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Why having a variety of biocides available matters to human health

Posted30th March 2020
Updated17th November 2023
Byghsclassific1

Well, what a week it’s been since my last CLP email, which was on .

We have been on Lockdown here in the UK since last Monday night, and India followed suit on Tuesday evening. Most of the EU was already on Lockdown, and my American cousins tell me that the USA is taking similar precautions, in fact most of the world seems to be working from home if they can, and “social distancing” when they are out and about.

As the rules for the UK’s Lockdown are changing regularly, I’m trying to keep all our colleagues in the UK updated with daily emails, and am also doing  every week day and reposting the videos to . If you aren’t already receiving these emails, and would like to, please reply to this email and let me know.

There’s also a news page on the Chemical Regulations Self Help Group website at  , which includes requests for help, news on how the chemical industry is helping the fight against coronavirus, links to UK government information, free resources for adult and child education, including our 3-video series ““, and craft patterns for people to try while they’re stuck at home.

This webpage has a link to the Chemicals Coffee Break, which is a Zoom chat at 2:30pm (UK time) every week day for anyone working from home or feeling isolated at work.

I’ve set up all of these things to do my best to support everyone while we are in Lockdown, feel free to participate if any of them would help. Please also feel free to connect on , follow us on  or like , which will keep you informed when new videos and information is posted.

So let’s get down to today’s CLP email, which is all about biocides, how they work, why they fail, and why it’s so important that we have a wide variety of them available to deal with a crisis like the one we’re in at the moment.

As I’m sure you already know the meaning of the word biocide, which is “the destruction of life”. It comes from the greek bios, “life” and Latin cide, used generically in English as “kill” (nerd fact, there are over 30 Latin words for kill ).

And you are probably also aware that there are many different types of biocide which kill different things in different situations, and which go by a multitude of names:

  • people and animals, where they’re called “poisons” or “toxins”
  • diseases of people and animals, when they’re called “medicines” or “veterinary medicines”
  • unwanted plants (herbicides), fungi (fungicides), insects (insecticides), which together are known as “plant protection products”
  • unwanted animal pests such as rodenticides, acaricides, insecticides, molluscicides etc “pesticides”
  • bacteria, moulds, slimes, fungi, viruses on food, “food preservatives”
  • bacteria, moulds, slimes, fungi, viruses on hard surfaces or textiles “biocides”, or “biocidal cleaners” or just “cleaners” or “cleaning agents”

You can see that some biocides are considered beneficial, like medicines, and others are unwanted, like poisons.

One of the problem with biocides is that they can often be the same substance but have different names (and be regulated differently) when used differently.

For example, warfarin is used as a rodenticide, to kill rats and mice which may eat and soil our food supply, through thinning their blood and causing them to bleed to death internally. It is also a drug which keeps many humans alive by thinning their blood to a (lesser, controlled degree), and preventing blood clots forming which might other wise kill them through clots on the lungs, the heart or the brain.

And of course nearly every substance is biocidal when used in the wrong way.

This point is often lost of the “Greens” who shout very loudly about all chemicals being dangerous, despite the fact that every physical thing in the universe, all humans included, are made of chemicals!

Water is essential to life, but if you inhale too much of it, you’ll drown. In fact, it’s the chemical which kills more people worldwide than all of the others put together, but no sane person is calling for it to be banned.

Anyway, you may be amused by this parody of “Green” concerns, “”, and also this  (#spoileralert dihydrogen monoxide = H2O = water).

At this point, you may be recalling the Paracelsus quote “the dose makes the poison”, or more accurately “What is there that is not poison? All things are poison and nothing is without poison. Solely the dose determines that a thing is not a poison.” We’ve known that substances are hazardous in certain circumstances for around 500 years, and probably much longer. Paracelsus gets the credit because he created the catchphrase.

But for this article, I want to focus on biocides under the Biocidal Products Regulation (BPR), that is biocidal cleaners. (We won’t include pesticides such as rodenticides which are gradually being brought into BPR).

Other types of biocide are covered under Plant Protection Products, Medicine, Vet Medicine and Food regulations).

This list of biocides does not include some of the most common cleaners, because these tend work on the physical destruction of the bacteria or microbe, and also because they’ve used without any loss of effect for hundreds if not thousands of years.

These include: heat (sterilising a needle in a flame before removing a splinter); hot water (boiling nappies to sterilise them); soap and surfactants, and bleach (disrupts cell walls); and strong alcohols (at much stronger concentrations than is safe to drink, and some alcohols are unsafe in any concentration or any amount).

These are all traditional cleaners we used in our homes for many years, for our bodies, our clothing and our hard surfaces.

However, in recent years there has been a great increase in the use of biocidal cleaners which come under BPR.

This is in part due to the rise of washing machines which have low-temperature wash programmes, and people being encouraged to wash as these low temperatures (30 and 40 oC). This trend for low-temperature laundry is entirely due to the Greens’ emphasis on the need for a low-energy economy to tackle the perceived problem of “man made climate change”.

What this has done is create a new problem, as heavily soiled laundry will still contain pathogens even after it has been washed. To resolve this, biocidal laundry detergents have been created.

At the same time, as science education becomes less effective, people seem to be more “germ-phobic”, and this fear, whether real or imaginary, has led to a great increase in the use of BPR-registered hard surface cleaners in the home.

We cannot blame the biocide industry for taking advantage of a growing marketplace, even if it is likely to have long term adverse effects on human health, as we will see.

