Phthalates or Phthalate Esters are esters of phtalic acid. They are used as plasticizers for polymer clay.
Over the last decade, safety concerns were raised regarding phthalates in polymer clay, although not all phthalates pose a health hazard and some are approved for medical applications. By the Consumer Products Safety Improvement Act of 2008 (CPSIA), the following six phthalates were restricted or banned:
As a result, some polymer clays were reformulated, and some new ones, with alternative plasticizers, were developed. Currently, all polymer clays on the US Market comply with CPSIA regulations.
Read more about phthalates in polymer clay on my Polymer Clay Safety page.