HPA Compendium of Chemical Hazards Sodium hypochlorite
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HPA Compendium of Chemical Hazards
Sodium hypochlorite
Key Points
Fire
Non combustible under normal conditions
Emits toxic fumes of chlorine when mixed with acidic or alkaline solutions
In the event of a fire involving sodium hypochlorite, use fine water spray and wear
liquid-tight protective clothing with breathing apparatus
Health
Exposure to sodium hypochlorite may arise due to ingestion, skin contact or splashes
in the eye; exposure to chlorine gas may occur by inhalation
Toxic by all routes
Corrosive
Acute ingestion may cause burns to the mouth and throat, nausea and vomiting
Acute inhalation may cause irritation of eyes and nose, sore throat, cough, chest
tightness, headache and confusion
Acute eye exposure may cause pain, lacrimation and photophobia
Acute skin exposure to household products is unlikely to damage intact skin. Chronic
exposure may cause irritation, inflammation and blisters
Sodium hypochlorite is not thought to cause cancer
Sodium hypochlorite is not thought to cause damage to the unborn child
Environment
Dangerous for the environment
Inform Environment Agency of substantial release incidents
Prepared by S Bull
CRCE HQ, HPA
2011
Version 3
SODIUM HYPOCHLORITE – CONTENTS
Contents
GENERAL INFORMATION
Background ................................................................................................................................... 5
Frequently Asked Questions ......................................................................................................... 6
INCIDENT MANAGEMENT
Hazard Identification...................................................................................................................... 9
Standard (UK) Dangerous Goods Emergency Action Codes 9
Chemical Hazard Information and Packaging for Supply Classification 10
Globally Harmonised System of Classification and Labelling of Chemicals (GHS) 11
Physicochemical Properties ........................................................................................................ 12
Threshold Toxicity Values ........................................................................................................... 13
Published Emergency Response Guidelines .............................................................................. 14
Emergency Response Planning Guideline (ERPG) Values 14
Acute Exposure Guideline Levels (AEGLs) 14
Exposure Standards, Guidelines or Regulations......................................................................... 15
Occupational standards 15
Public health guidelines 15
Health Effects .............................................................................................................................. 16
Major route of exposure 16
Immediate signs or symptoms of acute exposure 16
Decontamination and First Aid .................................................................................................... 17
Dermal exposure 17
Ocular exposure 17
Inhalation 17
Ingestion 18
TOXICOLOGICAL OVERVIEW
Toxicological Overview................................................................................................................ 20
Summary of Health Effects 20
Sources and route of exposure 21
Health Effects of Acute / Single Exposure................................................................................... 22
Human Data 22
General toxicity .............................................................................................................. 22
Inhalation ....................................................................................................................... 22
Ingestion ........................................................................................................................ 23
Dermal / ocular exposure .............................................................................................. 23
Delayed effects following an acute exposure ................................................................ 23
Health Effects of Chronic / Repeated Exposure .......................................................................... 25
Human Data 25
Dermal / ocular exposure .............................................................................................. 25
Contents: Page 2 of 28SODIUM HYPOCHLORITE – CONTENTS
Carcinogenicity .............................................................................................................. 25
Reproductive and developmental toxicity ...................................................................... 25
Animal and In-Vitro Data 25
Genotoxicity ................................................................................................................... 25
Carcinogenicity .............................................................................................................. 25
Reproductive and developmental toxicity ...................................................................... 26
References .................................................................................................................................. 27
Contents: Page 3 of 28Sodium hypochlorite
General information
Key Points
Fire
Non combustible under normal conditions
Emits toxic fumes of chlorine when mixed with acidic or alkaline solutions
In the event of a fire involving sodium hypochlorite, use fine water spray and wear
liquid-tight protective clothing with breathing apparatus
Health
Exposure to sodium hypochlorite may arise due to ingestion, skin contact or splashes
in the eye; exposure to chlorine gas may occur by inhalation
Toxic by all routes
Corrosive
Short-term ingestion may cause burns to the mouth and throat, and sickness
Short-tem inhalation may cause irritation of eyes and nose, sore throat, cough, chest
tightness, headache and confusion
Short-term eye exposure may cause pain, watering eyes and sensitivity to light
Short-term skin exposure to household products is unlikely to damage intact skin.
Long-term exposure may cause irritation, swelling and blisters
Sodium hypochlorite is not thought to cause cancer
Sodium hypochlorite is not thought to cause damage to the unborn child
Environment
Dangerous for the environment
Inform Environment Agency of substantial release incidents
Prepared by S Bull
CRCE HQ, HPA
2007
Version 1SODIUM HYPOCHLORITE – GENERAL INFORMATION
Background
Sodium hypochlorite is a green/yellow liquid Accidental skin or eye exposures are also
with the characteristic smell of chlorine. It quite common.
was first used as a bleaching agent and was
then discovered to be effective in controlling
wound infections. Subsequently, it is most
commonly known as household bleach and
as a disinfectant, a bleaching agent, in
medical treatments and used in the
disinfection of drinking water.
