This is a summary and explanation of the following research paper:

Insight into Cellular Uptake and Intracellular Trafficking of Nanoparticles

• Published: Online > Nanoscale Research Letters
• On: Oct 25, 2018

Key Takeaways for Relation of Nanoparticle Size to Cellular Update

• The paper summarizes: “Several studies have indicated that for cellular uptake of NPs, there is an optimum size of 50 nm at which NPs are internalized more efficiently and has a higher uptake rate. NP uptake was shown to decrease for smaller particles (about 15–30 nm) or larger particles (about 70–240 nm)”
• The context in this paper is in understanding optimal nanoparticle size for uptake in biomedical applications.
• It’s clear that cells can uptake nanoparticles from 15 nm to 240 nm. It’s possible that particles outside these sizes can still enter cells.

Review Summary

This paper is a review on research to date on the cellular uptake and intracellular trafficking of nanoparticles. In regards to plastic particles it can help us understand what size of particles may be able to pass through cell membranes, into cells, and between cells.

Here is a summary of the main points from this paper:

1. Cellular uptake pathways of nanoparticles: Nanoparticles can enter cells via various endocytotic pathways such as clathrin-mediated endocytosis, caveolae-mediated endocytosis, macropinocytosis, etc. The uptake pathway is determined by factors like nanoparticle size, shape, surface charge, hydrophobicity, etc.
2. Intracellular trafficking of nanoparticles: Once internalized, nanoparticles are transported within membrane-bound vesicles (endosomes) which fuse with lysosomes where the particles can be degraded. However, some nanoparticles escape this pathway and are released into the cytoplasm.
3. Effect of nanoparticle properties on uptake: Size is a key factor, with an optimal size of around 50 nm for efficient uptake. Shape also affects uptake, with spherical nanoparticles showing higher internalization. Positively charged nanoparticles have higher uptake due to interaction with the negatively charged cell membrane. Surface hydrophobicity also increases nanoparticle-cell membrane interactions and uptake.
4. Applications in nanomedicine: Understanding the cellular interactions and intracellular fate of nanoparticles is crucial for designing safe and effective nanoparticle-based drug delivery systems, imaging agents, etc. Modulating nanoparticle characteristics can help target specific cell types and intracellular compartments.

This is an explanation of the toxic effects micro- and nanoplastics can have on human health, as published in:

Impact of Microplastics and Nanoplastics on Human Health

Published In: Nanomaterials

On: Feb 11, 2021

Table 1 of this review paper, referencing 28 different sources, summarizes the potential effects plastic particles can have on our health.

Access this table on page 12 of the online article.

Key Takeaways

This table provides a basic understanding of the potential health impacts of micro- and nanoplastics, focusing on inflammation, oxidative stress, apoptosis, and metabolic homeostasis, and how these are influenced by the characteristics and sizes of the plastic particles.

The table shows that research studies have documented the toxic effects plastic particles can have on animal cells and human cells. The known short-term impacts include inflammation, cell damage, and metabolic disruption in cells. Many of these studies have been conducted in vitro (cell cultures outside of the body) or in mice.

Inflammation

• Characteristics of Plastic Particles: Various types of polystyrene and polyethylene particles, including those unaltered, carboxylated, amino-modified, and from prosthetic implants, can cause inflammation.
• Particle Sizes: Range from 1,000 nm to 0.2 µm.
• Key Points:
  • Inflammation is the body’s response to injury or infection, often causing redness, heat, swelling, and pain.
  • These plastic particles can increase inflammatory markers like IL-6, IL-8, TNFα, and others, leading to inflammation in different parts of the body including lungs, liver, and around prosthetic implants.

Oxidative Stress and Apoptosis

• Characteristics of Plastic Particles: Various modified and unmodified polystyrene particles can induce oxidative stress and apoptosis in different human cells.
• Particle Sizes: Range from 140 nm to 20 nm.
• Key Points:
  • Oxidative stress occurs when there’s an imbalance between free radicals and antioxidants, damaging cells.
  • Apoptosis is a process where cells program themselves to die. These plastic particles can trigger this process in cells, affecting their survival and health.

