Periodic Reporting for period 1 - PlasticsFatE (Plastics fate and effects in the human body)
Período documentado: 2021-04-01 hasta 2022-09-30
Due to their unique properties, plastics are widely used and found everywhere. In the environment, plastics degrade slowly to micro-plastics (MP) (< 5 mm) and nano-plastics (NP) (< 1 um). MP are also added, e.g. to cosmetics or released from textiles or tyre wear, and make up a complex mixture of polymers and associated chemicals (AC) added to improve their performance or adsorbed from the environment in concentrations much higher than the surroundings. There is strong evidence that humans are exposed to micro- and nano-plastics (MNP) through diet, drinking water or inhalation. However, our present understanding of the extent of human exposure to MNP is still poor, which is why scientifically sound data on exposure, fate and effects of MNP in humans is urgently needed. One challenge in assessing the impact of MNP and AC on human health is to make sure that our measurement and testing methods are capable of producing reliable data. Despite progress in measuring plastic particles in environmental media, reliable measurements and toxicity testing of these particles in the human body, in food, drinking water or air is still scarce. This is even more the case for NP particles that may enter human cells. The lack of robust scientific data and methodologies hampers the development of standards and test guidelines for science-based risk assessment and the implementation of relevant policies and regulations. PlasticsFatE will address these challenges by implementing a comprehensive measurement and testing program (“test the test”) to establish validated methods and robust data on human exposure, fate and hazard of MNP.
A test materials strategy has been established including relevant polymer particles (such as PE, PET, PP, PS) made available for method testing and validation. Two sets of particles have been provided including primary, secondary (cryo-milled, UV and T treated) and commercial MP particles (< 5 mm), and NP particles (< 1um) obtained by physicochemical and mechanical techniques. Data quality and reproducibility was ensured by size distribution measurements, and endotoxin contamination identified early on and measures taken to overcome this limitation. The most suitable measurement methods were tested (e.g. laser diffraction, optical/electronic microscopy, IR/Raman spectroscopy or ICP-MS) against these test materials and technical data sheets established based on particle size, morphology, composition and surface properties. Eu-doped PS and Raman was used to trace particles in human tissues.
The performance of spectroscopic, thermo-analytical and fractionation techniques to detect, identify and quantify MNP particles in complex matrices (like human tissue, food, water and air) was also tested, to determine how particle properties may change in exposure and hazard test media, or during sample preparation. A new dispersion approach was developed with stock and working dispersions for particle characterization and hazard and exposure assessment. The influence of several dispersants has been tested on particle behaviour (sedimentation, flotation) in abiotic and biotic test media assessed, including body fluids that mimic main exposure routes (inhalation, ingestion and translocation in blood). A protocol for dispersion of MP particles in biological media was successfully developed.
The current knowledge on human exposure and fate of MNP in the human body was critically reviewed to guide the analytical and experimental work and first studies initiated to detect and quantify MNP in food, drinks, air, and personal care products (PCP), and suitable digestion and analytical techniques tested for MNP in food and human tissues, to understand how particles translocate from primary organs (intestine, lung, skin, blood) into surrounding tissues and secondary organs (kidney, lymph nodes, liver, brain). To predict exposure to MNP after inhalation and ingestion, new fate and physiologically based pharmacokinetic (PBPK) models are being developed and tested.
First studies on hazard assessment have been carried out with particles of different size, shape and composition (Eu-doped PS, PE, PET and PP with sizes < 10 µm), and by testing and using various in vitro cell lines and biomarkers that represent main exposure routes and effects (see Figure 'Human exposure to MNPs'). Effects measured included cell viability, cytotoxicity, effects on barrier integrity, cellular uptake, bioaccumulation and immune-responses. In vivo studies will verify these in vitro studies.
No significant effects of acute exposure to MNP on cell viability was observed. Also, cell membrane integrity was not significantly affected. While data on bioaccumulation is still processed, first uptake experiments with Eu-doped PS proved positive in plants (lettuce) and human cells. A small induction of inflammatory response was observed and may indicate a potential risk, as it may trigger a cascade of events that can culminate in severe cell and tissue damage. Preliminary adsorption experiments showed particle internalization, but further investigation is needed, also to test the use of non-synthetic homologues, such as starch, as natural controls to distinguish between particle or polymer driven effects.
