Marine Litter Vital Graphics

Marine Litter

Vital Graphics

IMPACTS

synthetic fibres), polyvinylchloride (PVC used in pipes,

bottles and non-food packaging), epoxy resins (adhesives

and metal coatings) and styrenic polymers (styrene foam

insulation) as posing the highest human health risk

(Lithner et al., 2011). These plastic polymers (apart from

epoxy resin) are amongst the most common microplastic

litter encountered in the marine environment.

Plastic, a magnet for other contaminants

and harmful organisms

In the marine environment plastic can be both a source

and sink for contaminants. As well as releasing chemicals,

microplastics have been shown to adsorb compounds

like polycyclic aromatic hydrocarbons (PAHs) and metals

from the surrounding sea water. Due to their high surface

area to volume ratio, microplastics can concentrate

contaminants to orders of magnitude higher than in the

surrounding sea water (Mato et al., 2001). Substances

referred to as persistent, bioaccumulative and toxic

(PBTs), such as dichlorodiphenyltrichloroethane (DDT),

polychlorinated biphenyls (PCBs) and persistent organic

pollutants (POPs) are of particular concern. There is

evidence that hydrophobic contaminants such as POPs

are more likely to be adsorbed onto plastic polymers than

marine sediments (Tueten et al., 2007). Furthermore, older

plastic particles have been found to have higher levels

of POPs, suggesting that they continue to adsorb and

concentrate contaminants for as long as they remain in

the marine environment (Frias et al., 2010).

The ingestion of marine debris carrying these concentrated

toxins has potential to bioaccumulate up the food chain and

enter the human diet. However, although there is evidence

of the harmful impacts of these chemicals on marine

biota and human health (in men, women and children),

there is uncertainty regarding their bioavailability once

ingested. There is little research yet available on gender-

differentiated effects of these secondary chemicals that are

transferred up the food chain to humans along with the

microbeads. Bouwmeester et al. (2015) conclude that, from

available evidence, the dietary intake of POPs and other

additives adhering to marine microplastics will constitute

a minor component of exposure to these contaminants

compared to other exposure pathways (such as ingestion

of crops treated with herbicide, burning of waste, chemical

fires and industrial exposure).