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Unveiling the World of Corrosive Substances: A Guide to Hazardous Acids and Chemicals (Plus a Handy Checklist)

In the dynamic industrial environment, unexpected mishaps can occur in the blink of an eye: an employee encounters a corrosive chemical, potentially leading to severe chemical burns on the skin, eyes, and mucous membranes. This sobering reality highlights the critical need for stringent safety protocols when dealing with corrosive and irritating substances in your workplace.

This informative DENIOS article comprehensively explores corrosive substances, encompassing acids, alkalis, and the regulatory landscape. Dive into the essential aspects of identifying corrosive substances, implementing safe handling practices, understanding associated health risks, and establishing protective measures for yourself and your colleagues.

With this knowledge and a practical checklist tailored for hazardous substances in the workplace, you'll be empowered to proactively mitigate risks and cultivate a resilient, secure working environment.

Unlocking the Essentials of Corrosive Substances

  • Corrosive substances, called caustic substances, pose a significant threat, possibly inflicting irreversible harm to surfaces and tissues. Identified by the distinctive pictogram denoting a "corrosive effect," these substances encompass a spectrum of hazardous materials.

  • Among them are acids like hydrochloric acid, bases such as caustic soda, and oxidizing and water-reactive agents, each presenting unique dangers in various forms.

  • These substances have the potential to cause severe skin irritation, eye damage, and respiratory distress, with alkalis particularly notorious for their profound impact.

  • Categorized according to the standards set by GHS, corrosive substances are subject to stringent regulations, including oversight by the Canadian Environmental Protection Act, 1999 (CEPA)

  • Adherence to protective measures like the "STOP" rule is paramount when handling corrosive chemicals. Proper storage, complete with accurate labelling and secure containment, is imperative to minimize risks.

  • From commonplace cleaning products to industrial compounds, corrosives pervade our surroundings, necessitating vigilant handling to avert accidents and ensure safety for all.

Understanding Corrosive Substances

Corrosive substances, interchangeably called caustic or erosive agents, are characterized by their ability to corrode surfaces or cause permanent damage to living tissue. Identified by the distinctive pictogram denoting a "corrosive effect," these substances pose significant risks to materials and biological matter.

This category encompasses a range of hazardous materials, including:

  • Acids such as hydrochloric acid, sulfuric acid, and nitric acid.

  • Bases known as alkalis include caustic soda and concentrated alkaline solutions.

  • Compounds that react vigorously with water, either acidic or alkaline.

  • Substances with oxidizing properties that facilitate the removal of water.

The diverse nature of corrosive substances underscores the importance of proper handling and stringent safety measures to mitigate potential harm.


Corrosive substances are hazardous materials capable of irritating the skin and mucous membranes upon contact, leading to inflammation of the eyes and respiratory tract. Unlike corrosive substances, they do not induce permanent tissue damage. Common examples of irritants include citric acid, acetic acid, and certain drain cleaners. These substances are typically labelled with the hazard symbol denoting "irritant," warning of their potential to cause discomfort and irritation upon exposure.

Corrosive substances exhibit a range of properties that underscore their hazardous nature:

  • Contact with the skin can lead to itching, redness, and tissue damage.

  • Even in diluted form, splashes can cause severe damage to the eyes.

  • They manifest in diverse forms, including solid, liquid, gaseous, organic, or inorganic.

  • Interactions with other substances may provoke hazardous reactions, potentially generating toxic gases.

  • Corrosive substances can corrode metals, posing additional risks in specific environments.

Everyday Encounters: Common Corrosive Substances in Daily Living

Corrosive substances are frequently encountered in everyday scenarios, often disguised under trade names rather than their chemical identities. Here's a rundown of common corrosive liquids and their typical aliases:

Acids and Their Common Names:

  • Hydrochloric acid: often labelled simply as hydrochloric acid

  • Sulfuric acid: known as battery acid, vitriol oil, or accumulator acid

  • Nitric acid: sometimes referred to as Acidum nitricum

  • Hydrofluoric acid: typically recognized as hydrofluoric acid

Alkalis and Their Common Names:

  • Sodium hydroxide: commonly encountered as caustic soda or simply sodium hydroxide

  • Potassium hydroxide: known as caustic potassium, potassium hydroxide, potassium hydrate, or caustic potash

  • Ammonia: recognized as ammonium hydrate, ammonium hydroxide, or simply ammonia

  • Calcium hydroxide: often referred to as milk of lime or slaked lime

Despite their prevalence, corrosive chemicals may not always be readily identifiable, highlighting the importance of understanding their trade names and chemical compositions to ensure safe handling practices.

