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A 2021 study assessed 492 chemical products against seven planetary-boundary processes and found that 99.4% exceeded at least one allocated ecological budget. That result describes an absolute sustainability assessment method—not a finding that nearly all chemicals are toxic, unsafe to use, or harmful in every production context. It also is not a new survey of chemicals currently on the market.
What the 99.4% result means
Victor Tulus, Javier Pérez-Ramírez, and Gonzalo Guillén-Gosálbez reported the finding in a paper first published on 27 October 2021. Their analysis covered 492 chemical products. In the study’s framework, a chemical transgresses a planetary boundary when its impact exceeds the share of ecological capacity allocated to it. A transgression level greater than 1 means that assigned budget is exceeded.
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This is a threshold-based environmental sustainability result. It does not rank all chemicals as equally damaging, establish that each is dangerous to people, or show that a chemical must exceed a boundary under every possible production route. The authors found that some transgression levels were more than 200 times the allocated budget, while others were much lower. Read the paper in Green Chemistry.
How the assessment differs from a standard life-cycle comparison
Life-cycle assessment can compare environmental impacts among products or processes using indicators such as carbon footprint. Absolute environmental sustainability assessment (AESA) asks a different question: does an impact fit within an allocated share of Earth’s ecological capacity?
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- Relative assessment: compares impacts between options, such as which product has the lower impact on a particular indicator.
- Absolute assessment: compares an impact with a defined ecological budget; a transgression level above 1 means the assigned share is exceeded.
- Coverage: a carbon footprint captures a climate-related dimension, while this study considered several planetary-boundary indicators.
The authors linked life-cycle inventory flows to planetary-boundary control variables using characterization factors, then compared the resulting impacts with allocated budgets. The allocation matters: deciding how much of the global safe operating space belongs to a particular chemical is a central part of the method, not a neutral detail. The authors describe AESA as a possible complement to conventional life-cycle assessment, not a universally agreed replacement or regulatory classification.
Which planetary boundaries were included
The study assessed seven of the nine planetary-boundary processes. It did not assess all nine: atmospheric aerosol loading was omitted because the authors lacked a defined global boundary for it, and novel entities were omitted because a control variable was not then available.
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| Assessed process | Included? |
|---|---|
| Climate change | Yes |
| Stratospheric ozone depletion | Yes |
| Ocean acidification | Yes |
| Biogeochemical flows | Yes |
| Land-system change | Yes |
| Freshwater use | Yes |
| Change in biosphere integrity | Yes |
| Atmospheric aerosol loading | No; the study lacked a defined global boundary |
| Novel entities | No; a control variable was not then available |
Why a lower carbon footprint does not establish sustainability
The authors reported especially high transgression in carbon-related boundaries, including climate change, ocean acidification, and change in biosphere integrity. But they found no correlation between chemicals’ carbon footprints and their absolute sustainability transgression levels. A lower carbon footprint therefore does not by itself show that a chemical stays within every assessed ecological budget.
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That distinction is important when using a single metric to screen chemicals. A material can perform better on one indicator while still exceeding its allocated budget on another. The study’s multi-boundary approach makes that possibility visible, while its results remain dependent on the selected indicators and allocation method.
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What the reported exceptions do—and do not—show
Chemistry World reported that three chemicals—hexamethyldisilazane, selenium, and trimesoyl chloride—met the absolute criterion in the assessment. This list is attributed to Chemistry World’s account of the findings; it should not be read as a general certification of those chemicals across all production routes, uses, or environmental measures. Read Chemistry World’s report.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to interpret the result today
The paper provides a method for relating chemical impacts to planetary limits, and its 99.4% figure is a result for the 492 products and assumptions assessed in that 2021 study. The cited sources do not establish a repeat assessment of the same products as of 2026. The figure should therefore not be presented as a current census of the chemical market.
More broadly, an absolute threshold can help identify when impacts exceed an assigned ecological share, but the choice and allocation of that share require agreement. A 2022 discussion of chemistry and planetary boundaries likewise situates the issue in the context of the field’s response to boundary transgression. Read the Chemical Science perspective.
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