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SECTION 1. CHEMICAL IDENTIFICATION

CHEMINFO Record Number: 114
CCOHS Chemical Name: Sodium chlorite

Synonyms:
Chlorous acid, sodium salt
Chlorous acid, sodium salt, anhydrous
Chlorous acid, sodium salt, trihydrate

Chemical Name French: Chlorite de sodium
CAS Registry Number: 7758-19-2
Other CAS Registry Number(s): 49658-21-1
UN/NA Number(s): 1496
RTECS Number(s): VZ4800000
EU EINECS/ELINCS Number: 231-836-6
Chemical Family: Inorganic halogen oxygen acid salt / inorganic halogen oxo acid salt / chlorine oxygen acid salt / chlorine oxo acid salt / chlorous acid salt / chlorite / inorganic sodium compound / sodium salt
Molecular Formula: Cl-Na-O2
Structural Formula: Na.ClO2

SECTION 2. DESCRIPTION

Appearance and Odour:
Pure compound is a colourless, crystalline solid or powder. Technical grade is a white solid that may have a slight greenish tint due to trace amounts of chlorine dioxide; odourless. Slightly hygroscopic (absorbs moisture from the air).(1,26,27)

Odour Threshold:
Odourless

Warning Properties:
Information not available for evaluation.

Composition/Purity:
Sodium chlorite is commercially available as a pure solid material, or as a technical grade (solid or 25-80% water solutions). Technical grade sodium chlorite contains about 80% sodium chlorite. The remainder is mostly sodium chloride (about 17%), plus small amounts of sodium carbonate, sodium chlorate, sodium sulfate and alkali (usually very corrosive sodium hydroxide). The alkali is added to maintain the stability of the sodium chlorite.(1,26) Trace amounts of corrosive chlorine dioxide may be present as a product of decomposition.(1) Solid sodium chlorite exists in the anhydrous form (CAS 7758-19-2) and as the trihydrate, NaClO2.3H2O (CAS 49658-21-1).(1)

Uses and Occurrences:
Sodium chlorite is mainly used in the on-site production of chlorine dioxide. It is also used as an oxidizing agent in NOx and SOx combustion flue scrubber systems; for treatment and removal of toxic and odorous gases such as hydrogen sulfide and mercaptans; in textile bleaching and stripping; in disinfectant formulations and sterilization; in metallurgical and ore processing; as a biocide in drilling muds; and as a bleaching agent for edible and inedible oils, shellacs, varnishes, waxes and straw products.(1,33)
Sodium chlorite is not known to occur naturally.(19)


SECTION 3. HAZARDS IDENTIFICATION

EMERGENCY OVERVIEW:
Colourless, odourless crystalline solid or powder or white solid with a slight greenish tint. Slightly hygroscopic. Does not burn. Decomposes explosively under intense fire conditions forming oxygen and hydrogen chloride gas. MODERATE to STRONG OXIDIZER. Promotes combustion. Can be ignited readily by heat, shock or friction, and/or explode when contaminated by combustible or flammable materials (dry organic materials). Can form shock, heat or friction sensitive mixtures with finely divided metals, ammonia and amines, sulfur and sulfur-containing materials, red phosphorus and strong reducing agents. At low pH, reacts releasing corrosive and dangerously reactive chlorine dioxide. Pure sodium chlorite dust is not irritating to skin or eyes. Technical grade sodium chlorite can be CORROSIVE to the eyes and skin depending on the concentration of the solution, the amount of sodium hydroxide stabilizer present, the amount of available chlorine and the duration of exposure. Technical grade sodium chlorite may cause blindness and permanent scarring. TOXIC. May be harmful if swallowed.



POTENTIAL HEALTH EFFECTS

Effects of Short-Term (Acute) Exposure

Inhalation:
Solid sodium chlorite absorbs moisture from the air forming a pasty solid. Therefore, it is not likely to form a dust once exposed to room air. Mists formed from concentrated solutions are probably irritating to the nose and throat. The degree of irritancy depends on factors such as the concentration of the solution, the amount of sodium hydroxide present, the amount of available chlorine, the airborne concentration and the duration of exposure. There is no human or animal information available.