Classifying Corrosive Agents: Understanding Hazard Categories and Classification Systems

In compliance with the Workplace Hazardous Materials Information System (WHMIS), corrosive substances are classified utilizing the Globally Harmonized System (GHS). They recognize three primary hazard categories for corrosive substances:

  1. Skin corrosion/irritation

  2. Serious eye damage/irritation

  3. Corrosive to metals

Within the GHS framework, WHMIS further delineates classification into specific categories:

  • Category 1: Corrosive to the skin or eyes

  • Category 1A: Corrosive to the skin within 3 minutes or less

  • Category 1B: Corrosive to the skin in more than 3 minutes but less than 1 hour

  • Category 1C: Corrosive to the skin in 1 hour or more but less than 4 hours

  • Category 2: Corrosive to the skin or eyes without falling into category 1

  • Category 3: Corrosive to the respiratory tract

Additionally, the Dangerous Goods Ordinance governs storage and transport classification, focusing primarily on the corrosive effect on the skin:

  • Packaging Group I: Corrosive effect on the skin within 3 minutes

  • Packaging Group II: Corrosive effect on the skin in more than 3 minutes but less than 1 hour

  • Packaging Group III: Corrosive effect on the skin in 1 hour or more, but less than 4 hours

  • Packaging Group IV: Corrosive to metals

Corrosive substances are further classified based on their chemical properties and pH into distinct groups:

Acid-corrosive substances (C1 to C4) – pH below 7:

  • C1: Inorganic liquids

  • C2: Inorganic solids

  • C3: Organic Liquids

  • C4: Organic solids

Alkaline corrosives (C5 to C8) – pH above 7:

  • C5: Inorganic liquids

  • C6: Inorganic solids

  • C7: Organic Liquids

  • C8: Organic solids

Other corrosive substances (C9 to C11) that don't fit into the above categories:

  • C9: Liquids (not clearly acidic or alkaline)

  • C10: Solids (not clearly acidic or alkaline)

  • C11: Items (not clearly acidic or alkaline)

Accurate classification of corrosive substances is imperative to implement suitable protective measures and ensure these materials' safe handling, storage, and transportation.

Navigating Legal Frameworks: Regulations for Handling Corrosive Substances

In Canada, an array of laws, ordinances, and regulations govern the safe handling of corrosive substances. These encompass:

Regulatory Body Content
Canadian Environmental Protection Act (CEPA 1999) This act regulates the management of toxic substances, including some corrosive substances listed in Schedule 1.
Hazardous Products Act (HPA) These regulations classify and control controlled products, including many corrosive substances used in workplaces and consumer products. They define labelling, packaging, and safety requirements for handling these products.
Controlled Products Regulations (CPR) Specifies the hazard criteria for controlled products and requirements for product labels and MSDSs.
Transportation of Dangerous Goods Act (TDG Act) and Transportation of Dangerous Goods Regulations (TDG Regulations) These regulations govern the safe transportation of dangerous goods, including corrosive substances, by road, rail, air, and sea. They specify packaging, labelling, documentation, and training requirements for shippers and carriers.
Occupational Health and Safety (OHS) legislation Each province and territory have its own OHS legislation and regulations setting standards for workplace safety, including the handling of hazardous substances like corrosive materials.

Furthermore, comprehensive operating instructions and information, provided in the form of safety data sheets, are mandated for employees. These documents inform them about potential hazards and outline protective measures necessary for handling corrosive substances, as determined by risk assessments for hazardous materials.

Companies that violate transportation regulations concerning corrosive acids and alkalis may face fines or penalties, the severity of which depends on the nature of the violation and applicable laws and regulations.

Understanding the Health Risks Associated with Corrosive Substances

Corrosive substances pose significant health hazards upon contact with living tissues, including the eyes, skin, and mucous membranes.

  • Skin Contact: Corrosives can induce skin irritation, redness, tissue damage, and even open wounds. Even diluted splashes of corrosive substances can lead to severe injuries.

  • Eye Contact: Acidic and alkaline splashes can cause severe eye injuries, including tissue damage and potential blindness. Contact with corrosive substances can result in irritation, redness, swelling, and blurred vision.

