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CHEMINFO Record Number: 351
CCOHS Chemical Name: Sodium hypochlorite solutions

Hypochlorous acid, sodium salt
Javel water
Liquid bleach
Soda bleach
Sodium chloride oxide
Sodium oxychloride

Chemical Name French: Hypochlorite de sodium solutions
Chemical Name Spanish: Hipoclorito de sodio (disolución )

Trade Name(s):
Liquid chlorine

CAS Registry Number: 7681-52-9
UN/NA Number(s): 1791
RTECS Number(s): NH3486300
EU EINECS/ELINCS Number: 231-668-3
Chemical Family: Inorganic halogen oxygen acid salt / inorganic halogen oxo acid salt / chlorine oxygen acid salt / chlorine oxo acid salt / hypochlorous acid salt / hypochlorite / inorganic sodium compound / sodium salt
Molecular Formula: Cl-Na-O
Structural Formula: Na.OCl


Appearance and Odour:
Clear light yellow to greenish-yellow liquid, with a disagreeable, chlorine-like (bleach) odour.(13,14)

Odour Threshold:
Not applicable. Odour is due to decomposition products such as chlorine.

Warning Properties:
Information not available for evaluation.

Commercial strength sodium hypochlorite (liquid bleach) used by industries, laundries and in swimming pool sanitation is available in water solutions containing approximately 12.5-15.75% sodium hypochlorite (12-15% available chlorine). A weaker solution, used as household bleach, contains approximately 5.25% sodium hypochlorite (5% available chlorine). Sodium hypochlorite solutions produced on site for industrial processes, such as chemical pulp or textile bleaching, generally contain 30-40 g/L of available chlorine. The main impurities in these solutions include sodium chlorate, sodium carbonate, sodium chloride and sodium hydroxide.(15,24) Solid sodium hypochlorite can exist as the hydrate (2:5) (NaOCl.2.5H2O, CAS 55248-17-4), the pentahydrate (NaOCl.5H2O, CAS 10022-70-5) and the heptahydrate (NaOCl.7H2O, CAS 64131-03-9). Solid sodium hypochlorite does not have good stability (15,24) and is not commercially used. Therefore, this CHEMINFO review applies only to sodium hypochlorite solutions. The concentration of sodium hypochlorite solutions is often expressed in terms of percent available chlorine or alternatively in terms of percent sodium chlorite. Available chlorine represents the mass fraction of liberated chlorine in bleaching powder when bleaching powder reacts with hydrochloric acid.(16) To convert from one unit of measure to the other, the following formula can be used: % NaOCl (w/w) = Av.Cl2 X 1.05.(5)

Uses and Occurrences:
Sodium hypochlorite is used in chemical pulp and textile bleaching; as a commercial laundry and household bleach; as a sanitizer for swimming pools; as a disinfectant for municipal water and sewage; and as a disinfectant and sanitizer in dairy and food processing plants, hospitals and households. It is also used to control fungal plugging of oil production equipment; as a sweetening (desulfurizing) agent in oil refineries; and in the chemical industry for the production of hydrazine, chlorinated trisodium phosphate and organic chemicals.(15,24)
Sodium hypochlorite solutions produced directly by electrolysis of seawater or brine are used mainly in sewage and wastewater treatment, commercial laundries, large swimming pools and aboard ships to inhibit marine growth in seawater systems, for distilled water treatment and as a disinfectant for fish storage; to control slime, mollusks and algae in piping and tubes; for disinfection of seawater for secondary oil recovery; and for cyanide destruction.(16,24)


Clear light yellow to greenish-yellow liquid with a disagreeable, chlorine-like (bleach) odour. Does not burn. Decomposes when heated, during a fire or upon contact with acids releasing corrosive chlorine gas. During a fire, corrosive hydrogen chloride gas may also be generated. Reacts with primary and aromatic amines, ammonia and ammonium salts to form explosively unstable compounds. CORROSIVE to the eyes and skin. May cause blindness and permanent scarring.


