In the previous post, we explored the obvious effects of plastic pollution on animals. However, the effects are not the same for microplastics. The effects seem to produce chemical/biological effects on animals. According to Prokić et al. (2019), microplastics can result in “oxidative damage”, modify “antioxidative system and metabolism” and “neurotoxic” impacts. These effects have been determined by measuring the necessary biomarkers.
Woah those effects sound like really fancy terms that most of us probably do not understand. Well, let me try to simplify that for you. These effects mean that biological aspects like DNA , lipids, cells, reproduction, immunity, organs, behaviours (sensory, cognitive, motor), etc are damaged. This means that the normal way in which organisms and animals function are altered, mostly negatively.
Interestingly, the effects varied depending on three factors as named in the article. They were “size, doze and/or interaction with other xenobiotics” (Prokić et al., 2019). The smaller the size, the greater the damage because it is retained longer and is more bioavailable. For dose, the higher the dose, the greater the damage. Adding on, interaction with other xenobiotics mean that microplastics interact with other chemical pollutants such as mercury and pesticide, that can be found in the ocean or freshwaters as well. The damage to lipid containing structures changes the permeability of cell membranes, causing the greater transfer of toxic chemical pollutants that is absorbed onto the surface of microplastics into cells of organisms. These interactions can further complicate anticipated effects by altering the extent of the effects such as changing the toxicity of these chemical pollutants with regards to the organisms. This means that on top of the toxicity of microplastics, we have to take note of the toxicity of the other contaminants that exists with it.
Something that I was surprised was not stated as an factor was exposure. As we have learnt in lecture, as much as the dose matters, other factors like exposure (duration and frequency) to pollutants is important as well. I could only predict that a greater length of exposure would intensify the effects of microplastics and the chemicals absorbed onto it.
Overall, it seems that through more rigorous research, the effects of microplastics on a chemical/biological level has been discovered. However, I feel that these effects are not exhaustive and that we have an incomplete knowledge of the effects of microplastics. For instance, the effects of plastics may play out differently for each species of animal. Also, we do not know know how all microplastics (which consist of many types) react with all other chemical pollutants and environmental conditions. Having to consider so many possible factors and its corresponding effects, shows the complexity in understanding the ecotoxicity of microplastics.
Personally, it seems impossible to ever have a complete understanding and knowledge of the effects of plastic on the different species of animals. This means that the the effects we know of is an understatement to the actual severity of the the effects of plastic pollution on animals. Plastic pollution is a severe problem indeed!
References
Prokić, M.D., Radovanović, T.B., Gavrić, J.P. & Faggio, C. 2019, “Ecotoxicological effects of microplastics: Examination of biomarkers, current state and future perspectives”, TrAC, Trends in analytical chemistry (Regular ed.), vol. 111, pp. 37-46.
OOF, a long post indeed.. but don’t be afraid the next post will be a short one !!