Potential Impacts from Marine Plastics on Human Health

Although there are no current scientific studies correlating the direct consumption of fish or shellfish contaminated with microplastics containing or polluted with EDCs and the consequent endocrine disruption effects on human health, this is perhaps not surprising given the complexity of the issue [72,73]. One of the conclusions of the recent report of FAO on food safety [67] is that basic toxicological data on the consumption of micro- and nanoplastics in humans for a food risk safety assessment are essential lacking: the available data of toxicokinetics only include absorption and distribution, whereas no information is available on metabolism and little on excretion. It is not known whether or not ingested microplastics can be degraded into nanoplastics, and no data are available on the potential impact that cooking and/or processing seafood at high temperature may have on the toxicity of microplastics.

According to EFSA [74], a worst case estimate of exposure to microplastics after consumption of a portion of mussels (225 g) would be 7 pg of plastics. Based on this estimate and considering the highest concentrations of additives or contaminants reported in microplastics, and assuming complete release from microplastics, the microplastics will have a negligible effect on the total dietary exposure to persistent, bioaccumulative and toxic chemicals (PBT) and plastic additives, for example, in the case of bisphenol A (BPA), this would represent a contribution of less than 0.2% of the estimated dietary exposure to this compound in an adult of 70 kg.

With regard to existing evidence on the consequences of the uptake of micro- and nanoplastics by humans, medical literature on the impact of micro- and nanoplastics originating from inhalation or released from wear debris from plastic prosthetic implants shows diverse effects varying from DNA damage, changes in gene and protein expression, cell clotting, necrosis, apoptosis, proliferation and loss of cell viability, oxidative stress, increased Ca ions, inflammation and bone osteolysis, to lesions in organs [67].

However, at this time, the uncertainties surrounding potential health impacts remain high, and the data gaps, very large, including a lack of knowledge on the role and hazards of nanoplastics, potentially the most hazardous area of marine plastics [66,75]. Given the unavoidable increase in the coming decades of micro- and nanoplastics in the marine environment owing to the weathering and fragmentation of already existing “stocks” of marine macroplastics as well as future inputs, there is an urgency in better resolving the nature and scale of possible health effects, and in the meantime at least, to apply the precautionary principle.' Until the weight of the scientific evidence is more conclusive

Precautionary principle by virtue of which where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.

regarding the risk that diets rich in small fish in whole (i.e., including the guts), or in bivalves and crustaceans containing microplastics or nanoplastics in significant quantities, could affect human endocrine systems—especially during embryo and infancy stages—or induce hepatic stress or other related health affections, it would seem wise to assume that measures that can limit or avoid intakes of microplastics would be an appropriate and important priority for public policy.

Further scientific research is needed with urgency on the potential impacts to endocrine systems and overall human health, especially on developing stages, by the direct or indirect ingestion of marine micro- and nanoplastics.

 
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