Karen Masters, manager, Emergency Response Service, Reading Scientific Services, looks at recent contaminant scares in the food manufacturing sector, such as melamine, and the lessons that can be learned.
If the recent scandal of melamine contamination proves anything, it is that the food processing industry, and other sectors, must always be prepared for the unexpected. For that matter, the same conclusion could be drawn from any of the food and pharmaceutical scares involving other chemicals such as bisphenol A (BPA), acrylamide, sudan red, diethylene glycol, and semicarbazide.
Of course, preparing for the unexpected is never easy. Routine screening cannot pick out every potential contaminant, and the sheer variety of potential contaminants and ‘routes of entry’ means it is impossible to guard against them all. That said, a company can be prepared to the extent of building its own analytical capability or partnering with external laboratories that can alert it to potential/known dangers and provide expertise in developing methods for detecting whatever contaminants may come to light.
The melamine danger first emerged, not with the contaminated milk powder that gained all the headlines, but with contaminated pet food. On March 15, 2007, the USFDA reported that certain pet foods were sickening and killing cats and dogs. The FDA found melamine and cyanuric acid in vegetable proteins imported into the US from China, which were being used as ingredients in pet food.
A portion of the tainted pet food was also used to produce feed for farm animals, and some of these animals were processed into human food. While US Government scientists determined that there was very low risk to human health from consuming these animals, they called for all tainted feeds and vegetable proteins to be recalled and destroyed. Regrettably, the fact that melamine had killed cats and dogs did not stop it being added to milk, with disastrous consequences for consumers and for the food industry. Prosecutions have recently taken place in China with two men receiving a death sentence for their part in the scandal.
The first product found to be affected was powdered milk used in infant formulations. However, it rapidly became apparent that milk, milk beverages, yoghurt, ice cream, chocolate and ice cream bars were also contaminated. Many companies were forced to withdraw or recall products, especially in Asian markets, while the regulators in Europe and the US sought to implement rapid solutions to prevent contaminated supplies from entering local markets.
Melamine is an organic base used in plastics and resins, and it is banned in food. However, unscrupulous traders realised that melamine could be added to watered-down milk products to make them appear to contain more protein than they actually do. Melamine is a compound rich in nitrogen, and since a standard test for protein typically relies on measuring nitrogen levels, the addition of melamine represented a cheap but highly dangerous way of artificially appearing to boost the protein content.
It is not only melamine that has been used for this purpose. Other nitrogen-rich chemicals such as cyanuric acid and related compounds have been similarly implicated. It is the specific combination of cyanuric acid and melamine that many believe to be the main reason why so many pets died in the US cases referred to above. When cyanuric acid and melamine react, they form a precipitate, and it is possible this accumulated in the kidneys of the animals, causing their deaths.
From an analytical perspective melamine threw up several challenges – and in fact, most contamination incidents do. More often than not there is no published method for the extraction and analysis of the offending chemical, at least not one that is universally applicable to every matrix. Similarly, such methods as do exist may be suitable for detecting the contaminant at a certain level, but may not be sufficiently sensitive at the levels required.
This was much the case with melamine, and during the early stages of the crisis, as new cases were revealed involving an increasing number, and more varied types, of product, the goalposts kept moving in terms of what needed to be done to bring the contamination under control. By late September 2008, the European Commission set out its current position by asking Member States to carry out checks on all products imported from China that contained more than 15% milk and on products where the percentage of milk content cannot be established. Products containing more than 2.5mg/kg of melamine are to be destroyed.
However, at the time of issuing the call for checks, the published test methods could not be applied reliably to every food matrix, and so laboratories like Reading Scientific Services Ltd (RSSL) began to develop and validate its own methods.
By the beginning of October, RSSL was able to announce that it had developed two test methods for melamine that could be applied to a variety of different matrices. The first utilised HPLC (high performance liquid chromatography) and the other, more sensitive LC-MS (liquid chromatography mass spectrometry), allowing RSSL to offer detection limits as low as 1ppm depending on the matrix. Within a few days, RSSL had added an ELISA (Enzyme linked immunoassay) technique, which would prove useful in screening raw materials and for confirming the results obtained by other methods.
Thankfully, not every contamination incident hits hundreds of producers simultaneously on the scale of the melamine crisis. Many incidents are contained within one factory, perhaps because the contaminant has come from some oversight when cleaning or maintaining the plant, or because one batch of ingredients has been contaminated during processing, delivery or storage.
It is also the case that some chemical contaminants, such as illegal colours, are to some degree predictable, and therefore avoidable. Routine screening can be used to control the problem. But it is impossible to design a single screening procedure that will detect every known potential contaminant, never mind those that are unforeseen. Nonetheless, manufacturers must be ready to respond to all contamination threats, real or perceived, with rapid, reliable and sensitive methods that are applicable to their own products. In practice that means having their own well-equipped laboratories, or a partner who can develop new methods when the need arises.
As noted above, that is easier said than done. It is relatively easy for the legislators (and pressure groups) to issue immediate demands for testing and to propose revisions of maximum permitted levels for the latest ‘chemical scare’. Unfortunately, it is always much harder for the laboratory to be sure that its methods are able to meet these requirements in every case. Just because the method works with one product does not mean that it will work with others. Proving this applicability is especially complicated when, as was the case with melamine, the landscape was evolving with every new day.
The situation with melamine is similar to that currently pertaining to Bisphenol A (BPA) – used in the liners of some drink cans to prevent drinks from coming into contact with metal – in as much as safe limits are subject to review, and laboratories are having to consider whether existing detection methods will be sufficient for any pending revisions. BPA has been linked, by some, to heart disease and diabetes, although it is by no means clear whether BPA causes the health problems, or whether health problems are changing the metabolism of BPA. However, there is some evidence in animals that low-level chronic exposure to BPA can lead to reproductive and developmental problems, and the early onset of puberty.
While the FDA and the European Food Safety Authority (EFSA) appear comfortable with the current limit of consumption of 50µg/kg bodyweight per day, authorities in Canada have declared BPA a “toxic chemical” and are taking steps to curb human exposures.
Should such a change come about then this is one occasion where work at RSSL has already commenced on the development of a more sensitive LC-MS method than the HPLC method currently being used. As noted above, being prepared for the unexpected is not easy, but preparing for the possible is always a good idea. Contamination is a constant worry for any manufacturer of consumer goods, whether it occurs through malicious act (as with melamine) or adventitiously (as with BPA). The problem is, no one can be sure where the next incident is coming from, so manufacturers and their laboratories must always be ready to develop new methods that can provide the proof that supplies and products are unaffected and fit for market.
Contact Karen Masters RSSL, Reading Science Centre Whiteknights Campus, Pepper Lane Reading Berks RG6 6LA UK T +44 118 986 8541 F +44 118 986 8932 .(JavaScript must be enabled to view this email address) www.rrsl.com