Diethyl phthalate is produced by the reaction of ethanol with phthalic anhydride, in the presence of a strong acid catalyst: It finds some use as a specialist plasticiser in PVC, it has also been used as a blender and fixative in perfume.

Recent studies show that DEP, a phthalic acid ester (PAE), is enzymatically hydrolyzed to its monoesters by pancreatic cholesterol esterase (CEase) in pigs and cows.

[7][8][9][10] Dose response experiments in fiddler crabs have shown that seven-day exposure to diethyl phthalate at 50 mg/L significantly inhibited the activity of chitobiase in the epidermis and hepatopancreas.

[12] When pregnant rats were treated with diethyl phthalate, it became evident that certain doses caused skeletal malformations, whereas the untreated control group showed no resorptions.

[13] In a following study it was found that both phthalate diesters and their metabolic products were present in each of these compartments, suggesting that the toxicity in embryos and fetuses could be the result of a direct effect.