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Microplastics effects on human health are of growing concern and an area of research. The tiny particles known as microplastics (MPs), have been found in various environmental and biological matrices, including air, water, food, and human tissues. Microplastics, defined as plastic fragments smaller than 5 mm, and even smaller particles such as nanoplastics (NP), particles smaller than 1000 nm in diameter (0.001 mm or 1 μm), have raised concerns impacting human health. [1] [2] The pervasive presence of plastics in our environment has raised concerns about their long-term impacts on human health. While visible pollution caused by larger plastic items is well-documented, the hidden threat posed by nanoplastics remains under-explored. These particles originate from the degradation of larger plastics and are now found in various environmental matrices, including water, soil, and air. Given their minute size, nanoplastics can penetrate biological barriers and accumulate in human tissues, potentially leading to adverse health effects. [3] [4]
Plastics continue to accumulate in landfills and oceans, leading to pollution that negatively impacts both human and animal health. Notably, microplastics and nanoplastics are now ubiquitous, infiltrating our food chain and water supplies. Studies indicate that humans ingest significant amounts of microplastics daily through food, especially seafood [5] and inhalation, with estimates ranging from 39,000 to 52,000 particles per person annually [6] Additionally, the presence of microplastics in human feces suggests widespread exposure and absorption. [7] In scientific literature, combined microplastics and nanoplastics are referred to as MNPs or NMPs, or NMPPs for nano-and microplastic particles.
Understanding the sources and health effects of nanoplastics is crucial for developing effective public health policies. As plastics are an integral part of modern life, balancing their benefits with the associated health risks is essential. This research aims to provide evidence-based recommendations to mitigate the adverse health effects of nanoplastics, thereby informing future regulatory and policy decisions. The increasing presence of nanoplastics in the environment has raised concerns about their potential impacts on human health. Research has shown that nanoplastics can penetrate biological barriers, induce toxicity, and accumulate in organs, leading to various health issues [8] . Nanoplastics have been found in drinking water, food, and air, making human exposure ubiquitous [9] .
The major pathways of human exposure to micro- and nanoplastics (MNPs) are ingestion, inhalation, and dermal contact, with bioaccumulation varying based on particle size, composition, and physicochemical characteristics. Research suggests that MNPs above 150 μm typically remain confined to tissues and do not enter systemic circulation, whereas particles below 200 nm can breach cellular and tissue barriers, potentially reaching the bloodstream and other organs. [10] [11] [12] [13] This diversity in bioaccumulation pathways underscores the widespread yet nuanced risks of MNP exposure to human health.
Ingestion is one of the primary pathways of MNP exposure due to the omnipresence of these particles in food, beverages, and drinking water. Studies show that MNPs are detected in a variety of consumables, including drinking water, [14] [15] beer, [16] honey, sugar, [17] table salt, [18] [19] and even airborne particles that settle on food. [20] [21] [22] [13] Indirect ingestion includes toothpaste, face wash, scrubs, [23] [24] and soap [25] [26] and enter systemic circulation.
Marine products are particularly concerning sources of ingestion-related exposure due to the accumulation of MNPs in aquatic environments. Fish, bivalves, and other seafood are frequently contaminated with MNPs ingested through water and food, and humans consuming these animals are thus directly exposed to microplastic particles embedded in tissue. The entire soft tissue of bivalves, for instance, is eaten by humans, which increases the direct transfer of MNPs. In a study along the Mediterranean coast of Turkey, 1,822 microplastic particles were extracted from the stomachs and intestines of 1,337 fish specimens, with fibers accounting for 70% of these particles. [13]
Contamination is further compounded by plastic packaging and storage materials, which can leach MNPs over time, leading to additional ingestion from common foods and drinks. [10] [27] Fecal sample analyses estimate a daily intake of approximately 203–332 MNP particles, translating to an annual ingestion rate of around 39,000–52,000 particles. [6] [28] This suggests that daily MNP exposure from food and drink may be substantial, with significant implications for gastrointestinal and systemic health.
