Orthophenylphenol (OPP) is an antimicrobial agent used as a disinfectant and as a post-harvest preservative for citrus fruit and other fresh produce. Applied as a wash, wax coating, or impregnated wrapper, it suppresses moulds and decay organisms during storage and transport, extending the marketable life of oranges, lemons, and pears shipped over long distances. Residues are regulated with maximum limits, and treated citrus must often be labelled to inform consumers, since the compound concentrates in the peel. Toxicological reviews have set acceptable daily intakes, though some assessments flagged concerns at high doses, keeping it under periodic review. Its use illustrates the trade-offs of the fresh produce supply chain: without post-harvest fungicides, losses to rot would be far higher, but consumers increasingly expect minimal chemical treatment, pushing the industry toward biological alternatives.