  • Inhalation: Inhaling gases, vapours, or aerosols of corrosive substances can damage the respiratory tract and lungs, leading to symptoms such as coughing, difficulty breathing, chest pain, and in severe cases, chemical pneumonia.

  • Ingestion: Swallowing corrosive substances can damage the lips, oral cavity, throat, esophagus, and stomach, resulting in difficulty swallowing, vomiting, bleeding, and potentially chemical burns to internal organs.

  • Chemical Reactions: Accidents during the handling of corrosive chemicals can occur due to chemical reactions, leading to heat generation and additional hazards.

The severity of the corrosive effect depends on various factors, including the substance's chemical properties, quantity, concentration, and duration of exposure. Generally, alkalis are considered more hazardous than acids due to their more profound penetrating action.

Assessing the corrosive and irritating potential of acids and alkalis can also be done using their pH values.

Information regarding the specific material properties of corrosive substances can be obtained from the corresponding safety data sheet, among other resources.

Below is a list of corrosive substances, along with their associated health risks:

Hydrochloric acid Mild skin irritation to severe damage to the skin and underlying tissue
Sulfuric acid Strong corrosive effect on the skin and mucous membranes
Acetic acid Mild skin irritation and eye damage
Soda lye Severe chemical burns to the skin and respiratory tract
Caustic potash Strong corrosive effect on skin and mucous membranes
Ammonia Irritates the eyes, skin and respiratory tract
Chlorine Corrosive to skin, eyes and respiratory tract



Before working with hazardous substances, the Canadian Centre for Occupational Health and Safety (CCOHS) requires a documented risk assessment. This contains a list of all relevant substances and the dangers they pose. The employer must collect information from public sources such as safety data sheets to do this.

At the federal level in Canada, the Canadian Centre for Occupational Health and Safety (CCOHS) advocates for first-aid provisions in workplaces. All provinces and territories have their own Occupational Health and Safety (OHS) legislation mandating employers to furnish sufficient first-aid services and facilities, like eye wash stations and emergency showers. These requirements vary by jurisdiction, emphasizing the need to consult the relevant provincial/territorial OHS website or authority for precise guidelines.

Regardless of the risk assessment, CCOHS has a longstanding policy that Engineering and work practice controls should be the primary effort to reduce employee exposure to hazardous and corrosive chemicals.

Strategies for Hazard Control and Safety Measures:

Substitution or Elimination: Substitute hazardous chemicals with safer alternatives whenever feasible.

Technical Engineering Controls: Reduce exposure to hazardous chemicals through measures such as employing sump pallets, isolation, wet methods to minimize dust, dilution ventilation, and utilizing fume hoods.

Organisational Administrative and Work Practice Controls: Establish comprehensive protocols for managing corrosive substances, including tasks such as container labelling, developing operational guidelines, and providing staff training. Implement job rotation and adjust schedules to mitigate workers' excessive exposure to hazardous chemicals.

Personal Protective Equipment (PPE): Utilize personal protective equipment such as protective clothing, respiratory protection, gloves, and eye protection as primary safeguards.

Combining substitution, technical and organizational measures, and personal protective clothing offers the best strategy for minimizing the risk when handling corrosive substances.

Key Protective Measures for Handling Corrosive and Irritating Substances


  • Chemical Containers: Utilize appropriate devices such as hand pumps, dosing taps, and funnels when filling and dispensing small quantities from jerry cans to prevent spills. While automated dosing stations offer safe transportation of corrosive chemicals, precautions are necessary during container changes or suction lance removals.

  • Storage and Work Rooms: Ensure that rooms housing irritating and corrosive gases or vapours are well-ventilated to mitigate fire and explosion risks. Employ professional warning devices and detectors to detect escaping hazardous substances and trigger alarms promptly. Additionally, utilize floors resistant to the materials present for added safety. Please get in touch with us for help setting up compliant storage for corrosive and hazardous chemicals.

  • Storage Containers: Opt for containers, fittings, and hoses made from corrosion-resistant materials to ensure safe storage of corrosive substances.

  • Safety Cabinets: Consider utilizing special safety cabinets specifically designed for the storage of corrosive substances to enhance safety measures and minimize risks associated with hazardous materials.

  • Segregated Storage: Maintain separate storage areas for flammable substances, ensuring they are stored apart from corrosive ones, even if they are not inherently flammable. Corrosive substances should never be stored in locations such as above work areas, circulation areas, exits, passageways, airlocks, buffer rooms, under stairs, or on catwalks or platforms. Additionally, avoid temporary storage of acids and alkalis on stairs and corridors.

