B 5.0
What the specimen is sitting in
Formalin-fixed or formalin-free — a field that decides what your room has to be ventilated for, what your district will approve, and whether the shipment carries a hazardous-materials surcharge.
Two different things happen to a preserved specimen, and they are often confused: it is fixed, and then it is held.
Fixing is what stops decomposition and hardens the tissue enough to cut cleanly. It is done once, at the beginning, and formaldehyde is what does it. Every preserved specimen you will ever buy has been fixed, from anyone.
Holding is what the specimen sits in afterwards, for the months or years between fixing and the tray. That fluid can be a dilute formalin solution, or it can be a formalin-free holding fluid — and that is the choice you actually have.
So “formalin-free” does not mean the specimen was never near formaldehyde. It means residual formaldehyde has been reduced and the specimen is held in something else. Anyone telling you otherwise is selling you a word rather than a product.
B 6.0 The choice
Which one to order
For the overwhelming majority of school laboratories the answer is formalin-free, and it is what most districts now specify. Say which you need on the order; if you say nothing we will ask rather than guess.
| Formalin-fixed | Formalin-free | |
|---|---|---|
| Odour | Strong, sharp, and the thing students remember about dissection. | Mild. A room can be worked in for an hour without complaint. |
| Irritation | Eyes and airways, particularly for asthmatic students. | Substantially reduced. |
| Ventilation | Real mechanical ventilation, and a written risk assessment. | Ordinary classroom ventilation is generally sufficient. |
| District approval | Often requires specific sign-off; some districts prohibit it outright. | Usually the specified default. |
| Tissue | Firm, holds an edge well, traditional feel under a scalpel. | Slightly softer; excellent for teaching, marginally less crisp. |
| Shipping | Carries a hazardous-materials surcharge, $32.00 per consignment. | No surcharge. |
| Storage life | Very long, sealed and wet. | Long, sealed and wet. Check seals annually. |
General guidance for specifying an order. Your institution's safety policy, your district's rules and the current safety data sheet for any fluid you hold take precedence over this table.
B 7.0 In the room
Handling, storage and disposal
None of this is exotic, and most of it is the practice a school laboratory already runs. It is written down here because it is the sort of thing that gets assumed rather than said, and because a district safety officer asking a supplier for it should be able to find it.
Handling
Nitrile gloves, eye protection, no eating or drinking at the bench, hands washed afterwards. Rinse specimens briefly before the lesson if the holding fluid is noticeable — it makes the room considerably more pleasant and costs a minute.
Keep the room ventilated whichever fluid you are using. For formalin-fixed material that means mechanical ventilation and a risk assessment that names it.
Storage between sessions
Sealed, wet, cool and dark. A specimen dries out long before it rots, and a dried specimen is finished. Return it to a holding bag with a little fluid, seal it, and store it away from sunlight and heat. The thing to check at the start of a term is whether any bag has lost its seal over the summer.
Disposal
Preserved animal material and its fluid are not general classroom waste, and the rules are set locally rather than by us. Your institution's waste contractor, your district's policy and your state's requirements govern it. Ask your safety officer before the lesson rather than at the end of it, when thirty trays need emptying.
Living cultures are disposed of differently again: bacterial plates and slants are autoclaved or chemically disinfected before they go in the bin, never rinsed down a sink. Live invertebrates are not released into the environment under any circumstances — that is how a teaching organism becomes somebody's invasive species problem.
Safety data sheets
A current safety data sheet for any holding fluid supplied is sent with the order and is available on request at any time. Telephone (916) 386-2665 and ask; it does not need a form or an account.
Call (916) 386-2665Bacterial cultures supplied here are non-pathogenic teaching strains. They still require ordinary aseptic technique and proper disposal. Nothing in this catalogue is a pathogenic organism, and we do not supply one on request.
Before the first lesson
- Confirm which holding fluid your order is in — it is on the packing list.
- Check your district's position on formalin if the answer is formalin-fixed.
- Confirm how the waste will leave the building, before the trays are full.
- Have gloves and eye protection for the largest class, plus spares.
- Rinse specimens before handing them out if the fluid is noticeable.
Not sure what your district allows?
Telephone and describe the room and the policy. Formalin-free is the right answer for most school laboratories and it is what we will suggest unless there is a reason not to.
Niles Biological, Inc. · 9298 Elder Creek Rd, Sacramento, CA 95829