Global production of plastics is clearly on the increase and plastic products have become an inextricable part of our everyday life. Over a short span of about 75 years plastics have penetrated diverse application areas replacing conventional materials quite successfully. Continued growth in production is expected in the medium term but questions on the sustainability of plastics are being raised. A key aspect of sustainability of plastics and rubber materials is their potential environmental toxicity and in particular human toxicity. Plastic resins, however, are nontoxic materials, composed of macromolecules that are neither digestible nor absorbable in the gut. Toxicity of plastics often observed is attributed to the numerous additives mixed in with the resin during processing and fabrication of products, the residual monomers, or catalysts trapped in the resin and the chemicals picked up by the plastics from the environment. Of these, the additives are present at the highest concentrations in plastic products. Knowing and evaluating the additives commonly used, their potential toxicity, and their intake routes to human users are essential for the sustainability of plastics.