Potential contamination of on-farm water supplies with nitrofurans guidance

It has recently been discovered that the historic use of a nitrofuran product a suspendable furazolidone has resulted in the deposition of furazolidone sediments in old water tanks, which in turn has contaminated poultry receiving the water from such tanks. This discovery was made following investigations to determine why the furazolidone metabolite AOZ was occurring in some chicken from a UK producer, tested under the UK Government statutory surveillance scheme. The details of this finding were published by the FSA in a press release in October 2004. The link to it is below.

The investigation found that historic use of suspendable furazolidone, when it was approved for use, gave rise to sediments of the drug in the bottom of old water tanks. These sediments were re-suspended in the water by the use of an effervescent cleaning chemical. If poultry are supplied with water from such tanks, they may be exposed to a source of furazolidone that could theoretically lead to contamination of poultrymeat, and make it unfit for human consumption.

Poultry producers will need to act on this advice if they have:
a) ever used suspendable furazolidone at any time in the drinking water supply to their flocks;
b) water tanks which were in use prior to 1 January 1998; or
c) if they have sold poultry houses equipped with old water tanks (in use prior to 1 January 1998), which received suspendable furazolidone, to other poultry /food producers
If none of these circumstances applies then producers need take no further action.

Action required by affected poultry producers
You need to remove any sources of furazolidone contamination. We recommend that all water tanks to which furazolidone has previously been added, and that were installed prior to 1 January 1998, be replaced immediately. Where supply of new tanks is not possible immediately, cleaning of old tanks should be undertaken between crops and a new tank installed as soon as possible thereafter.

Cleaning must be undertaken by a licensed firm that specialises in the disposal of hazardous waste, under controlled conditions. Under no circumstances should the disposal of wastes take place on farm (land, water, slurry, or septic tank), as furazolidone may be highly toxic to aquatic life, persistent and strongly adsorbed to sediments/soil. Tank cleaning can only be regarded as a temporary measure and is not guaranteed to completely eliminate the source of furazolidone contamination.

In the meantime avoid:

• any movement of old tanks (which would disturb the sediment);
• use of biocides which act by effervescence (eg Proxitane® 5); or
• any other actions which would cause disturbance of any furazolidone sediment.

We are not advising against the use of effervescent biocides(, eg Proxitane® 5,) in newer water tanks installed after 1 January 1998.

If you have sold poultry houses equipped with old water tanks that have received furazolidone to other food/poultry producers, you should contact them immediately and either make them aware of this guidance or ask them to contact the FSA direct.

Precautionary measures for the future
Producers will wish to ensure that regular physical/visual inspection and cleaning of water tanks and feed bins is undertaken as part of routine good husbandry practices. (This is particularly important for feed bins which have been cleaned using water from affected tanks, and which may therefore contain furazolidone residues).

The problem that has been identified may have wider significance. Producers may therefore wish to review their operations in any location both in the UK and overseas where furazolidone may have been used in the past and ensure appropriate actions are taken to prevent contamination of poultry / poultrymeat.

Why is it important to take action on this issue?
Furazolidone is banned for use as a veterinary medicine. Exposure to furazolidone and its metabolites raises consumer health concerns, and these substances should not be present in food. It is therefore in the interests of the industry to follow the guidance laid out in this note.

What controls are there on furazolidone in foods?
Any confirmed concentration of this compound (or its metabolite AOZ) is non-compliant with EU legislation. However, a level of 1ppb has been set as the concentration at which the European Commission requires that enforcement action should be taken (product recall, issue of Rapid Alerts etc). If furazolidone, or its metabolites, are detected below this level, regulatory bodies and producers should take action to identify and eliminate the source of contamination.

How could this have happened when nitrofurans were banned for use in food producing animals so long ago?
Although EU wide rules introduced a ban on the use of furazolidone in food producing animals in 1995, this did not come into full effect until 1997. Prior to this nitrofurans could be administered to food producing animals, and there were furazolidone formulations that, despite their low solubility in water, were allowed for use in drinking water. It is believed that the use of such products resulted in a build-up of furazolidone-containing sediments, which caused the current problem. The situation was exacerbated by the fact that older tanks have side exits, which mean they cannot readily be completely emptied.

Water tanks that were in use before 1998 may still be in use today, and when effervescent chemicals are used for disinfection of these older water tanks furazolidone sediments may be re-suspended in the tank water. If poultry are supplied with water from such tanks, they may be exposed to a source of furazolidone that could theoretically lead to contamination of poultrymeat, and make it unfit for human consumption.

How widespread a problem is this likely to be for the poultry industry?
We do not expect this to be a widespread problem for the industry as suspendable furazolidone was not commonly used by the UK poultry industry. Moreover, if the problem was widespread, we would have expected it to have come to light before now, since effervescent cleaning methods for water tanks have been used by other companies in the poultry industry for some time.

How can I be sure that my produce is free from contamination?
The only way is to ensure that all older water tanks are replaced. For complete peace of mind you may wish to carry out some representative testing of water or poultry meat for furazolidone or AOZ respectively.

If water from my old tanks or poultry meat samples from my flock test positive for furazolidone or AOZ, what should I do?
Contact the FSA immediately.

Can I use effervescent chemicals for tank cleaning?
The FSA notes that some tanks are regularly cleaned using effervescent chemicals (such as Proxitane® 5). Older tanks in which furazolidone has been used should not be cleaned with (this or other) effervescent chemicals. We are not advising against the use of effervescent disinfectants for tank cleaning in newer tanks (installed after 1 January1998).

How should water/wastes from old tanks affected by furazolidone residues be disposed of?
Water and waste from tank cleaning must not be run into drains or septic tanks. All water and waste affected by furazolidone residues must be disposed of by a licensed firm that specialises in the disposal of hazardous waste. If water and waste is not disposed of appropriately, the wider on-farm environment may be contaminated, which may increase the risk of contamination of poultry meat. Advice on specialist contractors who can treat/dispose of wastes may be obtained from the Environmental Services Association.

Food Safety issues:
Food Standards Agency
Mark Toal
Email mark.toal@foodstandards.gsi.gov.uk
Tel: 020 7276 8529

General information:
British Poultry Council
email: bpc@poultry.uk.com

Disposal of hazardous wastes: Environmental Services Association:
http://www.esauk.org

National Farmers' Union
Peter King (Chief Poultry Adviser)
Tel: 020 7331 7308