Importance of Identifying Hazardous Materials in Construction Sites

Michael Tobias
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    Investing in accident prevention is a part of business ethics and corporate social responsibility. However, prevention also makes sense financially, and several studies have concluded that each dollar used for prevention saves $2 to $3 in accident costs. Of course, this is only the measurable financial impact, and the value of human lives cannot be described in dollars.

    To avoid risks, construction workers must know they exist in the first place. Even the most experienced personnel is at risk when hazards are hidden. Training is also important, since workers must know how to deal with each specific hazard; for example, a flammable material requires different precautions than a toxic material.

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    Hazardous materials are used in many industries, including construction. To label these materials, many governments have adopted the Globally Harmonized System of Classification and Labelling of Chemicals, or GHS. This system was developed by the United Nations, and it was implemented by OSHA for the USA in 2012.

    How Does the Globally Harmonized System Work?

    The GHS classifies hazards into three types, and it uses nine pictograms to label hazardous material containers. The GHS also standardized testing criteria and safety data sheets (SDS), with the goal of improving hazard communication around the world. Before the GHS, companies had to meet different standards for each country, and compliance costs were much higher.

    Depending on the properties of materials, the GHS classifies them into physical hazards, health hazards and environmental hazards. There are specific hazard classes under each type, and the following table provides some examples:

    GHS Hazard Type


    Physical hazards

    Explosives and flammable substances
    Oxidizing agents
    Pressurized gases
    Self-reactive and self-heating substances
    Corrosive substances

    Health hazards

    Acute toxicity
    Skin corrosion or irritation
    Eye damage or irritation
    Reproductive toxicity

    Environmental hazards

    Aquatic environment damage
    Ozone layer damage

    NOTE: This table only provides some examples of each hazard type, and there are more classes considered in the Globally Harmonized System.

    GHS Pictograms for Hazardous Material Labels

    Pictograms provide a convenient way to label material containers, since the hazards present can be made clear immediately. Materials that pose several hazards can use more than one GHS pictogram.



    The single flame pictogram is used for all types of flammable substances, and also for self-reactive and self-heating substances. This pictogram also covers pyrophoric substances, or substances that catch fire instantly when exposed to oxygen. It also applies for substances that emit flammable vapors when exposed to water.

    Oxidizing (flame over circle)

    The flame over circle pictogram is used for all oxidizing agents - solid, liquid or gas.

    Toxic (skull and crossbones)

    The skull and crossbones pictogram indicates acute toxicity. It is used for substances that are dangerous when inhaled, or when they touch the skin or mouth.


    The corrosion pictogram is used for substances that are corrosive for metals or the skin, and substances that can cause serious eye damage. This pictogram is also used for some explosives, flammable gases, self-reactive substances and peroxides.

    Explosive (exploding bomb)

    This pictogram covers explosives in general, and also several unstable substances, self-reactive materials and organic peroxides.

    Harmful (exclamation mark)

    This pictogram is not for a specific hazard, but for severe cases of other hazards. For example, it is used for Category 4 toxic substances, where the lethal dose (LD50) is higher than those using the skull and crossbones pictogram (Categories 1 - 3). The exclamation mark pictogram is also used for some cases of skin irritation, eye irritation and specific organ toxicity.

    Environmental hazard

    This pictogram shows a dead tree and fish, and it applies for aquatic environment hazards and environmental toxicity.

    Health hazard

    This pictogram is used for all substances that can have a negative health effect other than physical harm. This includes respiratory issues, carcinogenicity, reproductive toxicity, germ cell mutations, and damage to specific organs.

    Compressed gas (gas cylinder)

    The gas cylinder pictogram is used for compressed, liquefied and dissolved gases.

    Importance of Safety Data Sheets

    The amount of information that can be provided by a pictogram is limited, and for this reason the GHS also uses Safety Data Sheets (SDS) for substances. An SDS provides detailed information about a substance, and it also describes precautions and safety measures. The Globally Harmonized System requires 16 specific headings for an SDS:

    1) Identification
    2) Hazard(s) identification
    3) Composition/information on ingredients
    4) First-aid measures
    5) Fire-fighting measures
    6) Accidental release measures
    7) Handling and storage
    8) Exposure controls/personal protection
    9) Physical and chemical properties and safety characteristics
    10) Stability and reactivity
    11) Toxicological information
    12) Ecological information
    13) Disposal considerations
    14) Transport information
    15) Regulatory information
    16) Other information

    By following this format, suppliers can ensure that companies and their workers are fully informed about hazardous materials. An SDS complements pictograms with detailed information that cannot be condensed into a product label.

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    Tags : construction materials construction safety workplace safety health and safety hazardous materials

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