Exploring a safer alternative to eosin in soft tissue staining

CONTEXT: Hematoxylin–eosin (H&E) stain has stood the test of time as the standard stain for histologic examination of human tissues. Haematoxylin is a natural dye, on the contrary, its counterstain eosin is a synthetic dye which belongs to the xanthene group. Synthetic dyes are hazardous to human and animal health. With the increasing awareness of a green earth, it is advisable to use environment-friendly and biodegradable materials. Therefore, an attempt was made to develop as biofriendly substitute in the form of food colour as a counterstain for haematoxylin. AIM: To assess the staining ability of food colouring agents in routine staining and to compare its staining efficacy with Eosin. SETTINGS AND DESIGN: Two food colours were obtained and stain was prepared by using 70% ethyl alcohol as counterstain for haematoxylin. Different tissue structures such as epithelium, keratin, collagen fibers, muscles, salivary glands, adipocytes, blood vessels, RBCs were observed and evaluated. METHODS AND MATERIAL: Group A –10 slides stained with green food colour, Group B – 10 slides stained with tomato red food colour and Group C – 10 slides stained with conventional H and E. The stained sections were assessed and graded for nuclear staining, cytoplasmic staining, clarity, uniformity and crispness of staining. STATISTICAL ANALYSIS USED: The non-parametric Kruskal–Wallis and Mann–Whitney U tests were performed for statistical analysis. RESULTS: There was no statistically significant difference between the three study groups with respect to all the parameters except crispness of staining. The crispness of Tomato Red and H and E was better compared to green food colour. CONCLUSIONS: Food colouring agents can be used as a safe, biofriendly and inexpensive substitute to eosin in conventional soft tissue staining.