Today, approximately 70% of the total
amount of sodium hypochlorite produced is
used to make bleach used for household Drinking small volumes (below approximately
cleaners and laundry additives, used for their 200 ml in adults and 40-50 ml in children) of
bleaching, disinfecting and stain-removing sodium hypochlorite solution may cause
properties. burns to the mouth, throat and stomach,
nausea and vomiting, but is unlikely to cause
Household bleach usually contains serious injury. Ingestion of large amounts
approximately 5 % sodium hypochlorite may cause vomiting, drooling, abdominal
although some may contain up to 10 %. pain, diarrhoea and burns to the mouth and
Industrial bleaches are usually more throat. Sodium hypochlorite is irritating to the
concentrated, containing up to 50 % sodium skin and eyes, causing burns, inflammation
hypochlorite. and blister.
If sodium hypochlorite is mixed with acidic
products chlorine gas is produced. Breathing
in chlorine gas for a short period of time can
immediately cause burning sensation of the
throat and lungs, eye and nose irritation,
chest tightness, coughing and difficulty
breathing. In more severe cases increased
breathing rate, wheezing, swelling of the
airways and respiratory failure may occur,
It is also used for a number of industrial the onset of which may take up to 36 hours.
processes such as for commercial
laundering, in the manufacture of paper and People who have been exposed to chlorine
pulp, for industrial chemical synthesis and gas generally make a complete recovery,
disinfection of swimming pools. although a proportion may acquire a
condition known as reactive airways
Perhaps one of the most important dysfunction syndrome (RADS) in which the
applications of sodium hypochlorite is in the lungs become more sensitive to chemical
disinfection of public water supplies to irritants.
prevent the transmission of waterborne
diseases such as cholera and typhoid. If sodium hypochlorite is mixed with products
containing ammonia, this can result in the
Much of the general population is exposed to formation of chloramines, which are also
very low levels of hypochlorite via drinking- highly irritating gases.
water. Alternatively accidental or deliberate
ingestion is the most frequent route of
exposure, followed by breathing in gases
produced due to the mixing of sodium
hypochlorite with acid or alkaline products.
General information: Page 5 of 28SODIUM HYPOCHLORITE – GENERAL INFORMATION
Frequently Asked Questions
What is sodium hypochlorite?
Sodium hypochlorite is a green/yellow liquid with a characteristic smell of chlorine. It is
commonly known as bleach.
What is sodium hypochlorite used for?
Sodium hypochlorite is used as a disinfectant and as a bleaching agent. It is also used in the
disinfectant process of drinking-water and in swimming pools.
How will I be exposed to sodium hypochlorite?
Sodium hypochlorite may be accidentally or intentionally swallowed or spilt on the skin.
If bleach (sodium hypochlorite) is mixed with acidic cleaning products, chlorine gas is
produced which can be breathed in, although the concentrations produced should be
relatively low unless in confined spaces. Due to such inappropriate mixing of domestic
cleaning products or incorrect use of swimming pool disinfectants, accidental domestic
exposures to chlorine are not uncommon.
If there is sodium hypochlorite in the environment will I have any adverse health effects?
The presence of sodium hypochlorite in the environment does not always lead to exposure.
Clearly, in order for it to cause any adverse health effects you must come into contact with it.
You may be exposed by breathing, eating, or drinking the substance or by skin contact.
Following exposure to any chemical, the adverse health effects you may encounter depend
on several factors, including the amount to which you are exposed (dose), the way you are
exposed, the duration of exposure, the form of the chemical and if you were exposed to any
other chemicals.
Drinking small volumes of sodium hypochlorite solution may cause burns to the mouth, throat
and stomach, nausea and vomiting, but is unlikely to cause serious injury. Drinking larger
volumes (approximately 300 ml in adults; 100 ml in children) may cause abdominal pain,
vomiting, diarrhoea, and in severe cases breathing difficulties.
If sodium hypochlorite is mixed with acidic products, chlorine gas is produced. Minor
exposures, such as those usually seen when cleaning products have been mixed together,
may result in a burning sensation of the eyes and throat, coughing and sore throat. More
substantial exposure may cause breathing difficulties and swelling of the airways. Exposure
to high concentrations of chlorine may be potentially fatal due to the onset of a serious
condition called pulmonary oedema (pronounced “ed-eem-a”), where fluid enters the lung
and limits the body’s ability to absorb oxygen from the air. In most cases, symptoms usually
disappear within 1 – 4 weeks and people usually do not suffer any long-term effects.
However, a small proportion of individuals may acquire a long-term sensitivity to inhaled
chemicals known as ‘reactive airways dysfunction syndrome’ or RADS.
If sodium hypochlorite is mixed with an ammonia-containing cleaning product, chloramines
may be produced which are also highly irritating to the respiratory tract.
General information: Page 6 of 28SODIUM HYPOCHLORITE – GENERAL INFORMATION
Can sodium hypochlorite cause cancer?
There is no evidence to associate sodium hypochlorite or chlorine with cancer hence they
are not thought to be carcinogenic.
Does sodium hypochlorite affect children or damage the unborn child?
There is no evidence to suggest that sodium hypochlorite or chlorine can affect the health of
the unborn child.
What should I do if I am exposed to sodium hypochlorite?
You should remove yourself from the source of exposure.
