Testing & Efficacy

Here we look at critical factors for hygiene delivery and methods for testing products – including national and industry standard tests as well as customized tests.

Critical factors for hygiene delivery

The removal of visible dirt using normal cleaning products can easily be monitored by the user. But microbes are invisible and the efficacy of processes intended to leave a hygienically clean and safe result needs to be ensured in other ways.

Microbiological tests to measure any residual contamination are both complicated and take a long time to complete, so that routinely checking results is completely impracticable in most situations. In many cases, users do not have the expertise or resources to do such checks and consequently they rely on the I&I product supplier to assure the efficacy and reliability of their hygiene process.

Suppliers ensure good hygiene performance firstly by thorough testing of products, before they are put on the market, in conditions that reflect the intended use, and secondly by the development of detailed use instructions, including staff training where necessary, and/or by automatic control. Even the best performing product cannot guarantee results if it is not properly and appropriately used.

Developing a suitable combination of product and procedure to deliver the desired hygiene result must begin with choosing an ingredient that is effective against the relevant types of microbes. The different kinds of microbes (such as bacteria, fungi, viruses), and their different subgroups (e.g. gram-positive and gram-negative bacteria, myco-bacteria, yeasts and moulds, naked and enveloped viruses) and species, have different susceptibilities to different anti-microbial ingredients. Few ingredients are effective against all kinds of microbes: a product may even be highly effective against one type and harmless against all others.

Proven efficacy against the important types of microbes must also be established for each different field of application under the specific practical conditions for that use, because many other factors can affect the performance of a product, including:

  • the presence and nature of dirt (soiling), including organic matter.
  • the nature of the surface or material to which the product is applied – whether the surface is porous (wood, for example) or non-porous (tiles, metal etc).
  • the temperature of the surface on which the product is applied. Activity at different temperatures must be taken into account for products to be used in cold-rooms or at higher temperatures.

Different types of anti-microbial ingredients are susceptible to such factors to different degrees.

As well as the above factors, the efficacy of a disinfection process depends absolutely on using an adequate concentration of active ingredients and allowing an adequate time of contact between the product and the microbes to be inactivated.

Proper procedures are therefore of crucial importance. They must provide for adequate contact times and also allow, for example, for the dilution effect of use on wet surfaces. Using an otherwise-effective product at the wrong concentration, or in the wrong way, can be dangerous as it creates a false sense of security.

In certain critical areas, such as pharmaceutical production, complete hygiene processes need to be validated before implementation for routine use. In other areas the results of anti-microbial measures are verified retrospectively and their effectiveness documented after final control on site, e.g. via systems such as HACCP. While hygiene failures can be detected and corrected, the aim is always to identify, isolate and eliminate the cause to avoid the possibility of financial loss or risks to customers.

Methods for testing products

  • National and industry standard testsDeveloping and applying tests to establish the efficacy of biocidal products has been a constant preoccupation for manufacturers, users and regulators since disinfectant use began. Even when disinfectant use was in its infancy, efforts were made to standardize tests so that they could be widely applied. Historically, a variety of national and industry test standards have arisen in different countries, as each has tended to develop its own methods for the most frequent and most important application fields.Passing specified tests has often become a legal requirement for the sale and use of products, particularly in critical fields such as healthcare and food production. Such methods define all the important variables that must be taken into account for the specified use – the nature and degree of soiling, surface composition, water hardness and temperature for example. Even where not legally prescribed, manufacturers use the same principles to support their individual claims to their customers.Standard tests also define the relevant strains of micro-organisms against which the tests must be performed. Strains of microbes are specified which have a relatively low susceptibility to disinfectants compared to others of their type. They must also behave consistently under test conditions such that test results are reliable and reproducible. By selecting such representative species, efficacy against broad groups of microbes for defined product concentrations and contact times used in defined conditions can confidently be established. National and industry standards thus give vital guidance to manufacturers in developing products, establish a basis for comparison of products and formulations, and can provide assurance of efficacy at affordable costs.
  • Customized testsSometimes, new uses – or new ways of using products – arise where standard tests are not available, or efficacy against different organisms may need to be established. In such circumstances manufacturers need to develop ad-hoc tests, often by modifying standard ones. Such tests need to be scientifically substantiated for the intended use, and their results, including proper use conditions and limitations in efficacy must be clearly and appropriately communicated.
Contact the UKCPI on ukcpi@ukcpi.org or call 07843 199397.