The impact of plastic waste from hull coatings and cleaning must be measured before deciding on further steps, a new IMO report warns.
Microplastics, plastic particles smaller than 5mm, represent around 95% of manmade waste in oceans and are known to break down with potentially toxic effects. The IMO report argues that more research is necessary to determine whether regulation or other measures are needed.
Marine coatings often contain polymers, notably epoxy or acrylic. While most research into hull coatings focuses on biocide or heavy metal pollution, some studies have identified microplastics from marine paints in sediment. Others have identified that shipyard maintenance may transport microplastics by air or run-off water.
Abrasive, in-water hull cleaning may also cause loss of microplastics and further research is needed, IMO’s report said. Studies should determine whether sensitive ecosystems may be affected given the emergence of hull cleaning operations in several locations.
Self-polishing anti-fouling products, designed to slough off during a ship’s operations, were noted as a potential source of microplastic release. However, specific studies on this matter could not be identified.
The report suggests further areas for study to determine whether ship coatings are an important source of microplastics to the ocean.
“If so, the overall relative contribution to ocean microplastics from ship coatings, as well as the individual contributions from the normal use, maintenance and cleaning of coatings, need to be determined as the first step in further research efforts with a view towards informed management,” the authors concluded.
The impact of hull coatings and hull cleaning on ocean pollution would need to be balanced against the role that these technologies play in reducing biofouling. After a decision by IMO member states in April 2018, IMO’s Pollution Prevention Response sub-committee is reviewing biofouling guidelines first adopted in 2011.