‘The Government Chemist referee function . . . safeguards industry, government, and the criminal justice system from unwitting errors in analytical science’
One of the key measures responsible for halting the spread of the disease, which is still in effect today, was the ban on feeding cattle remains to cattle. Despite this, three years ago, the GCP became involved in a court case, the first of its kind in the UK, where this safety measure was alleged to have been flouted. A lorry carrying organic cattle feed was stopped and inspected in Cumbria because it had been suspected of previously transporting meat and bone meal (MBM), a form of banned cattle remains. The enforcement authority, the then Veterinary Laboratories Agency, using microscopy, reported the presence of muscle fibres and terrestrial animal bone. As is routine, the trader sent the second portion to a lab in another member state, which subsequently reported that MBM was not present, and the case was referred to the GCP. We prepared a series of in-house
standards of 0.01–1.0% MBM in a blank feed for avian, bovine, porcine and ovine species as a training set. Using glove bags and a dedicated lab area cleaned to DNA standards, we analysed the sample. This involved separation of animal remains by sieving and sedimentation in tetrachloroethylene, with subsequent
Figure 1 The aflatoxin B1 case: GCP findings confirm those of the Public Analyst (Note LC-MS/MS was carried out on A only)
4.000 Sub-sample A
3.500 3.000 2.500
2.000 1.500 1.000
0.500 0.000
Aflatoxin B1-GC GC PA LC-MSMS Aflatoxin B1-PA GC PA Legislative limit B1 LC-MSMS GC LC-MSMS PA LC-MSMS Chemistry&Industry • November 2012 27 Sub-sample B Sub-sample C
staining to identify the components by transmitted light microscopy. The constituents of animal origin were identified on the basis of typical microscopically-identifiable characteristics – muscle fibres and other meat particles, cartilage, bones, horn, hair, bristles, blood, feathers, egg shells, fish bones, scales. Fish scales and bones are particularly beautiful and characteristic. We examined six replicates of the milled feed and found a total of 70 minute bone fragments, identified by their irregular outline, characteristic shape and staining with alizarin red, with spaces in bone for nerves to pass through. Interestingly, however, using immunoassay and DNA techniques, while we could detect MBM in blank feed spiked at 0.1% and 1.0% with bovine MBM, we could not detect this in the referee sample with this method. We concluded that tissues containing mammalian DNA or protein were sparse in the sample and/or the limits of sensitivity for the immunology and PCR-DNA methods did not extend to the concentrations of constituents of animal origin present.
At the subsequent trial, the first
prosecution of its kind in the UK, the haulage company entered a guilty plea in the magistrate’s court and was sentenced in the Crown court. The company was fined £25,000 and ordered to pay £4500 costs. It is intriguing to think that, in contrast to the sophisticated mass spectrometry we use for much of our casework, the technique that cracked this case, light microscopy, is one that dominated the work of the Government Chemists of the 19th century. The Government Chemist referee
function remains a demand-led service in the UK to give businesses an avenue of technical appeal. Its work in diverse areas, from confirming meat and fish ingredients in a range of foods, through identifying potential choking hazards, to identifying illegal dyes and additives in food, safeguards industry, government, and the criminal justice system from unwitting errors in analytical science. It is a varied and interesting programme of work, which often involves collaboration with partners on a host of food related issues.
Each new week brings a fresh
problem – currently we are working on migration of formaldehyde from kitchen utensils and on unauthorised genetically modified rice – but those are stories for another day.
Michael Walker is a consultant referee analyst in the Government Chemist Programme at LGC, Teddington, Middlesex, UK.