The biocides which come under BPR generally work through poisoning the cell of the microbe so it dies off.

This means that they are vulnerable to a phenomenon called resistance. This is well-known in the medical world, with Methicillin-resistant Staphylococcus aureus (MRSA) being the most obvious example. This is where a microbe begins to tolerate a biocide, sometimes even to feed off it, and it no longer works.

However, resistance can also occur with any biocidal product used on microbes. As you might expect, once a pathogen has resistance to a substance in one context, it tends to have it in another. So microbes which have become resistant to a drug can also be resistant to the drug molecule if it were to be used in a cleaning product.

Where does resistance come from? Is this something which mankind has caused, by creating synthetic chemicals through reaction? In fact, resistance is part of a very old dance between multi-cellular organisms like plants and higher animals, and microbes like bacteria, fungi and viruses.

The microbes want to feed on the plants and animals (including us humans), so multi-cellular organisms have developed mechanisms to kill them, like pyrethrum which is created in some plants to poison insects. Then the microbes develop ways to react to the poison, so it doesn’t work, or even to use it as a food, the target organism develops new poisons, and so on, with an “arms race” where both sides are continually evolving.

To put this into perspective, the world is around 4.5 million years old, the oldest bacteria (prokaryotes) appeared 3,500 million years ago, the first multi-cellular organisms arrived on land about 1000 million years ago, mammals appear in the fossil record only 66 million years ago, hominids 6 million years ago, and modern humans only 250,000 years ago.

There’s a really good image of the Earth’s history as a 24-hour clock (noon is at 6pm)  .

So by creating new poisons for microbes, we are deliberately taking part in the “resistance arms race”, and, with hindsight, we shouldn’t be surprised when it happens. After all, microbes have been around an awful lot longer than we have, and can survive in very hostile environments such as the freezing Antartic, around sulphur vents of underwater volcanoes etc.

In order to deal effectively with resistance, there are three main tools.

  • Delay the onset of resistance by using biocides as sparingly as possible
  • Try to ensure that you kill all of the microbes effectively when you use a biocide
  • Evolve new biocides as resistance develops

We should all try to use biocides sparingly, to keep them useful for as long as possible. In terms of cleaning, we should use the traditional methods to clean our house and laundry, that is hot water, soap, and ordinary laundry detergent for clothes, and not use cleaners or laundry detergents containing biocides registered under BPR.

You can tell this from the label, it will say “kills germs” or similar, and there will be biocidal products listed on the label ingredients, which you can check at  using the chemical search to see if they are BPR-registered). Where we are worried about germs, we can continue to use bleach spray on surfaces, and liquid bleach on areas like the loo pan, because that doesn’t cause resistance.

The development of resistance is why I said earlier that using biocidal cleaners in the home may be a bad idea in the long term. The more we use biocides in the home, the more likely they are to develop resistance, and then they simply won’t work any more for us. If we use biocides where we don’t need to, we shorten the time for resistance to develop, and that can end up killing people from bacterial and viral infections.

This need to use biocides sparingly is known about in medicine, and is why your doctor is more reluctant to prescribe antibiotics than they used to be e.g. in the 1970s when I was growing up.

When we use biocides, we should try to make sure we use them thoroughly, and kill the pathogen completely, which will prevent that individual colony from starting to develop resistance. This is why our doctor always tells us to finish the course of antibiotics, even though we may feel better part way through.

The main method we can use against resistance is to evolve new products to out-compete the microbes. There are two ways of doing this:

  • Make new biocidal actives
  • Make new biocidal products at different concentrations, or combining two or more biocidal actives in different concentrations

Obviously, it is much more expensive and time consuming to develop new biocidal actives, so historically resistance was dealt with by making new biocidal products, that is new formulations containing different mixtures of biocides, and varying the concentrations.

And this brings back to the Biocidal Products Directive.

This has had a large impact on the number of biocidal products available on the EU marketplace, because a lot of the older biocidal actives which used to be made cheaply could not bear the costs of registration, so we have a reduced number of actives compared to e.g. 20 years ago.

Not only that, but biocidal products also need to be registered, in the exact concentration they will be used. And if it takes hundreds of thousands of euros to register each product, and 6 to 12 months to test and register it, it prevents new formulations being developed.

The overall workings of BPR have been to reduce the ability of the EU chemical industry to respond to biocidal resistance to the point where it is so slow that it exposes vulnerable people to resistant pathogens. People will die un-necessarily, because of these regulations.

And the Coronavirus outbreak is one of these times, where the virus mutates rapidly, and may be able to evolve biocide-resistant strains quickly, and yes, , it’s not just confined to bacteria.

The regulators are currently loosening the requirements for BPR at both ECHA and individual country level, and while this is welcome in the current crisis, it is not what is required in the long term.

We need a combination of allowing a much wider number of biocidal actives on the market, with a tightening on their use in non-essential applications such as household cleaners, and laundry detergents.

And if this means stopping the sale of low-temperature washing machines, and encouraging higher temperature laundry, then that is a small price to pay (especially as microbial resistance is a much more immediate and real risk to the human population than any hypothetical changes in the climate due to mans’ actions).

In the UK, we have the opportunity to do this under Brexit, and I would hope our friends in the EU are thinking about this as well.

I hope that this article has been interesting, and I will do my best to continue our Monday CLP articles throughout the Coronavirus crisis period.

Wishing you, your family and colleagues good health,

GHS Classification Courses from TT Environmental Ltd

30th March 2020

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