Maternal transfer of MNPs represents an emerging exposure route that affects infants directly. Recent studies have shown the presence of microplastics in breast milk, often leading to exposures in very young children. While it has already been established that chemicals [29] such as flame retardants [30] [31] [32] and pesticides [33] have been detected in breast milk, knowledge about microplastics is limited in comparison. A 2022 study [34] detected microplastic particles smaller than five millimeters in 75% of analyzed breast milk samples, raising concerns about infant exposure during critical developmental windows. [35] [36]
Exposure during developmental stages can lead to long lasting developmental defects or other issues later in life. While these detected levels were not above the currently established thresholds for unsafe levels, they show another possible route for microplastic ingestion. For some native population in north Canada and people who live near industrial factories, it is sometimes suggested by pediatricians that mothers not nurse their children, [37] over fear of ingestion of microplastics and other potentially harmful chemicals. It has been suggested that mothers should directly breast feed their children instead of from a bottle. Studies have shown that pumping milk, freezing it in plastic bags, then subsequently heating it up will increase the contamination of microplastics in the milk. [38] Similar results have been seen from heating plastic reusable food containers in a microwave, showing the release of both microplastics and nanoplastics. [39] It has been suggested that mothers try to avoid ingesting microplastics themselves, to try and avoid passing them onto their children through breastfeeding. Studies have shown that drinking water from plastic bottles has significantly greater detectable plastic content than tap water. [40]
These findings suggest that breastfeeding may inadvertently expose infants to endocrine-disrupting plastics, which could have lasting effects on growth and development. To mitigate these risks, pediatricians recommend reducing the use of plastic bottles and avoiding the heating or freezing of breast milk in plastic containers, as temperature fluctuations can increase MNP leaching.
Though less frequently examined, dermal exposure to MNPs occurs through contact with contaminated media like soil, water, and personal care products, including facial and body scrubs containing MNPs as exfoliants. [41] [42] [13] Although the skin generally acts as a barrier, conditions such as skin lesions or high exposure environments may allow for enhanced absorption of MNPs, particularly nanoparticles, which can penetrate the stratum corneum. Studies on dermal exposure highlight the potential for these particles to enter systemic circulation, especially if the skin barrier is disrupted by wounds or conditions that increase permeability, like pores such as sweat glands and hair follicles [10]
Inhalation is a critical but understudied route of MNP exposure, with airborne MNPs originating from urban dust, synthetic fibers from textiles, rubber tires, and household plastic items. [43] [10] These airborne particles may become suspended in the air due to wave action in aquatic environments or the spread of wastewater treatment sludge on agricultural fields. [13] Once inhaled, these particles may lodge in the lungs or, through mucociliary clearance, be ingested and enter the digestive system. [44] [20] [21] [45] Airborne microplastics have been detected in urban atmospheres, with reports showing a fallout of 29–280 particles per square meter per day on an urban rooftop, underscoring the potential for routine exposure. [4] Annual inhalation exposure rates are estimated at around 39,000–52,000 microplastic particles, with studies highlighting the significant contributions from synthetic textiles and urban dust sources. [6]
These findings collectively suggest that MNPs may accumulate in multiple organ systems depending on the exposure route, potentially leading to long-term health consequences as their presence in human tissues becomes more pervasive over time.
Incidental generation of MNPs is mechanical or environmental degradation or industrial processes such as plastic manufacturing (heating and chemical condensation) and intentional generation of MNPs occur during 3D printing.
The main route of workplace exposure is acute inhalation. [45] Workplace exposure can be high concentration and lasting the duration of a shift and thus short-term whereas exposure outside of work is at low concentration and long-term. [46] The concentration of worker exposure is orders of magnitude higher than the general population (e.g., 4×1010 particles per m3 from extrusion 3D printers [47] versus 50 particles per m3 in the general environment [48] ).