Effects of Short-Term (Acute) Exposure

Sodium hypochlorite does not easily form a vapour, but solutions decompose slowly on contact with air releasing corrosive chlorine gas. Chlorine can cause severe irritation of the nose, throat and lungs, and even death, depending on the airborne concentration. The amount of chlorine released from dilute sodium hypochlorite solutions (less than 5.25%) under normal conditions of use is not significant. However, with more concentrated solutions, if the pH is lowered, if the solution is heated or if mixed with acids, higher chlorine concentrations are released. Refer to the CHEMINFO review of chlorine gas for additional information.
Mists formed from solutions can probably cause mild to severe irritation of the nose and throat, depending mainly upon the airborne concentration and the strength of the solution. There is no human or animal information available about short-term inhalation exposure to mists from sodium hypochlorite solutions.

Skin Contact:
Sodium hypochlorite solutions can cause mild irritation to corrosive injury depending on the duration of contact, the concentration and pH of the solution, based on human and animal information. Corrosive materials are capable of producing severe burns, blistering and permanent scarring.
No irritation was experienced by 20 volunteers following application of a 1% sodium hypochlorite solution (pH unspecified) for 48 hours, under a patch. Weak or moderate irritation was experienced by 15/69 volunteers following application of a 2% solution (pH unspecified).(7) No skin reaction was observed in 3 volunteers following a 48-hour application of 0.25-2% solutions, under a covered patch.(6) Severe irritation was experienced by volunteers after 4-hour application of 5.25% sodium hypochlorite solution (pH 10.7) to unbroken skin, under a patch.(21) Slight redness and small wheals (hives) were observed in 4/10 volunteers within 20 minutes of application of 0.1 mL of 6% sodium hypochlorite solution (pH 11.2) to the forehead.(22)
Effects ranging from slight irritation to corrosive injury have been observed in animal studies.

Eye Contact:
Sodium hypochlorite solutions can cause mild irritation to corrosive injury, depending on the concentration and pH of the solution, and the duration of contact, based on human and animal information. Corrosive materials are capable of causing permanent eye damage, including blindness.
There are several reports of pain, and in some cases slight damage to the surface of the eye and/or cornea, being experienced after direct contact with commercial products containing sodium hypochlorite (approximately 5%). The eyes were flushed with water or a salt solution (saline) and the injury cleared within 1-2 days.(5,25,42) There are 3 reports of burns to the eyes with slow recovery following exposure to concentrated solutions (concentration unspecified).(25) No irritation to corrosive injury has been observed in animal studies.
Sodium hypochlorite solutions decompose slowly on contact with air and release chlorine gas. If mixed with acids or warmed to higher temperatures, significant concentrations of this gas are released. Chlorine gas is a severe eye irritant. Stinging, a burning sensation, rapid blinking, redness and watering of the eyes have been observed at chlorine concentrations of 1 ppm and higher.

Swallowing sodium hypochlorite solutions can cause irritation, pain and inflammation of the mouth, throat and stomach, as well as vomiting. In severe cases, serious effects including ulceration and perforation of the gastrointestinal tract and death can result.(27,32,43) The severity of effects depends on a number of factors including the amount ingested, the concentration and pH of the solution.(27) As little as 1 ounce (about 29.5 mL) of a solution with 15% available chlorine may be lethal.(27) For sodium hypochlorite solutions with 3-6% available chlorine, a lethal dose for humans of 200 mL has been reported.(5) Severe injury to the stomach was observed in an person who ingested approximately 1 quart (1 litre) of Clorox(R) (5.25% sodium hypochlorite; pH 10.8).(3) A woman who intentionally swallowed approximately 700 mL of Clorox(R) (5.25% sodium hypochlorite, pH 11.5) showed failing mental status, perforation of the stomach, and died of cardiac arrest 4.5 hours after ingestion.(43) Deaths have also resulted from aspiration of sodium hypochlorite solution into the lungs.(5) Vomiting and damage to the gastrointestinal tract have been observed in animal studies. Ingestion is not a typical route of occupational exposure.

Effects of Long-Term (Chronic) Exposure

Sodium hypochlorite solutions can slowly release chlorine gas. For a review of the potential health effects following long-term exposure to chlorine gas, refer to the CHEMINFO review on chlorine.

