More health issues we can blame on microplastics
Key Takeaways
Preclinical studies indicate that microplastics (MPs) contribute to the progression of disease in colorectal, skin, breast, and gastric cancers.
MPs compromise the mucosal barrier, absorb carcinogenic substances, and stimulate inflammatory responses, enhancing the risk of malignant transformation.
Although in its early stages, biodegradation by microorganisms offers a promising and eco-friendly method to efficiently break down MPs.
Since the 1950s, plastic production has surged approximately 200 times, hitting 400.3 million tons in 2022. Globally, just 10% of these plastics are recycled, with 18% incinerated and 50% ending up in landfills. The remaining 22%, littered into the environment, deteriorate into microplastics (MPs).[]
MPs can infiltrate our bodies via ingestion, inhalation, and dermal contact. Due to their minuscule size and durability, these particles permeate the bloodstream and accumulate in human organs and tissues, with chronic exposure increasingly associated with various cancers.
In an attempt to address this escalating man-made crisis, researchers are turning to microscopic species like fungi and bacteria for biodegradation.
Escalating cancer risk
The current evidence primarily comes from in vitro studies and short-term rodent models; however, it's almost certain that MPs promote carcinogenesis.
Colorectal cancer
A study published in Chemosphere highlighted that MPs as small as 0.25 µm could significantly enhance the mobility of cancer cells across four human colorectal cancer cell lines.[] This enhanced migration facilitates extensive spread within the body, potentially escalating the risk of metastasis.
Skin cancer
Researchers reporting in Ecotoxicology and Environmental Safety from 2023 observed the absorption of MPs by two cutaneous squamous cell carcinoma (CSCC) cell lines, SCL-1 and A431, in a concentration- and time-dependent manner. The proliferation of CSCC cells was significantly enhanced.[]
MPs also damaged the normal cells through NLRP3-mediated inflammatory responses and pyroptosis, a form of programmed cell death.
Breast cancer
A study published in Scientific Reports found that exposure to 16.4 µm fragment-type polypropylene MPs at a 1.6 mg/mL concentration altered gene expression related to the cell cycle in MDA-MB-231 and MCF-7 breast cancer lines. This alteration included the upregulation of the pro-inflammatory cytokine IL-6, which is associated with enhanced cancer progression.[]
Gastric cancer
Another study demonstrated that mice exposed to polystyrene (PS) MPs showed accumulation in stomach tissues, leading to gastric cancer.[] This exposure also altered gene expression, notably increasing asialoglycoprotein receptor 2 (ASGR2) levels, which enhances cancer characteristics and promotes resistance to chemotherapy and monoclonal antibody treatments.
These preclinical results speak volumes regarding the potential risks of MP exposure and its possible role in cancer development.
Mechanisms of microplastic interaction
Barrier disruption and cellular penetration
MPs disrupt protective barriers like the colonic mucosa and alter the makeup of symbiotic microbiota, facilitating the transport of carcinogens across the intestinal wall.[]
The Chemosphere researchers discovered that MPs integrate into the human body’s cellular processes and persist during cell division—as evident from their presence within the lysosomes of gastrointestinal cancer cells.
Carrier of carcinogens
MPs' carcinogenic potential is due to their ability to adsorb and transport carcinogenic toxins. Examples include the transport of persistent organic pollutants (POPs), hydrophobic organic chemicals, and polycyclic aromatic hydrocarbons (PAHs), which damage DNA directly.
Genotoxic effects
MPs can also directly induce genotoxic effects through direct interactions with DNA or indirect mechanisms such as generating reactive oxygen species (ROS) and inhibiting DNA repair mechanisms.
Additionally, MPs can instigate inflammation and modify cellular functions, promoting neoplasia and metastasis.
Biodegradation with fungi
Sure, plastics are sticking around, but we're not totally out of options. Biodegradation is the most efficient, eco-friendly, and cost-effective method for breaking down plastics.
A 2022 study identified over 200 fungi from various natural habitats capable of degrading different plastics. Another report discovered that Aspergillus tubingensis, a fungus commonly found in soil, can effectively colonize and degrade plastic surfaces.[]
Low-density polyethylene (LDPE), commonly known as polythene, is the most prevalent plastic type. More than 15 fungi species, including several Aspergillus members, have been recorded as capable of degrading LDPE.
Species of the genera Aspergillus, Trichoderma, Penicillium, and Pleurotus produce enzymes like cutinase, lipase, protease, esterase, laccase, and peroxidase. These enzymes make plastics more hydrophilic and break down high-molecular-weight polymers into smaller ones, speeding up degradation.[]
These research findings come at a critical time as the fourth session of the Intergovernmental Negotiating Committee (INC-4), recently convened in Ottawa, discussed a legally binding international agreement on plastic pollution.[]
Given the possible carcinogenic potential of MPs, their ubiquity in the environment necessitates immediate attention from healthcare professionals and policymakers. Additionally, epidemiological studies are warranted to establish the risk in humans.
What this means for you
As an HCP, you can help patients minimize exposure to MPs by recommending they avoid using single-use plastics and choose fresh, unpackaged produce over processed foods. Suggest replacing plastic containers with glass or stainless steel alternatives and opting for clothing made from natural fibers instead of synthetic materials. Advocate for the use of water filters capable of removing MPs from drinking water.