Aug 3, 2009: How toxic are pool chemicals?

What are pool chemicals?  Are they toxic?  To maintain commercial and private swimming pools, many chemicals are utilized to enhance and protect the water quality.  These chemicals minimize bacterial and algal growth, and maintain a pH to enhance disinfectant action while minimizing skin and eye irritation.


Chlorine systems are the most common systems. For residential pools, chlorinated isocyanurates are used and these dissociate to form hypochlorite ions which are the disinfectant and cyanuric acid.  Periodically, a “shock treatment” (granules or packets of sodium, calcium or lithium hypochlorite tablets) are utilized to recharge chlorine levels.  The pH needs to be maintained within a narrow range to minimize skin/eye irritation and to enhance the action of chlorine.  Sodium carbonate is used to increase pH. Muriatic acid or sodium bisulfate will lower pH.  To help prevent a build up of chloramine in the system, a “stabilizer” consisting of cyanuric acid is added.   Chloramine is formed from a reaction of chlorine with body fluids and lotions that are washed off into the pool.  Chloramine is what makes water smell like chlorine and is very irritating to eyes, airway, and skin.  Lastly a buffer called “alkalinity” is added to the system to maintain pH within its narrow range and consists of sodium bicarbonate.


Prevention is the key to reducing medical problems when exposed to these chemicals.  Medical concerns from these chemical exposures include:

  1. Chlorine/chlorinated isocyanurates: irritant to mucous membranes and upper airway primarily.  Primary treatment is removal to fresh air.  Oxygen and treatment for bronchospasm may be required.
  2. hypochlorites: irritant to corrosive, depending on concentration.  May release chlorine or chloramine when combined with acids.  Primary treatment is removal to fresh air. Oxygen and treating for bronchospasm may be required.  Flush skin.
  3. sodium carbonate: irritant to caustic. Primary treatment is removal to fresh air. Oxygen and treating for bronchospasm may be required.  Flush skin.
  4. sodium bicarbonate: minimal toxicity with dermal exposure.  Infants and small children may have significant fluid/electrolytes abnormalities if ingestion occurs.
  5. muriatic acid (HCl) and sodium bisulfate: skin burns, airway irritation to pulmonary edema, GI irritation and burns.  Primary treatment is irrigation and removal to fresh air.  Supplemental oxygen, bronchospasm treatment and supportive therapy may be needed.  If ingested, may need endoscopy to see extent of injuries.
  6. cyanuric acid: primarily an irritant to mucous membranes and upper airway.  Primary treatment is removal to fresh air. Oxygen and treatment for bronchospasm may be needed.


Typical dangers in mis-handling and mixing chemicals include:

  1. Chlorine product plus acid è chlorine or chloramine gas (very irritating and could cause pulmonary edema)
  2. Water dropped onto chemicalsèexplosion (always add chemical into pool water first)
  3. Mixing different types of chlorine productsèexplosion



Additional reading:


Question prepared by: John Benitez, M.D., MPH  Medical Toxicologist

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Donna Seger, M.D.

Medical Director

Tennessee Poison Center


Poison Help Hotline: 1-800-222-1222