Perchlorates are salts derived from perchloric acid (HClO₄). These compounds are colourless and odourless and can occur naturally or through manufacturing processes. Most perchlorate salts are highly soluble in water and have been used in medicine for over 50 years, particularly in treating thyroid disorders.
Perchlorates are stable at normal temperatures, but when heated, they undergo a chain reaction that releases large amounts of heat, potentially leading to explosions. This property makes perchlorates ideal for use in rocket motors, fireworks, flares, gunpowder, and explosives.
What are Perchlorates used for?
Perchlorates are used in a wide variety of applications, including:
Rocket fuels (as ammonium perchlorate)
Flares, explosives, blasting agents, and fireworks
Military munitions (e.g., grenades)
Production of perchloric acid and other perchlorate salts
Manufacturing of:
Matches
Dyes
Rubber and lubricating oils
Car airbag inflators
Road flares
Drying and etching agents
Gunpowder and batteries
Chlorine-based products and pool chemicals
Electronic components (tubes), paint, and enamel
Fertilisers, nuclear reactors, leather, and aluminium
Found in chewing tobacco
Potassium perchlorate is also used in certain thyroid function tests
Perchlorates are used in flares, explosives, blasting agents, and fireworks.
In the Environment
Perchlorates can exist as solids (on dry surfaces or in sealed containers) or as dissolved ions in water. Once in water, they split into positively and negatively charged ions, the latter known as the perchlorate anion.
Key environmental characteristics:
Highly soluble and mobile in soil → prone to leaching into groundwater
Do not volatilise from soil or water
Persistent in the environment but may eventually degrade via microbial activity
When released into the air, they settle through rainfall
Do not bioaccumulate significantly in animals
Sources and Routes of Exposure
Sources of Exposure
Human exposure to perchlorate primarily occurs through ingestion of food and milk. According to the U.S. Food and Drug Administration (FDA), the population ingests between 0.08 to 0.39 µg/kg/day of perchlorate from food.
Perchlorate has also been detected in drinking water supplies, including tap water and groundwater at various locations. Efforts are ongoing to determine how much exposure comes from food versus water.
Drying and etching agents, oxygen-generating systems
Matches, chlorine-based cleaners, and pool chlorination chemicals
Chewing tobacco, which has tested positive for perchlorate in several brands
Occupational exposure may occur through inhalation of perchlorate dust during manufacturing and handling. Accidental ingestion via dust deposition in the mouth is also possible.
Routes of Exposure
The main exposure routes for perchlorates are:
Ingestion: through contaminated food, milk, and water
Inhalation: of dusts or airborne particles
Dermal contact: particularly with contaminated soil
Health Effects
The toxic effects of perchlorate stem from the perchlorate ion itself, not from the accompanying elements like ammonium, potassium, or magnesium.
Perchlorate primarily affects the thyroid gland, interfering with its ability to absorb iodine, which is essential for producing hormones that regulate metabolism and other body functions.
However, a significant inhibition of iodine uptake is necessary before harmful effects are seen.
In studies with healthy volunteers, daily doses of 35 mg for 14 days or 3 mg for 6 months caused no thyroid or other health problems.
Long-term occupational exposure in workers to similar levels also showed no changes in the thyroid, liver, kidneys, or blood.
There is concern that high or prolonged exposure could lead to hypothyroidism (underactive thyroid), which may affect:
Skin, heart, lungs, kidneys, liver
Blood and gastrointestinal systems
Nervous and reproductive systems
Endocrine organs and skeletal structure
Animal studies confirm that the thyroid is the main target of perchlorate toxicity. However, no reproductive toxicity was observed in rats.
Safety
First Aid Measures
Eye Contact: Remove contact lenses if present. Flush eyes immediately with plenty of water for at least 15 minutes. Cold water may be used. Seek medical attention.
Skin Contact: Flush affected skin with plenty of water. Cover with an emollient. Remove contaminated clothing and shoes. Cold water may be used. Wash clothes before reuse. Clean shoes thoroughly. Seek medical attention.
Serious Skin Contact: Wash the area with disinfectant soap and apply an antibacterial cream. Get medical attention promptly.
Inhalation: Move the person to fresh air. If not breathing, give artificial respiration. If breathing is difficult, provide oxygen. Seek medical help.
Serious Inhalation: Move the person to a safe area as soon as possible. Loosen tight clothing (collar, tie, belt, waistband). If breathing is difficult, administer oxygen. If not breathing, perform mouth-to-mouth resuscitation. Get immediate medical assistance.
Ingestion: Do not induce vomiting unless directed by medical personnel. Never give anything by mouth to an unconscious person. If large amounts are swallowed, call a doctor immediately. Loosen tight clothing (collar, tie, belt, waistband).
Handling and Storage
Keep away from heat, ignition sources, and combustible materials.
Empty containers may still pose a fire risk—evaporate residues under a fume hood.
Ground all equipment that contains this material.
Do not breathe dust; take precautions against electrostatic discharge.
Wear appropriate protective clothing and, if ventilation is poor, respiratory protection.
Seek medical attention if you feel unwell—show the label when possible.
Avoid contact with skin and eyes.
Keep containers tightly closed and in a cool, well-ventilated area.
Store separately from acids, alkalies, reducing agents, and combustibles.
Exposure Control & Personal Protection
Engineering Controls
Use process enclosures or local exhaust ventilation to maintain airborne levels below recommended limits.
If operations generate dust, fumes, or mist, ensure sufficient ventilation is in place to control exposure.
Personal Protective Equipment (PPE)
When handling perchlorates, wear:
Splash goggles
Lab coat
Dust respirator (approved/certified)
Gloves
In case of a large spill, additional protection should include:
Full protective suit
Boots
Splash goggles
Dust respirator
Self-contained breathing apparatus
The suggested PPE may not be sufficient for all conditions. Always consult a specialist before handling perchlorates.
Regulation
United States
EPA: The United States Environmental Protection Agency adopted a Reference Dose (RfD) for perchlorate in 2005, and issued guidance regarding the cleanup of perchlorate at Superfund sites in 2006. EPA is currently evaluating whether there is a meaningful opportunity to reduce health risk through national drinking water regulation for perchlorate.
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