All data and methods developed and validated are feeding into a new integrated human and environmental risk assessment strategy that also uses a new prospective screening tool, specific IATAS (Integrated Approaches to Testing and Assessment) and decision trees to guide end-users during early design and production. The data produced will be made FAIR and stored in a central data repository within the eNanoMapper database to allow their reuse by stakeholders.
To demonstrate the applicability of the developed methodology under real conditions, case studies are performed that include occupational and environmental situations, and various monitoring activities at plastic packaging, production and recycling sites, to monitor exposure of workers through inhalation and early indicate inflammation or oxidative stress by a panel of new biomarkers. Also studies on long-term effects of MNP in food and their role as vectors for human pathogens have been established.
The performance of spectroscopic, thermo-analytical and fractionation techniques to detect, identify and quantify MNP particles in complex matrices (like human tissue, food, water and air) was also tested, to determine how particle properties may change in exposure and hazard test media, or during sample preparation. A new dispersion approach was developed with stock and working dispersions for particle characterization and hazard and exposure assessment. The influence of several dispersants has been tested on particle behaviour (sedimentation, flotation) in abiotic and biotic test media assessed, including body fluids that mimic main exposure routes (inhalation, ingestion and translocation in blood). A protocol for dispersion of MP particles in biological media was successfully developed.
The current knowledge on human exposure and fate of MNP in the human body was critically reviewed to guide the analytical and experimental work and first studies initiated to detect and quantify MNP in food, drinks, air, and personal care products (PCP), and suitable digestion and analytical techniques tested for MNP in food and human tissues, to understand how particles translocate from primary organs (intestine, lung, skin, blood) into surrounding tissues and secondary organs (kidney, lymph nodes, liver, brain). To predict exposure to MNP after inhalation and ingestion, new fate and physiologically based pharmacokinetic (PBPK) models are being developed and tested.
First studies on hazard assessment have been carried out with particles of different size, shape and composition (Eu-doped PS, PE, PET and PP with sizes < 10 µm), and by testing and using various in vitro cell lines and biomarkers that represent main exposure routes and effects (see Figure 'Human exposure to MNPs'). Effects measured included cell viability, cytotoxicity, effects on barrier integrity, cellular uptake, bioaccumulation and immune-responses. In vivo studies will verify these in vitro studies.
No significant effects of acute exposure to MNP on cell viability was observed. Also, cell membrane integrity was not significantly affected. While data on bioaccumulation is still processed, first uptake experiments with Eu-doped PS proved positive in plants (lettuce) and human cells. A small induction of inflammatory response was observed and may indicate a potential risk, as it may trigger a cascade of events that can culminate in severe cell and tissue damage. Preliminary adsorption experiments showed particle internalization, but further investigation is needed, also to test the use of non-synthetic homologues, such as starch, as natural controls to distinguish between particle or polymer driven effects.
All data and methods developed and validated are feeding into a new integrated human and environmental risk assessment strategy that also uses a new prospective screening tool, specific IATAS (Integrated Approaches to Testing and Assessment) and decision trees to guide end-users during early design and production. The data produced will be made FAIR and stored in a central data repository within the eNanoMapper database to allow their reuse by stakeholders.
To demonstrate the applicability of the developed methodology under real conditions, case studies are performed that include occupational and environmental situations, and various monitoring activities at plastic packaging, production and recycling sites, to monitor exposure of workers through inhalation and early indicate inflammation or oxidative stress by a panel of new biomarkers. Also studies on long-term effects of MNP in food and their role as vectors for human pathogens have been established.
For the first time validated measurement and testing methods, including reference materials, will be developed for MNP and integrated into a new human and environmental risk assessment strategy, to reliably assess true exposure to these particles in food, drinks, air and personal care products (PCP) and their fate and effects in humans. This will be also a milestone in the development of new standards (within VAMAS/TWA 45 or ISO/TC 147/SC2-JWG-1) and in the implementation of EU policies (such as the EU plastics strategy) and regulations (such as REACH). New fate and PBPK models and the use of advanced 2D/3D co-culture cell models and of new specific biomarkers will provide new insight into the mode of action that steer the complex interaction of MNP particles in human cells and may lead to oxidative stress, toxicity, (chronic) inflammation and to more specific endpoints for hazard identification. More work will be devoted to elucidate long-term effects and the still unknown role of chemicals associated with MNP by using more realistic MNP particles, exposure times and doses, and analytical methods (such as HPLC or ICP/MS) and co-exposure experiments to assess the combined effect of MNP polymers and these contaminants.