Microplastics and Their Effects on Human Health

Global plastic production has risen dramatically over the past 70 years to reach 460 million tons¹ and only 9% is recycled². The majority of plastic waste is being incinerated, dumped in landfills, and released into the environment, causing significant environmental and health problems, with only a tiny percentage that does not exceed 10.0% recycled in the USA. Plastics produce small fragments or particles through crushing, splitting and degradation during use and these small fragments are called microplastics.  

What are Microplastics? 

Microplastics are polymer fragments that can range from less than 0.2 inch (5 millimeters) down to 1/25,000th of an inch (1 micrometer). Anything smaller is a nano-plastic that must be measured in billionths of a meter. They are generated by fossil fuel derived plastics which can be classified into six categories based on their chemical composition: polyethylene, polystyrene, polypropylene, polyurethane, polyvinyl chloride, and polyethylene terephthalate, as shown³ in Figure 1. Like plastic, microplastics are also known for their stability and inability to degrade, meaning they can persist in the environment for decades⁴. 

Figure 1: Primary and Secondary Microplastics

Microplastics can enter the human body via a variety of ways as shown⁶ in Figure 2 below^. The life cycle of microplastics usually begins with the release of primary or secondary microplastics into the terrestrial and aquatic ecosystems, followed by their transport into water systems. Food contaminated with microplastics, particularly seafood, is the primary source of exposure route for humans⁷. 

Figure 2: Ways Microplastics Enter the Human Body

Evidence of Microplastics in the Human Body

Studies have shown accumulation of microplastics from different human biological samples. For example, Wibowo⁸ et al. collected stool samples from healthy participants from a fisherman community living in the coastal region of Kenjeran, Surabaya, and Indonesia. They found that 50% of the participants were positive for microplastics in their stool, with high-density polyethylene spotted as the most predominant contaminant. Ibrahim⁹ et al. reported that 100% of the sample collected had microplastic in human colectomy specimens, in which nine out of eleven subjects had colorectal cancer. 

In addition, researchers found that samples taken from the human placenta and fetal meconium contained polyethylene, polypropylene, polystyrene, and polyurethane¹⁰.  

In recent research, microplastic content in the feces of patients with inflammatory bowel disease was greater than that of healthy people. These studies also indicate a strong correlation between the severity of inflammatory bowel disease and fecal microplastics¹¹.  

To understand the impact of microplastics in pregnant women, one group studied its effect on pregnant mice and found plastic chemicals in the brain, heart, liver, kidney and lungs of the developing baby 24 hours after the pregnant mother ingested or breathed in plastic particles. 

Microplastics Associated Diseases

Epidemiological studies have shown that long-term exposure to microplastics is highly associated with cancer development in humans and animals¹². Due to their small size, microplastics can be directly consumed by various marine organisms and contaminate the human food chain via the bioaccumulation process¹³. 

Studies by one group provide direct evidence of plastic consumption in humans that may lead to the development of various cancers^{14, 15}. The toxicological studies revealed higher toxic equivalent factor due to microplastic thus significantly increasing the risk of cancer. 

Recently, Kim¹⁶ et al. demonstrated that long-term exposure to microplastics can increase the risk of stomach cancer. The presence of microplastics caused the elevated level of cancer-causing protein. In addition, the excess exposure to microplastics caused a decrease in survival rate and an increase in the growth of tumors. 

Prata¹⁷ et al. and Amato¹⁸ showed that microplastic intake might cause chronic inflammation and irritation, leading to deoxyribonucleic acid (DNA) damage and might have a toxicological impact on cancer development. 

More studies have linked microplastics to several health problems, including toxicity and carcinogenicity, when consumed by humans^{19, 20}. Due to the small size of microplastics, they have a high ratio of surface area to volume. Materials with a high surface area are highly toxic to cells and tissue and can damage deoxyribonucleic acid (DNA) inside the cells. The damaged DNA can mutate which in turn can lead to cancer¹⁴. These studies were corroborated by another group which showed DNA mutation caused by organic pollutants that are attached to microplastics in water²¹. 

Microplastics have also been linked to various immune system problems, such as immune cell death²² as well as intestinal inflammation²³. Since humans can ingest microplastics through inhalation, exposure to airborne particles of microplastics may cause asthma, cardiac disease, allergies, and autoimmune diseases¹⁴. 

Several studies have also linked microplastics to detrimental impacts on the cardiovascular system of humans leading to various health problems^{24, 25}. 

Microplastics also contain plasticizers which in turn can have a direct impact on human health. One group of researchers found a direct link of commonly used phosphate plasticizer as endocrine disruptor leading to breast cancer²⁶. 

The increasing prevalence of microplastics in consumer foods and beverages, and its impact on the gut microbiome have been widely studied and linked to fatigue, diarrhea, blood in stool, abdominal pain and cramping, reduced appetite and in some cases, leading to cholera, gut dysbiosis, inflammatory bowel disease, irritable bowel disease, chronic bowel disease, metabolic disturbances, and other stomach issues^{27, 28}.  

Microplastics Minimization

The microplastic minimization control approach follows an upside-down pyramid²⁹ as shown in Figure 3, starting with prevention, the most favored option, followed by reducing, reusing, recycling, refusing, rethinking, regifting, recovering (7 R’s), and ending with disposal.  

Although Reuse and Recycling of plastics is an effective of managing microplastics, it is not achieved due to a variety of reasons. Consequently, efforts should be focused on Prevention of plastics use.    

Using Biodegradable Plastics

Recent studies ^{30, 31} have shown biodegradable plastics offer a promising solution for replacing conventional plastics to mitigate generation of microplastics. These plastics (e.g. PHA) have been used in various applications such as pharmaceutical packaging ³², agriculture³³ and automotive industry³⁴.  

SmartSolve Technology – Part of A Solution

SmartSolve’s water-soluble X Series paper technology consists of paper with PVA as heat sealant, both of which are water soluble³⁵, biodegradable in water, and marine biodergradable³⁶. Consequently, as explained above, the X series material is not a source for microplastics³⁷ and offers a game-changing packaging solution for consumer products. More recently, a new technology platform, PureNil, has been developed where the heat sealant resin is bioderived and offers a complete solution towards sustainable packaging.