Plastic was created to be durable, versatile, and cheap. These factors transformed numerous industries and lifestyle factors. While plastic now has a somewhat tarnished reputation, it has made pivotal changes in our world for all the right reasons too. Some of them include changes made with medical supplies, lightweight transport and packaging of food products – reducing waste and contamination all while being cheap. Due to plastic being so cost efficient and convenient it has been mass produced. This has led to plastic building up in landfills and polluting our environment. Only 9% of plastic generated globally is estimated to be recycled, with the rest in landfills or natural environments. However, due to the irresponsible overproduction and disposal of plastic, it now poses numerous threats. Between 1950 and 2015 there was 6.3 billion tonnes of plastic waste generated globally.
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What Are Microplastics?
Because of the durability of plastic, it does not break down completely; it just breaks into smaller, more harmful plastic debris called microplastics. A microplastic is classified as a small piece of plastic that is 1 µm to 5 mm in size. This debris is so small that it cycles into nearly all parts of our environment and systems.
Two Main Types
1. Primary Microplastics
Primary plastics are small particles that go straight to the environment, usually intentionally made microplastics like in personal care products and plastic pellets. They may be used in care products like body scrubs or from human actions. The most common sources are laundering synthetic clothes or from wear and tear of tires; these two alone make up over half of primary microplastics.
2. Secondary Microplastics
Secondary microplastics come from the breakdown of larger plastic products, unintentionally created microplastics like plastic bags, fishing nets etc. The majority of the plastic in the ocean comes from secondary microplastic, these pose the greatest threat to the environment and health as they will continue to keep breaking down into nanoplastics.
What Are Nanoplastics?
Plastic particles that have a diameter below 100nm are known as nanoplastics, even smaller than microplastics. Nanoplastics come from the debris of microplastics or are manufactured intentionally for products. Nanoplastics pose more of a threat because of their small size and the quantity of them. One microplastic can degrade into billions of nano-plastics. These tiny particles are now found everywhere in the atmosphere, hydrosphere, biosphere and lithosphere. There is growing concern about the toxicity of nanoplastics on all living beings, especially humans. Nanoplastics are recognized to be more harmful than microplastics. Due to their tiny size and because they are hydrophobic, they have the ability to permeate through cell walls and cross pores.
How Do Microplastics Enter Food and Water?
Packaging and Bottles
Plastic can transfer from food packaging to the food item and then be ingested. Packaging materials commonly include polyethylene terephthalate, polystyrene, and polypropylene. These materials are prone to causing microplastic contamination through chemical leaching, exposure to high temperatures and physical abrasion. Storage, temperature, and plastic materials influence microplastic contamination. Foods with the greatest risk of microplastic contamination are canned fish, bottled water, meat and condiments. Food with a high fat content packaged in plastic like condiments or dairy products accelerates the breakdown of the plastic as the high fat and high acidity promote the breakdown into smaller particles. Researchers found that one litre of bottled water contained an average of approximately 240,000 plastic particles, around 90% of which were nanoplastics. Food packaging needs approval for not having toxic effects on humans; however, this is debated as numerous compounds have unknown health risks and effects and cannot be verified as safe or unsafe.
Heating Plastic
Heating up plastic increases microplastic degradation, especially particular materials in some plastics that are more heat-sensitive. After 60 minutes at temperatures above 30°C is when microplastics begin to be released in some of the most common plastic types. Research shows that warm water baths show the greatest breakdown of microplastics in food containers. Tea bags with plastic left in hot water pose a threat of high microplastic degradation. Another threat is Cookware with non-stick pans containing Polytetrafluoroethylene (PTFE); coated cookware releases micro/nano plastics which is likely adding thousands of microplastics to the human diet.
Food Processing and Supply Chains
Microplastics are found in meat and dairy products that are introduced during processing or in supply chains. Microplastics can be introduced via feed, packaging, and environment. Meat and dairy are consumed daily worldwide by billions. With such high consumption of these elements that are essential to human diets exposes long-term chronic exposure. Livestock feed or water introduces microplastic and the transfer to milk or tissues of animals that are then consumed by humans. From farm to consumption meat and dairy are introduced to plastic numerous times in various ways from farm to table.
Seafood and Marine Exposure
A large sum of existing plastic waste remains in the ocean and due to natural elements like the sun and waves, the breakdown of plastic into micro/nanoplastics is escalated. Fish have numerous health benefits and are promoted in peoples’ diets, however there is a risk of exposure to high levels of microplastic and nanoplastics. These plastic particles contaminate the water and the fish in them; this leads to people then ingesting microplastics through fish consumption.
Household Dust and Air
Our Indoor environment could also pose a threat through inhalation, ingestion and dermal contact. Inhalation of microplastic is just as possible as ingestion of microplastic in food. Studies show that the presence of microplastics is eight times higher indoors than outdoors. This presence of microplastics in the air can be inhaled, sources coming from preparing food, laundry – synthetic clothes, upholstery, textiles, and poor ventilation indoors. Microplastics is underestimated when we don’t consider inhalation factors.
What Does Current Research Say About Health Risks?