Skin Contact:
Pure, solid sodium chlorite is probably not irritating to the skin. The technical grade may be corrosive depending on factors such as the concentration of the solution, the amount of sodium hydroxide present, the amount of available chlorine and the duration of exposure. Corrosive materials are capable of causing severe irritation, burns and blistering.

Eye Contact:
Pure, solid sodium chlorite can cause mechanical irritation, with redness and tearing as it is rinsed from the eye. Technical sodium chlorite may be corrosive depending on factors such as the concentration of solution, the amount of sodium hydroxide present, the amount of available chlorine and the duration of exposure. In general, corrosive materials can cause permanent eye damage including blindness.

Ingestion:
Sodium chlorite is probably toxic if ingested, based on limited animal information. Pure, solid sodium chlorite may irritate the mouth, throat and stomach. Technical grade sodium chlorite may be corrosive. If ingested, corrosive materials can cause nausea, vomiting, diarrhea, cramps and pain. Sodium chlorite can also cause temporary damage to the red blood cells based on limited animal and human information. A man intentionally consumed 10 g sodium chlorite in 100 mL of water. Within minutes, he experienced abdominal cramps, nausea, vomiting and mental confusion. He showed methemoglobinemia, cyanosis (blue coloration of the skin) and had dark urine. Days later, he suffered cardiac arrest and was resuscitated. He also required treatment for acute renal failure.(40) No harmful effects were observed in volunteers that received single doses of approximately 0.05 mg/kg sodium chlorite.(24) Ingestion is not a typical route of occupational exposure.

Effects of Long-Term (Chronic) Exposure

Skin:
Dermatitis (reddening, thickening, itching, cracking) may occur from repeated or prolonged skin contact.

Blood/Blood Forming System:
Prolonged or repeated exposure to chlorites may cause harmful effects on the blood (anemia), based on animal information. This effect has not been observed in humans exposed to low levels of chlorite (less than 1 mg/kg/day) in drinking water.(19,24,25) Ingestion is not a typical route of occupational exposure.

INGESTION STUDIES: No significant adverse effects were observed in a 16-day rising dose tolerance study where men ingested 1000 mL sodium chlorite solution every 3 days at increasing concentrations with each dose (0.01, 0.5, 1.0, 1.8 and 2.4 mg/L). No harmful effects occurred in men who ingested 500 mL sodium chlorite solution (5 mg/L) daily for 12 weeks.(41)

Carcinogenicity:

There is no human information available. It is not possible to conclude that sodium chlorite is carcinogenic based on the available animal information.(19)

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 not assigned a carcinogenicity designation to this chemical.

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

Teratogenicity and Embryotoxicity:
Human studies have focused on populations exposed to chlorine dioxide-treated drinking water, which results in the formation of sodium chlorite in the water. It is not possible to draw firm conclusions about the potential developmental toxicity of sodium chlorite based on these studies, because of limitations.(42,43) This type of exposure scenario is not relevant to occupational situations.
In a two-generation study, slight fetotoxicity (reduced weight, slight developmental delays) was observed in rat pups at doses that produced early signs of toxicity in the parent generations. Other limited animal studies also suggest that developmental toxicity may occur in the presence of maternal toxicity.

Reproductive Toxicity:
There is no human information available. The available animal information does not suggest that sodium chlorite is a reproductive toxin.

Mutagenicity:
There is no human information available. It is not possible to conclude that sodium chlorite is mutagenic based on the available animal information. A positive result was obtained in a sperm morphology test in rats, which does not show the affect on DNA. Other tests using live animals have produced negative results.

Toxicologically Synergistic Materials:
There is no information available.

Potential for Accumulation:
Sodium chlorite does not accumulate in the body. In an oral study using rats exposed to radiolabelled sodium chlorite, 32% of the original dose of sodium chlorite was eliminated as chloride in the urine, while 6% was eliminated as chlorite within 72 hours. Of the recovered dose, 83% was found in the urine and 13% in the feces.(19)


SECTION 4. FIRST AID MEASURES

Inhalation:
If symptoms are experienced, remove source of contamination or move victim to fresh air. If symptoms persist, obtain medical advice.

