178 J. Cosmet. Sci., 73, 178–189 (May/June 2022) Address all correspondence to John S. Bajor, john.bajor@unilever.com The Safety and Efficacy of Petrolatum CAROL A. BOSKO, JEAN ADAMUS AND JOHN S. BAJOR Unilever Research, 40 Merritt Blvd, Trumbull, Connecticut, USA (J. B., C.B., Ret., J.E., Ret.) Accepted for publication February 23, 2022. HISTORY Petroleum jelly (PJ) was invented by Robert Chesebrough, a chemist, who was first inspired to investigate the properties of petroleum “wax” during a visit to the oil fields of Titusville, Pennsylvania in 1859. Chesebrough noticed that oil workers were using the waxy substance that accumulated at the top of the oil drills to help heal their cuts and burns. He brought the substance back to his lab in Brooklyn, New York, developed a procedure to purify the material, and undertook an effort to identify its utility. In 1865, Chesebrough applied for his first patent describing a triple refining process that created the PJ, or petrolatum, that we know today (1). So ardent was his belief in his “wonder jelly” that Chesebrough traveled around New York selling the semisolid from a horse-drawn cart as he purportedly burned himself. He then slathered the jelly onto his fresh wounds in front of crowds that had gathered to see his demonstrations. It was not until 1872 that Chesebrough dubbed his product Vaseline® (Unilever, Trumbull, Connecticut), from the German name for water (wasser) and the Greek word for oil (oilon) (2). The main advantage of Vaseline PJ (VPJ) versus other vegetable-based oils that were in use at the time was its stability and resistance to oxidation and hydrolysis. VPJ won numerous awards, including the grand medal at the Philadelphia Exposition of 1876 and the silver medal at the Paris Exposition of 1878. By the late 1880s, the product was so successful that production could not keep up with demand, and shortages occurred in 1885 and again in 1891 (3). At that time, Vaseline and Epsom salts shared the number one spot as the most prescribed products in a survey of pharmacists. Chesebrough survived to the age of 96 and attributed his longevity to eating a spoonful of VPJ every day (4). COMPOSITION PJ is an odorless, colorless, translucent, and semisolid mixture of hydrocarbons with a melting point ∼37°C. It is a purified derivative of petroleum, containing a liquid hydrocarbon fraction, paraffin wax, and a microcrystalline wax (5,6). Paraffin wax contains