If you have got sodium hypochlorite on your skin, remove soiled clothing, wash the affected
area with lukewarm water and soap for at least 10 – 15 minutes and seek medical advice.
If you have got sodium hypochlorite in your eyes, remove contact lenses, irrigate the affected
eye with lukewarm water for at least 10 – 15 minutes and seek medical advice.
If you have inhaled or ingested sodium hypochlorite seek medical advice.
.
General information: Page 7 of 28Sodium hypochlorite
Incident management
Key Points
Fire
Non combustible under normal conditions
Emits toxic fumes of chlorine and sodium oxide when heated to decomposition
In the event of a fire involving sodium hypochlorite, use fine water spray and liquid-
tight protective clothing with breathing apparatus
Health
Exposure may arise due to ingestion, inhalation of fumes from the stomach, skin
contact or splashes in the eye
Inhalation of fumes arising from mixing bleaches with hot water or toilet cleaners may
occur
Toxic by all routes
Corrosive
Ingestion may cause burns in the mouth and throat and vomiting
Inhalation may cause irritation of eyes and nose, sore throat, cough, chest tightness,
headache, ataxia and confusion. Pulmonary oedema may occur up to 36 hours after
exposure
Eye exposure may cause immediate pain, irritation, lacrimation and burning
sensation. Transient corneal injury may occur.
Skin exposure may cause irritation and contact dermatitis, but any effects on intact
skin are highly unlikely.
Environment
Dangerous for the environment
Inform Environment Agency of substantial release incidents
Prepared by S Bull
CRCE HQ, HPA
2011
Version 3SODIUM HYPOCHLORITE – INCIDENT MANAGEMENT
Hazard Identification
Standard (UK) Dangerous Goods Emergency Action Codes(a)
UN 1791 Hypochlorite solution
Use fine water spray. Wear liquid-tight chemical protective
clothing in combination with breathing apparatus*. Spillages
EAC 2X
and decontamination run-off should be prevented from
entering drains and watercourses.
APP -
Class 8 Corrosive substance
Hazards
Sub
-
risks
HIN 80 Corrosive or slightly corrosive material
UN – United Nations number; EAC – Emergency Action Code; APP – Additional Personal
Protection; HIN - Hazard Identification Number
* Liquid-tight chemical protective clothing (BS 8428) in combination with self-contained open circuit
positive pressure compressed air breathing apparatus (BS EN 137).
a
Dangerous Goods Emergency Action Code List, HM Fire Service Inspectorate, Publications Section,
The Stationery Office, 2009.
Incident management: Page 9 of 28SODIUM HYPOCHLORITE – INCIDENT MANAGEMENT
Chemical Hazard Information and Packaging for Supply Classification(a)
Sodium hypochlorite solution… % CL active
C Corrosive
Classification
N Dangerous for the environment
R31 Contact with acid liberates toxic gas
Risk phrases R34 Causes burns
R50 Very toxic to aquatic organisms
S1/2 Keep locked up and out of the reach of children
S28 After contact with skin, wash immediately with plenty of water
In case of accident or if you feel unwell seek medical advice
Safety phrases S45
immediately (show the label where possible)
Do not mix with other household chemicals containing
S50
ammonia or acidic cleaners
Avoid release to the environment. Refer to special
S61
instructions/safety data sheet
Specific concentration limits
Concentration Classification
C≥5% R31
a
Annex VI to Regulation (EC) No 1272/2008 on Classification, Labelling and Packaging of
Substances and Mixtures- Table 3.2.
http://esis.jrc.ec.europa.eu/index.php?PGM=cla (accessed 11/2011)
Incident management: Page 10 of 10SODIUM HYPOCHLORITE – INCIDENT MANAGEMENT
Globally Harmonised System of Classification and Labelling of Chemicals
)
(GHS)(a *
Skin Corr.
Skin corrosion, categories 1B
1B
Hazard Class
and Category
Aquatic Acute hazards to the aquatic
Acute 1 environment, category 1
Hazard H314 Causes severe skin burns and eye damage.
Statement H400 Very toxic to aquatic life.
Signal Words DANGER
* Implemented in the EU on 20 January 2009.
Specific concentration limits and M factors
Hazard Class
Hazard Statement
Concentration and Category
C≥5% EUH031 Contact with acids liberates toxic gas
a
Annex VI to Regulation (EC) No 1272/2008 on Classification, Labelling and Packaging of
Substances and Mixtures- Table 3.1.
http://esis.jrc.ec.europa.eu/index.php?PGM=cla (accessed 11/2011)
Incident management: Page 11 of 10SODIUM HYPOCHLORITE – INCIDENT MANAGEMENT
Physicochemical Properties
CAS number 7681-52-9
Molecular weight 74
Empirical formula NaClO
Common synonyms Sodium chlorate
State at room temperature Solid
Volatility Slightly volatile
Density 14 % aqueous solution: 1.2 at 20 °C (water = 1)
Flammability Non combustible
Lower explosive limit Data not available
Upper explosive limit Data not available
Water solubility Soluble in water
Solutions of sodium hypochlorite are storage hazards due to
Reactivity oxygen evolution. Reacts with primary amines, ammonium salts
and acids
Emits toxic fumes of chlorine and sodium oxide when heated to
decomposition or upon contact with acids. Incompatible with
strong acids, amines and ammonia; when combined chlorine
gas may be produced. On contact with metals hydrogen gas
Reaction or degradation may evolve. Sodium hypochlorite and primary amines react to
products form normal chloroamines, which are explosive. Hypochlorites
react with urea to form nitrogen trichloride, which explodes
spontaneously in air. Contact of hypochlorite with ammonium
salts and acid leads to the formation of nitrogen trichloride.