Skin Contact:
PURE SOLID: As quickly as possible, flush with lukewarm, gently flowing water for at least 5 minutes or until the chemical is removed. Remove contaminated clothing, shoes, and leather goods (e.g. watchbands, belts). If irritation persists, repeat flushing. Obtain medical advice immediately. Completely decontaminate clothing, shoes and leather goods before re-use or discard. TECHNICAL GRADE: Avoid direct contact. Wear chemical protective clothing, if necessary. Flush contaminated area with lukewarm, gently flowing water for at least 20-30 minutes, by the clock. If irritation persists, repeat flushing. Under running water, remove contaminated clothing, shoes and leather goods (e.g. watchbands, belts). Obtain medical attention immediately. Discard contaminated clothing, shoes and leather goods. NOTE: Keep contaminated clothing under water in a closed container until it can be safely discarded.

Eye Contact:
PURE SOLID: DO NOT allow victim to rub eye(s). Let the eye(s) water naturally for a few minutes. Have victim look right and left, and then up and down. If particle/dust does not dislodge, flush with lukewarm, gently flowing water for 5 minutes or until particle/dust is removed, while holding the eyelid(s) open. If irritation persists, obtain medical attention. DO NOT attempt to manually remove anything stuck to the eye(s). TECHNICAL GRADE: 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. Neutral saline solution may be used as soon as it is available. DO NOT INTERRUPT FLUSHING. If necessary, keep emergency vehicle waiting. Take care not to rinse contaminated water into the unaffected eye or onto the face. If irritation persists, repeat flushing. Quickly transport victim to an emergency care facility.

Ingestion:
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 milk is available, it may be administered AFTER the water is given. If vomiting occurs naturally, 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.
All first aid procedures should be periodically reviewed by a doctor familiar with the material and its conditions of use in the workplace.



SECTION 5. FIRE FIGHTING MEASURES

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:
Pure sodium chlorite is not shock-sensitive. It is only becomes shock-sensitive if it is contaminated with combustible organic matter.(1,26,29,30) It has been reported that anhydrous sodium chlorite can explode upon impact. The trihydrate is also reported to be percussion sensitive. However, it is highly probable that sodium chlorite was contaminated with organic matter in these situations.(26,29)

Sensitivity to Static Charge:
Pure sodium chlorite will not accumulate static charge. Since it does not burn, sodium chlorite will not be ignited by a static discharge.

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

Fire Hazard Summary:
Sodium chlorite is not combustible (does not burn). However, sodium chlorite is strong oxidizer and presents a serious fire and explosion hazard when contaminated with oxidizable, combustible, or organic materials (e.g. cloth, leather, greases, oils, solvents, paper, sawdust, wood, rubber and plastics) , and may be ignited readily by heat, friction or shock, and may spontaneously burn or explode.(1) Dry sodium chlorite decomposes above approximately 175 deg C forming sodium chlorate, sodium chloride and oxygen, which promotes combustion and may form an oxygen-rich atmosphere. The reaction is extremely exothermic (generates heat) and is therefore self-sustaining. Sodium chlorite decomposes explosively under intense 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. No part of a sodium chlorite container should be heated above 49 deg C (120 deg F).(32) During a fire, corrosive hydrogen chloride gas may be generated.

Extinguishing Media:
Sodium chlorite does not burn. Extinguish fire using extinguishing agents suitable for the surrounding fire and not contraindicated for use with sodium chlorite. Sodium chlorite is an oxidizing agent. Therefore, flooding quantities of water spray or fog should be used to fight fires.(31)

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. DO NOT use carbon dioxide, dry chemical powder or other extinguishing agents that smother flames, since they are not effective in extinguishing fires involving oxidizers.(32)

Fire Fighting Instructions:
Extreme caution is required in a fire situation. Evacuate area and fight fire from a protected, explosion-resistant location or maximum possible distance. Approach fire from upwind to avoid hazardous vapours and decomposition products.
If possible, isolate materials not involved in the fire, if this can be done without risk, and protect personnel. If sodium chlorite is not involved in the fire, move containers from the fire area only if they have not been exposed to heat. Explosive decomposition can occur under intense fire conditions. Use extreme caution since heat may rupture containers. 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.
Remove all flammable and combustible materials from the vicinity, especially oil and grease. Do not direct water directly on leak as this may cause leak to increase. 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 chlorite is cooled.

