Scheduled maintenance - Thursday, July 12 at 5:00 PM EDT
We expect this update to take about an hour. Access to this website will be unavailable during this time.
Very Toxic materials are substances that may cause serious harm to an individual if it enters the body. This document provides guidance on safe handling and storage practices and how to work safely with very toxic materials. Under WHMIS 1988 classification, very toxic materials are labelled as class D1A (Materials Causing Immediate and Serious Toxic Effects) or D2A (Materials Causing Other Toxic Effects). For more information about the hazards of very toxic materials and how they are identified, refer to the OSH Answers document entitled Very Toxic Materials and their Hazards.
Whenever possible, it is always best to avoid using a very toxic material either by eliminating its use (by changing the method or process for example) or by substituting the very toxic material with a less hazardous material. Unfortunately, it is not always possible to find a non-toxic (or less toxic) substitute that still does the job effectively and safely.
When considering substitution, the first step is to obtain the Material Safety Data Sheets (MSDSs) for all possible substitute materials. Find out about all of the hazards (health, fire, chemical reactivity) of these materials before making any changes. Caution must be exercised so as to avoid introducing a potentially more hazardous situation. Choose the least hazardous materials that can do the job effectively and safely. Learn how to work safely with them, too.
For more information about this topic, please see the OSH Answers Substitution of Chemicals: Considerations for Selection.
To prevent exposure to a very toxic material, strict control measures are required. Ventilation is a very important control measure for very toxic materials. Well-designed and well-maintained ventilation systems remove the very toxic vapours, fumes, mists or airborne dusts from the workplace before workers are exposed.
When considering exposure control measures such as ventilation, there are many considerations, including:
An assessment of the specific ways that a very toxic material is stored, handled, used, and disposed of is the best way to find out if existing ventilation controls (and other hazard control methods) are adequate.
Generally, with very toxic materials, general (dilution) ventilation does not provide sufficient protection. To prevent a very toxic material from entering the workplace, local exhaust systems are usually required. For larger scale operations, this may require designing the process so that the very toxic material is completely enclosed or isolated from the workplace environment. In other situations, where smaller amounts are used, glovebox isolation units or local exhaust systems are used. Leak detection systems with alarms may be desirable for some situations.
For any of these ventilation systems, particularly ones that deal with very toxic materials, it is important to ensure that:
For the storage of very toxic materials, ensure that the storage area is clearly identified with warning signs, is clear of obstructions and is accessible only to trained and authorized personnel.
Before storing very toxic materials, inspect all incoming containers to ensure that the containers are undamaged and are properly labelled. Do not accept delivery of defective containers. Also, be sure to store very toxic materials in the type of containers recommended by the manufacturer or supplier.
Some other important points for storage of very toxic materials include:
Very toxic materials must be stored in an appropriate storage area and location. In general, the storage area for very toxic materials should have the following characteristics. Many of these recommendations apply for safe chemical storage in general.
Safe handling and work procedures are crucial for workplaces where individuals use very toxic materials. It is vital that people working with hazardous materials such as very toxics are properly trained regarding the potential hazards. Remember, if, at any time an individual is unsure or has questions about working with a very toxic material, they should always talk with the supervisor.
This section refers to general safe handling practices for very toxic materials. Instructions and training for the specific handling of a particular very toxic material used a workplace is the responsibility of the supervisor (employer).
In general, when handling very toxic materials:
Very toxic waste material must be disposed of properly. Careless disposal of any hazardous waste presents a potential hazard to many individuals who may not be trained or equipped to deal with unexpected hazardous materials (e.g. caretaking staff, garbage collectors, plumbers, water treatment plant workers, firefighters, etc.). Careless disposal can also cause significant damage to the environment.
The following are some general recommendations for disposal of very toxic waste materials:
Good housekeeping is a very important way to prevent exposure to very toxic materials. A clean and orderly workplace is safer for everyone.