Reaction with formic acid becomes explosive.
Odour Disagreeable sweetish odour; faint odour of chlorine
Structure
References(a,b)
a
Sodium hypochorite (MEDITEXT® Medical Management). In: Klasco RK (Ed): TOMES® System.
Thomson Micromedex, Greenwood Village, Colorado (accessed 02/2010).
b
Chlorine (MEDITEXT® Medical Management). In: Klasco RK (Ed): TOMES® System. Thomson
Micromedex, Greenwood Village, Colorado (accessed 02/2010).
Incident management: Page 12 of 10SODIUM HYPOCHLORITE – INCIDENT MANAGEMENT
Threshold Toxicity Values
Sodium Hypochlorite
EXPOSURE VIA INGESTION
% SIGNS AND SYMPTOMS
Mild to moderate irritant; vomiting, skin burns, oral
≤ 10 % burns, drooling, dysphagia, cough, dyspnoea,
abdominal pain
Corrosive; vomiting, abdominal and retrosternal
> 10 %
pain, oesophagitis, diarrhoea, metabolic acidosis
Chlorine
EXPOSURE VIA INHALATION
ppm mg m-3 SIGNS AND SYMPTOMS
0.2 – 3.5 1 – 10 Odour detection
Mild mucous membrane irritation, tolerable for up
1–3 3–9
to one hour
5 14 Severe irritation of the eyes and respiratory tract
14 – 21 41 – 61 Dangerous if exposed for 30 – 60 minutes
35 – 50 101 – 145 Lethal in 60 – 90 minutes
430 1247 Lethal over 30 minutes
1000 2900 Fatal within minutes
References(a,b)
a
Sodium hypochorite (MEDITEXT® Medical Management). In: Klasco RK (Ed): TOMES® System.
Thomson Micromedex, Greenwood Village, Colorado (accessed 02/2010).
b
Chlorine (MEDITEXT® Medical Management). In: Klasco RK (Ed): TOMES® System. Thomson
Micromedex, Greenwood Village, Colorado (accessed 02/2010).
Incident management: Page 13 of 10SODIUM HYPOCHLORITE – INCIDENT MANAGEMENT
Published Emergency Response Guidelines
Emergency Response Planning Guideline (ERPG) Values(a)
Listed value Calculated value
Sodium hypochlorite
(ppm) (mg m-3)
ERPG-1*
ERPG-2** Data not available
ERPG-3***
Listed value Calculated value
Chlorine
(ppm) (mg m-3)
ERPG-1* 1 3
ERPG-2** 3 9
ERPG-3*** 20 58
* Maximum airborne concentration below which it is believed that nearly all individuals could be
exposed for up to 1 hr without experiencing other than mild transient adverse health effects or
perceiving a clearly defined, objectionable odour.
** Maximum airborne concentration below which it is believed that nearly all individuals could be
exposed for up to 1 hr without experiencing or developing irreversible or other serious health effects or
symptoms which could impair an individual's ability to take protective action.
*** Maximum airborne concentration below which it is believed that nearly all individuals could be
exposed for up to 1 hr without experiencing or developing life-threatening health effects.
Acute Exposure Guideline Levels (AEGLs)(b)
Sodium ppm
hypochlorite 10 min 30 min 60 min 4 hr 8 hr
AEGL-1†
AEGL-2†† Data not available
AEGL-3†††
ppm
Chlorine
10 min 30 min 60 min 4 hr 8 hr
AEGL-1† 0.5 0.5 0.5 0.5 0.5
AEGL-2†† 2.8 2.8 2.0 1.0 0.71
AEGL-3††† 50 28 20 10 7.1
†
The level of the chemical in air at or above which the general population could experience notable
discomfort.
††
The level of the chemical in air at or above which there may be irreversible or other serious long-
lasting effects or impaired ability to escape.
†††
The level of the chemical in air at or above which the general population could experience life-
threatening health effects or death.
a
American Industrial Hygiene Association (AIHA). 2010 Emergency Response Planning Guideline
Values and Workplace Environmental Exposure Level Guides Handbook, Fairfax, VA.(accessed
01/2011).
b
U.S. Environmental Protection Agency. Acute Exposure Guideline Levels,
http://www.epa.gov/oppt/aegl/pubs/chemlist.htm (accessed 01/2011).
