Diphenylamine is widely used as an industrial antioxidant, dye mordant and reagent and is also employed in agriculture as a fungicide and antihelmintic.

[7] Diphenylamine is produced by the thermal deamination of aniline over oxide catalysts: It is a weak base, with a Kb of 10−14.

Its anti-scald activity is the result of its antioxidant properties, which protect the apple skin from the oxidation products of α-farnesene during storage.

[11] Apple scald is physical injury that manifests in brown spots after fruit is removed from cold storage.

[13] Diphenylamine functions by binding nitrogen oxide degradation products, forming compounds like nitrodiphenylamine.

[14] Alkylated diphenylamines function as antioxidants in lubricants,[15] approved for use in machines, in which contact with food is not ruled out.

[18] The diphenylaminesulfonic acid is a simple prototype redox indicator, owing to its improved aqueous solubility compared with diphenylamine.

[6] The U.S. CDC's NIOSH lists the following symptoms of poisoning: irritation eyes, skin, mucous membrane; eczema; tachycardia, hypertension; cough, sneezing; methemoglobinemia; increased blood pressure and heart rate; proteinuria, hematuria (blood in the urine), bladder injury; in animals: teratogenic effects.

Diphenylamine was always the major residue, but 3 metabolites were found in good amounts in the apple samples, whose identification experts considered insufficient.

XenoBiotic Laboratories, Inc., USA, unpublished) cited in [6][25] There is a data gap on presence or formation of nitrosamines in apple metabolism or during processing.

Despite limited data, the information was sufficient for the EC to characterize the environmental risk as negligible, because the intended use of diphenylamine was indoors.

The assessment, received by the EFSA in 2007 started the peer review in October 2007 by dispatching it for consultation of the EC member states and the applicants, the two manufacturers, Cerexagri s.a., Italian subsidiary of United Phosphorus Ltd (UPL), and Pace International LLC.

As a result of the peer review, mostly lacking data about risk to consumers, and particularly the levels and toxicity of unidentified metabolites of the substance, the possible formation of nitrosamines during storage of the active substance and during processing of treated apples, and the lack of data on the potential breakdown product of diphenylamine residues in processed commodities, the EC decided on 30 November 2009 to withdraw authorizations for plant protection products containing diphenylamine.

(2009/859/EC) The 'European Diphenylamine Task Force' resubmitted an application to the EC with more data, and an additional report was received by the EFSA on 3 December 2010.