Diethyl phthalate is a colourless liquid with a slight aromatic odour and low volatility. Diethyl phthalate is used as a plasticizer for cellulose ester plastic films and sheets (photographic, blister packaging, and tape applications) and moulded and extruded articles (consumer articles such as toothbrushes, automotive components, tool handles, and toys). Diethyl phthalate was reported as an ingredient in 67 cosmetic formulations. Diethyl phthalate is used as a component in insecticide sprays and mosquito repellents. Diethyl phthalate is likely to undergo biodegradation in the environment. General population exposure in the USA, as estimated from urinary concentrations of the monoester, was estimated to be 12 µg/kg body weight per day (median value). Dermally applied diethyl phthalate penetrates the skin and can be widely distributed in the body, but it does not accumulate in tissue. Diethyl phthalate has irritant effects on the eyes, skin, and mucous membranes and can lead to central nervous system (CNS) effects in exposed workers. The exposure to diethyl phthalates (DEP), a parent compound of the monoethyl phthalate (MEP) metabolite, may be associated with increased risk of BC (Odds Ratio of 2.20, p value for trend, p<0.003).