Incident management: Page 14 of 10SODIUM HYPOCHLORITE – INCIDENT MANAGEMENT
Exposure Standards, Guidelines or Regulations
Occupational standards
LTEL (8 hour reference period): No guideline value
specified
WEL
STEL (15 min reference period): No guideline
value specified
Public health guidelines
DRINKING
No guideline value specified
WATER QUALITY GUIDELINE
AIR QUALITY GUIDELINE No guideline value specified
SOIL GUIDELINE VALUE AND
No guideline value specified
HEALTH CRITERIA VALUES
WEL – Workplace exposure limit; LTEL - Long-term exposure limit; STEL – Short-term
exposure limit
Incident management: Page 15 of 10SODIUM HYPOCHLORITE – INCIDENT MANAGEMENT
Health Effects
Major route of exposure(a)
Toxic via ingestion, inhalation, skin and eye contact. .
Inhalation of fumes arising from mixing bleaches with hot water or toilet cleaners may
occur.
Immediate signs or symptoms of acute exposure(b-g) b,c,d,e,f,g)
Inhalation of household bleach is NOT a respiratory hazard. Corrosive gases may be
produced when mixing bleach with household cleaners, which may cause pulmonary
irritation.
Inhalation of fumes from mixing products may cause irritation of eyes and nose with
sore throat, cough, chest tightness, headache, fever, wheeze, tachycardia and
confusion. Chemical pneumonitis, tachypnoea, dyspnoea and stridor due to laryngeal
oedema may follow. Pulmonary oedema with increasing breathlessness, wheeze,
hypoxia and cyanosis may take up to 36h to develop. Optic neuropathy has been
reported following acute inhalation.
Ingestion of small amounts can cause a burning sensation in the mouth and throat
and thirst. The oropharynx may look mildly inflamed but burns are unlikely. Nausea,
retching and haematemesis may occur but are unlikely to be severe. Large amounts
(more than 100 mL in a child or 300 mL in adults) cause retrosternal pain due to
corrosive oesophagitis, haematemesis, abdominal pain and tenderness, watery
diarrhoea and possibly melaena. Repeated vomiting may lead to glottal
contamination with subsequent oedema and difficulty in breathing. In severe cases,
hypernatraemic, hyperchloraemic acidosis, metabolic acidosis, hypotension, coma,
convulsions and cardiorespiratory arrest. The gastrointestinal mucosa may become
haemorrhagic, ulcerated and perforated. Shock may then occur. There is greater risk
pulmonary oedema (may take up to 36h to develop) with increasing breathlessness,
wheeze, hypoxia and cyanosis. ARDS has occurred after bleach ingestion.
Ingestion may cause systemic features including circulatory collapse, metabolic
acidosis, hypoxia, respiratory failure, acute renal failure, haemolysis and
disseminated intravascular coagulation (DIC).
Dermal exposure may cause tissue damage by saponification of fats. This casues
liquefaction burns and necrosis with a softening of the tissues which can further lead
to deep tissue penetration and full thickness burns.
Ocular exposure may cause pain, blepharospasm, lacrimation, conjunctivis, palpebral
oedema and photophobia.
TOXBASE - http://www.toxbase.org (accessed 01/2011)
a
TOXBASE: Hypochlorite, 07/2009.
b
TOXBASE: Household bleach (10% sodium hypochlorite), 12/2010.
d
TOXBASE: Corrosives – inhalation, 06/2010.
e
TOXBASE: Corrosives – ingestion, 07/2010.
f
TOXBASE: Skin decontamination – corrosives, 06/2010,
g
TOXBASE: Chemicals splashed or sprayed into the eyes, 07/2007.
Incident management: Page 16 of 28SODIUM HYPOCHLORITE – INCIDENT MANAGEMENT
Decontamination and First Aid
Important notes
Ambulance staff, paramedics and emergency department staff treating chemically-
contaminated casualties should be equipped with the Department of Health
approved, gas-tight (Respirex) decontamination suits based on EN466:1995,
EN12941:1998 and prEN943-1:2001, where appropriate.
Decontamination should be performed using local protocols in designated areas such
as a decontamination cubicle with adequate ventilation.
Dermal exposure(a,b)
Remove patient from exposure.
The patient should remove all clothing and personal effects.
Double-bag soiled clothing and place in a sealed container clearly labelled as a
biohazard.
Gently blot away any adherent liquid from the patient.
Wash hair and all contaminated skin with copious amounts of water (preferably warm)
and soap for at least 10-15 minutes. Decontaminate open wounds first and avoid
contamination of unexposed skin.
Pay special attention to skin folds, axillae, ears, fingernails, genital areas and feet.
Apply a soothing cream if there is any residual skin irritation.
Ocular exposure(c)
Remove patient from exposure.
Remove contact lenses if necessary and immediately irrigate the affected eye
thoroughly with water or 0.9% saline for at least 10-15 minutes.
Patients with corneal damage or those whose symptoms do not resolve rapidly
should be referred for urgent ophthalmological assessment.
Inhalation(d)
Remove patient from exposure.
Ensure a clear airway and adequate ventilation.
Give oxygen to symptomatic patients.
All patients with abnormal vital signs, chest pain, respiratory symptoms or hypoxia
should have a 12 lead ECG performed.
If the patient has clinical features of bronchospasm treat conventionally with
nebulised bronchodilators and steroids.
Endotracheal intubation, or rarely, tracheostomy may be required for life threatening
laryngeal oedema.
Apply other supportive measures as indicated by the patient’s clinical condition.