High chronic exposure to aerosolized MNPs occur in: the synthetic textile industry, the flocking industry, and the plastics industry consisting of the Vinyl Chloride supplier and the Polyvinyl Chloride manufacturer. [49]
The potential health impacts of microplastics vary based on factors, such as their particle sizes, shape, exposure time, chemical composition (enriched with heavy metals, polycyclic aromatic hydrocarbons (PAHs), etc.), surface properties, and associated contaminants. [76] [77]
Experimental and observational studies in mammals have shown that microplastics and nanoplastics exposure have the following adverse effects:
Despite growing concern and evidence, most epidemiologic studies have focused on characterizing exposures. Epidemiological studies directly linking microplastics to adverse health effects in humans remain yet limited and research is ongoing to determine the full extent of potential harm caused by microplastics and their long-term impact on human health. [91] [92]
Microplastics have been found in blood. [93]
As April 2024, there is no established NIOSH Recommended Exposure Limit (REL) for MNPs due to limited data on exposure levels to adverse health effects, the absence of standardization to characterize the heterogeneity of MNPs by chemical composition and morphology, and difficulty in measuring airborne MNPs. [94] [95] And thus, safety measures focus on the hierarchy of controls for nanomaterials with good industrial hygiene to implement source emission control with local exhaust ventilation, air filtration, and nonventilating engineering controls such as substitution with less hazardous materials, administrative controls, Personal Protective Equipment (PPE) for skin and respiratory protection. [96]
Research from the U.S. National Institute of Occupational Safety and Health (NIOSH) Nanotechnology Research Center (NTRC) show local exhaust ventilation and High Efficiency Particulate Air (HEPA) filtration to be effective mitigation to theoretically filter 99.97% of nanoparticles down to 0.3 microns. [96]
Environmental health is the branch of public health concerned with all aspects of the natural and built environment affecting human health. To effectively control factors that may affect health, the requirements that must be met to create a healthy environment must be determined. The major sub-disciplines of environmental health are environmental science, toxicology, environmental epidemiology, and environmental and occupational medicine.
Persistent organic pollutants (POPs) are organic compounds that are resistant to degradation through chemical, biological, and photolytic processes. They are toxic and adversely affect human health and the environment around the world. Because they can be transported by wind and water, most POPs generated in one country can and do affect people and wildlife far from where they are used and released.
Marine debris, also known as marine litter, is human-created solid material that has deliberately or accidentally been released in seas or the ocean. Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washing aground, when it is known as beach litter or tidewrack. Deliberate disposal of wastes at sea is called ocean dumping. Naturally occurring debris, such as driftwood and drift seeds, are also present. With the increasing use of plastic, human influence has become an issue as many types of (petrochemical) plastics do not biodegrade quickly, as would natural or organic materials. The largest single type of plastic pollution (~10%) and majority of large plastic in the oceans is discarded and lost nets from the fishing industry. Waterborne plastic poses a serious threat to fish, seabirds, marine reptiles, and marine mammals, as well as to boats and coasts.
Marine pollution occurs when substances used or spread by humans, such as industrial, agricultural and residential waste, particles, noise, excess carbon dioxide or invasive organisms enter the ocean and cause harmful effects there. The majority of this waste (80%) comes from land-based activity, although marine transportation significantly contributes as well. It is a combination of chemicals and trash, most of which comes from land sources and is washed or blown into the ocean. This pollution results in damage to the environment, to the health of all organisms, and to economic structures worldwide. Since most inputs come from land, either via the rivers, sewage or the atmosphere, it means that continental shelves are more vulnerable to pollution. Air pollution is also a contributing factor by carrying off iron, carbonic acid, nitrogen, silicon, sulfur, pesticides or dust particles into the ocean. The pollution often comes from nonpoint sources such as agricultural runoff, wind-blown debris, and dust. These nonpoint sources are largely due to runoff that enters the ocean through rivers, but wind-blown debris and dust can also play a role, as these pollutants can settle into waterways and oceans. Pathways of pollution include direct discharge, land runoff, ship pollution, bilge pollution, atmospheric pollution and, potentially, deep sea mining.