Prolonged or repeated contact with sodium hypochlorite may cause dry, red, cracked skin (dermatitis). In a 5-year survey, 17/130 (13.1%) of first-time attacks of dermatitis reported among chemical factory workers were attributed to the misuse of sodium hypochlorite to clean the skin (frequency of use and concentration not reported).(44)

Skin Sensitization:
It is not possible to conclude that sodium hypochlorite is an occupational skin sensitizer.
A few cases of skin sensitization have been reported, however, in all but one case, the individuals were predisposed to this type of reaction (reacting to other common allergens as well).(6,7,22) Two non-occupational cases of sensitization to sodium hypochlorite were confirmed by patch tests. Both individuals reported a history of skin reactions following exposures to products containing sodium hypochlorite and/or chlorine. Other family or personal history of allergies was not reported.(45,46) Negative results (0/86 and 0/90 individuals sensitized) were obtained in two unpublished sensitization tests on human volunteers (human repeated insult patch test) using 4% sodium hypochlorite solution.(5) Negative results were also obtained in an unpublished animal study.


There is no human information available. The International Agency for Research on Cancer (IARC) has concluded there is inadequate evidence for its carcinogenicity in experimental animals.(24) Mainly negative results have been reported in animal studies following exposure to sodium hypochlorite by ingestion. No firm conclusions can be drawn from results obtained in two skin application studies.

The International Agency for Research on Cancer (IARC) has concluded that this chemical is not classifiable as to its carcinogenicity to humans (Group 3).

The American Conference of Governmental Industrial Hygienists (ACGIH) has no listing for this chemical.

The US National Toxicology Program (NTP) has not listed this chemical in its report on carcinogens.

Teratogenicity and Embryotoxicity:
No specific conclusions about the potential developmental toxicity of sodium hypochlorite can be drawn from a human population study that examined the potential effects of chlorinating drinking water with sodium hypochlorite. Exposure in this study was based on the chlorination method and not the measured amount of sodium hypochlorite or its byproducts in the water.(52) Insufficient details are available to evaluate a multi-generation study in rats in which no harmful effects were found.

Reproductive Toxicity:
There is no human information available. No firm conclusions can be drawn based on the limited animal information available.

There is no human information available. The available animal information suggests that sodium hypochlorite is not mutagenic. A positive result (sperm-head abnormalities) has been obtained in one test using live mice. This test does not directly measure genetic damage. Negative results have been obtained in other tests with live mice.

Toxicologically Synergistic Materials:
There is no information available.

Potential for Accumulation:
Sodium hypochlorite does not accumulate in the body. It reacts with tissues.(27) A rat study using radiolabelled hypochlorous acid has shown that the radiolabel is absorbed fairly rapidly in serum and eliminated from plasma with a half-life of 44 hours. In an ingestion study with rats, trichloroacetic acid, dichloroacetic acid, chloroform, dichloroacetonitrile and trichloroacetonitrile were found in the stomach and/or plasma.(47)


Can release corrosive chlorine gas. Take proper precautions to ensure your own safety before attempting rescue; (e.g. wear appropriate protective equipment, use the "buddy" system.) Remove source of contamination or move victim to fresh air. If breathing is difficult, oxygen may be beneficial if administered by trained personnel, preferably on a doctor's advice. DO NOT allow victim to move about unnecessarily. Symptoms of pulmonary edema can be delayed up to 48 hours after exposure. Avoid mouth-to-mouth contact by using mouth guards or shields. Immediately transport victim to an emergency care facility.

Skin Contact:
Avoid direct contact. Wear chemical protective clothing, if necessary. As quickly as possible, flush with lukewarm, gently flowing water for at least 20 minutes, or until the chemical is removed. If irritation persists, repeat flushing. Under running water, remove contaminated clothing, shoes and leather goods (e.g., watchbands, belts). Completely decontaminate clothing, shoes and leather goods before reuse, or discard. Obtain medical advice immediately.

