Diethyl Phthalate and Cosmetics

March 17, 2006

DEP, or diethyl phthalate, is a clear, practically odorless liquid. It is the lightest in weight of the commonly used phthalates. In use for more than 50 years, it conveys a very important performance benefit to perfumes and other personal care products: when fragrances are dissolved in it, their scent lingers longer.

Because DEP has so many valuable applications in consumer products, it is among the hundreds of chemicals that will show up in "biomonitoring" tests. More precisely, its breakdown products will show up, because the parent compound breaks down quickly in the body. On the average, consumers have only about 1/100,000 of an ounce of DEP breakdown products in them at any given time, because any molecule of DEP that enters the body does not stay for very long. It is broken down rapidly and is eliminated from the body within hours. DEP does not build up in the body. In the environment, the same thing happens; DEP biodegrades rapidly, and is found in the environment at levels far below the no observed effect concentration (NOEC) seen in laboratory studies.

Safety Data

Humans are exposed to DEP primarily through the skin as they use personal care products. Some of those exposures are fleeting, as with soaps containing fragrances. Other exposures, such as from perfumes, are more lasting. But the average exposure, based on biomonitoring studies conducted by the U.S. Centers for Disease Control and Prevention, is some 130 times below the safety level set by the U.S. government to be protective of human health. And that safety level has a built-in safety factor of 1,000.

From time to time, special interest groups have tried to create a stir about DEP in their war against cosmetics, but it is difficult to understand why they bother. DEP has a very strong safety profile, according to reviews by agencies in the United States and in Europe. Europe’s Scientific Committee on Cosmetic Products reviewed DEP in 2002 and gave it a margin of safety of 15,000 when used as a fragrance solvent at concentrations up to 50 percent of the fragrance mix (or less than 2% of the total perfume product). In the United States, the Cosmetic Ingredient Review expert panel, in a process sanctioned by the Food and Drug Administration, found DEP "safe for use in cosmetic products in the present practices of use and concentration..."

In some cases, agencies charged with reviewing the safety of compounds, such as the National Toxicology Program, haven’t even bothered to review DEP because of the lack of evidence of reproductive or developmental toxicity. One small study claimed that a statistical correlation between DEP exposure and an effect in human sperm is generally viewed with caution because the study sample was very small, was drawn from a group of subfertile men, and lacked a control group. Similar studies have failed to support its findings.

In the environment, DEP rapidly degrades wherever it is – in the air, water, soil, or sediment. Because of this, and because DEP has a low potential to build up in organisms and shows a low degree of toxicity in aquatic wildlife, DEP has not been classified as a "PBT" by any agency – that is, it is not classified as persistent, bioaccumulative, and toxic.

Nevertheless, Greenpeace International has attempted to churn up a controversy by releasing its own review of DEP. It came to the curious conclusion that even though evidence for adverse effects from DEP "remains limited," precautionary actions should still be taken to limit its use! No regulatory agency in the U.S. or Europe agrees with Greenpeace and none is suggesting any concern for its continued use in cosmetics and other personal care products.