April 16, 2013

expert reaction to the results of tests for horse DNA and bute in meat

The European Commission published test results on EU-wide testing for horsemeat DNA and phenylbutazone, finding less than 5 % of the tested products had horse DNA and that about 0.5 % of the equine carcasses tested were found to be contaminated with bute.

Professor Peter Lees, Emeritus Professor of Veterinary Pharmacology, Royal Veterinary College, said:

“All relevant data are contained in the EFSA journal report 2013 11(4): 3190- running to 45 pages.

“The main conclusions in the EFSA report are:  

1. “On a given day, the probability of a consumer being both susceptible to developing aplastic anaemia and being exposed to phenylbutazone was estimated to range approximately from 2 in a trillion to 1 in 100 million”
2. “ The risk of carcinogenicity to humans from exposure was considered very low based on the available experimental data on organ toxicity and carcinogenicity, as well as the low exposure levels and the infrequent exposure to phenylbutazone from horse meat or adulterated beef-based products”

“I concur with these conclusions but would add the following comments:

“The report emphasises that “in view of the assumptions made to address most of the existing uncertainties, it was concluded that the current risk assessment is likely to overestimate the risks”. This is true but something of an understatement for the following reasons:

“a. As the report states, “The doses at which carcinogenicity was observed are more than three orders of magnitude higher than those that could be expected from potential exposure to phenylbutazone from horse meat”. Indeed the DAILY doses used in carcinogenicity studies were massive.

“b. A threshold dose of phenylbutazone has not been set for the rare incidence (1 in 30,000) of humans who develop aplastic anaemia when treated therapeutically every day with the drug for weeks or many months. Therefore, the report assumes, understandably conservatively, that ANY exposure of a sensitive individual might lead to a life threatening blood dyscrasia in that individual. Whilst this cannot be excluded, it is worth noting that I have calculated that in the worst case exposure scenario from our horse muscle residue data (500 µg/kg at slaughter) and assuming an individual consuming 200 g of pure horse meat (on a rare occasion), the intake would be 100µg, which is 2,500 times less than the daily therapeutic dose in humans. Based on median residue concentrations of 4.0 µg/kg reported by EFSA, the intake would be 0.8 µg, which is 312,500 times less than the daily therapeutic human dose.”

Prof Tim Morris, School of Veterinary Medicine and Science, University of Nottingham & Vice Chair of the British Horse Industry Confederation, said:

“Following the discovery of horse meat in beef products at the start of the year the European Commission has coordinated EU wide testing. Over the last 3 months, 4,144 beef product samples were tested for the presence of horse meat DNA and this revealed 193 traces of horse meat DNA (4.66%). 3,115 of the beef product samples were tested for the presence of phenylbutazone and 16 showed traces of the horse medicine phenylbutazone (0.51%), which is also known as ‘bute’. Meaningful comparison between countries is complicated by different testing methods and by the fact that in Britain and Ireland all horse meat is now being tested for phenylbutazone. 

“The EU has not yet given details of the actual amounts of phenylbutazone found in these samples, this would aid further assessing the health risk to consumers. However in the current situation the risks to consumers are likely to be almost negligible as:

• Side effects of phenylbutazone in people (a blood disorder known as aplastic anaemia) were only found when they were treated by doctors with the much higher clinical dose, and then only in 1 in 30,000 people. This medicine is no longer used in people.
• Amounts of  phenylbutazone from eating horse meat are likely to be tiny, as even if all the product is horse meat it is estimated that 24 hours after giving the medicine to horses amounts in the meat (in a horse entering the food chain) are only in parts per billion, very much lower than the human clinical dose.
• Only very low rates of horse meat contamination, and then that horse meat itself containing phenylbutazone, were found in this recent EU testing.

“This is why yesterday the European Food Safety Authority said in a 45 page expert report: ‘On a given day, the probability of a consumer being both susceptible to developing aplastic anaemia and being exposed to phenylbutazone was estimated to range approximately from 2 in a trillion to 1 in 100 million.’ (A trillion is a million million).

“These scientific tests reinforce the view that this issue remains primarily a food fraud but it serves as a real wake-up to tighten up all aspects of the food chain from farm or stable to the retailer: all involved – animal keepers, vets, businesses and the government have their part to play to ensure we know what we eat and that it is safe.”

Professor Sir Colin Berry, Emeritus Professor of Pathology, Queen Mary, University of London, University of London, said:

“You are more likely to be hit by a meteorite than get aplastic anaemia from Bute via horse meat.”