  • Secondary Containment: Install liquid-tight spill containment trays in storage rooms to prevent corrosive substances from seeping into the floor. Under no circumstances should spilled acids or alkalis be discharged into the sewer system.


Storage: Access to facilities, work areas, and storage rooms containing irritant and corrosive substances should be restricted to authorized employees only. These substances should be present in quantities necessary for operations and stored in designated locations rather than distributed throughout the workplace.

  • Labelling of Containers: Proper labelling of hazardous substances is essential to prevent confusion and accidents. Compliance with the Hazardous Substances Ordinance mandates the use of Globally Harmonized System (GHS) labelling, including substance names, hazard symbols (e.g., "Corrosive"), signal words ("Caution" or "Danger"), and relevant hazard and safety information (H and P phrases). While simplified labelling may suffice in certain intra-company situations, clear instructions and employee training on workplace hazards and protective measures are crucial.

  • Labelling of Storage Areas: Storage room doors should indicate the maximum permissible storage quantity for corrosive substances. Additionally, stationary containers should feature permanent indicators of the maximum permitted fill level, with overflow protection recommended.

  • Workplaces: Per The Hazardous Products Act (HPA) and Controlled Products Regulations (CPR), Workplaces must prominently display safety signs, warning signs, mandatory signs, prohibition signs, and information signs.

  • Instruction: All employees, including external personnel, must receive oral instruction on existing hazards and corresponding protective measures, as outlined in operating instructions. This instruction should occur before commencing work and at least annually (semi-annually for underage employees) and be delivered in a language understandable to all employees. Documentation of the instruction details and date, along with confirmation by the instructed individuals through signature, is required.


When handling irritating or corrosive substances, proper personal protective equipment (PPE) is crucial. These include:

  1. Eye and Face Protection: Eye protection is paramount. Safety glasses with side protection are suitable for observation tasks, while goggles or a full face mask with a multi-range filter are necessary when handling liquids that may splash. In situations involving gases, vapors, or aerosols, a full face mask is recommended. For increased risk of splashing, a face shield (visor) may be required, often in conjunction with other protective gear such as goggles, chemical aprons, boots, and gloves.

  2. Hand Protection: Durable plastic gloves are essential for hand protection. Select gloves based on the manufacturer's resistance information and intended use. Limit wearing time, regularly inspect for damage, and avoid handling hazardous substances whenever possible.

  3. Body Protection: Depending on the level of risk, coveralls, aprons, and boots should be worn, ensuring corrosive chemicals cannot penetrate footwear. Regularly inspect body protection for any signs of damage.

  4. Hygiene: Maintain cleanliness in the workplace and on work equipment. Promptly remove contaminants, and ensure that food does not come into contact with hazardous substances. Establish a skin protection plan, including skin protection, cleansing, and skincare products, to safeguard against exposure.


To mitigate the effects of contact with irritating or corrosive substances and prevent accidents, the following general measures are recommended:

  • Precautions for Corrosive Liquid Spills: Utilize drip trays or containment devices along with appropriate binders for acidic or alkaline chemicals to contain spills.

  • Emergency Preparedness and First Aid: Ensure the availability of first aid facilities such as emergency showers and eye wash stations to promptly flush affected areas with water in the event of skin or eye contact with hazardous substances.

  • Immediate Response for Injured Persons: Promptly evacuate the affected individual from the danger zone, seek medical attention, and inform medical personnel about the chemical substance and initial first aid measures undertaken.

  • Organization of Company First Aid: Provide emergency contact numbers, details of medical facilities, substance-specific information, necessary equipment procurement, and employee training on first aid procedures.

  • Treatment of Eye Injuries: Immediately and continuously rinse the affected eye with water for at least 20 minutes, remove contact lenses if feasible, and shield the unaffected eye.

  • Treatment of Skin Injuries: Remove contaminated clothing and thoroughly rinse affected skin and hair with water for at least 15 minutes.

  • Treatment for Respiratory Issues: Remove the affected individual from the hazardous area and administer oxygen if experiencing respiratory distress.


Our concise checklist offers comprehensive guidance for the safe handling of irritating and corrosive substances. It encompasses vital protective measures to mitigate health hazards and uphold workplace safety standards.


Below are the most frequently asked questions about corrosive substances such as acids, alkalis, etc.