When working with very toxic materials:
Personal cleanliness when working with very toxic materials provides protection not only for you but protects others as well (such as co-workers and family members).
Control measures such as ventilation, enclosure and work practices are examples of the preferred methods of protecting workers. If these measures are not feasible or unable to provide appropriate worker protection, then personal protective equipment may be required.
Choosing the right PPE for a particular job is essential. MSDSs should provide general guidance. Also obtain help from a qualified professional who knows how to evaluate the hazards of a specific job, especially those related to very toxic materials, and how to select the proper PPE.
Before a very toxic material is brought into the building and used:
The Personal Protective Equipment Section of OSH Answers has several question-and-answer documents on PPE programs including the selection, use and maintenance of various kinds of PPE.
It is crucial that any required PPE be worn when specified for a job. PPE can be very effective but not if you don't wear it.
Some very toxic materials can be harmful through skin contact. In these instances, it may be necessary to wear protective equipment such as gloves, aprons, boots, hoods or other clothing, depending on the risk of skin contact. Choose clothing made of materials that resist permeation, penetration or damage by the chemical. The Chemical Protective Clothing OSH Answers has general information on selecting gloves and other chemical protective clothing. The MSDS should recommend appropriate materials. If it does not, contact the chemical supplier for specific information.
Eye protection is important when working with very toxic materials. Selection of the most appropriate type depends on factors such as how the material is used, physical characteristics (e.g. fine powder, liquid, vapour, etc.) and potential health effects (e.g. eye irritant, skin irritant, toxicity through skin absorption, etc.). In some cases, it may be necessary to wear a face shield (with safety glasses or goggles) to protect the face from splashes. The Safety Glasses OSH Answers has information on selecting PPE for protecting the eyes and face. The current CSA Standard Z94.3 "Industrial Eye and Face Protectors," provides additional advice on selection and use of eye and face protectors.
Proper selection and fitting of respiratory protection can be quite complex and any time it is used in a workplace, it must be carefully monitored and controlled to ensure worker safety.
If respiratory protection is required in the workplace, a respiratory protection program must be developed, written and maintained as described in the Respirator Selection OSH Answers. Further guidance for developing a program can be found in the current CSA Standard Z94.4 "Selection, Care, and Use of Respirators." Follow all legal requirements for respirator use and approvals. These may vary between jurisdictions in Canada.
Careful selection of the appropriate respirator style and cartridges is an important component of any respiratory protection program. Respiratory equipment must be properly sized and the user must know how to fit-test, clean, maintain and store the equipment. Users must also know how often to change the cartridges. NEVER assume that "smelling" the very toxic material will indicate when to change the cartridge.
The time to figure out what to do during an emergency is BEFORE it happens. Be ready to handle emergencies such as fire, leaks or spills quickly and safely.
In the event of an emergency involving a very toxic material:
The MSDSs for the materials being used on the job are a good starting point for creating an emergency plan. MSDSs have specific sections on toxicity, fire and explosion hazards, including suitable fire extinguishing equipment and methods, spill clean-up procedures and first aid instructions. If the directions in each MSDS section are not clear or seem incomplete, contact the material's manufacturer or supplier for help. You can obtain help in developing emergency plans from many other sources too. Local fire departments can assist with fire emergency plans and training. Occupational health and safety and environmental enforcement agencies, provincial safety associations, St. John Ambulance, insurance carriers, professional societies in occupational health and safety, labour unions, trade associations, some local colleges and universities, and CCOHS can supply useful information at little or no cost.
Following these basic safe practices will help protect you from the hazards of very toxic materials:
Add a badge to your website or intranet so your workers can quickly find answers to their health and safety questions.
Although every effort is made to ensure the accuracy, currency and completeness of the information, CCOHS does not guarantee, warrant, represent or undertake that the information provided is correct, accurate or current. CCOHS is not liable for any loss, claim, or demand arising directly or indirectly from any use or reliance upon the information.