Hydrogen peroxide (\(\text{H}_2\text{O}_2\)) is structurally similar to water but contains an extra oxygen atom, giving it powerful oxidizing capabilities. This oxidizing power is the basis of its widespread use as a disinfectant, antiseptic, and bleaching agent in consumer and industrial products. While it is common in many households, its chemical reactivity means it poses a genuine hazard. The risks associated with hydrogen peroxide are directly tied to its concentration and the route of exposure.
How Concentration Determines Danger
The risk level of hydrogen peroxide is directly proportional to its concentration, distinguishing between an irritant and a corrosive agent. Common household solutions, typically 3%, are considered mild and are used for first-aid or cleaning. These low concentrations primarily act as irritants, causing temporary skin whitening or stinging due to the release of oxygen bubbles. Higher concentrations, such as 10% solutions used in hair bleaches or 35% industrial strengths, are significantly more hazardous. Solutions above 10% are corrosive and can cause chemical burns and tissue destruction. Industrial grades (70% to 90%) are highly reactive oxidizers capable of explosive decomposition when heated or contaminated. High concentrations are a severe hazard because they generate significant heat and oxygen gas, which can intensify fires.
Health Risks from Exposure
The potential for harm is determined by the route of exposure, with severity escalating dramatically with concentration.
Skin and Eye Contact
When \(\text{H}_2\text{O}_2\) contacts the skin, even dilute solutions cause temporary whitening due to oxygen bubbles in the capillaries. Concentrations above 50% can cause severe irritation, blistering, deep chemical burns, and permanent scarring. Ocular contact is particularly dangerous because the delicate tissues of the eye are vulnerable to its corrosive properties. Exposure to concentrations as low as 5% can cause severe irritation, pain, and corneal burns. Solutions greater than 35% risk permanent injury, including vision loss, if not treated immediately.
Ingestion Risks
Ingestion presents a unique physical hazard due to its rapid decomposition within the body. When swallowed, the compound quickly breaks down into water and a large volume of oxygen gas, leading to gastrointestinal irritation, abdominal pain, and vomiting. This rapid gas release can cause gastric distension and, in severe cases, a gas embolism. A gas embolism occurs when oxygen bubbles enter the bloodstream, potentially leading to cerebral infarction or respiratory arrest.
Inhalation Risks
Inhaling the vapors or mist of concentrated hydrogen peroxide, which is more likely in industrial settings, irritates the entire respiratory tract. Symptoms include coughing, a sore throat, and difficulty breathing. In high-exposure scenarios, this irritation can progress to pulmonary edema, a medical emergency where fluid accumulates in the lungs.
Safe Handling and Storage
Preventing accidental exposure requires following strict protocols for handling and storage, especially when dealing with non-household concentrations. Handling hydrogen peroxide should always occur in a well-ventilated area, preferably with a chemical fume hood to prevent vapor buildup. Personnel working with industrial grades must wear appropriate personal protective equipment, including chemical-resistant gloves, splash-proof goggles, and face shields. Hydrogen peroxide is unstable and decomposes naturally into water and oxygen, a process accelerated by heat, light, and contamination. Containers must be tightly sealed, opaque, and vented to prevent pressure buildup and to block light, which promotes decomposition. The chemical must be stored away from incompatible materials, such as organic substances, transition metals (like copper and iron), and strong acids or bases, as these can catalyze a violent decomposition reaction.
What to Do in an Emergency
Immediate and correct first aid can minimize the damage caused by accidental hydrogen peroxide exposure.
- For skin contact, the contaminated area must be flushed immediately and continuously with large amounts of water for at least 15 minutes, and contaminated clothing should be removed.
- Eye contact requires urgent intervention, necessitating continuous irrigation with water for a minimum of 15 minutes while holding the eyelids open to ensure thorough washing.
- If a person has inhaled the vapors, they must be moved immediately to fresh air, and medical observation is recommended for 24 to 48 hours afterward to monitor for delayed symptoms of pulmonary edema.
- In cases of ingestion, the person should drink large quantities of water to help dilute the stomach contents; however, vomiting should never be induced due to the risk of internal burns and gas embolism.
For any exposure beyond minor skin irritation, emergency medical attention must be sought immediately, and the regional Poison Control center should be contacted.