Eye Contact:
Avoid direct contact. Wear chemical protective gloves, if necessary. Immediately flush the contaminated eye(s) with lukewarm, gently flowing water for at least 20-30 minutes, by the clock, while holding the eyelid(s) open. Take care not to rinse contaminated water into the unaffected eye or onto the face. If irritation persists, repeat flushing. Neutral saline solution may be used as soon as it is available. DO NOT INTERRUPT FLUSHING. If necessary, keep emergency vehicle waiting. Quickly transport victim to an emergency care facility.

NEVER give anything by mouth if victim is rapidly losing consciousness, is unconscious or convulsing. Have victim rinse mouth thoroughly with water. DO NOT INDUCE VOMITING. Have victim drink 240 to 300 mL (8 to 10 oz) of water to dilute material in stomach. If vomiting occurs naturally, have victim lean forward to reduce risk of aspiration. Rinse mouth and repeat administration of water. Quickly transport victim to an emergency care facility.

First Aid Comments:
Provide general supportive measures (comfort, warmth, rest).
Consult a doctor and/or the nearest Poison Control Centre for all exposures except minor instances of inhalation or skin contact.
Some recommendations in the above sections may be considered medical acts in some jurisdictions. These recommendations should be reviewed with a doctor and appropriate delegation obtained, as required.
All first aid procedures should be periodically reviewed by a doctor familiar with the material and its conditions of use in the workplace.


Flash Point:
Not combustible (does not burn).

Lower Flammable (Explosive) Limit (LFL/LEL):
Not applicable

Upper Flammable (Explosive) Limit (UFL/UEL):
Not applicable

Autoignition (Ignition) Temperature:
Not applicable

Sensitivity to Mechanical Impact:
Not sensitive

Sensitivity to Static Charge:
Sodium hypochlorite solutions will not accumulate static charge. Since these solutions do not burn, they will not be ignited by a static discharge.

Combustion and Thermal Decomposition Products:
Chlorine, hydrogen chloride gas, oxygen gas and disodium oxide.

Fire Hazard Summary:
Sodium hypochlorite is not combustible (will not burn). It decomposes when heated, giving off corrosive chlorine gas and hydrogen chloride. Solutions decompose when exposed to sunlight, giving off oxygen gas.(14) However, the amount of oxygen produced is not sufficient to cause combustion. Explosive decomposition may occur under fire conditions and closed containers may rupture violently due to rapid decomposition, if exposed to fire or excessive heat for a sufficient period of time.

Extinguishing Media:
Sodium hypochlorite solutions do not burn. Extinguish fire using extinguishing agents suitable for the surrounding fire and not contraindicated for use with sodium hypochlorite.

Extinguishing Media to be Avoided:
DO NOT use dry chemical fire extinguishing agents containing ammonium compounds (such as some A:B:C agents), since an explosive compound can be formed.

Fire Fighting Instructions:
Evacuate area and fight fire from a safe distance or a protected explosion-resistant location or maximum possible distance. Approach fire from upwind to avoid hazardous gases and toxic decomposition products, such as chlorine and hydrogen chloride. Wear full protective suit if exposure is possible. See Protection of Firefighters.
If possible, isolate materials not involved in the fire, if this can be done without risk, and protect personnel. If sodium hypochlorite is not involved in the fire, move sodium hypochlorite containers from the fire area only if they have not been exposed to heat. Use extreme caution since explosive decomposition can occur under fire conditions and heat may rupture containers and release large amounts of oxygen. Otherwise, apply water from as far a distance as possible, in flooding quantities as a spray or fog to keep fire-exposed containers or equipment cool and absorb heat, until well after the fire is out.
Stay away from ends of tanks, but realize that shrapnel may travel in any direction. Withdraw immediately in case of rising sound from venting safety device or any discolouration of tanks due to fire. In an advanced or massive fire, the area should be evacuated. Use unmanned hoseholders or monitor nozzles.
Tanks or drums should not be approached directly after they have been involved in a fire or heated by exposure, until they have been completely cooled down. Clean-up or salvage operations should not be attempted until the sodium hypochlorite is cooled.