Diisobutyl phthalate (DIBP) is a phthalate ester having the structural formula C6H4(COOCH2CH 2)2. It is formed by the esterification of isobutanol and phthalic anhydride. This and other phthalates are used as plasticizers due to their flexibility and durability. They are found in many industrial and personal products, such as lacquers, nail polish and cosmetics. DIBP can be absorbed via oral ingestion and dermal exposure. When it comes to excretion, DIBP is first converted into the hydrolytic monoester monoisobutyl phthalate (MIBP). The primary excretory route is urine, with biliary excretion being noted in minor amounts. DIBP has lower density and freezing point than the related compound dibutyl phthalate (DBP).
A garbage patch is a gyre of marine debris particles caused by the effects of ocean currents and increasing plastic pollution by human populations. These human-caused collections of plastic and other debris are responsible for ecosystem and environmental problems that affect marine life, contaminate oceans with toxic chemicals, and contribute to greenhouse gas emissions. Once waterborne, marine debris becomes mobile. Flotsam can be blown by the wind, or follow the flow of ocean currents, often ending up in the middle of oceanic gyres where currents are weakest.
Marine plastic pollution is a type of marine pollution by plastics, ranging in size from large original material such as bottles and bags, down to microplastics formed from the fragmentation of plastic material. Marine debris is mainly discarded human rubbish which floats on, or is suspended in the ocean. Eighty percent of marine debris is plastic. Microplastics and nanoplastics result from the breakdown or photodegradation of plastic waste in surface waters, rivers or oceans. Recently, scientists have uncovered nanoplastics in heavy snow, more specifically about 3,000 tons that cover Switzerland yearly.
The environmental impact of the petroleum industry is extensive and expansive due to petroleum having many uses. Crude oil and natural gas are primary energy and raw material sources that enable numerous aspects of modern daily life and the world economy. Their supply has grown quickly over the last 150 years to meet the demands of the rapidly increasing human population, creativity, knowledge, and consumerism.
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be molded, extruded or pressed into solid objects of various shapes. This adaptability, plus a wide range of other properties, such as being lightweight, durable, flexible, and inexpensive to produce, has led to their widespread use. Plastics typically are made through human industrial systems. Most modern plastics are derived from fossil fuel-based chemicals like natural gas or petroleum; however, recent industrial methods use variants made from renewable materials, such as corn or cotton derivatives.
The North Atlantic garbage patch is a garbage patch of man-made marine debris found floating within the North Atlantic Gyre, originally documented in 1972. A 22-year research study conducted by the Sea Education Association estimates the patch to be hundreds of kilometers across, with a density of more than 200,000 pieces of debris per square kilometer. The garbage originates from human-created waste traveling from rivers into the ocean and mainly consists of microplastics. The garbage patch is a large risk to wildlife through plastic consumption and entanglement.
Microplastics are fragments of any type of plastic less than 5 mm (0.20 in) in length, according to the U.S. National Oceanic and Atmospheric Administration (NOAA) and the European Chemicals Agency. They cause pollution by entering natural ecosystems from a variety of sources, including cosmetics, clothing, food packaging, and industrial processes. The term microplastics is used to differentiate from larger, non-microscopic plastic waste. Two classifications of microplastics are currently recognized. Primary microplastics include any plastic fragments or particles that are already 5.0 mm in size or less before entering the environment. These include microfibers from clothing, microbeads, plastic glitter and plastic pellets. Secondary microplastics arise from the degradation (breakdown) of larger plastic products through natural weathering processes after entering the environment. Such sources of secondary microplastics include water and soda bottles, fishing nets, plastic bags, microwave containers, tea bags and tire wear. Both types are recognized to persist in the environment at high levels, particularly in aquatic and marine ecosystems, where they cause water pollution. 35% of all ocean microplastics come from textiles/clothing, primarily due to the erosion of polyester, acrylic, or nylon-based clothing, often during the washing process. However, microplastics also accumulate in the air and terrestrial ecosystems. Because plastics degrade slowly, microplastics have a high probability of ingestion, incorporation into, and accumulation in the bodies and tissues of many organisms. The toxic chemicals that come from both the ocean and runoff can also biomagnify up the food chain. In terrestrial ecosystems, microplastics have been demonstrated to reduce the viability of soil ecosystems. As of 2023, the cycle and movement of microplastics in the environment was not fully known. Deep layer ocean sediment surveys in China (2020) show the presence of plastics in deposition layers far older than the invention of plastics, leading to suspected underestimation of microplastics in surface sample ocean surveys.
