US EPA

In March 2014, EPA released the draft literature searches and associated search strategies, evidence tables, and exposure response arrays for DEP to obtain input from stakeholders and the public prior to developing the draft IRIS assessment. Specifically, EPA was interested in comments on the following:

• Draft literature search strategies
• The approach for identifying studies
• The screening process for selecting pertinent studies
• The resulting list of pertinent studies
• Preliminary evidence tables
  • The process for selecting studies to include in evidence tables
  • The quality of the studies in the evidence tables

The literature search strategy, which describes the processes for identifying scientific literature, contains the studies that EPA considered and selected to include in the evidence tables. The preliminary evidence tables and exposure-response arrays present the key study data in a standardized format. The evidence tables summarize the available critical scientific literature. The exposure-response figures provide a graphical representation of the responses at different levels of exposure for each study in the evidence table.

DEP is a colorless liquid with slight aromatic odor. It is soluble in water and slightly volatile. Impurities in technical DEP include isophthalic acid, terephthalic acid and maleic anhydride at levels of less than 1%. The DEP molecule contains two “ester” chemical groups. Ester chemical groups are generally susceptible to being hydrolyzed by a number of biotic and abiotic processes. Cleaving one DEP ester group leads to the formation of a monoester (monethyl phthalate – MEP) and cleaving both ester groups produces the diacid metabolite/degradate, phthalic acid.

DEP is used to improve the performance and durability of a number of products. As a plasticizer, it is added to plastic polymers to help maintain flexibility. It has been used in a variety of products including plastic films, rubber, tape, toothbrushes, automotive components, tool handles and toys. In addition to plastics, DEP is present in a wide range of personal care products (e.g., cosmetics, perfume, hair spray, nail polish, soap, detergent, and lotions), industrial materials (e.g., rocket propellant, dyes, packaging, sealants and lubricants), and medical products (e.g., enteric coatings on tablets and in dental impression materials). Previous uses as an inert ingredient in pesticide formulations are no longer allowed in the U.S.

EPA is undertaking an update to the Integrated Risk Information System (IRIS) health assessment for DEP. The outcome of this project is an updated Toxicological Review and IRIS Summary for DEP that will be entered into the IRIS database.

U.S. EPA. IRIS Toxicological Review of Diethyl Phthalate (DEP) (Preliminary Assessment Materials). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-13/302, 2014.