Protection of Fire Fighters:
The decomposition products of sodium hypochlorite, such as chlorine and hydrogen chloride are extremely hazardous to health. Do not enter without wearing specialized protective equipment suitable for the situation. Firefighter's normal protective equipment (Bunker Gear) will not provide adequate protection. Chemical resistant clothing (e.g. chemical splash suit and positive pressure self- contained breathing apparatus (MSHA/NIOSH approved or equivalent) may be necessary.


NFPA - Comments:
NFPA has no listing for this chemical in Codes 49 or 325.


Molecular Weight: 74.4

Conversion Factor:
Not applicable

Physical State: Liquid
Melting Point: -6 deg C (21 deg F) (5% solution) (14)
Boiling Point: Reported to slowly decompose above 40 deg C (104 deg F).
Relative Density (Specific Gravity): About 1.1 (5-10% solution); 1.2 (15% solution) (water = 1) (14)
Solubility in Water: Soluble in all proportions
Coefficient of Oil/Water Distribution (Partition Coefficient): Log P(oct) = -3.42 (estimated) (35)
pH Value: 10.8 (10% solution); 11.2 (80%) (calculated)
Vapour Density: Not available
Vapour Pressure: Does not form a vapour.
Saturation Vapour Concentration: Not applicable.
Evaporation Rate: Not available; probably very low
Critical Temperature: Not applicable


Sodium hypochlorite solutions decompose slowly at normal temperatures releasing low concentrations of corrosive chlorine gas. Decomposition is influenced by temperature, concentration, pH, ionic strength, exposure to light and the presence of metals, such as copper, nickel or cobalt , metal oxides, e.g. rust and other impurities, such as acids and amines.(15,16)

Oxidizing Properties:
Sodium hypochlorite solutions give off oxygen when heated or when exposed to sunlight.(14,15) However, the amount is small and will not cause or contribute to combustion. The solutions are, therefore, not considered to be oxidizing agents.

Hazardous Polymerization:
Does not occur.

Incompatibility - Materials to Avoid:

NOTE: Chemical reactions that could result in a hazardous situation (e.g. generation of flammable or toxic chemicals, fire or detonation) are listed here. Many of these reactions can be done safely if specific control measures (e.g. cooling of the reaction) are in place. Although not intended to be complete, an overview of important reactions involving common chemicals is provided to assist in the development of safe work practices.

PRIMARY AMINES (e.g. ethylamine) and AROMATIC AMINES (e.g. aniline) - react to form explosively unstable N-mono- or di- chloramines.(17,36)
AMMONIUM SALTS (e.g. ammonium sulfate and ammonium nitrate), AMMONIA, UREA or PHENYLACETONITRILE - form explosive nitrogen trichloride, if acid is present.(17)
ACIDS (especially hydrochloric acid) - contact releases corrosive chlorine gas.(24)
METALS (especially copper, nickel and cobalt) - accelerate decomposition.(15,16)
REDUCING AGENTS (e.g. hydrides, such as lithium aluminum hydride) - cause a violent reaction.(34)
ETHYLENEIMINE (AZIRIDINE) - form the explosive N- chloroethyleneimine.(17,36)
METHANOL - can form explosive methyl hypochlorite, especially in the presence of acids or other etherification catalysts.(17)
FORMIC ACID - becomes explosive at 55 deg C.(17)
FURFURALDEHYDE - dropwise addition of the aldehyde to a 10% excess of sodium hypochlorite solution at 20-25 deg C can lead to a violent explosion.(17)
ETHANEDIOL (ETHYLENE GLYCOL) - erupts violently after an induction period of about 4 to 8 minutes.(17)
SODIUM ETHYLENEDIAMINETETRACETATE (EDTA) SOLUTION and SODIUM HYDROXIDE SOLUTION - mixing the three solutions leads to vigorous foaming decomposition (17)

Hazardous Decomposition Products:
Chlorine, sodium chlorate.

Conditions to Avoid:
Heat, sunlight, acidic conditions, the presence of metals and other impurities.

