This ubiquity of plastic litter and its indelible human footprint in our oceans has prompted scientists to suggest that this current period should be classified as the plastics epoch. In the previous 2 posts, I endeavoured to highlight how the detrimental consequences of the widespread pervasiveness of plastics were discussed especially in relation to marine life ingesting plastics. However, it is imperative to note that the ramifications of plastic pollution do not stop with its physical harm. Besides, these adverse effects, plastics which consist of endocrine-disrupting additives and contaminants are causes of mounting concern. This is primarily because Gallo et al. (2018) argue that their composition of polymers and known/suspected toxic chemicals will inevitably make significant contributions to marine biota exposure to complex mixtures of chemical contaminants.
Almroth and Eggert (2019) corroborate this, highlighting how the source of chemicals in marine environments are often traced to leachates from plastic litter. For instance, chemicals deliberately added to the production of plastics such as flame retardants, phenols, UV stabilisers and pigments may leak out or via diffuse sources such as atmospheric deposition and wastewater due to the prevalent usage of chemicals and plastics globally. Other sources of chemicals in marine plastic litter also originate from the unintentional addition of chemicals such as BPA and vinyl chloride and the recycling of plastic waste.
One salient issue with chemicals in plastic litter is their endocrine-disrupting properties. Gallo et al. (2018) report how studies on marine life reveal that even low-level exposure to endocrine-disruptor chemicals (EDCs) – BPA, butyl benzyl phthalate, dimethyl phthalate etc. may engender permanent changes to endocrine systems in organisms as EDCs are capable of competing with, mimicking and disrupting the composite of endogenous hormones. Although more research is necessary, it was preliminarily discovered that any exposure to EDCs may cause populations to face low birth rates due to impaired reproduction lowered metabolism rates and higher incidences of hormone-sensitive cancers (A more in-depth analysis on the chemical effects on marine organisms will be discussed in a later post). In particular, Gallo et al. (2018) reveal that endocrine-disrupting activity is increasing due to growing concentrations of microplastics and bioaccumulation transmitted from the consumption filter feeders such as plankton (As was discussed previously!)
What came as a surprise to me was the fact that recycled plastic was not the better option as it also came with its own host of issues. According to Fawcett-Atkinson (2021), recycled plastics/polymers consist of high contents of toxic chemicals transmitted from source plastics that also reinforce greater rates of chemical exposure in marine environments. Gallo et al. (2018) also intimate how plastic waste collected for recycling purposes are typically exported to countries in the Global South that lack the knowledge and legal requirements on proper recycling methods and the extent of the concentrations of hazardous substance mixtures in recycled plastics.
Although more research is necessary to discover the full extent of plastic pollution in our marine ecosystems, it should be noted that urgent actions predicated on the precautionary principle such as policy reforms should be undertaken on a global level to limit the use of single-use plastics, instead of mitigation measures that have superficial impacts. There should also be the repatriation of plastic waste from the Global South where little to no environmentally-sound disposal systems exist in the interim, at least until educational programmes are administered and local communities are equipped with the technical know-how on how to effectively dispose of waste that prevents the leakage of any plastics in marine environments.
Stay tuned for the next post where more examples of chemical pollution in the marine environment will be discussed!
References
Gallo, F., Fossi, C., Weber, R., Santillo, D., Sousa, J., Ingram, I., Nadal, A. and Romano, D., 2018. Marine litter plastics and microplastics and their toxic chemicals components: the need for urgent preventive measures. Environmental Sciences Europe, 30(1).
Fawcett-Atkinson, M., 2021. The insidious side effects of recycling plastic. [online] Canada’s National Observer. Available at: <https://www.nationalobserver.com/2021/12/14/news/insidious-side-effects-recycling-plastic>