Occurrence, Degradation, and Effect of Polymer-Based Materials in the Environment

At a global scale, increasing human population and associated economic growth has lead to an increase in the demand for consumable goods such as those made from polymer-based materials (PBMs) (i.e., plastics and elastomers). During their lifecycle PBMs can be released into the environment from a variety of sources. Once in the environment, PBMs are exposed to a variety of mechanical and chemical weathering processes. This causes a change to the PBM structure and facilitates the disintegration of the PBM into increasingly smaller fragments (Andrady 2011). Furthermore these materials are now thought to be contributing to the build-up of chemicals in the environment via the leaching of chemical additives that are used in the manufacturing process (Erren et al. 2009). The majority of physical effects data regarding bulk PBM items identifies them as presenting a hazard to mammals and birds as they can become entangled and/or mistake PBMs as a food source (Derraik 2002). The majority of ecotoxicity data regarding PBM additives has focused on the effects of compounds that are generally referred to as having endocrine disruptive potential, such as the phthalates (Oehlmann et al. 2009). However, receiving environments are potentially exposed to a combination of both these physical and chemical components, as well as substances produced during degradation processes. Therefore, PBMs and their associated degradation products may compromise the viability of organisms at all trophic levels. At the base of the food chain primary producers may be more sensitive to substances that have a biological action. Nonselective and filter-feeding consumers could be susceptible to ingesting both bulk PBMs and fragmented particles, leading to the potential passage up the food chain to secondary and tertiary consumers. Despite this concern, PBMs are regarded under REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) as representing a low environmental concern because of their high molecular weight (ECHA 2012). However, the occurrence of PBMs and their associated chemical additives in the aquatic environment have been recognized as an emerging worldwide problem, and their impacts are now gaining a wider scientific and social audience (Hammer et al. 2012; Thompson et al. 2009).