Cruising EPA’s CompTox Chemicals Dashboard

April 14, 2021

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A flow chart showing information sources for EPA's CompTox Chemicals Dashboard. Image: Wikimedia Commons. Click to enlarge.

Reporter’s Toolbox: Cruising EPA’s CompTox Chemicals Dashboard

By Joseph A. Davis

One of the “joys” of environmental journalism is coming across the names of chemicals you may have trouble pronouncing — but that can kill people, either quickly or slowly. And there are a lot of them.

Databases have been part of our education about chemical toxicity and ecological consequences. There are also a lot of those. 

But there is one huge database that can help tell journalists and the public almost anything they need to know about a vast number of chemicals. It’s called the CompTox Chemicals Dashboard. 

CompTox launched in 2016, and is run by the U.S. Environmental Protection Agency, with its main office in Research Triangle Park, N.C. The data is “quality controlled,” as far as possible, and it is online, free, open, searchable by anyone and downloadable.

Currently, the database has grown to cover some 883,000 chemicals. And it is arguably higher-level than most other chemical databases, if only because it incorporates, integrates and subsumes most of them. 

It is in effect a database of databases. You can start searching at the main portal. 


First, alternate sources of chemical data

Remember that CompTox may not be the first or only database that journalists (or scientists) might want to consult, so it may help to discuss the differences. 

For instance, you may just want to find quick, accurate information about whether a chemical is toxic. So for simple questions about common chemicals — maybe, for example, you just want to know if benzene causes cancer, or whether atrazine mimics estrogen —you might sooner consult the Occupational Safety and Health Administration’s searchable MSDS database

Or for a broader look at a bigger group of chemicals, you might try the National Library of Medicine’s authoritative PubChem database. You might want to use the EPA’s Toxic Substances Control Act chemicals inventory. And if toxic releases are your quarry, you might go to EPA’s Toxics Release Inventory list of reportable chemicals.

Another long-established standard is the Chemical Abstracts Service, or CAS, run by the American Chemical Society. It sets a unique numeric identifier for every unique chemical, which helps with reference. You can use a CAS number to look up a chemical on CompTox. But apart from the unique registry numbers, CAS costs money.

Another database shut down under the Trump administration in December 2019, causing angst among free-data geeks, was the National Library of Medicine’s TOXMAP. It was handy because it arrayed in map form the occurrences of toxic pollution by lots of chemicals. There is no exact replacement. (You can make maps from EPA’s RSEI database.) Environmental journalists liked it because they often come at pollution geographically, and because it was user-friendly. RIP.


How to use CompTox data smartly

What matters to most people (and for the environment) are the chemicals commonly in commerce around the world — long estimated at roughly 40,000 to 60,000. Nowadays, though, many believe those old guesses are underestimates.

So it has become more important to uniquely identify and consistently distinguish individual chemicals. Engineers are still studying chemicals and bringing them into production and use. And to do so safely, industry, scientists and regulators need to know more. 

This tells you why the 883,000-chemical size of CompTox makes it primarily a database for researchers. 

For sure, CompTox is incredibly powerful in ways that make it useful to chemists, toxicologists and environmental scientists. You can look up a chemical in many different ways — not just by chemical name or CAS number, but by molecular weight and structure as well. 


Once you find a chemical of interest, 

you can follow links to a wide 

universe of research about it.


Once you find a chemical of interest, you can follow links to a wide universe of research about it. That includes “physicochemical, environmental fate and transport, exposure, usage, in vivo toxicity and in vitro bioassay data.” It goes beyond pure chemistry to tell us about environmental impact.

Another strength is CompTox’s ability to do batch searches. This is handy in an era where we worry about whole classes of chemicals. 

Sadly, few news stories get beyond the trite and easy “forever chemicals” moniker for the PFAS chemicals that are making so much news today. In reality, there are some 4,700 of them, which is one thing making them so hard to regulate. (It also makes them hard to write about.) 

But CompTox’s batch search capability makes it a little easier to deal with large lists of chemicals and to generalize about them. In fact, CompTox maintains a list of many lists of chemicals that you might want to investigate.


Applying AI, big data

One of the farthest-out capabilities of CompTox is its ability to make predictions using artificial intelligence. 

That’s right. If you give it information about a chemical’s molecular weight or structure, or chemical family, it offers predictions about (among other things) the likelihood of human exposure to a chemical or chemicals. Or the likelihood of toxicity. Or about what will happen to a chemical as it follows its life-cycle or metabolic pathway through the environment. 

Is this always accurate? Hardly. Even if it is not, it is helpful, especially when researchers are looking for the trouble that chemicals may cause. 

In the historical past, many of our problems with environmental toxicity were caused by not being able to imagine what could happen. (Or ignoring it.) Anyway, the predictive ability may mean we kill fewer rats while discovering things. 

Making predictions is not just a whizbang feature of CompTox; it is the ballgame. It is the future direction of much modern toxicology.

You can find more information about predictive toxicology, including on the EPA’s ToxCast program, on techniques and systems being used and on the application of big data.


Highly technical, but highly powerful

Much of what CompTox can do is beyond the ken of workaday environmental reporters — but it can still help journalists, if only by raising questions. 


It may raise the consciousness of

environmental and science writers

merely to know there are fields called

“computational toxicology” and “chemoinformatics.”


It may raise the consciousness of environmental and science writers merely to know there are fields called “computational toxicology” and “chemoinformatics.” (Computational Toxicology, get it?) 

It may be that on occasion (maybe more occasions), environmental journalists need to be interviewing people who work in these fields. It makes little splash, but EPA is way into computational toxicology and is collaborating with a broad community of other research organizations. 

One drawback is that the explanatory documentation for CompTox is not great — or not available in the place or context where it would be most helpful. What is there assumes you already know a good deal about chemistry, toxicology and the fate of chemicals in the environment.

But think of CompTox as the front end — the dashboard. Behind it is a lot of complicated, sophisticated knowledge and technology. An example is EPA’s Distributed Structure-Searchable Toxicity (DSSTox) Database. Or EPA’s Toxicity Forecaster (ToxCast). Or the National Library of Medicine’s PubChem database.

Sure, it’s technical. But if you are curious and want to explore how it may help answer questions in the stories you are working on, you can find more information about the CompTox Chemicals Dashboard explained (here too), its history and in this collection of primer videos.

Joseph A. Davis is a freelance writer/editor in Washington, D.C. who has been writing about the environment since 1976. He writes SEJournal Online's TipSheet, Reporter's Toolbox and Issue Backgrounder, as well as compiling SEJ's weekday news headlines service EJToday. Davis also directs SEJ's Freedom of Information Project and writes the WatchDog opinion column and WatchDog Alert.

* From the weekly news magazine SEJournal Online, Vol. 6, No. 15. Content from each new issue of SEJournal Online is available to the public via the SEJournal Online main page. Subscribe to the e-newsletter here. And see past issues of the SEJournal archived here.

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