Environment - Microplastics, an increasing menace to human health

                            Microplastics on the shore         GPT-5 AI generated

Microplastics are defined as being plastic particles less than 5 mm in size and have permeated/infiltrated nearly every part of the environment, including food, water, and air. Multiple recent studies published in peer-reviewed journals such as Nature Medicine and Environmental Science & Technology have shown mounting concern about their potential impacts on human health as well as the survival of multiple species of wildlife on the planet.

The use of plastics remains almost out of control despite effects to reduce the use of soft plastic shopping bags and plastic drinking straws. As a result the contamination from microplastics has become both widespread and continuing.

Exposure pathway

Humans are exposed to microplastics primarily through:

• Ingestion: Found in seafood, bottled water, salt, and even vegetables.
• Inhalation: Airborne microplastics from synthetic textiles and urban dust.
• Dermal contact: Though less studied, skin exposure may occur via some types of cosmetics or contaminated water.

The biological effects of microplastic exposure

Once inside the body, microplastics can interact with tissues and cells in several harmful ways:

• Inflammation and oxidative stress: Studies show that microplastics can trigger immune responses and generate reactive oxygen species, leading to cellular damage.
• Disruption of gut microbiota: Ingested microplastics may alter the composition of intestinal flora, affecting digestion and immunity.
• Translocation to organs: Nanoplastics (smaller than 1 µm) can cross biological barriers and accumulate in organs such as the liver, kidneys, and brain.

Physical and chemical hazards of microplastics

Microplastics are not inert and these substances carry:

• Additives: Plasticizers, flame retardants, and stabilizers that may be endocrine disruptors.
• Adsorbed pollutants: Persistent organic pollutants (POPs) and heavy metals that bind to plastic surfaces.
• Physical abrasiveness: Their shape and size can cause mechanical irritation in tissues.

A 2025 review in Nature Medicine highlights several key findings:

• Microplastics have been detected in human blood, placenta, and lung tissue.
• The toxicity depends on polymer type, particle size, shape, and surface chemistry.
• The presence of a biocorona, layer of proteins and biomolecules that forms around microplastics, can influence how the body reacts to them.

Despite continuing research on microplastic infilration, there remains considerable knowledge gaps. Long term exposure and chronic impact studies, dose-reponse relationships including level of toxocity, and population-level epidemiogical data do not exist. In the interim, the only action that people can take is to reduce their reliance on plastic - whether this be in food storage items, utensils, bottles and when cooking (including microwave heating of plastic food trays).