TOXBASE - http://www.toxbase.org (accessed 01/2011)
a
TOXBASE: Industrial bleach (>10% sodium hypochlorite), 12/2010.
b
TOXBASE: Skin decontamination – corrosives, 06/2010,
c
TOXBASE: Chemicals splashed or sprayed into the eyes, 07/2007.
d
TOXBASE: Corrosives – inhalation, 06/2010.
Incident management: Page 17 of 28SODIUM HYPOCHLORITE – INCIDENT MANAGEMENT
Ingestion(a,b)
Treatment is unlikely to be required if only small amounts have been ingested (less
than 100mL in a child; less than 300mL in an adult of household bleach). Give a small
glass of milk to drink
Ensure a clear airway and adequate ventilation.
Gastric lavage should NOT be undertaken due to the increased risk of aspiration.
Observe asymptomatic patients for at least 6 hours after ingestion. Monitor BP, pulse,
cardiac rhythm and respiratory rate.
Apply other supportive measures as indicated by the patient’s clinical condition.
a
TOXBASE: Hypochlorite, 07/2009.
b
TOXBASE: Sodium hypochlorite (household bleach) - features and management, 2009.
Incident management: Page 18 of 28Sodium hypochlorite
Toxicological overview
Key Points
Health effects of acute exposure
Ingestion of sodium hypochlorite may cause burns to the mouth and throat,
gastrointestinal irritation, nausea, vomiting and diarrhoea
Inhalation and ocular exposure to chlorine gas, produced when sodium hypochlorite
is mixed with acidic or alkaline solutions, results in burning of throat and lungs, eye
and nose irritation, chest tightness, coughing and sore throat. Exposure to higher
concentrations of chlorine may lead to tachypnoea, cyanosis, swelling of the airway,
and in severe cases, pulmonary oedema and respiratory failure
Sodium hypochlorite is corrosive and may irritate the skin or cause burning pain,
inflammation and blisters.
Ocular exposure may cause irritation, pain, lacrimation, photophobia and retinitis
Health effects of chronic exposure
Chronic skin exposure may cause skin irritation, pain, inflammation and blisters
IARC classified sodium hypochlorite in category 3 i.e. not classifiable as to the
carcinogenicity to humans
Sodium hypochlorite is not considered to be a reproductive toxin
Prepared by S Bull
CRCE HQ, HPA
2007
Version 1Toxicological Overview
Summary of Health Effects
Sodium hypochlorite itself may be toxic if ingested, or by dermal or ocular exposure. If mixed
with acidic solutions chlorine gas is produced, and mixing with ammonia based solutions
gives rise to chloramine solution, both of which contribute to the toxic effects.
Ingestion of small volumes of sodium hypochlorite causes burns to the mouth and throat,
gastrointestinal irritation, nausea and vomiting. Larger volumes (approximately 300 ml in
adults; 100 ml in children) may also cause abdominal and retrosternal pain and diarrhoea.
Aspiration of liquid may lead to pulmonary complications such as Acute Respiratory Distress
Syndrome (ARDS).
Inhalation of chlorine gas causes burning of the throat and lungs, eye and nose irritation,
chest tightness and coughing. At higher levels of exposure, tachypnoea, cyanosis and
swelling of the airway may occur. Pulmonary oedema and respiratory failure may arise in
severe cases, the onset of which may take up to 36 hours.
Sodium hypochlorite is corrosive and may irritate the skin or cause burning pain,
inflammation and blisters. Ocular exposure can cause irritation, pain, lacrimation and
photophobia.
Hypochlorite salts have been classified as Group 3 by International Agency for Research on
Cancer (IARC), i.e. compounds that are not classifiable as to their carcinogenicity in humans.
Toxicological overview: Page 20 of 28SODIUM HYPOCHLORITE – TOXICOLOGICAL OVERVIEW
Sources and route of exposure
In children the main route of exposure to sodium hypochlorite solution is via ingestion, whilst
in adults ingestion is relatively rare. In adults, inhalation of gases formed by the mixing of
sodium hypochlorite with acidic or alkaline solutions is the most frequent route of exposure.
Dermal or ocular exposure may also occur [1-3].
Sodium hypochlorite is commonly used as a general disinfectant and bleaching agent.
Household bleach may contain up to 10 % sodium hypochlorite but is usually about 5 %.
Industrial bleaches may be more concentrated (up to 50 %) [2]. Due to inappropriate mixing
of domestic cleaning products or incorrect use of swimming pool disinfectants, accidental
domestic exposures to chlorine are relatively common.
Toxicological overview: Page 21 of 28SODIUM HYPOCHLORITE – TOXICOLOGICAL OVERVIEW
Health Effects of Acute / Single Exposure
Human Data
General toxicity
Commercial household liquid bleach ranges from 5 - 10 % sodium hypochlorite and has a pH
of 11 to 12. Sodium hypochlorite is toxic due to the hypochlorite moiety [3] that is formed
when sodium hypochlorite is dissolved in water in alkaline conditions [4].
Although sodium hypochlorite solution itself is only moderately toxic, it liberates chlorine gas
when acidified e.g. if mixed with acidic cleaning agents. Mixing sodium hypochlorite with
ammonia-based solutions gives rise to chloramine compounds. Both chlorine and
chloramines are strong respiratory irritants hence contribute to the toxic effects [1, 3, 5, 6].
