Allergic response

29-Oct-2007 - Last updated on 14-Mar-2017 at 15:47 GMT

With product recalls for adventitious allergen contamination on the rise, Michelle Knott examines how firms are testing foods to ensure they are clear

The number of people suffering from allergies has trebled in the last 20 years. Each year over 6,000 people in England alone are admitted to hospital with allergic reactions and a quarter of those are suffering from life-threatening breathing difficulties, or anaphylaxis. So it's little wonder that allergies are big news, with talk of an epidemic.

The Food Standards Agency (FSA) launched its Allergy Alert service at the start of this year, and had already issued 30 notices by September. The vast majority of these were to do with incorrect labelling, although some were a result of accidental contamination. For example, peanuts got into cereal during packaging; incorrect ingredients introduced sulphites into falafel; and traces of milk were found in a hot chocolate drink (which is apparently a problem, even though the product was intended to be mixed with hot milk before consumption).

The original European directive on labelling in 2000 didn't even mention allergens, but this was amended in 2003 when the European Commission (EC) specified 12 allergenic substances that must be labelled if they or their derivatives are added to a product. In fact, two of these - sulphite and lactose - are not proteins and are therefore not true allergens, although they spark a similar response in those affected. The rules were amended again in 2005 with a list of 20 highly refined allergen derivatives that are exempt from labelling because they are deemed not to be allergenic. This list remains provisional until November 25, when the European Food Safety Authority (EFSA) will decide whether to exempt the derivatives for good.

Allergen labelling

Last year the EC added lupin and mollusc to the original list of 12 allergens. These will have to be included on labels by 2008, although companies are unlikely to wait until this deadline. This will not be the end of the story, however, since 'new' allergens are already emerging and could be added to the list in future. For example, pine nuts are causing problems for people across Europe.

All the legislation mentioned so far only applies to the labelling of intentionally added ingredients and takes no account of accidental contamination. However, 2002's general directive on food safety says that no unsafe food product should be put on the market, and it is this that has led to the rising tide of 'may contain' disclaimers.

"It's down to the individual manufacturer to decide whether their product is safe. The consequence is 'may contain' labelling, but it's only meaningful if used sparingly," says Dr Bert Popping, director of molecular biology and immunology at contract laboratory Eurofins.

The commercial pressure on manufacturers to try and remove such blanket disclaimers is obvious. "The UK is the most allergic population in Europe," says Simon Flanagan head of speciality analysis and allergy services for Reading Scientific Services (RSSL). "While an estimated two to three percent of adults and five to eight percent of kids suffer from clinically diagnosed allergies, around 35% of people in the UK perceive themselves to have a food intolerance. If they see a 'may contain' label on a product they're not going to touch it."

Risk assessment is the key tool for any company worried about potential allergen problems. "In food processing you're talking about very low levels of sensitivity, with allergens at parts per million levels," says Fiona Scholes, senior food advisor for Bodycote Health Sciences. "Some manufacturers may decide that dedicated lines are the way to go, while others operate their factories almost like high care medical facilities."

All the big labs offer auditing services so they can advise companies on their allergen control systems and whether they need allergen labelling on their products. And while testing can never be a substitute for good risk management, it plays a vital role in validating the complex procedures designed to prevent cross contamination.

The chief lab-based testing technologies are enzyme linked immunosorbent assay (ELISA) tests and DNA-based polymerase chain reaction (PCR) tests. ELISA tests use antibodies that bind to a specific protein and give a quantitative result. PCR detects the presence of DNA specific to, say, peanut or hazelnut, but only gives a qualitative result. Swabs and lateral flow testing kits are also available for use on the factory floor, but these are less sensitive and would normally only be used to perform spot checks as a routine back-up.

Testing is not straightforward

The biggest challenge is that testing is not straightforward - even for the labs. Companies would love to buy an off-the-shelf ELISA test for celery and get a valid result when using it on any foodstuff, but it's not that easy.

"We don't just use one test for everything because the sample matrix itself can have a bearing on detectability," says Flanagan. "You can get cross-linked antibodies that give a false positive, or some things can bind up the antibodies completely."

"With certain ELISAs, such as gluten, they'll deliver varying results with different process matrices and it can be hard to tell which one is the true value," adds Popping. "If it's a matrix we don't know too well we'll run two different tests. If they match it's probably safe to say that the result is the right order of magnitude, but if not we may not be able to say whether a company should label or not."

With a global market for ingredients, the lack of harmonised testing methods can be a nightmare for food manufacturers, although there is research underway to address the problem. For example, Eurofins is part of the MoniQA project, which is a global harmonisation effort with participants in 20 countries.

But so far it's every lab for itself, even within Europe. "The problem is that the number of validation studies [for different testing methods] is very limited," says Popping. "If each European Member State would put a little funding in we could easily produce validated methods for testing the entire allergen list. For now we've only got validated methods for peanut and hazelnut, with nothing for milk, egg, soya and the rest. It would actually be much more cost efficient for all the competent authorities if they could be confident that labs were using robust methods."

Lack of thresholds

The other thing that makes manufacturers nervous is the almost total lack of any threshold levels for allergens in the legislation (the exception being for sulphite below 10ppm). However, this doesn't mean that they have to aim for a magical - and unattainable - zero, according to Popping: "There is data in the literature on the trigger levels for various allergens. These should be used by labs to make a recommendation about how companies should label their products. If an allergen is present way below the trigger level, we can say it's very unlikely anyone is going to suffer a reaction like anaphylaxis."

For example, he says that a muesli bar might be considered allergen-free if someone would have to eat a kilogramme at one sitting in order to reach the trigger level. "Of course, if you're talking about chocolate, you have to consider that some people are chocoholics and might eat a kilogramme," he laughs.

In practice, this means that many companies could do away with 'may contain' disclaimers that are simply there because products are processed on multi-purpose lines. "If you have the option then a separate line is best," says Popping. "But you don't automatically have to have an allergen label just because you use the same production line if you can show that your cleaning procedures are good enough." It's essential to get expert advice on this approach, because it depends very much on the particular set up. For example, a bakery might find it very difficult to achieve the cleaning levels required between batches if it's dealing with very sticky dough.

Ultimately, allergens are a safety issue. In addition to the rules, companies need to apply good common sense if they are going to protect both consumers and themselves from allergen-related problems. "There is an issue over and above legislation," says Scholes. "You've got to look at the whole picture.

"For example, sulphite is considered absent [in the legislation] if a product contains less than 10ppm. But you might have a cake with cherries on the top and the allergen could all be packed into that one ingredient. It's highly conceivable that someone might pick all the cherries off a bun."

Food Manufacture is organising a conference on Product Recalls on March 6 2008 in Warwickshire. For more details contact: Helen Law at helen.law@william-reed.co.uk, tel: 01293 846587

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