If you’ve recently been shopping for a water bottle or a food container, you may have looked out for the label, “BPA-free.” Bisphenol A (BPA) is a harmful plastic additive commonly found in food packaging and receipt papers and has been shown to act as a hormone disruptor. For example, it interferes with estrogen binding to its receptors, which renders that hormone useless to the body. 

Or perhaps you’ve switched your non-stick pan for a stainless steel one after reports on perfluoroalkyl substances (PFAS) — a group of chemicals that can leach into the environment and potentially harm human health.

BPA and PFAS are examples of synthetic chemicals widely detected in everyday products. Their environmental impact and toxicity have been extensively reported, capturing attention in both the media and scientific communities.

However, BPA and PFAS may only represent a small portion of a much larger list of harmful chemicals.

“Certain chemicals are widely studied and have striking data results,” said Derek Muir in an interview with The Varsity. Muir — an emeritus scientist at Environment and Climate Change Canada, adjunct professor at U of T’s Department of Chemistry, and a recent appointee to the Order of Canada — continued, “I don’t think people are really that aware of the sheer numbers you see,” referring to the vast amount of chemicals being produced and used.

So, just how many chemicals are we talking about? According to a 2020 Environmental Science and Technology paper, over 350,000 different chemicals and mixtures have been registered for production and use across 19 regions and countries studied. But amongst these, how many are actually leaching into our environment?

Chemical inventories don’t match up with environmental studies

In Muir’s 2023 review of chemicals in commerce, he found nearly 20,000 registered substances in the Chemical Abstract Services database whose impacts on the environment have been studied. Of these, only about nine per cent are included in the US Chemical Substance Inventory, meaning they’ve been catalogued for regulation, a crucial first step in assessing and managing their safety. When considering the inventories of China and the European Union — which together account for the largest manufacturing and consumption of chemicals — less than five per cent of the registered chemicals have been studied in the environment.

“It’s really a small subset of what is in commerce,” said Muir.

The same chemical analyzed, again and again

The ‘Matthew effect,’ where the majority of environmental measurements focus on a small number of compounds, often influences environmental scientists. In fact, the top 100 most studied chemicals account for 34 per cent of all the papers reviewed.

“There’s a tendency to go over and over the same chemicals,” commented Muir.

These measurements can be challenging. Muir explained: “There’s a limited number of toxicity tests, [of chemicals] that are analyzed and studied, and of analytical standards.” There is a concern about investing significant resources to search for a needle in the environmental haystack. 

It’s not just the chemical that needs to be analyzed; sometimes, its degradation product — what the chemical breaks down into — can even be more lethal. A notable example is 6PPD, a chemical widely used in vehicle tires, whose oxidized product has caused decades of acute salmon mortality in Seattle and its surrounding regions.

The future of environmental chemical screening

“There seems to be… no formal regulatory process to require they be analyzed in environmental media,” said Muir. So, how can we improve chemical screening in the environment?

One possible solution would be to ask manufacturers to provide a reference chemical compound. This would create a baseline for analyzing environmental samples. Rather than spending resources searching for new chemicals, efforts could be directed toward monitoring the presence of known chemicals and tracking their pathways through the environment.

The second approach is turning to computational models that can predict the fate of organic molecules once released into the environment — without lifting a pipette. “A lot of the models are often quite good, really,” he added.

Lastly, artificial intelligence is becoming an important tool. With a growing number of chemicals being manufactured and used and limited resources for environmental scientists, ongoing efforts are being handed over to algorithms to find solutions.

So, the next time you walk down the kitchen supply aisle at your local store, you may need to look out for more than just the BPA-free label.