Metabolic Homeostasis

• Characteristics of Plastic Particles: Different polystyrene and polyethylene particles can disrupt metabolic homeostasis.
• Particle Sizes: Range from 200 nm to 0.5 µm.
• Key Points:
  • Metabolic homeostasis refers to the balance of chemical reactions in the body. Disruption can lead to metabolic disorders.
  • The particles can cause changes in metabolism, affecting gut microbiota, ion channel function, cellular energy levels, and nutrient transport, which might lead to metabolic disorders.

This is a summary and explanation of the following research paper:

Impact of Microplastics and Nanoplastics on Human Health

Published In: Nanomaterials

On: Feb 11, 2021

This paper is a review and explanation of available research studies and literature.

Key Takeaways:

1. Sources and Fate of Microplastics and Nanoplastics: The majority of plastics we are exposed to are land-derived and break down into micro- and nanoplastics, which are difficult to filter out from water systems.
2. Occurrence in Food Chain: Micro- and nanoplastics are prevalent in various food products and water sources, posing a risk of human consumption.
3. Uptake and Bioaccumulation in Human Body: The human body can intake these plastics through ingestion, inhalation, and dermal exposure, leading to potential bioaccumulation.
4. Cellular Uptake and Intracellular Fate: Once inside the body, these plastics interact with cells through various mechanisms, affecting cellular functions.
5. Potential Toxic Effects on Human Health: Studies suggest possible health risks, including inflammation, oxidative stress, and disruption of metabolic homeostasis.

Summary of Review

This study references 160 papers and also includes some diagrams that help explain how plastics can enter the bloodstream, enter cells, and disrupt processes. It’s worthwhile to look at the original study which is available online here.

Here is a little more detail on the key takeaways:

1. Sources and Fate of Microplastics and Nanoplastics: These plastics primarily originate from land-based activities and degrade into smaller forms. They persist in the environment due to their resistance to natural degradation processes.
2. Occurrence in Food Chain: They are found in a range of food products and water sources. Due to their small size, they can evade filtration systems and enter the human food chain.
3. Uptake and Bioaccumulation in Human Body: Humans can absorb these particles through eating, breathing, and skin contact. They may accumulate in the body over time, potentially causing health issues.
4. Cellular Uptake and Intracellular Fate: Once inside the body, they interact with cells in various ways. This interaction can affect cell functions and potentially lead to cellular damage or dysfunction.
5. Potential Toxic Effects on Human Health: The study indicates potential health risks such as inflammation, oxidative stress, and metabolic disturbances, though more research is needed to fully understand these effects.

This is a summary and explanation of the following research paper:

Discovery and quantification of plastic particle pollution in human blood

Published In: Environmental International

In: May 2022

Key Takeaways

• The study demonstrates for the first time that plastic particles are bioavailable for uptake into the human bloodstream, posing potential public health risks.
• The study detected four different types of plastic polymers in the blood of 22 healthy volunteers.
• The four types of polymers were:
  • Polyethylene terephthalate (PET)
  • Polyethylene (PE)
  • Polymers of styrene (this includes a sum parameter of polystyrene, expanded polystyrene, acrylonitrile butadiene styrene, etc.)
  • Poly(methyl methacrylate) (PMMA)

Summary of The Study

Objective and Methodology

The study aimed to measure plastic particles of size ≥700 nm in human blood.

It employed a sensitive sampling and analytical method using double shot pyrolysis-gas chromatography/mass spectrometry.

The research involved 22 healthy volunteers.

Key Findings

Four high production volume polymers were identified and quantified in human blood for the first time.

The polymers found were:

• Polyethylene terephthalate (PET)
• Polyethylene (PE)
• Polymers of styrene (including polystyrene, expanded polystyrene, acrylonitrile butadiene styrene, etc.)
• Poly(methyl methacrylate) (PMMA)

Polypropylene was also analyzed but was below the limits of quantification.