Corrosivity to Metals:
Sodium hypochlorite solutions (20%) are corrosive to brass (aluminum, naval and silicon) bronze, carbon steel, cast iron, Hastelloy, Inconel, nickel, stainless steels (types 304/347, 316 and 400 series) and silicon copper. Concentrated sodium hypochlorite is corrosive to most metals, including aluminum, copper, brass, bronze, carbon steel, Hastelloy, Inconel, lead, Monel, nickel and stainless steel type 400 series.(37,38) Sodium hypochlorite solutions are not corrosive to tantalum, titanium and zirconium. Dilute solutions are not corrosive to Hastelloy C/C-276 (10%), Incolloy (5%) and high silicon iron.(37,38)

Corrosivity to Non-Metals:
Sodium hypochlorite solutions attack some plastics (such as nylon, Bisphenol A-fumarate and isophthalic polyesters), elastomers (such as soft rubber, neoprene and nitrile Buna-N) and coatings (such as coal tar epoxy, epoxy and vinyls).(37,39) Sodium hypochlorite solutions do not attack acrylonitrile-butadiene-styrene (ABS), Butyl rubber, isoprene, hard rubber, natural rubber, polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), polyethylene, polypropylene, polystyrene, Teflon and Viton.(37)


LC5O (rat): greater than 5250 mg/m3 (5.25 mg/L) (4-hour exposure); cited as greater than 10.5 mg/L (10500 mg/m3) (1-hour exposure) (concentration not specified) (0/6 deaths) (1)

LD50 (oral, female mouse): approximately 7540 mg/kg; cited as 5.8 mL/kg ( 50% solution) (2) (relative density estimated at 1.3)
LD50 (oral, rat): 8910 mg/kg (undiluted) (1)

LD50 (dermal, rabbit): greater than 10000 mg/kg (undiluted) (1)

Eye Irritation:

Very dilute solutions have caused no irritation. More concentrated solutions have caused corrosive injury, which did not heal within 21 days.

No irritation was observed in rabbits following application of a 0.005% or 0.05% solution. Application of a 0.5% solution produced swollen and bloodshot inner eyelid at 2 and 6 hours. The animals returned to normal within 4 hours.(5) In another study, application of a 5% solution produced moderate to severe irritation in rabbits (average maximum Draize scores of 11, 39 and 40 out of 110 for volumes of 0.01, 0.03 or 0.10 mL; median days to clear 7, 18 and greater than 21 days, respectively).(4) Immediate pain was experienced by rabbits following application of a 5% solution (pH 11.1-11.6). When the eyes were rinsed with water within thirty seconds, effects were not severe (slight effects on the cornea and swelling of the inner eyelids) and lasted less than one day. When the solution was not rinsed away, the injury was more severe (swollen and bloodshot eyes), but healed within a week.(25) Severe irritation (scored 61.3/110) was observed in rabbits following application of undiluted sodium hypochlorite.(1)

Skin Irritation:

Very dilute solutions have caused negligible irritation, while more concentrated solutions have caused corrosive injury.

Negligible and slight irritation were observed in rabbits following application of 0.6 and 0.8% solutions.(5) Moderate tissue changes were observed in mice following application of a 0.525% solution by spraying or wiping 8 times/day for 2 consecutive days.(33) Slight irritation was observed in rabbits and guinea pigs following 4-hour application of a 5.25% solution (pH 10.7) using a patch.(21) Moderate irritation (Primary Irritation Indices of 1.4-4.6) was observed following 4-hour application of hypochlorite bleach (5.25% solution) using two different application techniques (chamber and patch).(5,20) In another test, moderate irritation was observed in rabbits following application of an approximately 5.5% solution.(5) Severe irritation (scored 5.08/8.00) and corrosive injury were observed following application of 0.5 mL of undiluted sodium hypochlorite for an unspecified duration to rabbit skin.(1)

Effects of Short-Term (Acute) Exposure:

Sodium hypochlorite solutions are corrosive following ingestion.

Vomiting was observed in dogs following ingestion of 5 mL of 5.25% sodium hypochlorite.(5) Extensive damage to the stomach, esophagus and small intestine were observed in a dog that died after ingesting 100 mL of a 5.25% solution (pH 10.8).(3).