What is the definition of corrosive?

"Corrosive" refers to substances and mixtures capable of causing damage or irritation to living tissue. Examples include acids, bases, and certain gases. Due to their potential to cause serious injury, handling corrosive substances requires extreme caution.

What is the Definition of "Highly Corrosive"?

"Highly corrosive" describes substances capable of inflicting severe damage to living tissues and surfaces. These substances are exceptionally reactive, often triggering rapid chemical reactions that result in severe skin and eye damage. Additionally, they possess the capacity to corrode metals, plastics, and various other materials. Due to their swift and potent action, highly corrosive substances can cause significant damage within a short period.


Acids exhibit corrosive properties primarily because of their high concentration of protons, which are electrically positive hydrogen ions. These ions possess high reactivity and can effectively etch or dissolve many substances, leading to their corrosive effect. This characteristic results in the destruction of living tissue and the erosion of surfaces. The intensity of the corrosive effect correlates with the concentration of the acid in its aqueous solution. Moreover, acids can react with bases, forming water and salts, which further contributes to their corrosive nature.


In the event of skin contact with corrosive liquids, prompt action is crucial. Follow these steps immediately:

  1. Rinse: Thoroughly rinse the affected area of the skin with lukewarm water, ensuring the removal of any contaminated clothing and jewelry.

  2. Emergency Call: If severe injury or uncertainty arises, promptly call emergency services and provide precise information about the corrosive substance involved.

  3. Treatment of Affected Area: Avoid further contact with the corrosive substance by wearing protective gloves and clothing. Keep the skin dry and clean, and apply sterile dressings to any open wounds. If symptoms persist or worsen, seek medical attention from a healthcare professional.

Always consult the specific safety data sheets and first aid instructions provided for the particular substance involved.


According to dangerous goods regulations, corrosive substances are classified under Class 8 of hazardous goods. This class encompasses substances with acidic or alkaline properties capable of causing injuries to the skin, mucous membranes, or internal organs upon contact, inhalation, or ingestion. Additionally, corrosive substances have the potential to impair or destroy other substances or goods during transport.


To neutralize a corrosive acid, you would typically use a base. This process involves a reaction between the acid and the base until a pH of 7 is reached, rendering the solution neutral. The corrosive effects of the acid and the base counteract each other during this reaction. It's important to note that this reaction releases significant energy and is exothermic, meaning it generates heat. Thus, caution should be exercised to avoid excessive heat buildup during the neutralization process.


The storage of toxic and corrosive substances must adhere to their hazard classifications and relevant regulations. Here are some fundamental guidelines for their safe storage:

  1. Separate Storage: Ensure that toxic and corrosive substances are stored separately from highly flammable materials.

  2. Labelling: Clearly label containers holding toxic and corrosive substances for easy identification.

  3. Safety Data Sheets: Maintain safety data sheets for all stored toxic and corrosive substances, providing essential information about their hazards and necessary protective measures.

  4. Safety Equipment: Have appropriate safety equipment readily available when storing toxic and corrosive substances, including protective gloves, suits, goggles, and acid-resistant boots.

  5. Ventilation and Containment: Store toxic and corrosive substances in well-ventilated areas with suitable containment facilities to capture any leaks.

  6. No Food Nearby: Prohibit the storage and consumption of food or beverages near toxic and corrosive substances.

  7. Cleaning: After handling these substances, ensure thorough cleaning of hands and face to remove any residue.

Safeguarding Against Corrosive Substances: Proactive Accident Prevention through Safe Handling

Safely managing corrosive substances, including acids and alkalis, is paramount for averting health hazards and accidents, both in professional and personal settings. These substances pose a significant risk of severe damage upon skin contact, underscoring the importance of accurate identification, classification, and labelling by Canadian regulations. Additionally, meticulous storage and handling procedures are imperative, with a prioritized emphasis on self-protection through comprehensive information and preparedness. For secure handling of corrosive substances, DENIOS provides a comprehensive array of solutions, ranging from regulatory-compliant warning labels to chemical storage cabinets and eyewash stations.

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The specialist information on this page has been compiled carefully and to the best of our knowledge and belief. Nevertheless, DENIOS Ltd cannot assume any warranty or liability of any kind, whether in contract, tort or otherwise, for the topicality, completeness and correctness either towards the reader or towards third parties. The use of the information and content for your own or third party purposes is therefore at your own risk. In any case, please observe the locally and currently applicable legislation.

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