Thermoplastic Rubber (TPR) is a common, flexible material used in a wide variety of consumer products, including children’s toys, footwear, power tool grips, and medical devices. TPR combines the elasticity of rubber with the manufacturing simplicity of plastic. Because TPR is ubiquitous in items with high human contact, consumers often question its potential toxicity. This article examines the composition of TPR and addresses whether it poses a health risk.
Defining Thermoplastic Rubber
Thermoplastic Rubber is not a single chemical but a class of materials known as Thermoplastic Elastomers (TPEs). These materials are copolymers, consisting of two different types of polymer blocks: a hard plastic segment and a soft, elastic rubber segment. The most common varieties of TPR are based on Styrene Block Copolymers, such as Styrene-Butadiene-Styrene (SBS) or its hydrogenated form, Styrene-Ethylene/Butylene-Styrene (SEBS).
TPR’s composition allows it to be melted and reformed repeatedly, like plastic, while retaining the flexibility of rubber. SBS-based TPR is often used for products requiring a glossy finish, while the more stable SEBS-based materials are chosen for applications like food contact items and medical devices.
Safety Profile and Regulatory Oversight
Standard, virgin TPR is considered non-toxic and chemically inert for most consumer applications. Its safety stems from its high molecular weight polymer structure, which is stable and not easily broken down by the human body. This stability reduces the likelihood of releasing harmful substances under normal use conditions.
TPR is often preferred over older plastics, such as Polyvinyl Chloride (PVC), because its base formulation does not require plasticizers like phthalates or Bisphenol A (BPA) for flexibility. Regulatory bodies, such as the U.S. Consumer Product Safety Commission (CPSC), restrict phthalates in children’s toys, a standard TPR easily meets. High-grade TPR formulations often undergo rigorous testing to obtain certifications from organizations like the U.S. Food and Drug Administration (FDA) for food contact or medical use.
Factors Influencing Material Safety
While the base polymer is safe, the final safety profile of a TPR product is influenced by manufacturing choices and external conditions. Manufacturers incorporate various additives, such as colorants, fillers, and stabilizers, to achieve specific characteristics or reduce costs. Poor quality control during compounding can introduce undesirable heavy metals or other harmful substances through low-grade additives.
The long-term durability of the material is also a factor, as polymer degradation can occur under extreme conditions. Prolonged exposure to high heat, harsh chemicals, or intense ultraviolet (UV) radiation can cause the polymer chains to break down. This degradation can potentially lead to the leaching of small chemical components or additives, which is a concern for items like outdoor gear or toys.