Recycled formalin: a new tool to mitigate the environmental impact of surgical pathology in routine practice.

Formalin is universally acknowledged as the gold standard for tissue fixation. However, it is a dangerous toxic chemical without any realistic substitute. Therefore, decreasing its use seems to be the only way to reduce its environmental impact. We assessed the feasibility of an innovative formalin recycling circuit based on the reuse of formalin following biopsy removal and paper filtration. We also assessed the efficiency of a policy of less formalin use in routine practice without compromising work quality and security. The recycled formalin was equivalent to new formalin in terms of its chemical and molecular properties, as well as the fixation, analysis, and storage of tissue samples. Moreover, its use for fixation did not affect molecular analyses. We calculate that our process would have decreased the total consumption of formalin in 2022 by 26% compared to 2021. This corresponds to financial savings of €4620, a 2434 kg CO₂ equivalent reduction in greenhouse gases, and substantial decreases in toxicity to humans and freshwater. Our recycled formalin circuit is a simple, easy-to-implement, efficient way to mitigate the environmental impact of formalin in surgical pathology without compromising the quality of analysis and the safety of the pathology staff.