Laboratories and chemicals go hand in hand. Many, if not most, of the chemicals in a medical lab are or can be hazardous in one way or another.

From time to time, it’s a good idea to do an audit of the chemicals and reagents stored in the lab using an inventory list or program. Besides helping to maintain adequate supplies, an accurate, up-to-date inventory list will prove invaluable in an emergency.

Of course, it’s best to avoid emergencies and if one does occur, to handle it correctly. Here are some general safety guidelines all lab personnel should know for the safety of everyone in and around the building:

  • Proper use of personal protective equipment (PPE)
  • How to use a fire extinguisher
  • Where to find eyewashes and emergency showers
  • What to do in the event of a fire or other emergency
  • Correct use of all tools and equipment
  • How to handle accidental spills
  • The location of Safety Data Sheets (SDS)
  • Proper handling of waste
  • How to handle and store all chemicals
General Chemical Storage Rules
With the general safety rules tucked away into our knowledge bank, we can delve a little further into the last one… chemical handling and storage. Here’s a quick rundown of 10 basic rules for storing and handling chemicals.
  1. Chemicals that fall under multiple hazard groups should always be stored and handled based on the highest risk category.
  2. Always store chemicals in their designated location. With the exception of buffers & salts, never store them on the bench top.
  3. Chemical stocks and/or waste are not to be kept in fume hoods… they pose an additional fire hazard and could be spilled. Clutter in a fume hood also interferes with air flow, which is essential for proper hood operation.
  4. Keep containers closed when not in use. This goes for waste as well as stock chemicals (liquid & solid) & solutions.
  5. Exposure to heat and sunlight can cause degradation and increase the risk of fire, so ensure that all chemicals are stored away from heat, sun, and especially flame.
  6. The only things to be stored under sinks are bleach and cleaning supplies.
  7. Make sure everything is properly labeled with dates received and opened. Hazards are to be clearly marked.
  8. Shelve liquids below solids (never above) with the most toxic of them at the lowest level. 
  9. Lock cabinets and doors when unattended to prevent unauthorized access to hazardous or costly materials.
  10. Do not store chemicals directly on the floor. Use a tray or bin to protect from accidental spillage or leakage during storage and when transferring liquids from large containers.
Chemical Storage Groups
The goal when storing chemicals is to avoid undesired reactions and keep everyone in the area safe. The most likely chemicals to react with each other, and therefore the types of chemicals that need to be kept away from each other are:
  • Acids and bases
  • Organic acids and inorganic acids
  • Oxidizers and reducing agents
  • Flammables, corrosives, and pyrophorics
  • Halogens and non-halogens
The following is a summary adapted from the Fred Hutchinson Cancer Research Center’s chemical storage guidelines breaking them into nine basic chemical groups with their appropriate storage requirements:
  • Group 1 – Flammable Liquids Flammable liquids are those with flashpoints lower than 100°F (37.8°C). Alcohols, acetone, acetaldehyde, and xylene are a few of the many. The cabinet with the big “flammable” on the front is where these belong.
  • Group 2 – Volatile Poisons Volatile poisons are toxics, poisons, and some known or suspected carcinogens. Formaldehyde, formamide, and phenol are among the chemicals included in this group in which inhalation presents a health risk. Store them in a flammable cabinet or refrigerator (if the container is smaller than a liter). They can be kept with Group 1 flammable liquids as long as there are no bases in the cabinet.
  • Group 3 – Oxidizing Acids Oxidizing acids will react with just about everything… even each other. Nitric, sulfuric, and chromic acid are a few. They need to be kept in a secondary container such as a tray, tub, or canister and stored on the bottom shelf of a corrosives cabinet in a separate compartment. When there’s only a bottle or two, they can be stored with, but on a shelf under, Group 4 liquids.
  • Group 4 – Organic and Mineral Acids Organic and mineral acids will react with bases and oxidizers. Acetic acid, glacial acetic acid, and formic acid are some examples. Acetic anhydride and trichloroacetic anhydride are more corrosive than most. Store these separately in a corrosives cabinet or with Group 7. A big exception to this rule is acetic acid… store it with the flammables.
  • Group 5 – Liquid Bases Liquid bases must be kept from contacting and reacting with acids. Aqueous sodium hydroxide, ammonium hydroxide, and glutaraldehyde are some of the liquid bases you might have on hand. Store them in a safety cabinet or in a tub or tray in a regular cabinet. If no volatile poisons are in the flammable cabinet, they can be stored there.
  • Group 6 – Liquid Oxidizers Oxidizing liquids don’t get along well with others. They’ll react with anything and everything bringing on corrosion or explosion. Ammonium persulfate and hydrogen peroxide (greater than or equal to 30 percent) are two examples. Keep larger volumes of these (more than three liters) in their own cabinet. Smaller volumes can be kept near other chemicals if necessary (such as in a refrigerator) as long as it’s double contained in a tray or tub.
  • Group 7 – Non-Volatile Poisons Non-volatile liquid poisons include toxic chemicals, known and suspected carcinogens, and mutagens like acrylamide and ethidium bromide. They must be kept from contacting other chemicals and can be stored in a cabinet or refrigerator. Never store on open shelves. Any containers bigger than a liter need to be kept below bench level as close to the floor as possible. Containers smaller than a liter can be stored above bench level if, and only if, they are on a shelf behind sliding doors. The only chemicals non-volatile poisons are fit to share space with are non-hazardous liquids like buffers.
  • Group 8 – Metal Hydrides/Reactives Chemicals in this group can react violently with water or air. Examples are sodium borohydride and lithium aluminum hydride. Double up on the container, follow the instructions on the label for keeping it wet or dry, and keep them away from other chemicals. They can cohabit with the Group 9 solids if they’re properly and securely double contained.
  • Group 9 – Solids Solids including both hazardous and non-hazardous can be stored in a cabinet or on an open shelf above the liquids. They can even be alphabetized if it suits your fancy.