Protection of Fire Fighters:
Sodium chlorite decomposition products, e.g. 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 (NIOSH approved or equivalent) may be necessary.



NATIONAL FIRE PROTECTION ASSOCIATION (NFPA) HAZARD IDENTIFICATION

NFPA - Health: 1 - Exposure would cause significant irritation, but only minor residual injury.
NFPA - Flammability: 0 - Will not burn under typical fire conditions.
NFPA - Instability: 1 - Normally stable, but can become unstable at elevated temperatures and pressures, or may react vigorously, but non-violently with water.
NFPA - Specific Hazards: Oxidizing material.

SECTION 9. PHYSICAL AND CHEMICAL PROPERTIES

Molecular Weight: 90.44 (anhydrous)

Conversion Factor:
Not applicable (does not form vapour).

Physical State: Solid
Melting Point: Decomposes at 180-200 deg C (356-392 deg F) (pure compound) (1,19)
Boiling Point: Not applicable (decomposes at 180-200 deg C)
Relative Density (Specific Gravity): 2.47 (pure) (water = 1) (28)
Solubility in Water: Very soluble (40.5 g/100 g at 20 deg C) (26)
Solubility in Other Liquids: Not available
Coefficient of Oil/Water Distribution (Partition Coefficient): Log P(oct) = -7.18 (estimated) (34)
pH Value: Not available
Vapour Density: Not applicable
Vapour Pressure: Does not form a vapour
Saturation Vapour Concentration: Does not form a vapour
Evaporation Rate: Very low at room temperature
Critical Temperature: Not applicable

SECTION 10. STABILITY AND REACTIVITY

Stability:
Dry solid sodium chlorite is normally stable, unless contaminated with organic matter.(30) At low pH (under pH 4), solutions decompose forming corrosive and dangerously reactive chlorine dioxide. Alkaline solutions are stable.(26)

Oxidizing Properties:
NFPA lists sodium chlorite (40% or less by weight) as a Class 2 oxidizer and sodium chlorite (over 40% by weight) as a Class 3 oxidizer. Class 2 oxidizers cause a moderate increase in the burning rate or cause spontaneous ignition of combustible materials with which they come in contact. Class 3 oxidizers will cause a severe increase in the burning rate of combustible materials with which they come in contact or will undergo vigorous self-sustained decomposition due to contamination or exposure to heat.(32)

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.


COMBUSTIBLE, OXIDIZABLE OR ORGANIC MATERIALS (e.g. cloth, wood, paper, greases, oils, solvents, rubber, leather and plastics) - mixtures can readily be ignited by heat or friction and may spontaneously burn. Some solid mixtures explode or may explode on heating, grinding, sparking or shock.(1,29,31)
ACIDS (e.g. hydrochloric acid, sulfuric acid, or oxalic acid) - reacts with evolution of corrosive and dangerously reactive chlorine dioxide gas.(29,31)
METALS - mixtures with finely divided metals may be explosive.(1)
SULFUR, ORGANIC SULFUR COMPOUNDS (e.g. dimethyl sulfide) and SULFUR-CONTAINING MATERIALS (e.g. sodium dithionite, natural rubber gloves) - very violent reaction can occur with sulfur compounds, or free sulfur (which may ignite), even in the presence of water.(29,31)
ETHYLENE GLYCOL - ignites at 100 deg C.(29)
RED PHOSPHORUS - reacts very exothermically (generates heat) in aqueous suspension above 50 deg C. The reaction can be explosive.(29,31)
AMMONIA and AMINES - form explosive compounds.(31)
REDUCING AGENTS (e.g. lithium aluminum hydride or sodium borohydride) - may react vigorously or violently.(27)

Hazardous Decomposition Products:
Chlorine dioxide (at low pH)

Conditions to Avoid:
Heat, sparks, friction, shock, impact, open flames, contaminants which react with sodium chlorite, acidic (low) pH

