< > Glossary & References / Miscellaneous Documents List / D35 Discussion Documents for the 2001 UK Foot-and-Mouth Disease Outbreak / Text Sections:
This document was
produced by MAFF as a specific response to the FMD outbreak in the UK in 2001 and was made
available on their website. Risk Assessments and specific recommendations related to the
conditions in the field at the time and should be viewed in this context as they may not
be applicable to outbreaks occuring under different circumstances.
FMD: Adjusting the pH as a means of disinfection against Foot and Mouth Virus
HEALTH & SAFETY
1. The appearance of a disinfectant on the MAFF approved list means only that it has been shown to be effective for the purpose at the dilution rates listed and HAS NO IMPLICATIONS FOR THE SAFETY OF THE PRODUCT.
2. Manufacturers and suppliers are obliged to provide Information on the hazards and safe use of their products in the form of safety data sheets and on labels, users must take note of this information and use the product accordingly. This information should also give guidance on what to do in the event of accidental spillage or exposure to the product.
3. As a rule of thumb, where there is a choice of products that will do the same job, the least hazardous should be selected.
4. Many disinfectants will be hazardous in one way or another and will require a risk assessment to be made, as required by the CONTROL OF SUBSTANCES HAZARD TO HEALTH (COSHH) Regulations, before they can be used. The assessment, WHICH MUST BE MADE BY THE USER, should be based on manufacturer's/ supplier's safety information and take into account the method of application and the circumstances of use.
5. A common hazard associated with many disinfectants is that they are corrosive, particularly in concentrated form, and can cause burns if they come into contact with eyes and skin. Contact should be avoided and protective clothing in the form of waterproof overalls, rubber gloves, and safety goggles, spectacles or face shields used.
6. Some disinfectants may also be respiratory irritants, again reference should be made to the manufacturer's/ supplier's safety information which will give advice on precautions and, if necessary, specify suitable respiratory protective equipment.
7. A few disinfectants on the list may contain Gluteraldehyde, this is known to be a respiratory sensitiser and it is recommended that alternative products are selected.
Use of Disinfectants
Either use an ALKALINE or an ACID disinfectant. Never try to use both together as they will cancel each other out to give a neutral pH and the virus will not be killed.
Before using any disinfectant you must clean off all mud, manure and other matter since most disinfectants will not work if there is manure, mud or any other material present.
ALKALINE DISINFECTANTS. These work by increasing the pH (more than 7)
1. 4% solution of sodium carbonate (also known as washing soda)
The effectiveness of the solution can be improved by the addition of detergent, such as household washing up liquid. Add 15 ml of detergent to each gallon (or 4.5 litres) of washing soda solution (or one tablespoon to each gallon or 4.5 litres)
This solution can be used for the cleaning and disinfection of all external surfaces (e.g. farmyards, animal accommodation, tractors, trailers, all vehicles, utensils, tools, boots, shoes, waterproof clothing etc). Hands may also be washed and fingernails scrubbed in this solution.
The solution can also be used to reduce infection at places where animals congregate around the farm (e.g. water troughs, feeding troughs, farm gates etc.) In especially muddy places a double strength solution can be used. It is also useful to scatter the dry crystals of washing soda on the surface and mix it into the mud.
The solution can also be used to spray or dip animals. In this case it must be washed off after 30 minutes or so to prevent any possible harmful effect.
Note: Soda solution may corrode metal and damage painted surfaces and for these items citric acid solution (plus a suitable detergent) is preferred. Citric acid or ortho-phosphoric acid may have some slight effect on galvanised metal, but as the virus is destroyed in less than one minute on clean surfaces, these can be quickly rinsed off with clean water. For this reason, galvanised containers are not suitable for use as disinfectant footbaths over long periods.
The killing of FMD virus by sodium carbonate is slower than that of the acid disinfectants, but washing soda itself has a cleaning action, and its residual disinfection capacity is long lasting.
AVOID CONTACT WITH THE EYES, NOSTRILS AND MOUTH OF BOTH THE OPERATOR AND THE ANIMAL. IF THIS SHOULD HAPPEN, THE SOLUTION MUST BE WASHED AWAY WITH COPIOUS AMOUNTS OF RUNNING WATER.
ACIDIC DISINFECTANTS. These work by lowering the pH (less than 7)
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