After animals are killed specifically for classroom dissection purposes they are then often preserved. Dissection animals are embalmed with a chemical preservative called formaldehyde (also known as methanal). Formaldehyde is a nearly colorless and highly irritating gas with a sharp odor. The liquid these dissection animals are contained in is actually formaldehyde dissolved in water called formalin. Formaldehyde is a known nasal and dermal carcinogen. It is also a sensitizer, causing allergy-related symptoms.

When students cut open these preserved dead animals, formaldehyde can be released. This formaldehyde can damage the children’s eyes, cause asthma attacks and bronchitis when exposed to this poison. Symptoms of formaldehyde exposure include eye, nose, throat and skin irritation. Other dissection chemical symptoms include a persistent cough, other respiratory ailments, headache, nausea and dizziness.

According to the U.S. Environmental Protection Agency, this chemical preservative can be linked to cancer of the throat, lungs, and nasal passages. Children may be more susceptible to the respiratory effects of formaldehyde than adults, according to the Agency for Toxic Substances and Disease Registry (ATSDR). Biology students should not be exposed to dead animals preserved in formaldehyde.