The toxicity of microplastics and its impact on marine organisms

The marine environment is confronted with vast amounts of plastic debris every year, of which microplastics are most abundant and found everywhere in the marine environment. This raises concerns about the toxic effects for marine organisms. In this essay, I tried to find out what is know so far and what the dynamics are behind the toxicity of microplastics. Up to now, abrasions and blockages of the gastrointestinal tract have been observed, just as endocrine disruptions by toxic leachates from microplastics (monomers and additives) and physical harm due to the sorption of hydrophobic organic contaminants to microplastics. However, the exact effects depend on many parameters and can be different for every organism, type of plastic, type of adhered contaminant and the environment. The digestive tract plays a role, due to certain defense mechanisms (filters) and specific retention time of microplastics. The migration potential of monomers and additives is itself dependent on many parameters and determines whether transfer can take place. The same applies to the hydrophobic organic contaminants, for which sorption and desorption processes are important in assessing potential harmful effects on organisms. It became clear that it is a very complex system and that there is not one simple answer. More research on different organisms, different life-stages of these organisms, contaminated microplastics and long-term effects is needed.