19 PS foam is not identified in all animals investigated. For example, a study of plastic debris and fur seals found PS and PS foam in the plastic debris, however there was no PS in the fur seals nearby (Eriksson and Burton 2003). Ingestion of different microplastics can depend on many factors, such as feeding strategy and gape size (feeding mouthpart or jaw size). While some species may avoid plastic ingestion, other species may also be drawn to plastic. 3.6 Exposure to chemicals A wide range of toxic compounds have been identified in plastic leachates, including monomers. These compounds can leach out from PS foam over time. Under certain conditions, PS foam has been shown to leach unreacted raw materials, including styrene and benzene, ethylbenzene (Ahmad and Bajahlan, 2007; Thaysen et al., 2018). These leachates have known toxic properties (Gibbs and Mulligan, 1997). EPS foam leachate, for example, which includes ethylbenzene, can impact the survival of a freshwater zooplankton (Thaysen et al., 2018). Styrene, has been shown to have many negative effects, including disruptions to endocrine systems (Lithner et al., 2011), lung tumors (Cruzan et al., 2001), liver damage (Carlson, 2002; Vogie et al., 2004), and genotoxicity (Vodicka et al., 2006). Styrenes are widely detected in coastal waters around the world and in Canadian waters on the Great Lakes (Environment Canada & Health Canada, 1993; Kwon et al., 2015). For more information on styrene, refer to Appendix 6 .3. Many additives and adsorbed contaminants can also leach from PS foam. Additives including surfactants and antioxidants, flame retardants and Phthalates can also leach and cause toxic effects (Hermabessiere et al., 2017). Due to the long-range transport of plastics in water, this can also mean the long-range transport of environmental contaminants, such as brominated flame retardants (Heeb et al 2010). In some parts of the world, PS foam has been cited as a source of chemicals to the environment (Rani et al., 2015; Jang et al., 2017) and to wildlife (Jang et al., 2016). EPS buoys were identified as a source of flame retardants (i.e. HBCDD) to oysters (Hong et al 2013) and mussels (Jang et al., 2016). Mussels on EPS debris accumulated higher levels of HBCD than mussels attached to other substrates, such as high-density polyethylene (HDPE) buoys, metal buoys, and rocks (Jang et al., 2016). Increased HBCDD content was found in oysters in a farm where PS floats containing HBCDD were used, even when oysters were not in direct contact with the PS (Hong et al., 2013). These studies show that PS debris acts as a source of additives in the marine environment and organisms inhabiting that debris, or even in their vicinity, can be directly influenced by the additives. Certain adsorbed contaminants can also leach into terrestrial environments when plastic is beached. PS foam blocks can adsorb mercury when in water and release it into soil when PS washes up on beaches (Graca et al. 2014). Over the pH range normally found in soil and surface waters (pH 5-9) PS foam can leach chemicals into the surrounding environment (Ahmad and Bajahlan, 2007; Thaysen et al., 2018). The environmental mobility of some additives is not well understood due to a lack of analytical data. Additives applied in different stages of the material production process are likely to have different physical and chemical properties. For example, lubricants added late in the production stage may be more likely to leech from PS compared to UV stabilizers and antioxidants that are incorporated into the plastic. Due to the ingredients, additives and mobility found in PS foam and the occurrence of PS foam in the environment, PS foam poses an environmental concern. Monomers A monomer is a type of molecule that can bond with other molecules into a long chain. Polystyrene is made up of a long chain of styrene monomers. Phthalates Phthalates are a group of chemicals used in hundreds of products, including toys, vinyl flooring, detergents, lubricating oils, food packaging, pharmaceuticals, and personal care products (nail polish, hair spray, aftershave, soap, shampoo). Often phthalates are listed as “perfume”or “fragrance” on ingredient lists in personal care products.