DIDP and DINP are phthalates — a family of chemical compounds primarily used to make polyvinyl chloride (PVC), sometimes called vinyl, flexible and pliant. Phthalates are used in hundreds of products in our homes, hospitals, cars and businesses.
The high molecular weight phthalates selected to soften plastics are used because of their strong performance, durability and stability. Because these high molecular weight phthalate plasticizers are tightly bound into the material in which they are added, they do not easily migrate out of the product or evaporate.
DINP is primarily used as a plasticizer to impart flexibility to PVC in consumer and industrial applications. These applications include wire and cable coating, building and construction (vinyl tiles, resilient flooring, PVC-backed carpeting, roofing, wall coverings, etc.), automotive (window glazing, doors, acrylic plastisol sealants in wheel wells, underbody coatings and paints), vinyl clothing (raincoats and boots, gloves, etc.), tool handles, flexible tubes, and hoses. Approximately 5% of DINP is used in non-PVC applications such as rubber polymers, inks and pigments, adhesives, sealants, and paints.
DIDP is also primarily used as a plasticizer to impart flexibility to PVC in consumer and industrial applications. These applications include building and construction (electrical wire coating, vinyl tiles, resilient flooring, PVC-backed carpeting, roofing, wall coverings etc.), automotive (upholstery and interior finishes such as synthetic leather for car interior seats and dashboards, undercoating, insulation for wire and cable, window glazing etc.), flexible tubes, profiles, and hoses. Other DIDP applications include use in inks, adhesives, sealants, synthetic lubricants and engine oils.
While they can be employed in a variety of applications, phthalates are not necessarily interchangeable. The characteristics of an individual phthalate often make it well suited to a particular product, allowing manufacturers to meet unique requirements for its use (function and safety specifications), appearance (texture, color, size and shape), and durability and wear.
We have full confidence in the safety of DINP and DIDP, and a manufacturer-requested review is the most expeditious way to have EPA evaluate the safety of key uses of these compounds against rigorous scientific criteria. This assessment of safety – backed by the peer review required by law - is important to businesses and consumers of these important products.
To achieve this goal, industry has voluntarily stepped forward on the strength of over 20 years of research on DINP and DIDP. In fact, the overwhelming international consensus, as found by the European Chemicals Agency (ECHA), the Australian National Industrial Chemicals Notification and Assessment Scheme (NICNAS), and Canada’s Ministry of Environment and Climate Change and Ministry of Health, is that these high molecular weight phthalates are safe as currently used.
We look forward to the EPA completing these risk evaluations within the timeframe set forth in TSCA, and consistent with the guidance to apply the best available science and to rely on the weight of the evidence, as required by the statute. We stand ready to assist the agency if additional information is needed to complete the reviews.