Class 6 dangerous goods are classified as toxic substances. According to the ADG Code, toxic substances can be defined as:
Substances that are liable to either cause death, serious injury or harm to human health from skin contact, ingestion or inhalation.
Aside from immediate health effects, toxic substances can also cause chronic health effects such as liver disease and cancer from exposure to lower concentrations over a number of years.
Failure to store and handle toxic substances in a safe and compliant manner can have other negative implications besides harm to human health. If toxic substances were released into the environment, they would have a major impact on living systems which would have a cumulative effect on the food chain. Also if toxic substances are not stored and managed according to the Australian Dangerous Goods Standards, there is a risk that your organisation will be financially liable due to non-compliance.
As toxic substances can have severe effects upon human health, the environment and the financial liability of your organisation, it is very important to store and manage them in a safe and compliant manner to reduce the risk of incidents. The Australian Standard that outlines the requirements for the storage and handling of toxic substances is AS NZS 4452-1997 - The storage and handling of toxic substances. Like many other Australian Dangerous Goods Standards, this standard outlines different requirements for the indoor storage and outdoor storage of toxic substances. We will now outline the requirements for the storage and handling of toxic substances in the workplace.
Outdoor storage of toxic substances
There are a number of different storage facilities that can be used for the storage of toxic substances, however most organisations like to use relocatable chemical storage containers that have been designed and manufactured in full conformance to AS NZS 4452. Most organisations use these toxic storage containers as they are the safest and most efficient method for storing toxic substances. Outdoor toxic substance storage containers must have a number of features to make them compliant with the Australian Standards. These features are outlined below.
To reduce risk to people and the environment, outdoor toxic substance storage containers must be constructed with certain specifications to reduce the risk of incidents. These requirements include:
- If a store has a floor area exceeding 25m2, it must have at least 2 means of access in and out of the store.
- Toxic substance stores must have walls and a roof and the main structural members must be non-combustible and resistant to attack from the harsh chemicals stored within the store.
- The floor of the container shall be designed in a way that allows it to be washed down with water.
- All areas within the store that are used for decanting shall have a floor that is capable of containing spills.
- The store shall be secured to prevent unauthorised entry.
- Racks and shelves within the container must be designed and constructed in such a manner that prevents the accumulation or pooling of toxic liquid.
- Any racking inside the container shall be designed in a way that provides a clear path of escape for emergencies.
To prevent toxic substances from leaking into the environment, toxic substance storage containers must have the means to contain any spills that may occur within the store. The required spill containment capacities are outlined in section 4.4.1 of AS NZS 4452. The net capacity of any spill containment compound shall be:
- For packing group 1; 100% of the aggregate volume of liquids kept
- For packing group 2; 25% of the aggregate volume of liquids
In all instances, the net capacity of the spill containment sump shall be at least the capacity of the largest container kept within the store.
Of the three different routes of exposure, inhalation is the most common form of exposure. To reduce the risk of intoxication from inhalation, outdoor chemical storage containers must be provided with adequate natural ventilation to keep the concentration of toxic vapours as low as practical. If the toxic substances within the store are listed in the workplace exposure standards, the airborne concentration of the toxic substances within the store must be kept below the maximum limits outlined in the workplace exposure standards.
Dangerous Goods Signage
To warn all workers and visitors of the risk associated with toxic substances, all chemical storage containers used for the storage of toxic substances must be marked with the relevant dangerous goods signage. The required signage for toxic substance storage containers is a class 6 dangerous goods diamond. An example of a class 6 dangerous goods diamond is shown below.
Class 6 - Toxic Substances
Provision of safety showers and eyewash stations
To reduce the risk of intoxication, an eyewash station and safety shower must be installed next to all chemical storage containers used for the storage of toxic substances. The eyewash station and safety shower must be provided within 7 metres, but no closer than 2 metres of the toxic substance store.
Indoor storage of toxic substances
If your organisation only uses smaller quantities of toxic substances, AS NZS 4452 gives you the provision to store these substances indoors. Toxic substances that are stored indoors must be kept in a compliant safety cabinet that has been manufactured in full conformance to AS NZS 4452. The maximum quantities of toxic substances that can be kept in an indoor storage cabinet is 250L. The design and construction requirements of indoor toxic storage cabinets are outlined below:
- The walls, floor, door and roof of the cabinet must be of a double walled sheet steel construction have a thickness of at least .75mm. The air gap between the walls must be at least 40mm.
- The cabinet must have self-closing, close-fitting doors.
- Any shelves within the cabinet must be perforated to allow for free air-movement.
- The cabinet must be lockable to prevent unauthorised access.
- The bottom of the cabinet must form a liquid-tight sump that is at least 150 mm deep and capable of containing at least 25% of the aggregate storage capacity of the cabinet.
- If a mechanical ventilation system is required, it must be designed by an appropriately qualified engineer.
As toxic substances can have severe effects upon human health, the environment and the financial liability of your organisation, it is very important to store and manage them in a way that reduces the risk of workplace incidents. Toxic substance can be safely stored by following the guidelines in this article and adhering to the requirements outlined in AS NZS 4452. When storing and handling toxic substances in the workplace, it is good to be aware of the chemical and physical properties associated with toxic substances. If you would like more information on the properties of class 6 toxic substances and other classes of dangerous goods, download our FREE eBook by clicking on the image below.