Toxic substances are chemicals that will cause harm to human health when they enter the body through inhalation, skin absorption or ingestion. The Australian Dangerous Goods Code (ADG code) classifies them as Class 6, Division 6.1 Toxic Substances. The ADG Code also provides a standard definition for toxic substances.
Division 6.1 Toxic Substances - These are substances liable either to cause death or serious injury or to harm human health if swallowed or inhaled or by skin contact.
Some toxic substances can be found in everyday products like household cleaning chemicals, prescription drugs, alcohol, pesticides and cosmetics. Toxic substances can also be found in environmental pollutants such as vehicle emissions. The average person will encounter a number of toxic substances without even leaving their home. Because people have frequent contact with toxic substances on a daily basis, it’s important to understand the dangerous properties of toxic substances so that you can minimise the risks that they have on your health.
Risk to people
There are three ways that toxic substances can enter your body and cause harm to your health. These include;
- Skin absorption
Some toxic substances such as organic solvents and organic pesticides can be absorbed through your skin and enter your bloodstream. Ingestion is the least common form of exposure and it mostly occurs when people eat, drink or smoke after handling toxic substances. Inhalation is the most common form of exposure which occurs when you come into contact with airborne toxic substances. Inhaling toxic chemicals can induce intoxication leading to both acute and chronic effects.
Acute effects are those affects that are experienced immediately upon exposure. These effects include irritation to the throat, lungs and lining of your nose. Chronic effects are long term effects that are experienced months and years after initial exposure. These effects include lung disease and cancer. Cancer can arise from exposure to benzene and it can remain dormant for many years before symptoms are shown. When cancer is detected during its later stages, it can be hard to determine the exact cause.
Commonly used toxic substances
There are a number of toxic substances that are used in workplaces and laboratories on a regular basis. Some examples include; methylene chloride, isopropyl alcohol and hydrogen peroxide.
Methylene chloride is a colourless solvent with a sweet odour. Upon exposure, this substance can cause harm to the central nervous system and irritation to your eyes and skin. It can also induce headaches, nausea, dizziness and drowsiness. These symptoms have a severe effect on your coordination. High exposure to methylene chloride can cause death.
Isopropyl alcohol has many effects similar to methylene chloride. Exposure to isopropyl alcohol vapour will irritate your eyes and respiratory tract.
Hydrogen peroxide is an oxidising agent with toxic properties. It is used as a bleaching agent, antiseptic and oxidiser. If hydrogen peroxide vapours are inhaled, it can cause severe pulmonary irritation. If it is ingested it may induce vomiting, stomach aches and gastric distension. If high concentrations of hydrogen peroxide are ingested it can sometimes cause death.
Toxic substances storage standards
Safe storage is an important element of keeping everyone in the workplace safe from toxic chemicals. In Australia and New Zealand the requirements for safe and compliant storage of toxic substances is set out in the Australia Standard AS NZS 4452-1997 - The Storage and Handling of Toxic Substances. This standard outlines the types and quantities of toxic substances that can be stored indoors at any one time. This standard also specifies cabinet design and construction requirements including:
- Wall thickness
- Sump capacity
- Closing mechanism specifications
- Shelf design
AS NZS 4452-1997 also sets out the requirements for the positioning of toxic storage cabinets so as to minimise risk to people, property and the environment.
How to store toxic substances
Section 4 of AS NZS 4452-1997 sets out the requirements for the storage and handling of packages containing toxic substances. This includes the requirements for the construction and use of toxic storage cabinets.
When indoor toxic storage cabinets are used for the storage and handling of toxic substances, they must be installed in a location that is well away from any incompatible substances. Incompatible substances will react dangerously and cause harm to people, property and the environment. For information on how to segregate incompatible classes of dangerous goods, refer to the dangerous goods segregation guide.
AS NZS 4452-1997 also specifies 250 Kg as the maximum quantity of toxic substances allowed to be stored inside a single cabinet.
The design of toxic storage cabinets must include lockable self-closing self-latching doors, perforated shelves to allow for free air movement and a liquid-tight sump. The sump of the cabinet must be 150mm deep and capable of containing at least 25% of the cabinets maximum storage capacity. This sump is used to contain any spills that may occur within the cabinet.
All sides of the toxic storage cabinet - walls, floor, door and roof - must have a double-walled sheet steel construction. The sheet steel used to construct the walls must be at least 0.75mm thick. The space between the sheets must be an open air space or filled with a non-combustible insulation. The main construction of the cabinet must be resistant to melting at temperatures of up to 850 ºC. However this doesn’t include components such as seals and gaskets.
When positioning a toxic storage cabinet, it's important to have it close to a hand washing facility and well away from emergency exits and stairwells. The Australian Standard also specifies that no more than one 250L toxic storage cabinet to be used in each 100 square meters of floor space. Also the separation distance between any two toxic storage cabinets shall be no less than 3 meters.
AS NZS 4452-1997 does not make ventilation of toxic storage cabinets a mandatory requirement. However, if the concentration of airborne contaminants within the cabinet is above the workplace exposure standards, ventilation will be required. Where a ventilation system is installed, it is important that the system doesn’t compromise the structural integrity of the cabinet. The ventilatoin system must also be designed by an appropriately qualified engineer.
As there is are a lot of toxic substances found in the workplace, it is important that you understand their chemical and physical properties so that you can take proactive measures to reduce the risk that they may pose on you and the people in your workplace. For more information on how to segregate toxic substances from other incompatible dangerous goods, download the free eBook by clicking on the image below 👇.