Skip to main content
Move the World.
AI Could Replace Chemical Testing on Animals
Credit: Daniel Watson

Most consumers would be dismayed with how little we know about the majority of chemicals. Only 3 percent of industrial chemicals – mostly drugs and pesticides – are comprehensively tested. Most of the 80,000 to 140,000 chemicals in consumer products have not been tested at all or just examined superficially to see what harm they may do locally, at the site of contact and at extremely high doses.

I am a physician and former head of the European Center for the Validation of Alternative Methods of the European Commission (2002-2008), and I am dedicated to finding faster, cheaper and more accurate methods of testing the safety of chemicals. To that end, I now lead a new program at Johns Hopkins University to revamp the safety sciences.

As part of this effort, we have now developed a computer method of testing chemicals that could save more than a US$1 billion annually and more than 2 million animals. Especially in times where the government is rolling back regulations on the chemical industry, new methods to identify dangerous substances are critical for human and environmental health.

How the computer took over from the lab rat

Our computerized testing is possible because of Europe’s REACH (Registration, Evaluation, Authorizations and Restriction of Chemicals) legislation: It was the first worldwide regulation to systematically log existing industrial chemicals. Over a period of one decade from 2008 to 2018, at least those chemicals produced or marketed at more than 1 ton per year in Europe had to be registered with increasing safety test information depending on the quantity sold.

Our team published a critical analysis of European testing demands in 2009 that concluded the demands of the legislation could only be met by adopting new methods of chemical analysis. Europe does not track new chemicals below an annual market or production volume of 1 ton. But the similar size U.S. chemical industry brings about 1,000 chemicals at this tonnage range to the market each year. However, Europe does a much better job in requesting safety data. This also highlights how many new substances should be assessed every year even when they are produced in small quantities below 1 ton, which are not regulated in Europe. Inexpensive and fast computer methods lend themselves to this purpose.

Our group took advantage of the fact that REACH made its safety data on registered chemicals publicly available. In 2016, we reformatted the REACH data, making it machine-readable and creating the largest toxicological database ever. It logged 10,000 chemicals and connected them to the 800,000 associated studies.

This laid the foundation for testing whether animals tests – considered the gold standard for safety testing – were reproducible. Some chemicals were tested surprisingly often in the same animal test. For example, two chemicals were tested more than 90 times in rabbit eyes; 69 chemicals were tested more than 45 times. This enormous waste of animals, however, enabled us to study whether these animal tests yielded consistent results.

Our analysis showed that these tests, which consume more than 2 million animals per year worldwide, are simply not very reliable – when tested in animals a chemical known to be toxic is only proven so in about 70 percent of repeated animal tests. These were animal tests done according to OECD test guidelines under Good Laboratory Practice – which is to say, the best you can get. This clearly shows that the quality of these tests is overrated and agencies must try alternative strategies to assess the toxicity of various compounds.

Big data more reliable than animal testing

Following the vision of Toxicology for the 21st Century, a movement led by U.S. agencies to revamp safety testing, important work was carried out by my Ph.D. student Tom Luechtefeld at the Johns Hopkins Center for Alternatives to Animal Testing. Teaming up with Underwriters Laboratories, we have now leveraged an expanded database and machine learning to predict toxic properties. As we report in the journal Toxicological Sciences, we developed a novel algorithm and database for analyzing chemicals and determining their toxicity – what we call read-across structure activity relationship, RASAR.

This graphic reveals a small part of the
chemical universe. Each dot represents a
different chemical. Chemicals that are
close together have similar structures
and often properties.

This graphic reveals a small part of the
chemical universe. Each dot represents a
different chemical. Chemicals that are
close together have similar structures
and often properties. Credit: Thomas Hartung, CC BY-SA

To do this, we first created an enormous database with 10 million chemical structures by adding more public databases filled with chemical data, which, if you crunch the numbers, represent 50 trillion pairs of chemicals. A supercomputer then created a map of the chemical universe, in which chemicals are positioned close together if they share many structures in common and far where they don’t. Most of the time, any molecule close to a toxic molecule is also dangerous. Even more likely if many toxic substances are close, harmless substances are far. Any substance can now be analyzed by placing it into this map.

If this sounds simple, it’s not. It requires half a billion mathematical calculations per chemical to see where it fits. The chemical neighborhood focuses on 74 characteristics which are used to predict the properties of a substance. Using the properties of the neighboring chemicals, we can predict whether an untested chemical is hazardous. For example, for predicting whether a chemical will cause eye irritation, our computer program not only uses information from similar chemicals, which were tested on rabbit eyes, but also information for skin irritation. This is because what typically irritates the skin also harms the eye.

How well does the computer identify toxic chemicals?

This method will be used for new untested substances. However, if you do this for chemicals for which you actually have data, and compare prediction with reality, you can test how well this prediction works. We did this for 48,000 chemicals that were well characterized for at least one aspect of toxicity, and we found the toxic substances in 89 percent of cases.

This is clearly more accurate that the corresponding animal tests which only yield the correct answer 70 percent of the time. The RASAR shall now be formally validated by an interagency committee of 16 U.S. agencies, including the EPA and FDA, that will challenge our computer program with chemicals for which the outcome is unknown. This is a prerequisite for acceptance and use in many countries and industries.

