Discover how melamine sponges release trillions of microplastic monthly, their environmental impact, and ways to minimize this pollution.
Melamine sponges, widely appreciated for removing tough stains and scuffs without additional cleaning agents, owe their effectiveness to their unique abrasive qualities. However, the breakdown of these sponges during use results in the shedding of microplastic fibers. A study in Environmental Science & Technology by the American Chemical Society highlights that over a trillion microplastic fibers from these sponges are released globally each month.
Constructed from poly(melamine-formaldehyde) polymer, melamine foam combines rigid plastic strands into a lightweight, soft, yet highly abrasive material. This composition makes it ideal for scrubbing but also leads to the foam breaking into smaller fragments as it wears down, releasing microplastic fibers into wastewater systems. These fibers eventually reach ecosystems, where they can be ingested by wildlife and enter the food chain. Researchers, including Yu Su, Baoshan Xing, and Rong Ji, investigated how sponge density and surface roughness influence the rate of foam breakdown and quantified the amount of microplastic fibers released.
Research Findings on Microplastic Emission
A study conducted on melamine sponges revealed important insights into microplastic fiber release. Several sponges from three popular brands were tested by repeatedly rubbing them against textured metal surfaces, causing the foam to degrade over time.
“Sponges made from denser foam wore down more slowly and produced fewer microplastic fibers than those made from less dense materials,” the researchers observed.
It was determined that a single sponge releases approximately 6.5 million fibers per gram of worn-out sponge. An assumption was made that, on average, sponges experience 10% wear during use.
To estimate the global impact, sales data from Amazon in August 2023 was analyzed. Based on consistent monthly sales, it was calculated that melamine sponges could contribute 1.55 trillion fibers to the environment each month. This figure accounts for only one online retailer, suggesting the true scale of emissions may be significantly greater.
To address this issue, recommendations include designing denser, more durable sponges to reduce wear and fiber release. The adoption of natural cleaning alternatives free from plastics is also encouraged. Additionally, installing filtration systems in homes and wastewater treatment facilities could help capture microplastic fibers before they reach the environment.
https://doi.org/10.1021/acs.est.4c00846
Abstract
The abrasion of synthetic textile fibers is a significant factor in the generation of environmental microplastic fibers (MPFs). The extent to which polymer sponges designed specifically for surface cleaning have a tendency to release MPFs during normal use remains unknown. Here, the tribological behaviors of melamine cleaning sponges (also known as “magic erasers”) with different strut densities against metal surfaces of different roughness were investigated using a reciprocating abrader. The MPFs formed by sponge wear under various conditions were characterized in terms of their morphology, composition, and quantity. They were mainly composed of poly(melamine-formaldehyde) polymer with linear or branched fiber morphologies (10–405 μm in length), which were formed through deformation and fracture of the struts within open cells of the sponges, facilitated by friction-induced polymer decomposition. The rate and capability of MPF production generally increased with increasing roughness of the metal surface and density of the struts, respectively. The sponge wear could release 6.5 million MPFs/g, which could suggest a global overall emission of 4.9 trillion MPFs due to sponge consumption. Our study reveals a hitherto unrecognized source of the environmental MPF contamination and highlights the need to evaluate exposure risks associated with these new forms of MPFs.
