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CHEMINFO Record Number: 310
CCOHS Chemical Name: Trichloroisocyanuric acid

Trichlorocyanuric acid
1,3,5-Trichloroisocyanuric acid

Trade Name(s):
Fichlor 91

CAS Registry Number: 87-90-1
UN/NA Number(s): 2468
RTECS Number(s): XZ1925000
EU EINECS/ELINCS Number: 201-782-8
Chemical Family: Halogenated nitrogen heterocyclic compound / halogenated symmetrical triazine / halogenated symmetrical triazinetrione / chlorinated symmetrical triazine / chlorinated symmetrical triazinetrione
Molecular Formula: C3-Cl3-N3-O3


Appearance and Odour:
White crystalline powder or granules with chlorine odour. Slightly hygroscopic (absorbs moisture from the air).

Odour Threshold:
Not applicable to TCC. Chlorine odour results from decomposition of TCC.

Pure TCC has approximately 91.5% available chlorine.

Uses and Occurrences:
Used as bactericide, algicide and sanitizer in dry bleaches, dishwashing compounds, scouring powders, water treatment (including swimming pools) and sewage treatment. TCC dissolves in water to give a bleach solution (hypochlorous acid and cyanurate).



Effects of Short-Term (Acute) Exposure

Overexposure to TCC dust can cause irritation of the nose and throat, with symptoms such as sore throat and coughing (5). One TCC manufacturer reports that no irritation occurs among workers exposed to 0.5 mg/m3 of chlorinated isocyanurate dust (1).

Respiratory irritation occurred in workers finishing and packaging both TCC and sodium dichloroisocyanurate (NaDCC). Average chlorinated isocyanurate dust levels were 2.4 mg/m3. It is not clear which material was more irritating or present at the highest concentration. The exposed people wore full-facepiece air-purifying respirators with dust, mist and fume filters, and acid gas cartridges.
The plant respiratory protection program did not seem adequate (6).

Skin Contact:
TCC solid or dust can cause skin irritation with effects such as skin redness (5). If allowed to remain on the skin, solid TCC may cause severe irritation or corrosive injury to the skin.

Eye Contact:
TCC dust or solid can cause eye irritation with redness and pain (5). If allowed to remain in the eyes, TCC can cause severe irritation or damage to the eyes.

TCC can cause burns to the mouth, throat and digestive tract.

Effects of Long-Term (Chronic) Exposure

INHALATION: In one limited study, all workers in a plant finishing and packaging TCC and NaDCC (average chloroisocyanurate dust concentration of 2.4 mg/m3) reported at least one work-related respiratory symptom such as: cough, wheezing, shortness of breath, increased phlegm production, irritated throat, sinus problems and nosebleeds.
There was no significant difference in prevalence of symptoms between smokers and non-smokers or different job categories. The median length of employment was 21 months for men and 17 months for women. All workers wore full-facepiece respirators with dust, mist and fume filters, and acid gas cartridges. The plant respiratory protection program appeared inadequate.
Other symptoms included headaches and skin problems. It is not clear which material was present at the highest concentration or which was more likely to cause the reported effects (6).

SKIN: No skin irritation occurred when the entire forearms of 10 people were immersed 8 times a day for 7 days into a neutralized solution of water and TCC (100 mg/L as available chlorine). No evidence of sensitization was seen when the procedure was repeated for another 7 days after a 2-week rest period (2). Repeated skin contact with solid TCC may cause skin irritation and a rash.


No information

The International Agency for Research on Cancer (IARC) has not evaluated the carcinogenicity of this chemical.

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:
Fourteen out of 18 women reported problems with or changes in their menstrual cycle since starting jobs with exposure to both TCC and NaDCC (average chloroisocyanurate dust levels of 2.4 mg/m3).
The significance of these effects is unclear because of a number of factors including lack of a non-exposed (control) group, lack of accurate menstrual histories and a small study population (6).