Corrosivity to Metals:
No corrosivity data is available for pure solid sodium chlorite. Sodium chlorite solutions (technical grade) are corrosive to carbon steel, cast iron, types 12 Cr and 17 Cr stainless steel, nickel and nickel-base alloys, such as Monel and Inconel (10-40% solutions), aluminum (10%) and copper, bronze and brass (10%) at normal temperatures.(35) Sodium chlorite solutions (technical grade) do not attack some stainless steels (types 304/347 and 316 (5% solution; up to 150 deg C), 20-25-4.5 (10%) and E-Bright 26-1 (up to 90 deg C)), Hastelloy C/C-276 (10%) and titanium (10-30%; up to 93 deg C).(35,36)

Corrosivity to Non-Metals:
Sodium chlorite does not attack most plastics, elastomers and coatings. However, it can attack some plastics (such as acetal copolymer (10% solution), acrylonitrile-butadiene-styrene (ABS) (10%), isophthalic polyester, polypropylene and polyvinyl chloride, elastomers (such as ethylene-propylene-diene, ethylene-propylene terpolymer, Viton (FKM), Nitrile Buna and natural rubber) at normal temperatures.(36,37) Polyvinylidene fluoride (PVDF) (Kynar), Teflon (TFE), Fluorocarbon FEP, Bisphenol A-fumarate (50% solution) Chemraz (polyfluoroelastomers (FPM)), Hypalon (chloro-sulfonyl-polyethylene (CSM)), isoprene, Kalrez (polyfluoroelastomers (FPM)), have excellent resistance to sodium chlorite.(36,37)


SECTION 11. TOXICOLOGICAL INFORMATION

LC50 (rat): 230 mg/m3 (4-hour exposure; whole body aerosol exposure); cited as 0.23 mg/L (9)
Note: This value is taken from a draft, unaudited study.

LD50 (oral, rat): 165 mg/kg (11-unconfirmed; original in Japanese)
LD50 (oral, mouse): 350 mg/kg (11-unconfirmed)
LD50 (oral, guinea pig): 300 mg/kg (11-unconfirmed)

Skin Irritation:

Application of 0.5 mL of a 34.5% solution of technical grade (80%) sodium chlorite for 4 hours produced no to very slight irritation in rabbits (graded a maximum of 1/4 for redness and 0/4 for swelling).(12)

Effects of Short-Term (Acute) Exposure:

Ingestion:
Effects on the blood (increased fragility, increased size and enzyme changes in red blood cells) were observed when mice were given 100 ppm sodium chlorite in drinking water (approximately 20 mg/kg/day) for 30 days. These effects were not observed at 1 or 10 ppm (approximately 0.2 or 2 mg/kg/day).(8) In another study, female mice showed no significant adverse effects after 28 days of exposure to 0, 20, 200, 1000, 3000 or 6000 mg/kg/day (cited as 0, 0.1, 1, 5, 15 and 30 mg/L) sodium chlorite in drinking water. A slight effect on the immune system (significantly increased CD8+ cells) was observed at the high dose only.(44)

Effects of Long-Term (Chronic) Exposure:

Harmful effects on the blood have been observed in rats, cats and monkeys following administration of oral doses as low as 4 mg/kg/day for over 30 days. Studies which evaluated reversibility have shown that the animals rebounded from this effect. Irritant effects (ulceration) on the lining of the stomach have been observed at doses as low as 25 mg/kg/day.

