Working With Chemicals
Chemical hygiene refers to working ‘in a clean manner’ with chemicals. The purpose of a chemical hygiene program is to reduce the risk of injuries and illnesses from working with and around chemicals. To this end Prudent Practice (NRC, 2011) recommends that we consider four fundamental principles before beginning any work with chemicals.
- Plan ahead
- Do not underestimate hazards or risks
- Minimize exposure to chemicals
- Be prepared for accidents
Awareness of the health and safety hazards posed by the various chemicals and procedures used in the workplace, especially those that directly affect you, is an important first step in the planning of any experiment. Alberta OHS legislation requires that you assess new procedures and processes to identify all hazards prior to beginning any work. You are then required, where elimination of the hazard is not possible, to implement all appropriate measures, including engineering, administrative and personal protective equipment to control the hazards. For chemicals:
- Consider not only the health effects (see Appendix 1), but also physical hazards (flammable, combustible, explosive, oxidizing, pyrophoric, or reactive properties) posed by chemicals.
- A full evaluation of the hazards associated with chemical exposure should not simply consider toxicity of the chemical; it must also consider the parameters associated with an exposure that would contribute to overall toxic potential. The potential harm presented by exposure to a chemical includes not only the quantity or concentration of that chemical, but also the route of the exposure, the distribution of the exposure over time, the time needed to induce an injury or illness in addition to other factors (see Appendix 1).
- Take into account any laboratory conditions, beyond the specific proposed work, that might increase the hazards or create new hazards.
- Consult the appropriate MSDSs/SDSs to be sure that you are familiar with procedures for proper, handling, storage, and disposal of the chemicals that you plan to work with.
Never Underestimate the Risks
It is important to recognize that all chemicals are hazardous, requiring only the appropriate exposure, under the right conditions, to cause harm. Chemicals are considered harmful substances under legislation because their properties, application and presence, create or could create a danger to the health and safety of workers exposed to them. They are capable of causing ill health or adverse effects at the time of exposure or potentially later in your life and in future generations (IUPAC 2007).
- Treat all unknown or unfamiliar chemicals or substances as hazardous.
- Assume that a mixture of chemicals is more hazardous than its most hazardous component.
- Never use any substance that is not properly labelled – it may not be what you think it is.
“There are no harmless substances, only harmless ways of using substances” Emil Mrak (1901–1987)
Minimize Exposure to Chemicals
Quite simply, avoiding or minimizing contact with chemicals is the most efficient way to protect one’s self, since a chemical can only exert its potential harmful effects through an exposure. Without contact (inhalation, injection, ingestion, or absorption via the skin or eyes) all other aspects of exposure are irrelevant.
The relationship between exposure and effect or response is well defined in toxicology and is summarized in dose-response or dose-effect curves with LD50 and LC50 as common measures of chemical toxicity. These curves demonstrate that all chemicals, given sufficient exposure, can cause harm. It is important, therefore, to minimize exposure to any chemical, regardless of its toxicity rating. Given the considerable diversity of chemicals in academic laboratories, general precautions for handling chemicals, as well as specific procedures for the actual chemicals being used, should be considered.
With dose-response curves we recognize that relatively ‘safe’ chemicals can cause harm if we are subjected to a large enough exposure, however, it is also clear that relatively ‘toxic’ chemicals can cause little harm if exposure is prevented or sufficiently small. Exposure to any chemical, even relatively safe chemicals, must be minimized because of the potential for systemic accumulation and complicated interactions with other chemicals. The following are general precautions that should be taken to reduce chemical exposure:
Where possible, substitute for a less hazardous chemical in analytical procedures. Always evaluate substitutions before making changes to procedures.
Fume hoods are a primary means of controlling and preventing exposure, especially by inhalation, to airborne chemicals. It is recommended that, whenever possible, fume hoods should be used when working with chemicals and other harmful substances.
- Be aware of, and follow, all policies and procedures that apply to your workspace.
- Read and familiarize yourself with MSDSs/SDSs for all chemicals required in your work.
- Develop written standard operating procedures. SOPs outline the steps in analytical processes, making it easier to perform hazard assessments and can be modified to include methods for controlling identified hazards.
- Train workers, or ensure that you are trained, to perform procedures properly and safely. SOPs can be especially useful as training documents.
- Maintain good personal hygiene and a clean workspace to reduce the chance of accidental exposure.
- Wash hands thoroughly after working with chemicals, even if gloves were used.
- Wash hands before leaving the lab, especially prior to consuming food or beverages.
- Wipe chemical drips/residues from containers and work surfaces.
- Avoid ingestion by not pipetting by mouth, and by not eating, drinking, chewing gum, or applying cosmetics while near or within chemical use or storage areas.
- Cell phones and use of music headphones should be avoided while working in the lab. The distraction can increase the potential for an accident and they can become contaminated if handled while working with chemicals.
- Use good laboratory practices outlined in Basic laboratory safety.
Personal Protective Equipment (PPE)
Good personal hygiene and the proper use of PPE are important measures for preventing unintentional chemical exposure, especially those contaminating laboratory surfaces. PPE can also help to prevent contamination outside the laboratory by protecting your personal clothing.
