Déchets marins et microplastiques

5. What is the impact of micro plastics on the marine environment?

While the effect of large debris is well documented, the effect of small particles is less well known.

In the context of the overall marine litter problem, harm can be divided into three general categories:

1. Ecological, e.g. mortality or sub-lethal effects on plants and animals through entanglements, captures and entanglement from ghost nets, physical damage and ingestion including uptake of micro-particles (mainly micro-plastics) and the release of associated chemicals, facilitating the invasion of alien species, altering the structure of communities living on the sea floor.
2. Economic, e.g. cost to tourism, damage to vessels, fishing gear and facilities, losses to fishery operations, cleaning costs; and
3. Social, e.g. a reduction in aesthetic value and public safety.

Ingestion of plastics by animals can already be considered an undesirable exposure, no matter what other implications it might have. In addition, this ingestion could have detrimental effects on the health of animals either directly through the presence of plastics in their digestion, or through the release of chemicals.

For most of the chemicals involved, their hazard, or potential to cause (eco)toxicological harm is already well known. These chemicals can be in the plastics already as additives, or either taken up by plastics once they are in the ocean. What remains unclear is their degree of bioavailability once adsorbed to plastics. The fact that such chemicals have been identified in plastics in the open ocean could on its own indicate that there is the potential for harm.

It has been shown that the organisms at the lower levels of the food chain can ingest small fragments of plastics, and so these particles make their way up the food chain through predators. Tiny plastic particles can even find their way into living cells, where they can stay for long periods of time

There is a need for further research to understand the impact of micro-plastics on different levels of the food chain. There is also a need for understanding which organisms are likely to ingest plastics, which animals could be used as indicators for the presence of PBTs in the food chain, and what impacts could there be on humans through their food. These contaminants are present in the environment and accumulate within the food chain also in the absence of plastics. The real unknown is to what extent plastics increase the exposure of organisms to contaminants.

One interesting approach to dealing with management of the coastal zone is to integrate the concepts of ecosystem services and their valuation which might make tackling the problem more attractive when considering the cost for action. It is however very difficult to apply cost-benefit analysis to ecosystems. More...