Picric acid (which should ALWAYS be covered with water), although explosive if it dries out, can be stored with the Group 9 solids. Note: if it does happen to dry out, call in the bomb squad. Seriously… don’t open it. All it could take is the friction of opening the bottle with some dried solid crystals on the threads.

Always check the label and reference Section 7 of the chemical’s Safety Data Sheet for full handling and storage instructions. In additional to any written policy or regulations by the institution, it’s important to follow all local, state, and national guidelines and/or standards for handling, storage, and disposal of lab materials and chemicals.

Liquid Nitrogen and Dry Ice Storage

Although not a chemical in the same sense, liquid nitrogen (LN2) and/or dry ice (CO2) are present and used frequently in many medical labs… and they can be deadly in more than one way if not handled and stored correctly. The vapors, both nitrogen and carbon dioxide, rapidly displace the oxygen in the air. All it takes is an unknowing breath or two of either of these colorless, odorless gasses for the unsuspecting victim to be knocked unconscious. Once out, continued lack of oxygen can quickly lead to death by asphyxiation.

The risks associated with LN2 and CO2 are now being addressed in the CAP accreditation program (as of August, 2018). You can read more about it in the October 2018 issue of CAP TODAY.


Things change… new and improved procedures and processes are developed. Different chemicals are added to the mix. New technicians arrive. And seasoned veterans leave. For the safety and wellness of all, take the time to ensure that the chemicals in your lab are being handled correctly.

To find chemical storage solutions for your pathology lab, check out PathSUPPLY or call us at 800-631-3556.

Related resources:
National Institute for Occupational Safety and Health (NIOSH) Pocket Guide to Chemical Hazards
Occupational Safety and Health Administration (OSHA) Standard 1910 – Hazard Communication
National Institute of Health (NIH) PubChem Database
Fred Hutchinson Cancer Research Center Environmental Health & Safety guidelines
Picric acid article