Appropriate PPE is essential for worker protection and is best used in combination with controls such as fume hoods and safe work practices.
Alberta OHS legislation requires that all skin be protected from harmful substances that may injure the skin on contact, or may adversely affect health if absorbed through the skin. Full skin coverage is required at all times in the laboratory.
Minimum PPE, including floor-length pants, closed-toe shoes, safety glasses with side shields, and laboratory coats must be worn at all times in the laboratories.
Protection must be upgraded if determined to be necessary by a hazard assessment.
Be Prepared for Accidents
In addition to more obvious hazards, your workspace should be examined to identify measures that can be taken to prevent chemical exposure through an accidental spill or release. Continued vigilance is required to detect and correct unsafe conditions as they occur.
You should be focused on your work – Cell phones and music headphones can be distracting, increasing the potential for an accident, and should be avoided while working in the lab.
Be aware of the location, and have access to, all necessary emergency equipment, including spill kits, fire extinguishers, emergency showers and eyewash stations before you start working with chemicals
- Many chemical spills occur as a result of improper transport within and between laboratories.
- Carry glass containers in specially designed bottle carriers or a leak resistant, unbreakable secondary container.
- Use a cart when transporting large, heavy or multiple containers. The cart must have high edges or secondary containment that will control any spills or leaks.
- Use a gas cylinder handcart when moving large gas cylinders. Ensure the cylinder is securely strapped to the cart.
- Ensure that the receiving container is large enough and is not overfilled.
- Use spill containment trays to catch leaks and spills when transferring liquids.
- When transferring liquids from large containers use pump or siphons (not initiated by mouth) instead of pouring.
- When transferring flammable liquid from drums, ensure that both the drum and receptacle are grounded and bonded together to avoid an explosion initiated by a static electric spark.
Handling & Use
- Observe basic laboratory work safe procedures – e.g. add acid to water, not water to acid
- Work in a fume hood whenever possible.
When setting up and working with laboratory apparatus:
- Inspect laboratory glassware for cracks or defects before using it.
- Secure flasks and beakers to prevent them from tipping over.
- Ensure the work area is free of unnecessary clutter.
- Select equipment that has a reduced potential for breakage (e.g. Pyrex).
- Close chemical containers securely
- Keep the outside of containers clean and free of drips etc
- Keep chemical containers tightly closed when not in immediate use.
Proper storage is essential to reducing hazards associated with chemicals in the laboratory, especially in the event of accidental spill, break or leak. In academic laboratories, it is not necessarily the amount of individual chemicals that is of most concern; it is the number and the variety of different chemicals, especially if chemicals with incompatible properties are stored within close proximity of each other. Inadvertent mixing of chemicals can result in fires, hazardous fumes/gases/vapors, and explosions.
Maintain only the minimum number and amount of chemicals. Laboratories are encouraged to purchase only the quantities of chemicals needed for immediate use. Long term storage of chemicals is not advised.
Segregation of chemicals in storage, based on hazard category and compatibility, is essential to reduce or eliminate hazardous chemical reactions. Check labels, MSDSs/SDSs, and chemical incompatibility charts (see Forms, Links and Manuals) to determine best storage practices. Separate each group from the others by one of the following methods:
1. Chemicals with a low risk can be stored together on open shelving. Dry chemicals with different compatibilities can be separated by shelf or by separate areas of a shelf.
2. Use physical barriers such as different cabinets, cabinet dividers, or shelves with spill containment.
3. Use compatible secondary containment (trays, or buckets) large enough to contain the material in the event of a spill.
4. Store chemical groups far enough away from each other to ensure that no mixing occurs.
Store hazardous materials, especially liquids (including squeeze bottles), in secondary containment to minimize the spread of spills in the event of a broken or leaking container.
Secondary containment is a means of containing and controlling chemical spills to reduce the risk of chemical exposure, fire, explosion, etc. Secondary containment capacity must be 110% of the largest container or 10% of the aggregate volume of all containers, whichever is larger. Secondary containment containers must be made of materials that are resistant to the chemicals contained in them.
Properly label all containers containing chemicals. Labels must be securely attached and legible.
Exposure to heat or direct sunlight should be avoided to prevent degradation of chemicals and/or deterioration of storage containers (making them less susceptible to breakage).
Chemicals should not be stored higher than eye level (of the shortest person). Do not store liquid chemicals above counter top level without a raised lip on the shelf or secondary containment. Store large bottles and containers, and heavy materials, on lower shelves.
Chemicals must never be stored on the floor, even temporarily, because they could be knocked over and broken.
Chemicals must not be stored in fume hoods because their containers block proper air flow, reduce available work space, and exacerbate hazards in case of fire or spill.
Do not store chemicals under a sink.
Only compressed gas cylinders that are in use and properly secured should be kept in the lab.
Stored chemicals should be inspected periodically for deterioration and container integrity. Check that caps and closures are secure and free of deformation. Ensure that metal containers are free of rust, bulges or signs of pressure buildup.