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What is a Biohazard?

What is a Biohazard?

Let’s start with the basics: “What is a Biohazard?”

A biological hazard or biohazard, refers to any biologically derived substance – containing harmful microorganisms or toxins – that pose a threat to the health of other living organisms, such as humans, animals and the environment.

Biohazards can harbour harmful agents, such as viruses, bacteria, fungi and parasites, as well as other biological toxins. These substances can be encountered through various means, such as human or animal blood, tissues, bodily fluids and other contaminated materials.

Exposure through inhalation, ingestion or direct contact can lead to infections, infestations or disease.

The term “biohazard” comes from the Greek word bios, meaning “life”, indicating that the source of the hazard is biological in nature. This distinguishes it from chemical hazards, which involve toxic substances that originate from non-living sources.

Biological hazards can lead to infectious disease outbreaks, animal plagues and insect infestations and are commonly found in unsanitary or high-risk environments such as crime scenes, scientific laboratories, medical facilities and regions effected by conflict or extreme poverty.

We offer specialised removal and decontamination services for a range of different chemical and biological hazards, ensuring your space is restored to a condition safe for use. For many, it can often be unclear what qualifies as a biohazard, which is why our teams are always on-hand to provide further guidance.

In the meantime, let’s explore some common examples you may encounter in everyday life.

The Biological Agents Behind Biohazards

Microorganisms and biotoxins are considered the biological agents or direct cause of the biohazard, due to the harmful nature they have against living organisms

Microorganisms

Viruses

Some of the most common respiratory viruses seen in the UK, such as COVID-19, influenza and RSV, are primarily transmitted through saliva. However, viruses can also spread through other forms of contact, including the sharing of blood or other bodily fluids, as seen with conditions like HIV, chickenpox and herpes.

The fatality rates of history’s most severe infectious disease outbreaks highlight the devastating impact of biohazard exposure, with the UK alone recording over 200,000 deaths during the recent COVID-19 pandemic. In our blog, we explore the history of pandemics and the critical importance of deep cleaning.

What is a biohazard - Covid-19 Virus.

Bacteria

In the UK, prevalent examples of harmful bacteria include E. coli, Campylobacter and Salmonella.

Animals and food have long been common routes for bacteria to spread, historically contributing to the creation of plagues.

The Plague of Justinian, which was estimated to have reached Europe around 541 AD, was the first major plague recorded to strike the continent. From this point, plagues became a recurring problem across Europe, with the 1346 bubonic plague, known as the “Black Death,” estimated to have killed around 50% of the population.

Both outbreaks were caused by the same strain of Yersinia pestis bacteria, which spread through fleas on rodents. Thankfully, with the introduction of efficient sanitation and antibiotics, the risk of such widespread consequences and transmission is minimal in the modern day.

Fungi / Mould

Fungi are microorganisms that feed on organic matter, commonly encountered as mushrooms, yeast and mould. One notable type of household mould is Stachybotrys, also known as black mould, which can have serious health consequences with prolonged exposure.

We provide specialised mould remediation services for properties affected by mould. To learn more about the dangers of mould, read our blog: Don’t Ignore Damp and Mould This Winter.

What is a biohazard - Mould.

Parasites

Parasites are microorganisms that typically live on or inside a host. Examples include worms such as tapeworms, threadworms, Cryptosporidium, Giardia, lice and scabies.

Whilst some parasites, like lice, are highly contagious, they are generally considered relatively harmless.

Other Biological Toxins

Poisonous Substances

Common examples of poisonous substances include venom secreted by animal glands, botulinum toxin (the active ingredient in injectable Botox) and ricin produced by the castor oil plant. The severity of toxicity varies; for instance, Botulism from contaminated food can cause severe food poisoning, however Botox which derives from the same toxin, is considered safe by the Medicines and Healthcare products Regulatory Agency (MHRA).

Lab-based Residue

In the scientific and medical industry, experiments are often conducted utilising living organisms, such as humans, plants and animals. Chemical by-products that are bacterial, viral or toxic, such as endotoxins from pharmaceutical drug production, can often be produced as a result of this research.

The Control of Substances Hazardous to Health Regulations 2002 (COSHH) is the main legislation in place in the UK that regulates the use of these substances in labs.

Common Carriers of Biohazards

Carriers or sources of biohazards are the means by which harmful agents are transmitted.

Human or Animal Bodily Fluids

Bodily fluids are a common route of transmission for various biological hazards. For instance, bloodborne pathogens like HIV and hepatitis are often transmitted through needles and sharps.

These fluids can be found in tissue, human remains, medical or surgical waste, as well as in soiled bedding and used PPE, all of which can be contaminated.

Medical Waste Bin.

Crime scenes and medical facilities are particularly high-risk areas for these types of biohazards, requiring strict health and safety protocols. In our blog: “It’s Not Just Crime Scenes That Need Bodily Fluid Disposal”, we discuss the various situations where clean up of bodily fluids is necessary.

Human, Animal and Pest Waste

Another common route for the spread of disease is through human, animal and pest waste. This includes droppings and faecal matter from rodents, which can transmit leptospirosis, along with pigeon guano, dead pests and other animal carcasses.

Pests are considered a high health risk due to the bacteria-laden environments they inhabit. The prevalence of food poisoning highlights the importance of regularly decontaminating food preparation areas, where pests can harbour if not properly managed.

Rodents in restaurant.

Environmental Sources

One often overlooked source of biohazard exposure is environmental contamination, such as contact with floodwater or buildings that harbour mould due to poor ventilation.

Exposure to Biohazards

The consequences of biohazard exposure vary depending on the type of hazard, the method of exposure and your overall health at the time. Whilst some exposures may cause no harm, others can result in more serious effects.

Common reactions include;

  • Respiratory issues
  • Nausea and vomiting
  • Gastrointestinal problems
  • Flu-like symptoms
  • Infections of cuts or scrapes
  • In some severe cases, fatality.

The Biohazard Symbol

The biohazard symbol is an internationally recognised pictogram used to alert the public to the presence of harmful substances. It is commonly displayed in medical facilities and waste disposal areas to indicate potential risks.

Biohazard Symbol.

Biohazard Classification

The Health and Safety Executive and COSHH classifies biohazards based on the level of risk they pose to humans and the environment, with Risk Group 1 representing low risk and Risk Group 4 indicating very high risk.

The Importance of Professional Biohazard Cleaning Services

As a home or business owner, it is your responsibility to ensure your property is safe for all who use it, whether family, friends or employees. If you encounter a biohazard, make sure to cordon off the area to minimise risk of exposure.

With the use of appropriate PPE and cleaning chemicals, low-risk biohazards can be safely managed at home or on-site. However, if uncertain, it’s always best to seek professional assistance – your health is not worth the risk .

We offer a variety of biohazard cleaning services, including Trauma & Crime Scene Decontamination, Ozone treatments, Needle & Sharps disposal, Animal Foul cleaning and several other specialised and discreet options to suit your needs.

If you’re unsure what qualifies as a biohazard or need urgent advice, contact us on our 24-hour helpline. With over 50 branches across the UK, we have a specialist team located within just 23 miles of your postcode.

Published: 31 Mar 2025