Ingestion:
Decreased red blood cell count and related effects on the blood were observed after 7 months and reduced body weight was observed after 10 and 11 months in a study in which rats were given 10 or 100 mg chlorite/L in drinking water (approximately 0.8 or 8 mg/kg/day sodium chlorite). The study did not assess whether these effects were reversible.(13) A harmful effect on red blood cells (slight hemolytic anemia) was observed in rats given doses as low as 100 mg chlorite/L (approximately 8 mg/kg/day) in drinking water for 30 or 60 days. Recovery (compensation) was observed when rats were exposed for a 90 days, indicating that the effect was not permanent. Subtle enzyme changes were observed at doses as low as 50 mg/L chlorite (approximately 4 mg/kg/day).(14) Harmful effects on the blood (destruction of red blood cells) was observed in cats given 3.0 to 7.0 mg/kg/day chlorite (4.0 to 9.4 mg/kg/day sodium chlorite) in drinking water for 5 weeks.(14) Harmful effects on the blood (e.g. decreased red blood cell count in both sexes, reduced hematocrit and hemoglobin levels and increased methemoglobin in males) were also observed in rats following oral administration of 80 mg/kg/day for 13 weeks. The study did not assess whether the effects disappeared after exposure ended. Some effects were also observed at 10 and 25 mg/kg/day, but they could not be conclusively attributed to the treatment.(15) Similar effects on the blood have been observed in monkeys receiving about 3.8-60 mg/kg/day in drinking water for 30-60 days. Compensation was observed (the effect was not permanent).(16) Harmful effects on the lining of the stomach, including ulceration, were observed in 15/30 rats following 13-week oral administration of 80 mg/kg/day and in 2/30 animals at 25 mg/kg/day (administered as a 0.25% water solution). Reversibility was not assessed.(15) In a limited study (7 animals/group), harmful effects on the kidney were observed in rats given 100 or 1000 mg/L sodium chlorite in drinking water (approximately 6 or 60 mg/kg/day) for 2 years. The author concluded the effect was a non-specific salt effect.(17, unconfirmed)

Carcinogenicity:
The International Agency for Research on Cancer (IARC) has concluded that there is inadequate evidence for the carcinogenicity of sodium chlorite in experimental animals.(19) Conclusive evidence of carcinogenicity has not been obtained in studies where rats and mice were given sodium chlorite in drinking water or following skin application to mice.
Negative results were obtained in a study where rats received 300 or 600 ppm (18-41 mg/kg/day) in drinking water for 85 weeks. This study was terminated early because the animals developed a viral infection. Mice received 250 or 500 ppm chlorite (approximately 48 or 95 mg/kg/day sodium chlorite) in drinking water for 85 weeks. Increased liver and lung tumours were observed in males only, but this result was not significant when compared with data for historical controls.(3,19) Clear evidence of carcinogenicity was not observed in a study in which mice were given 250 or 500 ppm sodium chlorite in drinking water (approximately 62 or 125 mg/kg/day) for 80 weeks. An increase in benign lung tumours (pulmonary adenomas) was observed however there was no dose-response relationship.(10) No carcinogenic effects were observed when sodium chlorite was applied to mouse skin (4 mg/application in acetone) twice a week for 51 weeks. Sodium chlorite promoted the development of skin tumours in mice previously treated with a known carcinogen, however the result was not statistically significant. This study is limited by the small group size (20 animals) and lack of a promoter control group).(4)

Teratogenicity, Embryotoxicity and/or Fetotoxicity:
In a two-generation study, slight fetotoxicity (e.g. reduced weight, slight developmental delays) was observed in rat pups at doses that produced early signs of toxicity in the parent generations. Other studies also suggest that slight developmental toxicity may occur in the presence of maternal toxicity.
In a two-generation study, rats were exposed to 0, 35, 70 or 300 ppm sodium chlorite (technical grade; 81.4% pure; remainder primarily sodium chloride and small amounts of sodium hydroxide and sodium chlorate) in drinking water for 10 weeks pre-mating through weaning of the F2 generation. Reported doses were 0, 4, 8 or 30 mg/kg/day for females and 0, 5, 10 or 39 mg/kg/day for males. Dose-related decreases in water consumption were noted in F0 male and female parent animals exposed to 70 and 300 ppm and in F0 males exposed to 35 ppm. For F1 parent animals, dose-related decreases in water consumption were observed for males in all dose groups and for females exposed to 300 ppm. Body weight and food consumption were significantly decreased for F1 males exposed to 300 ppm. Significant neurological effects were not observed in the offspring, except for small, statistically significant decreases in auditory response, which were observed at 70 and 300 ppm. At 70 and 300 ppm, reduced pup weight and slight developmental delays were observed in some pups of the F1, F2a and/or F2b generations. Some pups showed minor blood changes, including evidence of mild methemoglobinemia at 300 ppm, but these effects were not considered clinically important. No alterations in serum thyroid hormone levels were observed.(47) Rabbits were exposed to 0, 200, 600 or 1200 ppm sodium chlorite (technical grade; 80.6% purity) in drinking water on days 7-19 of pregnancy. Reported doses were 0, 10, 26 or 40 mg/kg/day. At 26 and 40 mg/kg/day, maternal toxicity (decreased food and water consumption; decreased body weight) and fetal toxicity (decreased weight and delayed skeletal ossification) were observed. At 10 mg/kg/day, no maternal or developmental effects were observed.(18) Rats were exposed to 0, 1, 10 or 100 ppm sodium chlorite for 14 days prior to mating, during mating and throughout pregnancy and lactation. Approximate doses were 0, 0.1, 1.0 or 10 mg/kg/day. No significant affects on body weight gain or food consumption were noted. Thyroid hormone levels (T3 and T4) were significantly decreased at days 21 and 40 in the offspring of animals exposed to 10 mg/kg/day.(6) It is not known if these changes persisted beyond day 40. Other studies are limited by factors such as incomplete reporting, the use of only one dose group and/or small group size.(7,8,45,21,48) Two more studies cannot be fully evaluated due to lack of detail.(20,46-unconfirmed)