No information


If symptoms are experienced, remove source of contamination or move victim to fresh air. Obtain medical attention immediately.

Skin Contact:
Gently blot or brush away excess chemical quickly. As quickly as possible, flush contaminated area with lukewarm, gently running water for at least 20 minutes, by the clock. Under running water, remove contaminated clothing, shoes and leather goods (e.g., watchbands, belts). Obtain medical attention immediately. Completely decontaminate clothing, shoes and leather goods before re-use or discard. Contaminated clothing may be a fire hazard.

Eye Contact:
Gently blot or brush away excess chemical quickly. Immediately flush the contaminated eye(s) with lukewarm, gently flowing water for 20 minutes, by the clock, holding the eyelid(s) open. Take care not to rinse contaminated water into the non-affected eye. Obtain medical attention immediately.

Have victim rinse mouth thoroughly with water. DO NOT INDUCE VOMITING. Have victim drink 240 to 300 mL (8 to 10 oz.) of water. If vomiting occurs naturally, repeat administration of water. Obtain medical attention immediately.

First Aid Comments:
Provide general supportive measures (comfort, warmth, rest). Consult a physician 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 physician familiar with the material and its conditions of use in the workplace.


Flash Point:
Does not burn.

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

Autoignition (Ignition) Temperature:
Not applicable

Combustion and Thermal Decomposition Products:
Chlorine and other hazardous gases

Extinguishing Media:
TCC does not burn. Fires involving TCC may be extinguished using dry chemical or carbon dioxide.

Fire Fighting Instructions:
Use water spray to cool containers exposed to fire and massive quantities of water to dilute material involved in a fire or spilled from containers (8).


NFPA - Health: 2 - Intense or continued (but not chronic) exposure could cause temporary incapacitation or possible residual injury.
NFPA - Flammability: 0 - Will not burn under typical fire conditions.
NFPA - Instability: 2 - Undergoes violent chemical change at elevated temperatures and pressures, or reacts violently with water, or may form explosive mixtures with water.


Molecular Weight: 232.41

Conversion Factor:
Not applicable

Physical State: Solid
Melting Point: Decomposes at 225-247 deg C (437-477 deg F)
Boiling Point: Not applicable
Relative Density (Specific Gravity): Greater than 1 at 20 deg C (water = 1)
Solubility in Water: Slightly soluble
Solubility in Other Liquids: Soluble in chlorinated and highly polar solvents
pH Value: 2.0-3.7 (1% solution)
Vapour Density: Not applicable
Vapour Pressure: No information
Saturation Vapour Concentration: Not applicable
Evaporation Rate: Not applicable
Critical Temperature: Not applicable


Stable when dry. Reacts non-violently with water to form a bleach solution (hypochlorous acid and cyanurate).

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.

ORGANIC MATERIALS (including all flammable and combustible materials) - reaction may cause fire (3,8)

OXIDIZABLE MATERIALS - reaction may cause fire

NITROGEN-CONTAINING COMPOUNDS (including ammonia, ammonium salts, urea) - may form hazardous nitrogen trichloride (NCl3) (3,8)

HYDRATED SALTS - may create heat, decomposition and rupture of sealed containers (8)

ACIDS (especially HCl) - generates chlorine gas (3)

ALKALINE MATERIALS (e.g., soda ash) - reaction can generate NCl3 (3)

REDUCING MATERIALS - can react violently (5)

Hazardous Decomposition Products:
Nitrogen trichloride, chlorine

Corrosivity to Metals:
No information

Stability and Reactivity Comments:
In strong water solutions (concentrations greater than 0.5% available chlorine), TCC can break down forming hazardous NCl3 (2,3,8).


LD50 (oral, rat): 406-750 mg/kg (2,RTECS)
LD50 (dermal, rabbit): 20,000 mg/kg body weight (RTECS)

EYE IRRITATION (rabbit): Chlorinated isocyanurates are generally corrosive when applied to rabbit eyes (1). 50 ug of TCC applied to rabbit eyes for up to 24 hours caused severe irritation (RTECS). 5 mg of TCC applied to rabbit eyes caused severe irritation within 20 minutes (4).

