While chemical safety includes many individual elements, ranging from right-to-know training, to personal protective equipment (PPE), to material safety data sheets (MSDS), these elements should be part of a larger, overall system. This system's aim is to protect all employees from chemical hazards they may encounter at work.
Chemical safety is a system of standard operating procedures that receives, transports, stores, uses and disposes of chemicals in a safe and prudent manner. This process actually begins before a chemical is even ordered, and it doesn't end until the substance is properly disposed of.
The system is a living system, growing, changing and adapting to the potential dangers of the substances that are being used. It is also a partnership - one between labor and management designed to produce what all parties want: a safe work environment.
Let's look at the some of the operating procedures involved in a chemical safety program.
1) Prior to orderingBefore a chemical is ordered, the person requesting the material should attempt to substitute a less hazardous substance. In some facilities, prior approval from management and the safety department is needed if the desired chemical is a known or probable human carcinogen, acutely toxic substance, or presents a pronounced physical hazard, such as an explosion.
An MSDS for the substance should be on hand before the chemical is received. After reviewing this document you can decide if additional/specialized engineering controls, PPE, storage facilities and spill control measures are needed.
Also, having the MSDS prior to receipt of the chemical allows time for employee training in the safe handling and use of the material.
2) Receipt and transportAll packages containing chemicals, including gas cylinders, must be inspected for leaks and damage before being transported to the assigned storage site. The personnel that inspect these packages should be wearing the appropriate level of PPE: safety glasses and chemical-resistant gloves at a minimum. Things to look for:
- physical damage: dents, tears, scrapes, dirt, paint/ink from other containers;
- evidence of tampering;
- signs of leaks or spills: discoloration, odor, wet packaging, powder coming from the container.
If there are any indications of a spill or leak, evacuate the immediate area and call for aid.
If there are no signs of damage or leaks, the material may be transported to its assigned storage area. If the material is a particularly hazardous substance, notify the safety department and the person requesting the material. If a chemical requires refrigeration or freezing, and transport to the designated storage site is delayed, make arrangements for proper preservation of the compound.
Do not hand carry chemical packages. Packages containing chemicals should be transported to the appropriate storage site on a cart that has raised sides. If the package has been opened, place the substance in a secondary containment vessel and then on the cart.
3) Storage/inventoryChemicals are stored according to properties. Acids are stored separate from bases, flammables are stored in special cabinets, oxidizers are stored away from organics, and so on. After storing according to chemical properties, then and only then may chemicals be sorted alphabetically.
Refrigerators/freezers used for chemical storage must be labeled to that effect. Food or beverages must be kept out unless they are being used for testing; they should bear a prominent label that states they are not for human consumption. Refrigerators/freezers being used for storing flammable chemicals should be explosion-proof.
The chemical inventory in a stock room or other storage area must be inspected at least once a year. During these inspections, examine each bottle to see if the chemical is still safe to use and that the container hasn't been breached. (See "Warning Signs" sidebar.)
Certain classes of chemicals must be checked more frequently. Peroxide-forming compounds that have been opened should be checked every three months at a minimum. Visual inspection of the container and contents using a non-hazardous light, such as a flashlight, can detect the presence of very high levels of peroxides in organic solvents stored in glass bottles. Check to see if the clear solvents contain: suspended wisp-like structures, crystal formation, cloudiness or gross contamination. Contact your safety department or hazardous waste contractor immediately if they do.
If none of these conditions exist, the solvent may be tested using a commercially available test strip. These strips can measure up to 100 mg/L peroxide as H2O2. Some experts recommend that this concentration be used as the maximum safe concentration and that solutions containing higher values than this be disposed of.
4) Point of useWherever chemicals are used, measures must be taken to reduce personnel exposure. Among these measures are engineering controls, including: fume hoods, glove boxes, local exhaust systems and robotic equipment.
These systems need to be inspected and tested on a regular basis, with the date of the last inspection being posted on the device. When working with a particularly hazardous substance, have the device tested immediately prior to use.
Another safety requirement is the posting of appropriate safety signage. Additionally, in areas where carcinogens, reproductive toxins, and chemicals of high toxicity are used, access to the area should be limited to only those people who need to be there.
5) DisposalChemical disposal must conform to the local hazardous waste regulations. Most regulations require secondary containment and storage in a secure area. Only authorized personnel should be allowed into this part of the facility. Spill equipment should be stored outside the secured area to allow easy and safe access in case of an emergency.
An empty container is not truly empty. Until it has been cleaned, there will always be chemical residue inside it. PPE should always be worn when handling these "empties" until decontamination/cleaning has taken place.
SIDEBAR: Warning SignsWhat to look for when inspecting your chemical inventory:
- Is the label discolored? Something in the cabinet may have leaked.
- Are there crystals around the cap? For some chemicals, such as potassium chloride solutions, this is not abnormal.
- Is the container or cap bulging?
- Is the cap cracked?
- Does the container have a "sucked in" look or show signs of corrosion?
- Is there a film on the container?
- Is the bottle warm to the touch?
- Is there a precipitate in an otherwise clear reagent?
- Has the reagent turned color? This is normal in the case of open nitric acid bottles but a danger sign for most other reagents.
- Is there obvious contamination, such as discoloration or specks in the substance?
- Is the chemical past the expiration date assigned by the manufacturer?
- Is the substance giving off a strange odor? If so, initiate a spill response.