Reproductive Toxicity:
The available information does not suggest that sodium chlorite is a reproductive toxin.
No harmful effects on reproduction were observed in two generations of rats dosed at 0, 35, 70 or 300 ppm in drinking water, for 10 weeks pre-mating through weaning of the second generation. Reported doses were 0, 4, 8 or 30 mg/kg/day for females and 0, 5, 10 or 39 mg/kg/day for males.(47) Harmful effects on sperm (abnormal shape and a decrease in sperm direct progressive movement) were observed in rats that received 100 or 500 ppm sodium chlorite in drinking water (approximately equivalent to 10 or 50 mg/kg/day) over 66-76 days prior to and during mating. No effects were observed on reproductive outcome.(6) Sperm head abnormalities were not observed in mice orally dose with 8, 20 or 40 mg/kg/day for 5 days.(5) Negative results were obtained in another test for multiple spermatotoxicity endpoints (organ weight, sperm count, sperm morphology and sperm motility) in which rats were given 100 or 200 mg/kg/day sodium chlorite solution orally for 5 days or 1 day, respectively.(22) Effects on reproductive outcome was not assessed in these studies.

Mutagenicity:
It is not possible to conclude that sodium chlorite is mutagenic based on the available information.
A positive result has been obtained in a sperm morphology test using live rats exposed orally.(6) However, this test does not provide proof of mutagenicity, because it does not evaluate DNA damage. Negative results have been obtained in tests (micronucleus test, bone marrow aberration test) where mice were exposed orally.(5,23) Positive results were obtained in a study when the sodium chlorite was injected, an irrelevant route of exposure.(23)
Positive results have been obtained in tests using cultured cells and bacteria.(2,23)


SECTION 16. OTHER INFORMATION

Selected Bibliography:
(1) Kaczur, J.J., et al. Chlorine oxygen acids and salts: chlorous acid and chlorites. In: Kirk-Othmer encyclopedia of chemical technology. 4th ed. Vol. 5. John Wiley and Sons, 1993. p. 981-997
(2) Ishidate, M., Jr., et al. Primary mutagenicity screening of food additives currently used in Japan. Food and Chemical Toxicology. Vol. 22, no. 8 (1984). p. 623-636
(3) 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
(4) 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 (Oct. 1984). p. 299-304
(5) 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
(6) Carlton, B.D., et al. Sodium chlorite administration in Long-Evans rats : reproductive and endocrine effects. Environmental Research. Vol. 42 (1987). p. 238-245
(7) Couri, D., et al. Assessment of maternal toxicity, embryotoxicity and teratogenic potential of sodium chlorite in Sprague-Dawley rats. Environmental Health Perspectives. Vol. 46 (1982). p. 25-29
(8) Moore, G.S., et al. Toxicological effects of chlorite in the mouse. Environmental Health Perspectives. Vol. 46 (Dec. 1982). p. 31-37
(9) Chlorine Dioxide Panel, Chemical Manufacturers Association. Initial submission: letter submitting preliminary information from an acute inhalation study in rats on sodium chlorite with attachment. Chemical Manufacturers Association, Nov. 1, 1991. EPA/OTS 88-920000094. NTIS/OTS0534543
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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: 2004-04-12



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