Special Focus
Adhesives for Multilaminate Films: A Lesson in GMPs
Apr 2002
George G. Misko
Concerns about packaging materials were raised precipitously with a report by a Danish magazine, Borsens Nyhedsmagasin, that aromatic amine components present in adhesives used in multilaminate films are migrating into food in which it is packaged. Aromatic amines being carcinogenic, that could be a real problem.
The magazine stated that the Danish Veterinary and Food Agency has withheld from the public the findings from a closed seminar to discuss the problem of glue residues-specifically, aromatic amines-in foodstuffs. So, "in order to uncover the extent of the problem," the magazine enlisted the Steins Laboratory to carry out tests on a number of foodstuffs sold in plastic wrapping by large supermarkets in Denmark.
According to the magazine, the Steins test results showed that eight out of 10 of the tested foods contained carcinogenic aromatic amines in quantities that exceeded the recommended safe limits by 30 to 100 times. The article went on to lament the absence of strict controls, and lambaste a system in which "all parties involved try to 'pass the buck.'" The "scandal," the story states, "highlights the need for much tougher authority control with the quality of both foodstuffs and packaging materials."
But the magazine had the journalistic rug pulled out from under its story by an Aug. 15, 2001, press release issued by the director of Steins Laboratory. The release emphasized that the initial tests of packaging for aromatic amines "are not validated as yet and cannot be used to substantiate any argument at this stage."
According to the lab, the samples tested, primarily extracts, were forwarded to the lab for testing to establish the presence of aromatic amines from the packaging in the extracts. "Based on the tests conducted so far, Steins Laboratorium A/S cannot prove that the packaging liberates aromatic amines to the foodstuffs," it said.
The preliminary values, the lab explained, were calculated in the water department, as the test material has not been registered as relating to food safety. Until a closer examination is carried out in the lab's foodstuff department, "it is not possible to express an opinion as to whether or not the packaging emits aromatic amines to the foodstuffs, and whether or not such potential migration is a cause for concern in relation to food safety."
This pretty effectively killed the Borsens story, which received no widespread attention in the United States. However, the story also provides a good reminder of the need to follow good manufacturing practices (GMPs) throughout the food packaging industry.
Suitable Purity Remains Key
In flexible packaging films, isocyanate-based adhesives are used to bond several layers together to make a functional package which can be effective in myriad ways, including as an oxygen barrier and a light permeation barrier. However, aromatic amines can form if isocyanate monomers react with water. When the adhesive is cured, i.e., the moisture evaporates, the aromatic amines will not be available to migrate to food.
Assurance that the adhesive has adequately cured is, in FDA parlance, a GMP requirement. For food packaging materials, these requirements, although only generally expressed, are found at 21 C.F.R. § 174.5.
Far and away, the most critical GMP admonition for packaging materials is that they be suitably pure for the intended use. This means that the food-contact material may not impart anything to food that can make it harmful or deleterious to health or impart an off- taste or odor to food. In this regard, FDA points out that even if a food-contact material complies in all respects to the specifications or limitations set out in the applicable regulations, its use will, nonetheless, be viewed as violating the Federal Food, Drug, and Cosmetic Act if it results in adulteration of food.
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