Pollution

Antibiotic Pollution

In 1968, after serious outbreaks of drug-resistant salmonella were linked to the use of antibiotics in livestock, the Swann Committee was set up. Its remit was to consider the dangers of drug resistance in animals given antibiotics and the risks this posed to human health. It advocated seriously restricting the use of antibiotics that were used by both animals and humans (Swann, 1969).

By the time the report was published it had been considerably watered down and after enormous lobbying by the industry, the government retreated even further from Swann’s recommendations and the use of antibiotics in farming rapidly expanded, including the use of drugs used by both humans and animals. Which is one reason why we have arrived where we have, with superbugs regularly dominating the headlines and human life seriously threatened.

There is a growing awareness of antibiotic resistant bacteria and superbugs in the public at large but if media reports are anything to go by, most believe the problem stems from the over-prescribing of antibiotics by doctors. The global use in livestock farming for treating diseases (therapeutic), preventing diseases (prophylactic) and simply to make animals grow faster (growth promoting) is rarely mentioned.

Despite an EU-wide ban on growth-promoting antibiotics added to animal feed from1 January 2006, similar quantities of antibiotics are now given for ‘disease prevention’ (resulting in the desired growth promotion)! In the UK, these prescription-only antibiotics are even advertised to livestock farmers for their growth-promoting properties in defiance of an EU Directive seeking to end this practice!

There are detailed reports on why antibiotic use in farmed animals is causing a threat to human health (for example see Richard Young’s The Use and Misuse of Antibiotics in UK Agriculture parts 1 to 4 from www.soilassociation.org). Farm use of antibiotics have caused antibiotic resistance to medical drugs in several types of food poisoning (eg salmonella, campylobacter and E coli) and drugs of last resort for treating strains of the hospital superbug, vancomycin-resistant Enterococci (VRE), which infects wounds and incisions (Therlfall J, 1999).

Resistance in food poisoning bacteria has come about mainly from using antibiotics routinely to prevent disease. In the case of VRE, resistance came from using growth-promoting antibiotics in farmed animals.

In simple terms, antibiotics have been massively overused by farmers in intensive farms to make the animals grow quickly and ‘efficiently’ and to attempt to stop the rapid spread of disease in conditions that bacteria are able to spread like wildfire. This overuse has led to bacteria becoming resistant to the drugs so that when the same drugs are used to treat humans, they no longer work.

The issuing of reports has continued and so has the ignoring of them, such is the power of the livestock lobby.

In 1997, the World Health Organisation (WHO) issued a report calling for a restriction in the use of antibiotics in farmed animals. In 1998 the National Research Council & Institute of Medicine was even stronger in its condemnation. In 1999, the UK government’s own Advisory Committee on the Microbiological Safety of Food also issued a massive report and agreed with the WHO. Also in 1998, the Soil Association, which represents organic farmers in the UK, issued its own damning report (followed by three more).

Despite this extraordinary amount of scientific interest and a plethora of recommendations advocating restraint, restriction and a rethink, the drugs have kept flowing and the scale of antibiotic resistance has grown. Weakness, cowardice or self interest has prevented consecutive governments from taking the action necessary to protect human life.

The British Medical Association summed up what many people now believe when its former chairman, Sandy Macara, stated: “There is a real prospect that the majority of our antibiotics could become impotent for the purposes upon which we have relied upon them for 40 years.” This would transform society, essentially taking us back to pre war days when infectious diseases were prevalent. It would also place an extremely high risk on invasive surgery such as hip replacements.

One of the arguments of the farming lobby to justify ‘business as usual’ has been that there is no proof positive that antibiotics used in animals have played any part in producing the resistant strains that now threaten humans. Of course, the claim beggars belief but all those reporting independently on the subject are convinced there is a strong link but admit that providing proof strong enough to satisfy the empirical standard of experimental biology is difficult.

However, a team of researchers reporting in the journal PLoS Medicine in 2007 found that animal agriculture not only plays a part in the problem but constitutes an even more important source of these deadly mutations than medical prescribing.

Antibiotics and resistant bacteria are found in the air and soil around farms, in surface and ground water and in wild animal populations and on much of the meat produced by these places. Those handling and using meat face high exposure to the bacteria but researchers concede that infection is likely to be slow, hard to trace and equally hard to prove.

Despite this, the researchers were satisfied that transmission of the bugs from agriculture had a greater impact on humans than over-prescribing. When Denmark banned growth promoting antibiotics there was a drop in the prevalence of resistant bacteria in farmed animals, around farms, on meat and in people (Smith D, 2006). So both the source and the remedy seem pretty clear.

