SEBS is actually a form of thermoplastic [[elastomer]] (TPE) with [[styrene]] added.  Green Peace lists SEBS as an acceptable alternative to PVC in toys.  Polyolefin plastics such as [[Polyethylene]] (PE) and [[Polypropylene]] (PP) are the most common building blocks for SEBS, which don't need plasticizers (like phthalates) or stabilizers (like lead) for flexibility.