A concise assessment of the risks to human health and the environment posed by exposure to N-phenyl-1-naphthylamine, a lipophilic crystalline solid that is used as an antioxidant in various lubrication oils and as a protective agent and antioxidant in rubber and rubber mixtures for various products, including tyres. Concerning sources of human and environmental exposure, the report cites evidence that the chemical may be released to soil and surface waters from the leakage of lubrication oils or leaching from decaying tyres and rubber products. Emission to the atmosphere may arise from exhaust gases during production and processing, and during the vulcanization of rubber mixtures. Presence in the environment is expected to be low. Limited studies indicate that the chemical is distributed to soil, sediment, and water, and to a much smaller degree, to air, suspended sediment, and biota. In view of its moderate to high potential for sorption to organic soil constituents and its limited mineralization in soil, the chemical is likely to have geoaccumulation potential. Studies demonstrate high acute toxicity in fish and Daphnia.