Chronic Dosed-Feed Toxicity/Carcinogenicity Study of 2-Hydroxy-4-Methoxybenzophenone (HMB, C10260; CAS No. 131-57-7) in Sprague-Dawley rats (G822872B). Chronic Dosed-Feed Toxicity/Carcinogenicity Study of 2-Hydroxy-4-Methoxybenzophenone (HMB, C10260; CAS No. 131-57-7) in Sprague-Dawley rats (G822872B)

2-Hydroxy-4-methoxybenzophenone (HMB) is an approved Food and Drug Administration (FDA) over-the-counter Category I product considered to be a deterrent to ultraviolet (UV) radiation-induced skin cancer. HMB is used in pharmaceuticals, plastic products, fabric coatings, finishes, and cosmetics. Exposure to HMB occurs through both occupational and consumer routes. HMB is used in skin moisturizing products and sunscreen lotions. In plastics manufacturing, HMB is used in surface coatings and polymers including ABS resins, cellulosic esters, polyesters, polystyrenes, rubber, flexible and rigid vinyl, and vinylidene chloride. HMB readily penetrates the skin and bioaccumulates in lipid-rich tissues. Uptake from the gastrointestinal tract is rapid. This study will characterize the toxicologic and carcinogenic potential of HMB administered in dosed feed to Sprague-Dawley rats given its potential for widespread human exposure as a broad-spectrum sunscreen. Overall design: Following 13 weeks of treatment (0 and 10000 ppm groups), rat were sacrificed and the liver removed and sectioned with one section taken for histopathology and one section placed in RNAlater and treated according to the manufacturer's protocol. The sample placed in RNAlater was minced into 2-3 mm pieces, maintained on wet ice until the end of necropsy, and subsequently refrigerated overnight. The liver samples were then frozen in liquid nitrogen and maintained at -80 degrees centigrade until shipped frozen to an NTP-designated laboratory for RNA extraction and microarray assessment using the Affymetrix GeneChip® Rat Genome 230 2.0 array.