Symptoms of sodium hypochlorite exposure may be immediate, or may be delayed for
several hours [5].
Inhalation
Intoxication following the inhalation of sodium hypochlorite vapours is extremely rare as
chlorine gas is not released by bleach solutions in appreciable amounts under normal
conditions. The toxicity of sodium hypochlorite solution by inhalation is predominantly due to
the mixing of bleach with acids and the release of highly irritant gases [1]. Metabolic acidosis
may occur in rare cases following significant inhalation of sodium hypochlorite [7].
Mixing sodium hypochlorite with acids releases chlorine gas, although in most cases the
concentration of chlorine liberated are not sufficient to cause adverse health effects. In rare
cases, inhalation of chlorine gas, produced from mixing sodium hypochlorite with acid causes
immediate burning of the throat and lungs, eye and nose irritation, chest tightness, coughing,
sore throat, wheezing and dyspnoea [3, 5-7]. In severe cases, bronchospasm, pneumonitis,
upper airway oedema, pulmonary oedema or oedema of the glottis may develop [7].
Mixing sodium hypochlorite with ammonia-based solutions results in the formation of
monochloramine and dichloramine, both of which are respiratory irritants [5].
In most cases respiratory irritation occurs immediately, followed by a latent period of 5
minutes to 15 hours, after which time breathlessness and bronchospasm may occur [1]. In
most cases symptoms are usually resolved in 1 – 4 weeks [5, 8]. However, in some
instances pulmonary damage may lead to long-term Reactive Airways Dysfunction
Syndrome (RADS), a chemical irritant-induced type of asthma following an acute respiratory
exposure to an irritant gas [3, 8, 9]. In addition, Acute Respiratory Distress Syndrome
(ARDS), as a result of pneumonitis, has been reported in patients following inhalation of
chlorine following the mixing of bleach and other hydrochloric acid [7, 8].
Toxicological overview: Page 22 of 28SODIUM HYPOCHLORITE – TOXICOLOGICAL OVERVIEW
Ingestion
At low concentrations (up to 10 %), such as those used for household bleach, sodium
hypochlorite is a mild to moderate irritant that rarely produces necrosis or significant mucosal
injury. Ingestion is not expected to cause severe or permanent damage of the
gastrointestinal tract and recovery is usually rapid. At higher concentrations (> 10 %) it is
corrosive. The critical pH for corrosivity is thought to be 12.5 [1, 4].
Ingestion of small volumes (up to 200 ml in adults; 50 ml in children) of sodium hypochlorite
solution (< 10 %) usually causes minimal health effects. In some cases it may cause burns to
the mouth, throat, oesophagus and stomach, pharyngeal pain and inflammation,
gastrointestinal irritation, nausea and vomiting [2, 3, 7, 9]. Dysphagia, stridor, drooling,
abdominal pain and dyspnoea may also occur [4, 10]. Severe irritation is uncommon unless
contact is prolonged or a large volume is ingested [2].
Ingestion of large amounts (approximately 300 ml in adults; 100 ml in children) of sodium
hypochlorite (< 10 %) or more concentrated sodium hypochlorite (> 10 %) may cause
corrosive oesophagitis, haematemesis, abdominal and retrosternal pain, diarrhoea and, in
some cases, malaena and metabolic acidosis [3, 7, 9], although symptoms other than
vomiting do not strongly correlate with the amount of sodium hypochlorite ingested [4]. In
rare cases, the gastrointestinal mucosa may become haemorrhagic, ulcerated and
perforated, leading to shock [9].
Hypernatraemia, hyperchloraemia, hypotension and cardiovascular collapse may rarely
develop after ingestion of extremely large volumes of sodium hypochlorite (volumes not
stated) [7].
Aspiration of sodium hypochlorite or aspiration of contaminated vomit may occur. This
secondary source of pulmonary exposure may lead to ARDS [1-3].
Dermal / ocular exposure
Sodium hypochlorite itself is corrosive and may irritate the skin or cause burning pain,
inflammation and blisters. Skin damage may not be immediately apparent and may continue
to develop over time [3].
Ocular exposure to household bleach can cause mild irritation and temporary discomfort if
eyes are washed immediately [1]. Irritation becomes more severe and prolonged if eyes are
not washed. More concentrated solutions can cause pain, blepharospasm, lacrimation,
conjunctivitis, photophobia, necrosis and chemosis of the cornea, clouding of the cornea,
iritis, cataract formation and retinitis [3, 9].
Delayed effects following an acute exposure
Most children who ingest bleach swallow only small amounts and experience only vomiting
and gastrointestinal irritation. Pulmonary complications such as ARDS result from aspiration
[2]. A study of 19 children who ingested household bleach showed no short or long-term
sequalae [4, 11]. In contrast, severe respiratory sequelae was reported in a toddler [11].
Potential sequelae following ingestion of sodium hypochlorite solution include bleeding,
perforation, scarring and stricture formation following corrosive injury to the mouth, throat,
Toxicological overview: Page 23 of 28SODIUM HYPOCHLORITE – TOXICOLOGICAL OVERVIEW
oesophagus and stomach, oesophageal obstruction, pyloric stenosis and vocal cord
paralysis [3].