The average concentration of these plastic particles in blood was 1.6 µg/ml.

Significance

This study is the first to provide a measurement of the mass concentration of plastic particles in human blood.

It underscores the bioavailability of plastic particles for uptake into the human bloodstream.

The findings indicate potential public health risks and highlight the need for further research into the implications of microplastic pollution in humans.

This is a summary and explanation of the following research paper:

Microplastics in Drinking Water: A Review and Assessment

• Published In: Current Opinion in Environmental Science & Health
• In: Feb 2019

Key Takeaways:

• This paper is a review – it compiles and discusses findings from various studies on the presence, sources, and potential health implications of microplastics in drinking water.
• Reports of microplastics (MPs) in tap water and bottled water have been confirmed since 2017.
• Studies have detected MPs in tap water globally, with variations in concentration levels between countries. Developed countries reported higher concentrations compared to less-developed ones.
• MPs enter drinking water sources through various pathways, including environmental degradation of plastic, industrial spills, washing machine effluents, and wear and tear of plastic items in use.

Review Paper Summary

The research paper titled “Microplastics in Drinking Water: A Review and Assessment” presents a comprehensive analysis of the presence, sources, and potential human health implications of microplastics in drinking water. Here’s a summary of the key findings and discussions in the paper:

Evidence of Microplastics in Drinking Water (DW)

• Reports of microplastics (MPs) in tap water and bottled water have been confirmed since 2017.
• Studies have detected MPs in tap water globally, with variations in concentration levels between countries. Developed countries reported higher concentrations compared to less-developed ones. The majority of these particles were fibers.
• Bottled water also contains MPs, with the highest average particle counts found in samples from reusable plastic bottles. Particle sizes were predominantly small.
• Water treatment plants show varied concentrations of MPs in raw and treated water. Different methodologies have been used to identify and quantify these particles.

Sources and Pathways for Contamination

• MPs enter drinking water sources through various pathways, including environmental degradation of plastic, industrial spills, washing machine effluents, and wear and tear of plastic items in use.
• Surface waters near urban areas are commonly contaminated with MPs. Atmospheric transport is also suggested as a potential route for MPs to enter water sources.
• Wastewater treatment plants can remove a significant portion of MPs, but still, a considerable amount can enter the aquatic environment through effluents and sludge.

Implications for Human Health

• The risk characterization of MPs to humans via drinking water is not yet adequately determined due to gaps in exposure and hazard assessments.
• There is potential exposure to chemicals sorbed to MPs in drinking water. However, the contribution of MPs in drinking water to total dietary intake of environmental contaminants and additives is relatively small.
• Particle toxicity of MPs in the human body is a concern. Size, shape, and chemical composition of MPs may influence toxicological risk.
• The potential for smaller particles to translocate across the gut layer and cause tissue damage is an area requiring further investigation.

This is a summary and explanation of the following research paper:

Microplastics in air: Are we breathing it in?

• Published In: Current Opinion in Environmental Science & Health
• In: Feb 2018

Key Takeaways:

• Air samples were taken from indoor (two apartments and one office) and outdoor locations (two locations on the roofs of buildings).
• Microplastics were found in samples from all areas in the study. The study reported that concentrations of fibers, including microplastics, were present in both indoor and outdoor air.
• The indoor concentrations ranged between 1.0 and 60.0 fibers per cubic meter, while outdoor concentrations were significantly lower, ranging between 0.3 and 1.5 fibers per cubic meter.

