Novel entities

The introduction of synthetic chemicals, plastics, and other human-made materials into Earth’s systems.

Novel entities comprise human-made chemicals, naturally occurring chemicals that are mobilized by humans, human-made particles like plastics and human-modified life forms. Produced and released in myriad forms and huge quantities, they can interact and accumulate in ways that threaten Earth‑system processes. For example, many harmful chemicals (such as banned pollutants and plastics) are still widespread globally, accumulating in animals like marine mammals and causing adverse effects on wildlife and humans.

However, our understanding of planetary scale exposure and impacts is still fragmented due to the amount and tremendous diversity of novel entities. To track this planetary risk, we use a practical proxy: the proportion of novel entities that undergo rigorous safety assessment before widespread use. That share is currently low, and on this basis the Planetary Boundary for Introduction of Novel Entities is considered transgressed – the creation of new substances far outpaces our capacity to evaluate them. Future assessments may incorporate additional metrics, such as production volume, environmental release, and mixture effects, to refine our understanding of this planetary risk.

Control Variables

The Planetary Boundary for Novel Entities covers a wide range of human-made materials and substances — including synthetic chemicals, heavy metals, plastics, radioactive materials, and even genetically modified organisms. Together, they represent a growing and complex pressure on the Earth system, but their combined impacts are hard to measure. For now, the boundary is tracked through the percentage of untested chemicals in use worldwide. This share has grown rapidly as chemical production expands far faster than our ability to test or regulate it. As a result, the boundary has been transgressed, marking a clear warning that humanity is introducing new substances into the environment faster than we can ensure they are safe.

Impacts

Novel entities are now found in every part of the planet — from mountain soils to ocean depths. Some trap heat in the atmosphere, others harm plants and animals, and many build up in food webs or water systems. Once released, they are difficult or impossible to remove, meaning their effects can last for centuries.