PLASTIC IN PLACENTA: WHAT IS IT? WHAT TO DO?

In the last century, the global production of plastics has grown exponentially to reach over 350 million tons per year produced in the world, part of which ends up polluting the environment [1]. Microplastics (MPs) are defined as plastic particles smaller than 5 mm [2]. MPs are found everywear. In experimental contexts cellular absorption, accumulation of MPs and nanoplastics have been demonstrated, in animals and human tissues [3- 6]. Within biological tissue, plastic particles can cause a foreign body reaction and trigger local immunoreactions [7]. MPs can act as a carrier for other chemicals, such as environmental pollutants or plastic additives, which can leak and cause exposure to hazardous substances [5-8]. We found MPs in human placenta [9] and in human breastmilk [10]. MPs were found also in meconium of newborns, even in higher concentrations than in adults’ stool [11] and blood [12]. All this confirms that the exposure to MPs begins indeed in the earliest stages of human life. MPs interact with humans’ placental cells; if they are capable to alter energy pathways, as they do in animal models, there could be numerous concerning consequences. Our group also demonstrated and photographed, for the first time, the presence of MPs in the intracellular compartment of human placentas; we localized MPs and demonstrated the presence of important morphological and structural alterations of the cellular intracytoplasmic organelles associated with their presence [13]. Using variable pressure scanning electron micros- copy (SEM) and transmission electron microscopy (TEM), the study demonstrated that MPs are within lipid membranes and can be easily confused with cell organelles such as lysosomes, peroxisomes, lipid droplets and multivesicular bodies; this amply demonstrates that Johann Wolfgang von Goethe (1749-1832) was right when he claimed that: “We only see what we know”. In all the observed samples, the stress of the endoplasmic reticulum is demonstrated, which is dilated (cribriform aspect of the syncytium trophoblast cells); there are many vesicles communicating with each other discreetly electrondense, with secretory material inside, covered by ribosomes and not (degranulation). The presence of the alterations of the intracytoplasmic organelles, together with the presence of the MPs, in all the samples examined, is very important, since endoplasmic reticulum stress and mitochondrial dysfunction could play a decisive role in the progression of human non- transmissible diseases (NTDs). This gives rise to the hypothesis that environmental pollution from plastics is partially responsible for the epidemic of NTDs that characterizes the modern world [14].