Effects of Long-Term (Chronic) Exposure:

Slight liver damage (biochemical changes) was observed in rats given drinking water containing 0.2 and 0.4% sodium hypochlorite for 13 weeks. Approximate doses were 200 or 400 mg/kg/day. These effects were not observed in rats receiving 25-100 mg/kg/day (cited as 0.025-0.1%). Some absolute organ weights (lungs, liver and spleen in males; salivary gland, lungs, heart and brain in females) were significantly lower at 400 mg/kg/day (0.4%). However, no microscopic changes were observed in any organs.(12) Rats were given drinking water with 0, 0.05 or 0.1% (males) or 0, 0.1 or 0.2% (females) sodium hypochlorite for 2 years. Approximate doses were 0, 50 or 100 mg/kg/day for males or 0, 100 or 200 mg/kg/day for females. A dose-related in mean body weight was observed, from week 16 on. No other significant changes were observed.(12) Effects on the immune system (reduced spleen weight and impaired macrophage functions) were observed in rats given drinking water containing 15 or 30 ppm sodium hypochlorite (approximately equivalent to 1.5 or 3 mg/kg/day) for 9 weeks. No harmful effects on the immune system were observed at 0.5 mg/kg/day (5 ppm).(49) Limited experiments showed no harmful effects in male guinea pigs or male rats exposed to sodium hypochlorite in water for 5 or 6 weeks, respectively. (Doses were 8.1 mg/kg/day sodium hypochlorite (cited as 50 mg/L available chlorine) for male guinea pigs and up to 16.5 mg/kg/day sodium hypochlorite (cited as up to 15.7 mg/kg/day available chlorine) for male rats).(48) Limitations include data-reporting inconsistencies and the use of only 1 exposure level for the guinea pig experiment.

Skin Sensitization:
Negative results (0/20 guinea pigs sensitized) have been obtained for 8% sodium hypochlorite solution in a skin sensitization test.(5) Insufficient details are available to evaluate a report of a positive result (positive reactions in 2/10 animals) obtained using 6% sodium hypochlorite (pH 11.2) with the guinea pig ear swelling test for non-immunological contact urticaria.(22)

The International Agency for Research on Cancer (IARC) has concluded that there is inadequate evidence for the carcinogenicity of sodium hypochlorite in animals.
A significant increase in cancers was not seen in animals drinking water containing sodium hypochlorite for 2 years at concentrations up to 2000 ppm (rats) or 1000 ppm (mice).(8) Similarly, in another study, no dose-related increase in tumours was observed in rats given drinking water containing 0.05, 0.1 and 0.2% sodium hypochlorite (up to approximately 125 mg/kg/day) for 104 weeks.(12) Negative results were also obtained in a 6-generation study in which rats were given drinking water containing 100 mg/L chlorine (approximately 7 mg/kg/day for adults). This study is limited by small group size.(24-original unavailable in English) Firm conclusions cannot be drawn from a more recent study in which increases in stomach tumours (3 different types) were observed in male rats and increases in lymphomas and leukemias were observed in female rats after they received 100 mg/L and 750 mg/L sodium hypochlorite in drinking water (approximately 6.25 and 47 mg/kg/day). This study is limited by factors such as lack of statistical evaluation of the results and lack of a dose response relationship.(29) No significant increase in skin tumours was observed following application of a 1% solution (10 g/L) to mice for 51 weeks.(9) In another study, a more than 10.5% solution (applied 45 times over a period of 245 days) promoted the development of skin tumours in mice following skin application of a known carcinogen. This study is limited by a lack of statistical evaluation.(10)

Teratogenicity, Embryotoxicity and/or Fetotoxicity:
There is insufficient information available to draw any conclusions.
No harmful effects on growth or survival were observed in seven generations of rats given chlorinated drinking water containing 100 mg/L available chlorine (approximately equivalent to 7 mg/kg/day sodium hypochlorite for adults).(24) There is insufficient information available in English to adequately evaluate this study.