Chlorine was used as a chemical warfare agent during World War I hence has been widely
documented. In follow-up studies of survivors there was no evidence of permanent lung
damage following inhalation of chlorine gas. Most studies indicated acute respiratory disease
but fewer chronic sequalae [5, 6]. In contrast, more recent reports have suggested that
chronic sequalae following acute exposure may be more prevalent than previously thought,
such as toxic pneumonitis with respiratory compromise [5, 11].
There is some evidence to suggest that exposure to chlorine may also be associated with
long-term neuropsychological changes [12].
Toxicological overview: Page 24 of 28SODIUM HYPOCHLORITE – TOXICOLOGICAL OVERVIEW
Health Effects of Chronic / Repeated Exposure
Human Data
Dermal / ocular exposure
Chronic dermal exposure to sodium hypochlorite solution may cause skin irritation [3].
Carcinogenicity
No data were available from studies in humans on the carcinogenicity of hypochlorite salts
and there was inadequate evidence for the carcinogenicity of hypochlorite salts in
experimental animals. Overall, the IARC assigned hypochlorite salts to Group 3, i.e.
compounds that are not classifiable as to their carcinogenicity in humans [13].
Reproductive and developmental toxicity
There are no data indicating that sodium hypochlorite, without severe maternal toxicity, is
associated with adverse effects on reproductive function, pregnancy or lactation in humans
[14].
Animal and In-Vitro Data
Genotoxicity
Sodium hypochlorite has been shown to have some mutagenic activity in both bacterial and
mammalian cells in vitro [5]. Chromosomal aberrations were induced in Chinese hamster
ovary cells exposed to 0.5 mg ml-1 sodium hypochlorite in the presence of S9 mix, although it
was questioned whether such clastogenic effects were due to cytotoxicity. Chromosomal
aberrations were also demonstrated in Chinese hamster cells treated with 500 g ml-1
sodium hypochlorite without metabolic activation [5]. Sodium hypochlorite was weakly
genotoxic in human leukocytes in vitro at concentrations similar to those used in disinfection
processes, as measured by the Comet assay, or at concentrations 5- to 10-fold higher than
those used for water disinfection, measured by Saccharomyces cerevisiae strain D7 [15].
There is no evidence for activity in vivo [5]. Oral administration of chlorine at pH 8.5 (where
hypochlorite predominates) did not induce chromosomal aberrations or micronuclei in bone
marrow of CD-1 mice [16].
Carcinogenicity
Carcinogenicity of sodium hypochlorite was investigated in rats treated with 500 or 1000 mg
L-1 sodium hypochlorite for 104 weeks. No tumours were attributed to sodium hypochlorite
exposure (EHC). Studies on female mice suggested that sodium hypochlorite could act as a
tumour promoter although it largely depended on the initiator used [5].
Toxicological overview: Page 25 of 28SODIUM HYPOCHLORITE – TOXICOLOGICAL OVERVIEW
Several in-vivo studies have been carried out to assess carcinogenicity of sodium
hypochlorite. Male and female mice and rats were orally administered sodium hypochlorite
for two years; two strains of female mice had dermal application of sodium hypochlorite;
sodium hypochlorite was tested for its promoting effects in two strains of female mice
following initiation with 7,12 dimethylbenz[a]anthracene and 4-nitroquinoline 1-oxide,
respectively; male and female rats were administered sodium hypochlorite in drinking water
in a multigeneration study. All studies reported negative results. However, none of the
studies evaluated were considered adequate by IARC to draw definite conclusions [13].
Hypochlorite was classified in category 3 by IARC (not classifiable as to carcinogenicity in
humans); animal studies indicate that solutions of chlorine in water are not carcinogenic [13].
The National Toxicology Program (NTP) investigated the carcinogenicity of chlorine (up to
275 ppm) and chloramine (up to 200 ppm), dissolved in drinking water, in a two year
carcinogenicity bioassay in mice and rats. There was no evidence of carcinogenic activity of
chlorinated or chloraminated drinking water in male rats or male and female mice [17].
Reproductive and developmental toxicity
Sperm-head abnormalities in rats were increased (the significance of which is unknown)
following oral administration of 4 and 8 mg kg-1 bw day-1 sodium hypochlorite prepared from
chlorine gas for 5 weeks [16]. However, no such effects were reported in another study in
male rats treated for 56 days prior to mating and no adverse effects in reproductive outcome
were observed in female rats treated 14 days prior to mating and through gestation [5].
Furthermore, animal studies have demonstrated no reproductive or teratogenic effect of
chlorine [5, 6].
Various in-vivo studies have indicated no reproductive or developmental effects due to
chloramines [5].
Overall, experimental data suggests that hypochlorite does not have any adverse effect on
the reproductive system.
Toxicological overview: Page 26 of 28SODIUM HYPOCHLORITE – TOXICOLOGICAL OVERVIEW
References
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based on sodium hypochlorite: review of acute toxicology and poison control centre
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compounds. IARC. Lyon.
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This document will be reviewed not later than 3 years or sooner if substantive evidence becomes
available.
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