Gregory G. Bond, Ph.D., MPH, FACE
Manitou View Consulting, LLC

Over the past several decades, experts have made various estimates of the number of chemicals in global commerce – ranging from 25,000 to more than 140,000. This large range reflects the many uncertainties that exist1, and providing a robust, credible estimate has been difficult. A study published in Environmental Science & Technology in February 2020 estimated the total number of “chemicals on the global market” may exceed 350,000 – a number nearly 2.5 times the upper range of previous estimates. But is that really the correct number?

I have more than a passing interest in this topic; in December 2019, my colleagues and I published a paper in the journal of Toxicology & Industrial Health that estimated between 40,000 and 60,000 industrial chemicals2 are currently on the global market. We further estimated that about 6,000 chemicals account for more than 99 percent of the total volume of chemicals in commerce globally.

On the surface, the two estimates seem vastly different. But on closer examination, the variances are largely due to differing methods and definitions, which, when more closely harmonized, yield numbers that are much closer together. 

Differences in Methods and Definitions Are Critical

The ES&T study is based on an analysis of 22 chemical inventories2 from 19 countries/regions.  The scope and data available from those inventories differ markedly, which complicates efforts to combine their information for assessment.

By contrast, the T&IH study relied on chemical inventories from five regions – Canada, China, the European Union, Japan and the United States – largely because those regions account for more than 75 percent of global chemical production and more than 90 percent of annual global chemical research and development spending, and thus may likely contain the largest share of unique industrial chemicals in commerce. 

Individual national and regional inventories likely include a substantial overlap in chemicals listed, particularly for the largest volume chemicals, so simply combining raw numbers across inventories will lead to a gross overestimate. Both studies tried to address this by conducting electronic comparisons of chemical identities, using Chemical Abstract Service (CAS) numbers and/or chemical names to eliminate the overlap, which both studies acknowledged was an imperfect process. 

Another challenge is that most national chemical inventories include chemicals that never actually made it to the market or were withdrawn. If not addressed, this too can lead to overestimates of the actual number of chemicals currently in commerce. 

Among the inventories included in the ES&T study, only the EU REACH and the U.S. Environmental Protection Agency’s TSCA Inventory Update databases have mechanisms for weeding out these chemicals, and even then, they may be imperfect. The researchers addressed this issue by separately reporting the number of chemicals registered3 more recently, between 2010 and 2019, under the assumption that those chemicals were most likely to be still in commerce. 

This assumption is probably true for the EU REACH database. Because the cost to register a substance is substantial, companies aren’t likely to register substances that aren’t truly on the market.  But for other national inventories, including the TSCA database, notification costs can be much lower (or non-existent) than the cost of not initially notifying, so the cost incentives are to over-report rather than under-report chemicals to most inventories.

The ES&T study authors also separately reported chemicals that had been registered before 2010, but for which no information on current commercial status is publicly available, as well as chemicals that have only been “pre-registered,” but not officially registered, and thus may not have been produced and used.

My colleagues and I took a different approach – our study accepted that all of the EU REACH-registered substances (around 21,500) and U.S. TSCA Inventory Update entries designated as “active” (around 26,200) were currently in commerce.  Likewise, it assumed that all of the Canadian Domestic Substances List (about 19,500), Japan (about 12,000) and China (approximately 35,700) inventory entries5 were also currently in commerce – which likely over-estimated the numbers of chemicals truly in commerce in those regions.

Finally, both teams faced the challenge of extrapolating estimates from inventories created by a relatively small number of countries/regions, to the rest of the world. The ES&T study did not make such an extrapolation, stating instead that it likely underestimated the total on the global market. The T&IH study extrapolated its findings using two different assumptions: under a more liberal assumption, we increased our estimate derived from the five regions by 10 percent (based on the cumulative 90 percent of global R&D spending figure cited above).  

Under a more conservative assumption, we used only inventories from the EU, United States and Japan, which try to eliminate chemicals that are no longer in commerce, and increased our estimate by 5 percent, to account for additional, unique chemicals from the rest of the world.

Results Not That Different

Media reporting on the ES&T study has focused almost exclusively on the 350,000 estimate, ignoring the numerous limitations addressed above and acknowledged by the authors themselves. That estimate also ignores the authors’ critical sub-classification by commercial status, which yielded the following:

  1. 69,000 chemicals in commerce;
  2. 261,000 chemicals that were notified to governments prior to 2010 that cannot be verified as currently being in commerce; and
  3. 26,000 chemicals that were pre-registered only, and never officially registered with governments.

