Contaminants from packaging materials

Nerin, C., Philo, M.R. Salafranca, J. and Castle, L. (2002). Determination of bisphenol-type contaminants from packaging materials in aqueous foods by solid-phase miceoextraction-high-performance liquid chromatography, J. Chrom. A, 963, 375-380. 

This chapter is divided into seven main sections. The first of these sections is focused on technological contaminants, namely heterocyclic amines, acrylamide, furan, chloropropanok and their fatty acid esters, polycycKc aromatic hydrocarbons, monocyclic aromatic hydrocarbons, nitroso compounds, and ethyl carbamate. Other sections deal with microbial toxins (mycotoxins and bacterial toxins), persistent organohalogen contaminants (such as polychlorinated biphenyls, dibenzodioxins and dibenzofurans), chlorinated ahphatic hydrocarbons, pesticides (persistent chlorinated hydrocarbons and modem pesticides), veterinary medicines and contaminants from packaging materials. Presented for each of these contaminants are structures, properties, occurrence and the main sources of dietary intake, mechanisms of formation, possibilities of food contamination, prevention and mitigation and health and toxicological evaluations. 

Formaldehyde, along with other short-chain aldehydes such as acetaldehyde, is a low molecular weight, volatile, reactive contaminant that can be present at low levels from a variety of sources (e.g., excipients such as polyethylene oxide, polyethylene glycol (64,65), or from carbohydrate degradation (66), solvent contamination (51), packaging materials (52), etc.). Formaldehyde is known to react with amines (Fig. 33) to form a reactive N-hydroxymethyl compound (a hemiaminal) that can further react with other nucleophiles. Reaction of formaldehyde with amino acids (67) can cause... 

The majority of toxicants in foods are contaminants, (e.g., microbial toxins, pesticide residues, leachable chemicals from packaging materials, food coatings, traces of heavy metals). However, the major issue in food safety is the contamination of food by mycotoxins in items such as milk and milk products, meat and meat products, and peanuts (groundnuts). Aflatoxin is highly toxic and lethal, and its carcinogenic potential is well established, even at doses as low as 0.05. ig. Mycotoxins also infect food products like rice, pulses, tapioca, and betelnuts. (Table 10-2). 

Many foods contain mineral oil material, either because of contamination from environmental sources or from packaging materials, lubricating oils, release agents, or as components in meat or eggs owing to the presence of paraffin oil or waste oils in the animal feed. 

Formaldehyde can occur in chemical products as a component added directly in the manufacturing process or as a component added in raw materials. Some components can release formaldehyde as part of their function in the products, i.e., formaldehyde releasing preservatives (Flyvholm and Andersen 1993). Besides these intentional occurrences of formaldehyde, it can occur as residues from synthesis of other product components and from formation during storage and handling of raw materials or end products. Contamination from packages coated with formaldehyde resins has also been reported. 

From packaging material. Traces of heavy metals from metal foils or cans or from wrapping paper can contaminate food and diffuse into the fat or oil phase. 

The main sources of contamination of the food chain with mono-cycHc aromatic hydrocarbons are oil spills, but also include a variety of coatings and plastics. MonocycHc aromatic hydrocarbons may also arise as products of the combustion of various materials. Food contamination occurs primarily by absorption from the air and water, and in animals from the surrounding environment. Another type of food contamination is migration from packaging materials. In recent years, much attention has been paid to contamination of yoghurt and biscuits by styrene (vinylbenzene) released from the polystyrene used to manufacture various packagings. 

Lau O.-W., Wong S.-K. Contamination in food from packaging material. Journal of Chromatography A, 882 255-270 (2000). 

Food Additives and Contaminants Committee (1970). Report The Leaching of Substances from Packaging Materials into Food, HMSO, London. 

Sorted plastic packaging materials are shipped, usually in bales, to processing plants to be converted to polymer resins. The bales are broken and the bottles sorted to ensure that only one type of polymer is further processed. Processing consists of chopping and grinding the bottles into flakes. These flakes are washed. Processing steps such as flotation are used to remove polymeric contaminants from the flakes (15,16). The flakes are melted and converted into pellets. 

Contamination. Manufacturers of cosmetics must be careful to guard against chemical and microbial contamination. Chemical contamination, which may result from the presence of undesirable impurities in raw materials, is avoidable by adhering to rigid specifications for raw materials. Compendial specifications and pubHcations by the CTFA and other professional societies form the basis of most intracompany raw material specifications. Moreover, all packaging components must meet not only physical and design specifications but also such chemical requirements as extractables and absence of dust and similar contaminants (see Packaging, cosLffiTics and pharmaceuticals). 

Paper is one of the oldest and most commonly used packaging materials. Generally it is used to keep a product clean and for mechanical strength when combined with other materials. It does not protect a product from atmospheric change, but only from mechanical contaminants such as dirt. Coated papers are much more functional. Waxed papers fall into this category and provide much better protection from moisture and, in some cases, from gas (oxygen) transmission. 

---