Despite this, it is difficult to discover accurate figures on the amounts of animal antibiotics used in the UK (see below for published figures), the types of animals treated and the number and why they are used.

Farmers have a statutory obligation to keep a record of all antibiotic use in treatment books but a government committee in 1999 found that 50 per cent had no book, 25 per cent had a book but it was not used or was out of date and only 25 per cent had up-to-date records. Of course, what record keeping does exist is entirely in the hands of the farmer so there was no way of telling how accurate even the up-to-date books were. The reason for using eight-year old statistics is that any information on antibiotic use is hard to come by.

The government will naturally boast that it has transformed the use of antibiotics by banning some and encouraging alternatives. The evidence is that when one growth promoting antibiotic is banned the use of others simply increases (see below).

Across the third world, of course, where intensive animal farming is exploding fastest, there are no bureaucratic requirements or controls at all and so antibiotic use is even more unregulated than it is in the UK. One of the biggest problems in creating antibiotic resistant bacteria is under-dosing so that bacterial infections are not entirely wiped out and those remaining are the most resistant, which then go on to reproduce and recolonise. With antibiotics being expensive commodities, there is always a financial incentive to undertreat, particularly in comparatively poor countries.

In most intensive farming, antibiotics are administered through food – a very much hit and miss affair. This was half-heartedly controlled by banning some medicated feed but farmers were still allowed to sprinkle antibiotics on top of the feed in troughs so long as they registered and kept records. The Soil Association estimates that 10,000 farms may have failed to register and are ‘top dressing’ illegally.

Some figures are available from the US, which produces 22.7 million kg of antibiotics annually and a half is used in livestock farming. Of this, 80 per cent is for growth promotion by controlling bacteria in the intestines of animals and improving their feed conversion rate.

Much of this passes through the animals and finds its way into the environment as residues. Through a process that no one fully understands but includes the passing of genetic material from one bacterium to another, antibiotic-resistant strains can pass on their resistance to other, unrelated bacteria. Benign bacteria can pass resistance to pathogenic (disease causing) bacteria and those with this resistance out-compete and propagate faster than those without it. No wonder the UN FAO refers to this as a ‘source of considerable environmental concern’.

A frightening example of a superbug from farmed animals transferring to humans is happening in the Netherlands now. The superbug methicillin-resistant Staphylococcus aureus (MRSA) is already a high-profile, persistent problem in many UK hospitals. Now a new strain of MRSA (identified in 2004) has developed amongst intensively farmed pigs, chickens and other livestock on the Continent. MRSA in farmed animals has already transferred to farmers, farm-workers and their families in the Netherlands, causing serious health impacts. Forty per cent of Dutch pigs and 50 per cent of pig farmers have been found to carry farm-animal MRSA (Soil Association, 2007). In the Netherlands, MRSA has been found in 20 per cent of pork, 21 per cent of chicken and 3 per cent of beef on sale to the public. Dutch scientists and government officials blame this new strain of MRSA in farmed animals on the high levels of antibiotics used in intensive livestock farming (Soil Association, 2007).

The UK government has committed itself to reducing the amount of antibiotics used in UK farming yet overall levels remain high. Despite an EU-wide ban on growth-promoting antibiotics added to animal feed, similar quantities of antibiotics are simply being prescribed by vets for disease prevention (Soil Association). Veterinary use of antibiotics used for therapy or disease prevention in UK farmed animals has increased by 3.5 per cent, from 405 tonnes in 1999 to 419 tonnes in 2005, despite a fall in overall livestock numbers. In the UK, over 90 per cent of veterinary antibiotics are used in pig or poultry production (Goodyear, 2006).

Although currently banned in Europe, there is widespread use of hormones in animal agriculture in the US and some other countries. As with drugs, they readily find their way into the environment and as with antibiotic resistance, it is difficult to prove beyond doubt that they damage the environment.

However, the UN FAO feels that because they can affect the endocrine system (a series of glands throughout the body that cover such things as growth, including sexual organs) this would account for dramatic changes that have been seen in wildlife – changes in rates of growth, cases of feminisation or masculinisation of fish and the increased rates of breast and testicular cancer and changes in the male genital tracts of mammals. This, of course, includes humans!

There are other substances used in animal farming that pollute the environment, including detergents, disinfectants, heavy metals, pesticides and fertilisers.

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