From tampons to toothpaste: Natalie Bennett’s crusade against hidden biocides

29 May 2025

Green peer Natalie Bennett is on a mission to curb the unchecked use of antimicrobial chemicals in everyday products. In a candid conversation with CIWEM’s Planet Possible podcast, she explains why we need to rethink our relationship with the invisible microbes all around – and within – us.

Natalie Bennett wants to restrict the use of microbe-killing chemicals in our mouthwash, toothpaste and tampons. The Green Party peer, leader of her party from 2012 to 2016, recently bought a private members’ bill to Westminster to regulate so-called biocides – human-made pesticides, fungicides and herbicides – in consumer products.

These chemicals don’t just impact the bugs we think of as ‘bad’ – those ones that make us sick – but every microbiome in the human body, from the most understood, such as that in our gut, to the lesser studied communities of microorganisms in the lungs, vagina and skin. Biocides directly threaten the health of all who use the products that contain them, says Bennett, but also have extremely concerning wider impacts too. Not only do they contribute to antimicrobial resistance, a threat to humanity that’s been compared to that of the climate crisis, but they have untold effects on our environment, as they are washed down the drain and into water supplies.

This month on CIWEM’s Planet Possible podcast, host Niki Roach talks to Bennett about her Biocides Bill, the environmental philosophy that informs her thinking, and the role of the education system in public and environmental health.

We offer a taster of their fascinating conservation here and you can listen to the full conversation by searching for Planet Possible in your favourite podcast app or via the show’s website. Follow the podcast to stay updated on our monthly deep dives into pressing environmental challenges.

Now, over to Niki and Natalie…

Niki Roach: Is there a legitimate reason why biocides, these microbe-killing chemicals, should be in consumer products?

Natalie Bennett: Someone with a diabetic ulcer, for example, may need a whole lot of applications of antibiotics to get rid of the infection in that ulcer. Chlorhexidine is in large amount of our mouthwash – it may not be needed for standard use, but there may be occasions when you might go to the dentist or go to the pharmacist and explain your problem, and it might be appropriate. It's not saying never use biocides in any product whatsoever, just that we shouldn’t just be putting them out there [thoughtlessly].

We've seen an explosion in the use of these substances, and the reason for that is essentially advertising. People who are listening to this might go out and see a billboard advertising something as antibacterial or antifungal, and, of course, COVID helped magnify this. Advertising suggests that it's better, but actually, the United States Food and Drug Administration has put out statements that antibacterial soap is absolutely no better than just standard soap, and in fact it’s harmful.

NR: So it’s not just the UK looking to restrict these?

NB: The US is significantly ahead of us. One of the famous examples of this is triclosan in hand washes, which was identified as a huge problem and banned a decade ago by the US. You could still go to a supermarket shelf in the UK, and you will find many products containing triclosan.

What's different about the Biocides Bill and this approach, and this is something that I've developed with a series of interns and supporters from the British Society for Antimicrobial Chemotherapy and from the Centre for Long-Term Resilience, is that we're saying no biocides. The approach that the US and most other places have taken is banning one particular product. But of course, this creates what's known as the ‘whack-a-mole problem’, in that if you ban one product (and we've seen this with PFAS, for example, the forever chemicals), they just produce another, probably with even worse environmental and public health impacts. So we’re starting from the basis of, let's stop this, unless you can show there is a really good reason.

NR: Where are you up to with the bill? What happens next?

NB: This is a private members’ bill and private members’ bills almost never become law. They're really more of an educative process, a way of bringing the issue to the forefront. The ideal case is that you have a private members’ bill, and 10 years later, that bill will be incorporated in a government bill and become law.

But to answer the technical question, we've had the second reading, we will then go to committee stage. Hopefully it will go through the next stages in the House of Lords, and will clear the House of Lords, and then it goes down to the House of Commons, but it won't progress. I can always remain in hope, but I wouldn't claim to anyone that's a likely outcome.

NR: Give me a sense of why this is important to you.

NB: I see this as part of a very broad attempt to change the way we all think. I have a book out at the moment called Change Everything, and this is part of my small steps towards changing everything. The Stockholm Resilience Centre at Stockholm University identifies nine planetary boundaries. Now I wouldn't say that [framework] is perfect, but it at least gives us an attempt at a holistic and earth system science approach to decision making.

Climate is the one everyone knows about. Most people probably talk a bit about biodiversity, the collapse in natural systems. This whole issue of biocides is part of a broader issue of what's known as novel entities – pesticides, pharmaceuticals and plastics – all these substances that, essentially, nature has no mechanism to deal with, that are toxic to life, and we are spraying them out into the environment in huge quantities. We have almost no understanding of that cocktail effect – the way in which your body, the animal drinking at the stream, the algae in the stream, isn't just exposed to one of these things, it's got this whole cocktail of pesticides, pharmaceuticals, microplastics, nanoplastics, bombarding it from all sides.

This bill is an attempt to start with some very specific things, but also get people thinking about how we have to live within the physical limits of this one fragile planet.

More than that, my green politics, if you like, comes through the understanding that we could all have a decent life, we can look after climate and nature – if we use the resources of the planet, care for them and share them out fairly. That's the foundational place. So I'm going from the tampons and the mouthwash right through to changing everything.

NR: The products that you're talking about with the Biocides Bill, what do we know about their impact on our wider environmental systems, things like water and soils?

NB: Very little. Exeter University is doing a lot of really excellent research. A lot of this is so new, and it's not funded because, who's going to fund this? Pharma companies want to fund things that will get products approved. Governments have cut massively their amount of funding. Environmental funding is under extreme threat. So we don’t really know the impact.

We need to bring in the precautionary principle here and that's, if we don't know if something's going to make a mess, maybe we should just not do it. Lip service is paid very often to the precautionary principle, but actually, you just look at what's happening, you think of what's in the river down the road from your house, and we are pumping all of these materials in, and we haven't given any thought at all to the impacts.

The classic example of this was microbeads. Somehow or other it was decided that tiny bits of plastic should be put into face scrubs, into toothpaste, into all sorts of substances that were going to be washed down the sink. And no one stopped and asked, but what's going to happen to all of this plastic, and what's the impact going to be?

That's one case where we saw rapid action. The US acted before us to ban microbeads in cosmetic products and the UK followed a few months later. But that was one tiny fraction of what we're actually putting out there [now, in the case of biocides].

NR: You can physically see the plastic pollution happening with the microbead and I wonder whether it's sometimes harder for people to get behind the idea of biocides, because it's almost invisible.

NB: When we're talking about biocides, I think what we need is a real transformation of thinking. An understanding that bacteria, fungi, all the other microbes, are part of our life. They are part of us, and they are part of our world, and we want to keep all of that in balance, not go around spraying things to kill them every time we get the chance.

Listen to the full conversation here. You can search also for Planet Possible in your favourite podcast app. Subscribe so as not to miss an episode.

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