Horse Meat - Should we be Worried?
Steve Bentley Fri, 08 Feb 2013 16:01:00 GMT
Three scientists from the School of Applied Sciences offer their opinions on how the contaminated meat scandal might have happened, how it might have been detected and whether consumers should be worried.
Featuring Dr Helen Martin, Dr Graham Williams and Dr Rachel Airley
Transcript
DR HELEN MARTIN:
Well the food industry in this country has very strict rules and regulations as to what is in products and what isn’t. So if it is a ready meal bought from a supermarket it is labelled with all of those ingredients, and when somebody buys a product there will be certain date codes on that product which can be traced back to the original sources. Now a composite product like a lasagne or a shepherd’s pie is made up from many different ingredients from many different food manufacturers and potentially from many different countries if you trace back to the original raw materials. So a date code or a batch code on a product should tell the food manufacturer exactly what materials, what batch codes of ingredients have been used in which batch of product.
Now food manufacturers have to label their products with the ingredients so that people can look at those ingredients and decide whether or not they want to buy it. Some people avoid certain products because of allergies, so they might be lactose intolerant or have an allergy to gluten, so they can look on the label and avoid certain ingredients and avoid certain products. So it’s very important that food manufacturers get those labels right.
The problem here is that some contamination happened at some point. With the low levels of pork DNA that were found in the beef burgers, that was likely an accidental contamination. So pork products were likely processed in the same meat processes as the beef, clean down wasn’t quite as effective as it should have been, so a little bit of cross-contamination happened, therefore small amounts of the pork DNA were found.
When you’re talking about larger percentages of the wrong meat – 29% horse meat in beef burgers and in a lasagne you’re finding up to 60% of horse meat that shows something has gone seriously wrong. So it’s either deliberate – one would hope it’s not – or it’s gross negligence, somebody just hasn’t done the right sort of checks and that’s ended up in the product at some point.
In terms of the checking of the DNA in certain products to make sure you’ve got the right meat in the right products and so they’re labelled correctly, there will be routine checks. There will be some sort of standardised procedure or some formula of checking and the overall responsibility of that lies with the Food Standards Agency. So there will be random checks will take place from time to time. The food industry and the Food Standards Agency has now built in additional checks on top of that, so there are 224 different products that they are going to check in the next little while to check for the right meat in the right product. So they’ve stepped up that checking considerably, I think.
DR GRAHAM WILLIAMS:
If you gave me a sample and you asked me to tell you what species it was, what I would do is I would carry out a test that would identify and quantify something called mitochondrial DNA. This is a form of DNA that is present in all species but it is slightly different. So what we do is we exploit the differences between species, so mitochondrial DNA in humans will be different to mitochondrial DNA in horses and in cows. So we would look for the section of mitochondrial DNA that is specific to Equus Caballuswhich is the horse.
Then what we’d do is a test to target that area and carry out a technique called Quantitative PCR or Real Time PCR. What this does is it grows and amplifies this section of the DNA. We add a fluorescent to it, and as it grows and amplifies the fluorescence increases, so we use this instrument and what it tells us is if this particular part of the DNA present, and if it is present how much of it is there?
So this technique which we use is very sensitive. So for example with the current situation where we have lasagne with alleged horse meat in it, the microwave meals have already been through the cooking process so the chances of getting mitochondrial DNA in these samples is actually quite low. So we need to have a very sensitive technique and this real time PCR is very very sensitive. We can detect DNA down to billionths of a gram and so we can detect very very low levels as well as quantify it.
DR HELEN MARTIN:
In terms of any health risks associated with horse meat, if the horse meat is intended for human consumption then no, because the meat will have been treated hygienically, well hopefully, and undergone the proper procedures in order for that to be edible. So in terms of a health risk, no, the horse meat should be absolutely fine, but of course if people are buying beef burgers, they want beef burgers and not horse, so it’s more of a consumer preference thing rather than a safety thing.
But if a horse isn’t intended for consumption there is a potential that it might contain certain drugs which of course can be dangerous to human health.
DR RACHEL AIRLEY
In horses, phenylbutazone is what we would call a non-steroidal anti-inflammatory drug, so it’s used particularly in racing horses for injuries. As they get older they might develop osteoarthritis so for the pain and fever and for injuries that are associated with racing in particular.
We don’t give phenylbutazone to horses that are intended for human consumption because phenylbutazone is actually a banned drug. It was withdrawn from use in humans because of the possible adverse effects that can take place in humans. So what usually happens, if a horse has been given phenylbutazone for vetinary purposes, because it’s had an injury, it has to go in its records. Horses come with a passport, so if there is evidence of phenylbutazone administration on the horse’s passport then it is not cleared for human consumption. In fact when horses are eaten in certain European countries quite a lot, such as France and Belgium there is quite stringent regulation in association with presentation of passports and the full medication history of a horse that comes for slaughter to make sure that phenylbutazone doesn’t get into the food chain.
Some of the side effects that it can lead to that can be quite dangerous are liver and renal failure and if it’s taken over a long period of time it can lead to a condition we call aplastic anaemia which means that people can lose or weaken their immune system.
I don’t think there’s any cause for concern at the moment. This is the sort of thing that you could risk if somebody was completely unlucky and had a totally unpredictable reaction which would land them in hospital and it could be potentially life threatening, which would be very very rare and very unpredictable. Or we’re talking about exposure over the long term, so somebody would have to eat low levels of phenylbutazone for a very long time to increase their risk of getting any of these effects. So I don’t think that people should be unduly worried about this at all.
What I would advise is that if somebody things that they have been eating these contaminated burgers or meals and they get any suspect bruising or they find that they’re picking up illnesses more often than they would, they would be advised to go to the doctor and have a blood test and make sure that their immunity, their blood is functioning correctly. But I would tell people with those symptoms to go to the doctor anyway, whether or not they think they’ve eaten horse meat.