Reproductive Toxicity:
There is insufficient information available to draw conclusions.
An increase in abnormal sperm (shape) was observed in mice receiving 1.6 to 4.0 mg/kg/day hypochlorite in drinking water (as sodium hypochlorite). Effect on reproductive outcome was not assessed in this study.(11) No effects on fertility were observed in a 6-generation study in which rats were given drinking water containing 100 mg/L chlorine (approximately equivalent to 7 mg/kg/day sodium hypochlorite for adults).(24) There is insufficient information available in English to adequately evaluate this study.

The available information does not suggest that sodium hypochlorite is mutagenic. A positive result has been obtained in a sperm morphology test using live mice. However, this test does not directly measure genetic damage. Negative results have been obtained in other in vivo tests.
Abnormal sperm shape was observed in mice following oral administration of 1.6-4 mg/kg/day hypochlorite (as sodium hypochlorite) (pH 8.5) for 5 consecutive days. Other toxic effects were not reported.(11) Sodium hypochlorite was not mutagenic in other tests (chromosomal aberrations, aneuploidy and micronucleus test) with live mice using similar doses.(11,24,51)
A positive result (chromosomal aberrations) was obtained in a test using cultured human cells.(23,24-unconfirmed) Positive results were also obtained in a number of tests using bacteria and cultured mammalian cells.(23,24-unconfirmed,30,31) A negative result (unscheduled DNA synthesis) was obtained in hamster embryo cells.(50)


Selected Bibliography:
(1) Anonymous. Sodium hypochlorite. Data sheet no. 18-4/70. Industrial Bio-Test Laboratories, Inc., Northbrook, Illinois, 1970 (NIOSHTIC Control No. 00066084)
(2) Momma, J., et al. Acute oral toxicity and ocular irritation of chemicals in bleaching agents. {English Abstract.} Food Hygiene Journal. Vol. 27 (1986). p. 553
(3) Strange, D.C., et al. Corrosive injury of the stomach: report of a case caused by ingestion of Clorox(R) and experimental study of injurious injuries. Archives of Surgery. Vol. 62, no. 3 (Mar. 1951). p. 350-357
(4) Griffith, J.F., et al. Dose-response studies with chemical irritants in the Albino rabbit eye as a basis for selecting optimum testing conditions for predicting hazard to the human eye. Toxicology and Applied Pharmacology. Vol. 55 (1980). p. 501-513
(5) Racioppi, F., et al. Household bleaches based on sodium hypochlorite: review of acute toxicology and poison control center experience. Food and Chemical Toxicology. Vol. 32, no. 9 (Sept. 1994). p. 845-861
(6) Eun, H.C., et al. Sodium hypochlorite dermatitis. Contact Dermatitis. Vol. 11, no. 1 (July 1984). p. 45
(7) Habets, J.M.W., et al. Sensitization to sodium hypochlorite causing hand dermatitis. Contact Dermatitis. Vol. 15 (1986). p. 140-142
(8) Kurokawa, Y., et al. Long-term in vivo carcinogenicity tests of potassium bromate, sodium hypochlorite, and sodium chlorite conducted in Japan. Environmental Health Perspectives. Vol. 69 (Nov. 1986). p. 221-235
(9) Kurokawa, Y., et al. Studies on the promoting and complete carcinogenic activities of some oxidizing chemicals in skin carcinogenesis. Cancer Letters. Vol. 24, no. 3 (1984). p. 299-304
(10) Hayatsu, H., et al. Potential cocarcinogenicity of sodium hypochlorite. Nature. Vol. 233 (Oct. 15, 1971). p. 495
(11) Meier, J.R., et al. Evaluation of chemicals used for drinking water disinfection for production of chromosomal damage and sperm-head abnormalities in mice. Environmental Mutagenesis. Vol. 7 (1985). p. 201-211
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Information on chemicals reviewed in the CHEMINFO database is drawn from a number of publicly available sources. A list of general references used to compile CHEMINFO records is available in the database Help.

Review/Preparation Date: 2004-04-14

Revision Indicators:
Bibliography 2004-11-21
EU classification 2004-11-21
EU risks 2004-11-21
EU safety 2004-11-21
EU comments 2004-11-21
pH 2006-01-05

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