Researchers in Italy have identified microplastic (MP) fragments in four human placentas that were donated for study after delivery.
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“The presence of MPs in the placenta tissue requires the reconsideration of the immunological mechanism of self-tolerance,” wrote Antonio Ragusa, MD, of San Giovanni Calibita Fatebenefratelli Hospital, Rome, and colleagues. “Placenta represents the interface between the fetus and the environment.”
In a pilot observational study published in Environment International, the researchers used Raman microspectroscopy to analyze placentas from six women with physiological pregnancies for the presence of MPs. MPs were defined as particles smaller than 5 mm resulting from the degradation of plastic in the environment, such as plastic objects, coatings, adhesives, paints, and personal care products. Data from previous studies have shown that MPs can move into living organisms, but this study is the first to identify MPs in human placentas, the researchers said.
Polypropylene and pigments identified
A total of 12 microplastic fragments were identified in tissue from the placentas of four women; 5 in the fetal side, 4 in the maternal side, and 3 in the chorioamniotic membranes, which suggests that MPs can reach all levels of placental tissue, the researchers said. Most of the MPs were approximately 10 mcm in size, but two were roughly 5 mcm.
All 12 of the MPs were pigmented; of these, 3 were identified as stained polypropylene and the other 9 contained pigments used in a variety of items including coatings, paints, adhesives, plasters, finger paints, polymers and cosmetics, and personal care products. The researchers used a software program to analyze the pigments and matched them with information from the European Chemical Agency for identification of the commercial name, chemical formula, International Union of Pure and Applied Chemistry name, and Color Index Constitution Number.
The mechanism by which MPs may enter the bloodstream and access the placenta remains unclear, the researchers said. “The most probable transport route for MPs is a mechanism of particle uptake and translocation, already described for the internalization from the gastrointestinal tract. Once MPs have reached the maternal surface of the placenta, as other exogenous materials, they can invade the tissue in depth by several transport mechanisms, both active and passive, that are not clearly understood yet.”
The range in location and characteristics of the particles found in the study suggest that passage of MPs into the placenta may be affected by physiological conditions and genetics, as well as food and lifestyle habits of the patients, the researchers said.
The study findings were limited by several factors including the small sample size and observational study design.
However, the presence of MPs in the placenta could affect the pregnancy in various ways, including immunity, growth factor signaling, maternal-fetal communication, and trafficking of various cell types and macrophages, the researchers wrote. In addition, MPs could have a transgenerational effect on metabolism and reproduction.
“Further studies need to be performed to assess if the presence of MPs in human placenta may trigger immune responses or may lead to the release of toxic contaminants, resulting harmful for pregnancy,” they concluded.