Sodium hydroxide, aka lye and caustic soda, is an alkaline chemical known for its causticity. It is a co-product of chlorine, and in its raw form, it can be found in flakes, crystals or chips. Its chemical formula is NaOH. [1,2,3]
Sodium hydroxide is used across a range of applications in various industries. It is used in soap-making and other cleaning products and disinfectants. Sodium hydroxide is used in a variety of pharmaceutical products, and in the energy industry, it is used in fuel cell production. The chemical is also used in the water and food industries for various applications, including water treatments and curing, respectively. Sodium hydroxide is used in the textile industry and in the treatment of wood and paper products.
Routes of Exposure [4,5]
The main routes of exposure to sodium hydroxide are skin and eye contact.
People can also be exposed to sodium hydroxide dust through inhalation.
Higher levels of sodium hydroxide in the air are found nearer the ground. This means that children are potentially more likely to exposed to higher rates than adults because they are closer to the higher source.
Sodium hydroxide poisoning affects a range of systems, including the integumentary and respiratory systems.
Acute Effects 
Severity of symptoms depend on the level and type of exposure.
Acute exposure from skin contact to the chemical can result in red, burning, blistering and painful skin, which can lead to permanent scarring. Burns from the chemical may not be immediately painful; the onset of pain could be delayed. Acute eye contact to sodium hydroxide can result in swelling, pain, blurred vision and redness in the eye. It can also cause permanent blindness. If the chemical is ingested, it can cause nausea, vomiting, diarrhoea, stomach cramps and death.
Chronic Effects [4,6]
Chronic exposure to sodium hydroxide is toxic to multiple body systems. Long term exposure to the chemical can cause dermatitis, erosion of the teeth, and inflammatory and ulcerative changes in the mouth. It can also result in long-term breathing difficulties; repeated exposure to high dust concentrations could result in changes to lung function. Chronic exposure to the chemical can also result in frequent bouts of bronchial pneumonia, and bronchial irritations with a cough.
~h2First Aid Measures 
- Ingestion: If swallowed, contact a medical professional immediately. DO NOT INDUCED VOMITING. If vomiting occurs, place patient in the recovering position. If the person is conscious (and not showing signs of signs of sleepiness), they are able to have water to rinse out their mouth. They are then allowed to drink it slowly—and as much as they can comfortably drink.
- Skin contact: Remove all contaminated clothing, footwear and accessories. Do not re-wear clothing until it has been thoroughly decontaminated. Immediately rinse affected areas with plenty of water. Contact a doctor immediately.
- Eye contact: Flush eyes (including under the eyelids), with water for at least 15 minutes. Removal of contact lenses should only be done by skilled personnel. Contact a medical professional immediately.
- Inhalation: Take victim away from the contaminated area to the nearest fresh air source and monitor their breathing. Prosthesis that could block the airway, such as false teeth, should be removed. Keep the victim warm. If the victim is not breathing, and you are qualified, you may perform CPR with a one-way valve or protective mask. Immediately contact a medical professional.
- General: Never administer anything by mouth to an unconscious, exposed person.
Exposure Controls/Personal Protection 
Engineering controls: Emergency eyewash fountains and quick-drench areas should be accessible in the immediate area of the potential exposure. Ensure there is adequate ventilation. Use a local exhaust ventilation or process enclosure, to limit the amount of chemical dust in the air.
- Personal protection: Safety glasses, protective and dustproof clothing, gloves, an apron and an appropriate mask or dusk respirator. Wear impervious shoes. Do not wear contact lenses. For specifications regarding other PPE, Follow the guidelines set in your jurisdiction.
The Occupational Safety and Health Administration (OSHA) has set a permissible exposure limit (PEL) concentration limit for sodium hydroxide of 2mg/m3.
Safe Work Australia has set an 8-hour time-weighted average (TWA) for sodium hydroxide of 2mg/m3 has been set.