What’s ‘plastic rock’ now found across 5 continents?

A peculiar form of rock containing plastic has been discovered worldwide, primarily composed of plastic generated and discarded.

This deposit is a fusion of rock and plastic polymers derived from human waste that have undergone compression. Plastic rocks have been identified in 11 countries on both coastal and inland areas across five continents.

These rocks depict the global magnitude of plastic pollution with a researcher informing Newsweek that the rocks pose a pressing threat to ocean sustainability and ultimately to human health.

Within the scientific community, there is some disagreement regarding the nomenclature for these deposits with various terms proposed. Some of these terms describe plastic rocks formed in specific manners.

Numerous terms have been suggested, including "plastistone," "plastiglomerate," "plasticrust," "plastitar," "plastisandstone," and "anthropoquinas."

The initial instance of a plastic rock was documented in Hawaii almost a decade ago by geologist Patricia Corcoran and designated as "plastiglomerate."

Deyi Hou, an associate professor of environment at Tsinghua University in China and author of a recent paper investigating the formation and prevalence of what it terms plastistones and explained, "Molten plastic, sand grains, clasts from rock, coral, shells, and wood debris were held together after campfire burning on Kamilo Beach, Hawaii, USA," to Newsweek.

Hou and colleagues explained in a recent paper that plastic rocks may form via a wide range of methods.

Place where plastic rocks have been found 

Plastic rocks have been found in Bangladesh, Brazil, China, Hawaii, India, Italy, Japan, Peru, Portugal, the Spanish Canary Islands, and the United Kingdom.

What is plastic rock and how is it formed?

The proportions of plastic polymers present in these rocks closely mirror the proportions found in plastic waste.

The global formation of plastic rocks is a direct consequence of the plastic pollution being discharged into the environment, amounting to approximately 22–48 million metric tons annually, as stated by the authors.

The pollution is more severe in certain locations they noted including cities, mulched agricultural soils and sites where plastic waste is dumped.

Rocks incorporating plastic are anticipated to become more prevalent as a component of natural geological processes and endure for an extended period, as reported.

Plastic rocks might also influence the microbial communities in the soil and the surrounding environment, potentially causing repercussions for local ecosystems. Adding to the complexity, plastic rocks also release microplastics which are minuscule fragments of pollution that are recognized to have disseminated worldwide, reaching even human and animal bodies.

The complete findings of the study were published in the journal Earth-Science Reviews.