Research Paper Summary

The study “Microplastics in air: Are we breathing it in?” focuses on the presence and potential health impacts of airborne microplastics, particularly fibrous microplastics (MPs), in various environments. Here are the main points:

1. Increasing Production of Plastic Textile Fibers: The study notes the significant increase in plastic textile fiber production, which contributes to the generation of fibrous microplastics. These fibers are found in atmospheric fallout and both indoor and outdoor environments.
2. Inhalation and Health Risks: There’s concern that some fibrous microplastics can be inhaled. While many are likely cleared by the body’s mucociliary clearance mechanisms, some may persist in the lungs, particularly in individuals with compromised clearance mechanisms. This persistence can cause biological responses like inflammation.
3. Contaminants: Fibrous microplastics can carry contaminants like Polycyclic Aromatic Hydrocarbons (PAHs) and additives from plastics (e.g., dyes, plasticizers), which could lead to health effects like reproductive toxicity, carcinogenicity, and mutagenicity.
4. Occurrence and Characteristics in the Environment: The study reviews findings on the occurrence of fibrous MPs in the air and their characteristics. It discusses their size, composition, and concentration levels in different environments, including the differences found in indoor and outdoor air.
5. Human Exposure: The potential for human exposure to fibrous MPs through inhalation and accumulation in the human body is addressed. The study suggests that fibrous MPs are durable and likely to persist in the lung.
6. Occupational Health Risks: The study highlights specific health risks for workers in industries that handle synthetic fibers, such as increased respiratory irritation and interstitial lung disease.
7. Potential Mechanisms of Toxicity: The study explores the potential mechanisms by which fibrous MPs could cause harm, including inflammation, secondary genotoxicity due to the formation of reactive oxygen species, and possible links to fibrosis and cancer.
8. Recommendations: The authors call for more research to better understand the human health impacts of fibrous MPs, emphasizing the need for collaboration across various scientific disciplines and recommending specific approaches for monitoring and reporting.

This is a summary and explanation of the following research paper:

Prevalence and characteristics of microplastics present in the street
dust collected from Chennai metropolitan city, India

• Published In: Chemosphere
• In: April, 2021

Key Takeaways:

• This study assessed the extent of microplastic pollution in the road dust of Chennai, a major metropolitan city by collecting samples and using Raman spectroscopy, and conduct SEM-EDS (Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy) for elemental analysis of the microplastics​​.
• The study found variations in microplastic abundance across different locations in Chennai. The majority of these microplastics were fragments (92.46%), with fibers constituting only 7.54%.

Research Paper Summary

The research paper “Microplastics in City Dust” presents the following key findings:

Assessment of Microplastic Pollution in Chennai

This study, the first of its kind reported from India, assessed the extent of microplastic pollution in the road dust of Chennai, a major metropolitan city. “Street dust” is defined as dust accumulated on the ground in various locations around the city. The collection process involved sweeping the ground with a small paintbrush within a quadrat of 1 square meter at each sampling location.

The average microplastic abundance was estimated to be 227.94 ± 91.37 particles per 100 grams of street dust. The paper doesn’t provide information on whether these amounts are considered high low.

The authors sampled sixteen different locations across the city and found microplastics in all of their samples.

Objectives of the Study

The main objectives were to estimate the abundance of microplastic particles in street dust, identify the polymers in these microplastics using Raman spectroscopy, and conduct SEM-EDS (Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy) for elemental analysis of the microplastics.

Findings on Microplastic Abundance and Composition

The study found variations in microplastic abundance across different locations in Chennai. The majority of these microplastics were fragments (92.46%), with fibers constituting only 7.54%. This contrasts with other studies, such as one conducted in Bushehr city, Iran, where the majority of microplastics were fibers.

Microplastic Pollution as a Widespread Concern

The presence of microplastics in substantial quantities in street dust is indicative of the pervasive nature of microplastic pollution in urban environments. This study adds another dimension to the understanding of microplastic pollution, which is not only confined to aquatic environments but also prevalent in urban settings like street dust.

Implications and Future Research Directions

The study emphasizes the need for increased awareness and surveillance on the fate of plastic waste in Chennai, especially being a coastal city where waste can easily enter marine environments. The paper suggests the need for more studies on the direct impact of microplastics in street dust on human health and the association of microplastics with secondary contaminants, such as PAHs (Polycyclic Aromatic Hydrocarbons), and their potential health implications.