SKIN IRRITATION (rabbit): Chlorinated isocyanurates can be severely irritating or corrosive when applied to rabbit skin under a bandage for 24 hours (1). 500 mg of TCC applied to rabbit skin for 24 hours caused moderate irritation (RTECS);
10 mg of dry TCC applied to rabbit skin caused acid-type burns. When the TCC was moistened with water prior to application, the burns were more severe (4).
In another study, dry TCC powder caused no irritation when applied to rabbit skin for 24 hours (2).

INHALATION: Rats inhaled TCC dust at concentrations of 3, 10 and 30 mg/m3 for 6 hours/day, 5 days/week for 4 weeks. The TCC was sieved to produce respirable particles. Rats exposed to 10 and 30 mg/m3 had runny noses, excess saliva, tears and difficulty breathing. Some effects may have resulted from rats swallowing TCC while cleaning themselves.
These animals also had changes in body and organ weights and some other tests compared to non-exposed rats. No harmful effects were seen in rats that breathed 3 mg/m3. None of the exposed rats died (1).

CHRONIC INGESTION: There have been several studies of the effects on rats of TCC administered in drinking water. These studies concern the safety of TCC for water treatment, rather than to occupational exposure.

Two studies used concentrations of 400, 1200, 4000 and 8000 ppm TCC for 1 month (2) or 2 months (1). The highest doses (4000 and 8000 ppm) caused increased deaths, decreased growth, difficulty breathing and gastrointestinal bleeding in the longer study (1). No major effects were seen in the shorter study (2).


Selected Bibliography:
(1) Hammond, B.G., et al. A review of toxicology studies on cyanurate and its chlorinated derivatives. Environmental Health Perspectives. Vol. 69 (1986). p. 287-292
(2) Canelli, E. Chemical, bacteriological, and toxicological properties of cyanuric acid and chlorinated isocyanurates as applied to swimming pool disinfection : a review. AJPH. Vol. 64 (Feb. 1974). p. 155-162
(3) Kirk-Othmer encyclopedia of chemical technology : vol. 24. 3rd ed. John Wiley & Sons, 1984. p. 427-441
(4) Cyanuric acid and chlorinated derivatives CAS No. 108-80-5 : chemical hazard information profile (draft report). U.S. Environmental Protection Agency, March 13, 1981
(5) Handling chemicals safely. 2nd ed. Dutch Association of Safety Experts, Dutch Chemical Industry Association, Dutch Safety Institute, 1980. p. 920
(6) Health hazard evaluation report 81-467-1138. NIOSH, July 1982. p. 1-27
(7) Palassis, J., et al. Sampling and analysis of chlorinated isocyanuric acids. American Chemical Society, ACS Symposium Series No. 149, 1981. p. 123-135
(8) Fire protection guide to hazardous materials. 13th ed. Edited by A.B. Spencer, et al. National Fire Protection Association, 2002. NFPA 49
(9) Patty's industrial hygiene and toxicology. 3rd rev. ed. Vol. 2A. John Wiley & Sons, 1981. p. 2765-2769
(10) European Communities (EC). Commission Directive 2000/32/EC. May 19, 2000

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: 1988-04-29

Revision Indicators:
PEL-TWA 1993-03-01
NFPA (reactivity) 1993-03-01
Trans PEL-TWA 1993-04-01
TDG 1994-03-01
Sampling 1996-01-01
Protective equipment 1996-01-01
EU number 1996-01-01
NFPA (health) 1996-01-01
US transport 1998-03-01
EU Class 2000-05-01
EU Risk 2000-05-01
EU Safety 2000-05-01
Bibliography 2002-02-08
Bibliography 2003-03-25

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