Polyester is a synthetic fiber, a polymer derived primarily from polyethylene terephthalate (PET), which is a thermoplastic material made from petroleum. This fiber has become a dominant material in the global apparel industry, largely due to its low production cost and mechanical strength. Its wide application is seen in everything from activewear to everyday clothing, valued for its durability and resistance to wrinkles. Understanding the physical consequences of wearing this material requires examining how its inherent properties interact with the human body.
Impact on Thermoregulation and Skin Moisture
The chemical structure of polyester makes the fiber inherently hydrophobic, meaning it repels water rather than absorbing it into its core structure. This property is often marketed as “moisture-wicking,” where sweat is moved across the fabric surface to promote faster drying. However, this same characteristic can interfere with the body’s natural cooling process, especially in tightly woven or non-performance-grade fabrics.
When sweat is produced, its evaporation from the skin is the primary mechanism the body uses to dissipate heat and maintain a stable internal temperature. Since polyester fibers do not absorb moisture, they can instead trap humidity and heat in a microclimate layer directly against the skin. Studies comparing polyester garments to natural fibers like cotton have shown that subjects wearing polyester experience higher chest skin temperatures during exercise.
This retention of heat and humidity can lead to an earlier onset of sweating and a higher overall rate of perspiration without a corresponding increase in cooling efficiency. The body struggles to cool itself effectively because the evaporative process is hindered by the trapped, saturated air pocket around the skin. Wearing polyester can thus result in a greater sensation of wetness and discomfort, as the body works harder to regulate its temperature.
Potential for Skin Irritation and Allergic Contact Dermatitis
Wearing polyester can lead to skin reactions, which generally fall into two categories: irritant and allergic contact dermatitis. Irritant contact dermatitis is the more common reaction, often triggered by the physical environment created by the fabric. The combination of trapped sweat, elevated skin temperature, and friction from the synthetic fibers can irritate the skin, particularly in areas where fabric rubs, such as the elbows, knees, and groin.
Allergic contact dermatitis, conversely, is an immune system response to specific chemical substances present in the fabric. Synthetic textiles require a range of chemical treatments during their manufacturing process to achieve desired properties like color and wrinkle resistance. These chemicals, such as disperse dyes and formaldehyde-based finishing resins, can leach from the fabric onto the skin, triggering a hypersensitivity reaction in susceptible individuals.
While the polyester fiber itself is considered biologically inert, the chemicals used to process it are known sensitizers. Disperse dyes are loosely bound to the synthetic fibers and can easily transfer to the skin, causing a delayed, itchy, and inflamed rash. Therefore, any skin reaction to a polyester garment is more likely a response to the auxiliary finishing agents used on the textile.
Bacterial Growth and Odor Retention
The hydrophobic nature of polyester also has a significant impact on the development of body odor. Human sweat is composed of two main components: water-based secretions and oily secretions (sebum) from the skin’s glands. While polyester repels the water component, its synthetic, oil-attracting (oleophilic) nature causes it to strongly adhere to the lipids and organic compounds found in sebum and dead skin cells. These oily residues embedded in the polyester fibers are the primary food source for odor-causing bacteria.
By trapping this nutrient-rich environment against the body, the fabric promotes the rapid proliferation and metabolic activity of these microorganisms. This leads to the production of volatile organic compounds, which are perceived as a stronger and more unpleasant odor compared to natural fibers. Furthermore, these hydrophobic odor compounds and the bacterial biofilms that form are more difficult to remove completely during a standard washing cycle, leading to “odor retention.”
Chemical Residues and Microfiber Concerns
Beyond the immediate effects of heat and moisture, two long-term concerns involve residual chemicals and the shedding of microfibers. Polyester textiles are often treated with various functional chemicals, including flame retardants and water repellents. These chemical residues can be absorbed through the skin, especially when the fabric is warm and moist from sweat, potentially contributing to a person’s overall chemical exposure load. Some of these substances are known endocrine-disrupting chemicals that may interfere with the body’s hormonal systems. The risk of absorption is heightened when the skin barrier is compromised or when the fabric is worn for extended periods.
Additionally, polyester clothing sheds microscopic strands of plastic, known as microfibers, during both wear and laundering. These tiny plastic particles can become airborne and subsequently inhaled, or they may settle on the skin. While the long-term health consequences of microfiber inhalation and skin absorption are not yet fully understood, their presence in the human body is a growing concern, linking the textile to the broader issue of microplastic exposure.