What Scientists Know So Far
Studies show that humans ingest about 223.7 million microplastics with only 41% of that being excreted. Laboratory and animal studies show microplastics have numerous negative impacts including oxidative stress, inflammation, intestinal barrier damage, and growing concern on chronic exposure from daily consumption. Microplastics and nanoplastics can enter all organs. The smaller the plastic particle (nanoplastics), the more dangerous as they can enter epithelial cells and tissues. Microplastics have now been found throughout the entire body, bodily fluids like blood, urine and even breast milk, as well as in our tissues and organs, particularly our livers, kidneys, lungs, placenta and even in our brains. Some of the potential health effects include oxidative stress, neurotoxicity, reproductive toxicity, carcinogenicity and effects on metabolism.
What Is Still Unclear
Detectable in food and water; however, with current data, a causal relationship between microplastics and adverse health outcomes cannot be proven. Comparison is increasingly more difficult as gathering controls is impossible due to widespread plastic contamination as well as difficulty narrowing the exposure to one source, as multiple potential exposures would be present. Laboratory studies also fail to reflect real-world scenarios. All these factors contribute to microplastics and health being understudied.
Examples:
1. Safe vs harmful exposure thresholds are still being researched
There is no standardized method for studying exposure to microplastics in humans, making research inconsistent. It is difficult to minimize to a particular exposure source, chemical composition and whether it was inhaled or ingested, as people have previously been exposed or will be exposed through various other sources throughout a trial. There is no standardized method to measure exposure from a source or level of exposure in humans. The only way to predict exposure in humans is the level of microplastic excreted; this is also unreliable and understudied. These uncertainties and gaps in knowledge make finding an exposure threshold difficult.
2. Particle size may matter
The health impacts of nanoplastics compared to microplastics are understudied, even though clear evidence shows they may pose more risk to human health. The smaller the particle, the more hazardous; however, size detection is difficult. Nano-plastics are more likely to enter blood and tissues as they are small enough to permeate through membranes. With nano-plastics being more dangerous, there are also a lot more nano-plastics in our environment than microplastics; one microplastic can degrade into billions of nano-plastics.
3. Chemical additives may matter
Plastic is filled with chemical additives for flexibility, colour, heat resistance or durability. Microplastics further breakdown to nano-plastics, then leach chemicals. These added chemicals can have negative impacts on human health. PFAS, phthalates, and bisphenols are some examples. There are over 10,000 chemical additives that may be added to plastic, and lots of their risks are not known. Thousands of these chemicals have no hazard classifications. More information and restrictions on chemicals being added to plastics are required.
4. Long-term cumulative effects need more evidence
Prolonged exposure increases the risk of each associated disease with microplastic exposure. With less than half the amount of plastic that’s consumed being excreted, meaning the human body has built up cumulated plastic. Prolonged exposure to microplastics is associated with possible gut issues, chronic inflammation, autoimmune disease, lung diseases, neurodegenerative disorders, CVD and high cancer risk. More research is required to understand the pathways of microplastics in the body that lead to these effects.
5. More Clinical Research Is Needed
Studies on mice show issues relating to fertility, inflammation and metabolic disorders. Plastic has been found in vital organs that can disrupt their function. This is also linked with having a high risk of cancer as well as creating resistance to cancer therapies. Nanoplastics need to be studied for the potential damage they pose to human cells and whether they can be excreted safely. Important to find safe exposure thresholds to put protocols into place.
Why Exposure Reduction Still Makes Sense
While avoiding microplastics every day is impossible, reducing your exposure is not. We don’t know the full extent of risks currently, meaning people should remain cautious of exposure to microplastics in food and water. It is still important to protect our health from the health risks of plastics and keep exposure to a minimum where possible. Plastic accumulates in the body over time; reducing exposure may keep accumulation of plastic to a minimum. Even without suitable scientific evidence on all the impacts of microplastics, we still know it has numerous negative health impacts. Avoiding microplastics protects the environment as well as humans and is beneficial in multiple areas.
Top Ways to Avoid Microplastics in Food and Water
1. Use Glass or Stainless Steel Water Bottles
2. Avoid Heating Food in Plastic Containers
3. Choose Fresh or Minimally Packaged Foods More Often
4. Reduce Highly Packaged Convenience Foods
5. Filter Drinking Water Where Appropriate
6. Store Food in Glass, Ceramic or Stainless Steel
7. Limit Plastic Tea Bags and Single-Use Pods
8. Wash Produce Thoroughly
9. Improve Kitchen Ventilation and Dust Control
10. Be Smart With Takeaway Habits
11. Choose natural fiber clothing
Conclusion
While in today’s world complete avoidance of microplastics is unrealistic, reducing exposure can help in lowering the potential of related risks and helps reduce plastic over-consumption. No one can eliminate exposure completely. The goal is risk reduction, not perfection.
Plastic is unique in that it is impossible to erase all possible exposures, and it is present in the majority of our food and water each day. Reducing exposure by avoiding certain routes of plastic ingestion/inhalation can make a difference. Working as a collective to consciously reduce consumption of plastic can help in reducing overall exposure of everyday plastic consumption. Staying up to date and making smarter choices like following the top ways to avoid microplastics makes a difference for your health and the environment.
Co-authored by: Una Cremin