Ocean governance is the conduct of the policy, actions and affairs regarding the world's oceans. Within governance, it incorporates the influence of non-state actors, i.e. stakeholders, NGOs and so forth, therefore the state is not the only acting power in policy making. However, ocean governance is complex because much of the ocean is a commons that is not ‘owned’ by any single person or nation/state. There is a belief more strongly in the US than other countries that the “invisible hand” is the best method to determine ocean governance factors. These include factors such as what resources we consume, what price we should pay for them, and how we should use them. The underlying reasoning behind this is the market has to have the desire in order to promote environmental protection, however this is rarely the case. This term is referred to as a market failure. Market failures and government failures are the leading causes of ocean governance complications. As a result, humankind has tended to overexploit marine resources, by treating them as shared resources while not taking equal and collective responsibilities in caring for them.
Plastic pollution is the accumulation of plastic objects and particles in the Earth's environment that adversely affects humans, wildlife and their habitat. Plastics that act as pollutants are categorized by size into micro-, meso-, or macro debris. Plastics are inexpensive and durable, making them very adaptable for different uses; as a result, manufacturers choose to use plastic over other materials. However, the chemical structure of most plastics renders them resistant to many natural processes of degradation and as a result they are slow to degrade. Together, these two factors allow large volumes of plastic to enter the environment as mismanaged waste which persists in the ecosystem and travels throughout food webs.
The plastisphere is a human-made ecosystem consisting of organisms able to live on plastic waste. Plastic marine debris, most notably microplastics, accumulates in aquatic environments and serves as a habitat for various types of microorganisms, including bacteria and fungi. As of 2022, an estimated 51 trillion microplastics are floating in the surface water of the world's oceans. A single 5mm piece of plastic can host 1,000s of different microbial species. Some marine bacteria can break down plastic polymers and use the carbon as a source of energy.
The Shaw Institute, formerly the Marine & Environmental Research Institute, is a 501(c)(3) nonprofit scientific research organization based in Blue Hill, Maine and New York City. The institute conducts research into ocean pollution, flame retardants, microplastics and plastic pollution, sentinel species and climate change.
Rubber pollution, similar to plastic pollution, occurs in various environments, and originates from a variety of sources, ranging from the food industry processing chain to tire wear. Synthetic and natural rubber dust and fragments now occur in food, airborne as particulates in air pollution, hidden in the earth as soil pollution, and in waterways, lakes and the sea.
Iseult Lynch is an Irish chemist and Professor of Enivornmental Nanoscience at the School of Geography, Earth and Environmental Sciences at the University of Birmingham. Her research focuses on the safety of nanoparticles in the environment and their interactions with biological entities.
Particulate pollution is pollution of an environment that consists of particles suspended in some medium. There are three primary forms: atmospheric particulate matter, marine debris, and space debris. Some particles are released directly from a specific source, while others form in chemical reactions in the atmosphere. Particulate pollution can be derived from either natural sources or anthropogenic processes.
Plasticosis is a form of fibrotic scarring that is caused by small pieces of plastic which inflame the digestive tract.
The Mediterranean Sea has been defined as one of the seas most affected by marine plastic pollution.
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