbone, F.; Sansebastiano,  K.;  Battaglia,  M.A.; and 
Leoni, V.  2003   Exposure to chlorite and chlorate in drinking water
and adverse pregnancy outcomes in Italy.  Epidemiology.  14 (5): S24.

Ames, R.G. and  Stratton, J.W, 1987..  Effect of chlorine dioxide water
disinfection on hematologic and serum parameters of renal dialysis
patients.  Archives of Environmental Health.: 42(5): 280-285.)

Cedergren, M.I.; Selbing,  A.J.; Lofman, O.; and  Kallen, B.A.J. 2002 
Chlorination byproducts and nitrate in drinking water and risk for
congenital cardiac defects.  Environmental Research Section A.  89:
124-130.

Michael,  G.E.;  Miday,  R.K.; Bercz, J.P.;  Miller, R.G.;  Greathouse,
D.G.;  Kraemer, D.F.; and  Lucas, J.B. 1981.  Chlorine dioxide water
disinfection: a prospective epidemiology study.  Archives of
Environmental Health.  36(1): 20-27.

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