Endocrine Abstracts

Environmental pollution by microplastics has been transcending usual stakeholders (such as policymakers and scientists) to become a public concern. The conspicuous, widespread occurrence of (micro)plastics together with the publicization by the media of its potential impacts on wildlife and human health have contributed for this state of affairs. Microplastics, typically defined as plastic particles smaller than 5 mm, have been detected throughout the marine, freshwater and terrestrial environment, as well as in many items commonly consumed by/in contact with humans. This pervasive presence makes Human exposure certain (but exposure-dose has yet to be established). Some microplastic fibers and particles are small enough to become internalized and transported within the body. Moreover, they include added chemicals (from the production process) and can act as “chemical sponges” that sequester and, subsequently, release toxic xenobiotics. However, critical data are lacking to accurately estimate human exposure and effects: small sized microplastics (<100 µm) are seldom measured (and some sources are virtually ignored); the methods for identifying and measuring the particles is highly variable between studies rendering their comparison difficult and leading to under or overestimations; most studies do not identify the polymers present in the analyzed samples, which constitutes a problem since each polymer has different additive chemicals and affinities for contaminants; sample analysis results seldom include mass measurements; studies of human and animal health effects are too few and too limited, and those available test for unrealistic doses; most human exposure media are not sampled, while others are over studied (i.e., seafood ingestion). This leads us to inevitably conclude that, despite the acceleration in scientific research into the effects of microplastics exposure, no broad conclusions toward human health can, at this point, be drawn. However, “absence of evidence is not absence of presence” and further research is binding.