From nail bars to firefighting foams: how chemicals are deemed safe enough or too harmful

If you’ve sat in a nail salon recently, you may well have encountered TPO or trimethylbenzoyl diphenylphosphine oxide to give it its full chemical name. You won’t have seen the name on the bottle. But if you’ve had your gelled fingers under a blue-violet lamp, TPO could well have been part of the process.

TPO is what chemists call a photoinitiator – basically, a chemical that reacts when it’s hit with UV light. When your nails go under the lamp, TPO breaks apart and helps link tiny liquid molecules together, turning the polish into that solid, shiny, long-lasting gel layer.

It’s smart chemistry, and it’s one reason gel manicures last so much longer than normal nail polish. But recently, the EU banned TPO because research suggests it might increase the risk of cancer and could be harmful to the reproductive system.

Meanwhile, alternatives such as benzophenone and other common photoinitiators come with concerns of their own.

Benzophenone, for instance, is listed as a possible endocrine disruptor, meaning it may interfere with hormones. Another common substitute for TPO, called TPO-L is harmful to aquatic life and may cause skin allergies. None of this is hidden. The European Chemicals Agency maintains a public database where anyone can look up chemicals and find their hazard classifications and environmental data.

The point is not that nail varnish is dangerous. It is that even everyday products involve chemistry that is more complex than we might assume and that decisions about what is “safe enough” involve weighing risks, benefits and available alternatives.

The same pattern has played out recently with two much wider-reaching chemicals: Pfas, so-called “forever chemicals”, and glyphosate, a herbicide used in agriculture.

Recently, the European Commission announced new restrictions on Pfas in firefighting foam. It did this because Pfas don’t break down in the environment and can build up in living things over time, which can be harmful. Meanwhile, the use of glyphosate has been under review, with the EU approving its continued use and the UK due to make a decision in the next year or so.

None of these decisions happen instantly or automatically. Here is how chemical safety is regulated.

What Reach does

Pharmaceuticals are tightly controlled globally, but chemicals aren’t always regulated as strictly. However, in the EU and UK, chemicals are managed under a system called Reach that is often described as one of the most comprehensive chemical regulations in the world.

The basic difference in how we treat medicines versus chemicals comes down to how we think about risk. Chemicals are expected to be safe when used properly. Medicines, on the other hand, are allowed to have some risks if the benefits outweigh the risks.

That’s why harsh cancer treatments, which can have serious side-effects, are still considered acceptable – because they can save lives. And it’s also why very dangerous chemicals can still be made and used, as long as there are strong safety measures in place.

Under Reach, companies must register their chemicals and provide detailed information on a chemical’s properties, hazards and safe handling. The principle here is: “no data, no market”.

Regulators then evaluate that information – and can request more if needed. Such substances may then be authorised, meaning they can only be used if companies can demonstrate that risks are controlled or that societal benefits outweigh them while safer options are developed.

If a substance poses an unacceptable risk that cannot otherwise be managed, regulators can restrict or ban specific uses of chemicals. Later if evidence emerges that suggests a chemical can cause cancer, harm reproduction, persist in the environment, accumulate in living things, or otherwise be hazardous, it might be added to a list of “substances of very high concern”.

Reach is a strict, step-by-step system that requires companies to prove their chemicals can be used safely. But in reality, we often only learn the full effects of a chemical over time, once it is being used outside the lab and in everyday life. That’s why decisions about chemicals such as TPO, Pfas and glyphosate can change slowly and sometimes take many years to fully settle.

Safe and sustainable by design

As a result of cases such as these, many feel that despite Reach being one of the most comprehensive chemical regulations in the world, it isn’t enough. This has led to a philosophy known as safe and sustainable by design, where, instead of making a chemical and then proving it is safe, a material is designed with safety and disposal or recycling in mind.

In this area, artificial intelligence may well prove to have a major role. AI is increasingly being used to predict toxicity of chemicals and so allow them to be flagged before they are manufactured.

Chemistry has built the modern world, given us durable coatings on the ends of our fingers, high-yield crops, non-stick pans, waterproof jackets and thousands of other unnoticed conveniences. It has also given us chemicals that travel too far, last too long and accumulate where they were never intended.

The challenge is not to stop using chemistry. It is to use it wisely. Whether we are talking about manicures, farmland, or emergency foam, the principle should be the same: use chemistry that does the job, without leaving a legacy. The more we can predict that, the fewer surprises we’ll find later.

This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Mark Lorch, University of Hull

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Mark Lorch does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.