Why are they hazardous?

The fluids employed in spirit collections vary but often include one or more toxic or flammable substances. The specimen is ‘fixed’ using toxic substances that arrest deterioration and maintain appearance. The specimen is then immersed in preservative fluids, and periodically topped up or transferred to yet further preservative fluids. For example, the use of ethanol (alcohol) renders fluids flammable and the use of formaldehyde (formalin) fixatives renders the specimen’s tissues highly toxic. Some specimens can be transferred into less hazardous fluids such as paraffin.

Poorly fixed or preserved specimens may contain active pathogens (see topic Biological hazards) and fungi (see topic Mould).