The potential is enormous: The RASAR approach is in essence based on chemical data that was registered for the 2010 and 2013 REACH deadlines. If our estimates are correct and chemical producers would have not registered chemicals after 2013, and instead used our RASAR program, we would have saved 2.8 million animals and $490 million in testing costs – and received more reliable data. We have to admit that this is a very theoretical calculation, but it shows how valuable this approach could be for other regulatory programs and safety assessments.

In the future, a chemist could check RASAR before even synthesizing their next chemical to check whether the new structure will have problems. Or a product developer can pick alternatives to toxic substances to use in their products. This is a powerful technology, which is only starting to show all its potential.

Thomas Hartung is a Professor of Environmental Health and Engineering at Johns Hopkins University. This piece originally appeared at The Conversation.

The Conversation

Up Next

State of Surveillance
New Tech Can See Through Walls and ID People by the Way They Walk
gait recognition
State of Surveillance
New Tech Can See Through Walls and ID People by the Way They Walk
A California-based lab is using gait recognition and radio frequency to create a surveillance system that can see behind walls.

A California-based lab is using gait recognition and radio frequency to create a surveillance system that can see behind walls.

ELIYSIUM
Can Science Make People Live Healthier for Longer?
Can Science Make People Live Healthier for Longer?
Watch Now
ELIYSIUM
Can Science Make People Live Healthier for Longer?
An MIT researcher has turned 30 years of aging research into something you can use right now.
Watch Now

Most of medical science focuses on combating disease and managing the impact of aging. But one MIT researcher wants to tackle aging head on. Through decades of research, Dr. Leonard Guarente has uncovered a basic mechanism to regulate aging and co-founded Elysium to turn his research into a product. Elysium’s mission is to help people live healthier for longer. Freethink is proud to present this story in partnership with...

Superhuman
These Gloves Can Teach You to Play the Piano. And Maybe Heal Your Brain.
These Gloves Can Teach You to Play the Piano. And Maybe Heal Your Brain.
Watch Now
Superhuman
These Gloves Can Teach You to Play the Piano. And Maybe Heal Your Brain.
Through "passive haptic learning", these gloves can teach you how to play the piano in an hour. Braille in four hours. Now researchers want to see if victims of traumatic brain injuries can use these gloves to re-learn critical skills.
Watch Now

Georgia Tech researchers Thad Starner and Caitlyn Seim have developed a pair of gloves for playing piano that can magically get you up to speed in just an hour. They've also taught blind people to read braille in four hours, a process that usually takes up to four months. The gloves work through a process called passive haptic learning, and is another great discovery from Georgia Tech researchers. Basically, they vibrate in...

Dispatches
Researchers Want to Create A Traffic Cop for the Sky
Researchers Want to Create A Traffic Cop for the Sky
Dispatches
Researchers Want to Create A Traffic Cop for the Sky
A new kind of radar could direct drone traffic safely around city skies.

A new kind of radar could direct drone traffic safely around city skies.

Why Researchers Built a Robot Snake
Why Researchers Built a Robot Snake
Watch Now
Why Researchers Built a Robot Snake
Believe it or not, there's a good reason this robot snake exists
Watch Now

When building robots, scientists often struggle to perfect the robot's movements. They turn to the natural world in order to solve this problem, finding inspiration from animals such as spiders, dogs, and even humans. However, studies show that even though we live in a world that is largely built for humans, robots that appear to be too "human-like" make people uneasy. Thus, researchers at Carnegie Melon developed a...

Coded
This Research Team Wants to Hack Your Car
This Research Team Wants to Hack Your Car
Watch Now
Coded
This Research Team Wants to Hack Your Car
What happens when an SUV going 75 miles-per-hour down a highway is hacked from a remote computer?
Watch Now

What happens when an SUV going 75 miles-per-hour down a highway is hacked from a remote computer? Two researchers in Pittsburgh want to make sure we never find out. As cars have become more automated, they’re becoming more hackable. But the only way to stop car hacking is to actually learn how to hack into cars and uncover their vulnerabilities.

Coded
Nico Sell Thinks Hackers Can Be a Force for Good
Nico Sell
Coded
Nico Sell Thinks Hackers Can Be a Force for Good
After criminals hijacked the term, Sell is on a mission to change our perception of hackers.
By Michael O'Shea

After criminals hijacked the term, Sell is on a mission to change our perception of hackers.

Coded
WATCH: Trailer for Our New Show, Coded
WATCH: Trailer for Our New Show, Coded
Coded
WATCH: Trailer for Our New Show, Coded
Meet the programmers on the frontlines of the war over security and privacy.
By Mike Riggs

Meet the programmers on the frontlines of the war over security and privacy.

Technology
How to Send Mail to a Person With No Address
send mail without address
Technology
How to Send Mail to a Person With No Address
Millions of people have no address. They can’t get mail, they can't vote, they can’t get aid, and they don’t have...
By Mike Riggs

Millions of people have no address. They can’t get mail, they can't vote, they can’t get aid, and they don’t have rights. One company wants to change that.