Last reviewed 19 June 2013

In this first article of a two-part feature, Dr. Heather Mawhinney gives an overview of the regulation of biocides and their role in disinfection.

Introduction to biocides

The term “biocide” describes a very diverse group of products which includes disinfectants, pest-control products, insect repellents and preservatives. A biocidal product can be defined as one which controls harmful or unwanted organisms, such as viruses, bacteria, fungi, insects and animals, through chemical or biological means, using the active substance(s) it contains or generates.

This first article of a two-part feature on biocides gives a general overview of their regulation and role in disinfection whilst the second article considers their safe selection and use for the purposes of disinfection.

Regulation of biocides

Although biocides are used to protect human and animal health, due to their intrinsic properties and uses, such products may themselves also pose health risks and be harmful to the environment. Because of their nature it is imperative that there are safeguards in place to ensure that products containing biocides can be used without causing harm to people, the environment or wildlife.

It is vital therefore to ensure that only biocidal products safe for use are placed on the market. In the UK, the HSE is the Competent Authority for biocides and as such, it assesses the safety of such products and the active substances they contain, and it puts conditions on the use of these products.

Making biocidal products available on the market has been subject to the Biocidal Products Directive (BPD) since 1998. Although the BPD ensured high standards of health and environmental protection, it proved extremely costly for industry. There has been recent work to revise this legislation, and the new Biocidal Products Regulations (BPR) (in force from 1 September 2013) has a transitional period for certain provisions. The new BPR repeals and replaces the Biocidal Products Directive (Directive 98/8/EC) and makes some significant changes to the way biocidal products are regulated in the European Union, as well as how “treated articles” and “food contact materials” containing biocides are regulated.

The new Biocides Regulations aim to simplify and streamline existing EU requirements without reducing the level of protection it offers to health and the environment. Generally speaking, the new BPR retains and consolidates the legal framework established under the current BPD.

Types of biocides

There is a wide spectrum of biocidal substances available on the market; major types include halogen compounds, metallic compounds, organosulfurs, organic acids and phenolic substances. Biocides have been categorised into 23 different product types which fall into four main groups.

  • Group One — Disinfectants and General Biocidal Products, eg human hygiene products, food area and veterinary products.

  • Group Two — Preservatives, eg wood preservatives and cooling preservatives.

  • Group Three — Pest Control, eg includes insecticides and rodenticides.

  • Group Four — Other Biocidal Products, eg preservatives for foodstuffs and embalming fluids.

Use of biocides for disinfection

Worldwide, the biocide market is witnessing an increase in demand on account of growing demand for pure water and the entry of environmentally friendly products. However, growth in the market is hindered by rising raw material costs and difficult and expensive registration processes.

Recent market research has revealed one of the main application areas of biocidal substances is in washing and cleaning products, where, in some instances, the intended effect is not always primarily biocidal but actually bleaching. This application area can be further sub-divided into:

  • surface disinfection, eg using sodium hypochlorite

  • laundry disinfection/cleaning clothes, eg using hydrogen peroxide

  • machine dishwashing, eg using products containing dichloroisocyanurates

  • water purification in swimming pools, eg using dichloroisocyanurates.

Users of biocides

Biocides can be used by people in the course of their job or business, as well as members of the public in their homes.

As biocides are intended to control harmful or unwanted organisms, it is important that there are safeguards to ensure these products can be used without causing harm to people, the environment or wildlife. Everyone who uses biocides is responsible for ensuring that they use them correctly and effectively. This will be discussed in more detail in Part 2 of this article.

Biocides selection

Biocides should be carefully selected. The following list contains some of the criteria which should be considered.

  • Effectiveness: ability to kill bacteria, minimum concentration and contact time. Safety: personnel risk assessment, neutralisation requirements, registration, discharge to environment and persistence.

  • Compatibility with other system fluids: solubility, partition coefficient, pH, temperature, hardness, level of total dissolved solids, presence of metal ions, sulfates or sulphides.

  • Handling: corrosiveness to metals and elastomers, freeze point, thermal stability, separation of components, shelf life, storage requirements.

  • Approval: details of approved products can be found via the Chemicals Regulation Directorate (CRD), which is a part of HSE and ECHA databases.

Consideration of the antimicrobial efficacy of different biocides is an important basis on which to design an effective disinfectant regime appropriate to the hygiene requirements of the area/plant/equipment. Do not assume that all the active components of disinfectants have the same spectrum of effect. Sources of contamination are also a crucial factor.

Additionally, depending on the selected biocide, it may be necessary to neutralise or deactivate the biocide in order to avoid it killing non-target organisms after use, eg on release of treated water or downstream of a treated area. Certain biocides may create toxic by-products which may persist and/or accumulate making disposal problematic.

Biocide application

Therefore, the implementation costs of biocide applications must incorporate the cost of the biocide, the detoxicant (if required), and the application method. Planning and design activities in this phase may include research and development, modeling (including impact and required specific mitigation measures), site selection and regulatory approval. .

Once the disinfection regime has been decided, implemented and is up and running, the predominant operations and maintenance costs would include application of the biocide and detoxicant, and effectiveness and water quality monitoring programs.


Good hygiene is the practice through which good health and wellbeing is promoted by people making themselves and their surroundings clean, by cleaning and, when necessary, applying disinfection products to break the chain of infection.

Cleaning and disinfection are the two strands of good hygiene. Cleaning is the mechanical or chemical removal of dirt and soil from an object or an area. This is normally achieved by cleaning with soap or detergent, and then rinsing with water to remove visible dirt, allergens and germs. Disinfection is appropriate in situations where there is high risk of transmission of germs; the targeted use of a disinfectant helps prevent infections by destroying harmful organisms and preventing them from spreading.

Disinfectants have become essential products in today’s world, both for domestic and industrial purposes. Through their contribution to good hygiene, biocides help maintain high standards of public health, while at the same time, enhancing people’s quality of life.