The figures above also include polymers, mixtures and other categories of chemicals that did NOT meet the definition of “industrial chemicals.” In fact, the study authors reported that nearly 32 percent (75,000 out of 235,323) of the inventory entries that listed CAS numbers were actually polymers, mixtures and other categories, and they could not reliably calculate a percentage for those entries that lacked CAS numbers.

Thus, if one more closely harmonizes the differing methods employed by the two groups working independently, our estimate of 40,000 to 60,000 and their estimate of the number of chemicals in commerce (69,000) appear much more comparable.

Similar Conclusions and Recommendations

Although the two studies arrived at different estimates of the numbers of chemicals in commerce, both seem aligned on conclusions and recommendations. Both agree that a significant barrier to quantifying the number of chemicals in commerce is that most regions across the world lack robust inventories to reliably identify those chemicals. 

The ES&T study makes a number of useful and relevant recommendations to address this, including:

  • Encouraging countries or regions that lack chemical inventories to establish one.
  • Developing “excellent practices” for such inventories, in terms of information to include, the form it should take, and relevant quality assurance and quality control procedures.
  • Developing a global inventory with information from different regional inventories that is managed by a third party. This inventory could be managed in a way that protects company research and property rights, as well as potentially include a broader class of chemicals than those used solely for industrial purposes.

My colleagues and I cited similar opportunities in our paper, and we also envisioned taking them further, to assemble an international database that would include relevant hazard, exposure, use and risk information on individual chemicals. 

Much more remains to be done in order to increase the pace at which chemical hazards and risks are identified and prioritized. Although much progress has been made in the nearly 15 years since the United Nations formally adopted its Strategic Approach to International Chemicals Management (SAICM) in 2006, significant gaps remain, particularly in developing countries that may lack sufficient resources and expertise.

Citing the T&IH study, the International Council of Chemical Associations (ICCA) announced its proposal for an “international navigator” – a global repository of publicly available information on chemicals.  ICCA’s vision is that a navigator could be based on existing databases such as the OECD eChemPortal or others from the EU, United States, Canada, Japan and others.  ICCA is currently in discussions with a wide group of stakeholders about how such a navigator could meet their needs and be operationalized.

Significant progress can be achieved by focusing on shared goals, understanding and acknowledging our differences and committing to work collaboratively together to achieve them.

Endnotes

1 The major barriers to estimating the numbers of industrial chemicals in commerce, include: (1) a lack of chemical inventories for most countries/regions in the world; (2) uncertain and variable definitions of “chemicals”, “industrial chemicals”, and “in commerce”; (3) varying production and/or import volumes for reporting; (3) uncertainty as to whether chemicals initially notified to governments remain on the market and/or whether new chemicals notified since then were even ever brought to the market; (4) poor/incomplete or duplicate chemical identities; (5) chemical identity claimed as Confidential Business Information (CBI); and (6) unintended incentives for companies to over report or misreport.

2 The T&IH study used a definition of industrial chemicals consistent with the EU REACH Guidance on Registration and focused on discrete substances manufactured or imported at 1 tonne/annum and excluded active ingredients in pesticides, biocides, veterinary products, and pharmaceuticals, production wastes, non-isolated intermediates, polymers (although the monomers and any additives are included), naturally occurring chemicals and several other categories.

3 While the authors describe them as chemical inventories, several of them (e.g., US TSCA Chemical Data Reporting, EU Pre-Registered Substances, Nordic countries Substances in Preparations, India Inventory of Hazardous Chemicals, etc.) actually do not serve as national chemical inventories and were created and maintained for different purposes. Thus, treating them as if there are all inventories risks overlooking important differences.

4 The authors use of the terms “registered” and “registration” applied to all 22 inventories is somewhat unusual and prone to misinterpretation as those terms are actually used in reference to only a few of them (e.g., the EU REACH database). Registration most often implies a high cost barrier for companies wishing to gain government authority approval to place a new chemical on the market. A more accurate term for most of the databases would be notification, which implies a much lower cost barrier.

5 The numbers presented here represent the totals after removing entries designated as polymers. The estimate of 12,000 chemicals on the Japanese market derives from a Japan Ministry of Environment submission to SAICM, which asserted there were 11,897 industrial chemicals on their market produced or imported at 1 ton/year or more.