Plastics are commonly used for packaging in the food industry. The most popular thermoplastic materials that have found such applications are polyethylene (PE), polypropylene (PP), poly(ethylene terephthalate) (PET), and polystyrene (PS). Unfortunately, most plastic packaging is disposable. As a consequence, significant amounts of waste are generated, entering the environment, and undergoing degradation processes. They can occur under the influence of mechanical forces, temperature, light, chemical, and biological factors. These factors can present synergistic or antagonistic effects. As a result of their action, microplastics are formed, which can undergo further fragmentation and decomposition into small-molecule compounds. During the degradation process, various additives used at the plastics’ processing stage can also be released. Both microplastics and additives can negatively affect human and animal health. Determination of the negative consequences of microplastics on the environment and health is not possible without knowing the course of degradation processes of packaging waste and their products. In this article, we present the sources of microplastics, the causes and places of their formation, the transport of such particles, the degradation of plastics most often used in the production of packaging for food storage, the factors affecting the said process, and its effects.

PH-responsive membranes prepared by treating chitosan (Ch) with glutaraldehyde (GA) or with GA and sulfuric acid (SA) were studied. The structure and properties of the membranes were characterized by Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and elemental analysis. The effect of the cross-linking process both on the dynamic swelling behaviour of the hydrogel membranes and on the mechanism of water transport through those membranes was investigated in buffer solutions of different pH (1.2–9.5). The mechanism of water transport through the hydrogel chitosan membranes was affected by membrane composition and pH of the swelling medium. Non-cross-linked Ch membrane showed a non-Fickian swelling behaviour in the pH range 6.5–9.5. Chitosan membrane cross-linked with GA (Ch/GA) showed less-Fickian or Fickian swelling behaviour in all buffer solutions. In the case of chitosan membrane cross-linked with GA and SA (Ch/GA/SA), at low pH (lower than the pK _a of the hydrogel) the water transport was controlled more by polymer relaxation than by penetrant diffusion. The experimental data clearly suggested that the swelling process in all buffer solutions obeyed second-order kinetics. Values of an apparent swelling rate constant for Ch/GA and Ch/GA/SA membranes were of the same order of magnitude for acidic and neutral swelling media but they increased for alkaline solutions.