The increased demand for preserved foodstuffs packaged for immediate consumption has led to significant centralization of food production and strong industrial development in this direction. This situation has stimulated a parallel search for new technologies, both in terms of developing food products which are suitable for preservation as well as in the choice of packaging that is compatible with distribution.

While the consumption of convenience products has improved food quality, it has at the same time exposed a large number of people to the risks of infection and toxicity, which may exist when a product eludes the hygenic and health checks set forth in the procedures codified for sampling and analysis that must be carried out on all foodstuffs and their containers, and applied to the methods used for preserving and transporting them.

Food which is industrially prepared, even when produced in accordance with established safeguards, may constitute a risk for consumers following environmental contamination to the containers in which the food is packaged. Risks are linked to these ready-to-use products (which do not require heat treatment or cooking and are sold in disposable containers) which may serve as carriers for microrganisms or toxic substances.

Tinned beverages are a prime example. Although the product is acceptable from a hygenic point of view, consumption may allow the ingestion of substances which are hazardous to health.

The beverage, whether drunk directly from its container or poured into a glass, comes into contact with the cover of the container and its rim, carrying with it whatever substances have been deposited there. Possible pollutants include those which may be found in the environment (dust, bacteria, moulds, dirt), those of animal origin (usually from rodents, insects or domestic animals) and those produced by humans (handling during distribution or by consumers themselves).

In addition to exposure to pollutants whose origin is bacteriological, tins may also be contaminated by chemically toxic substances (particularly sprays used as insecticides or rodent killers and cleaning products) widely used for disinfecting and cleaning of warehouse premises.

Especially during the summer months, the condensation which forms on the outer surface of tins which have been refrigerated, favors the detachment of contaminating substances, which, together with the condensation may then be suspended in the beverage.

When the contents of a tin is not consumed within a reasonably brief span of time, the residues of beverage which remian on the lid and its rim form an ideal sustratum for wide-spectrum microbe development. In addition, the immission of possible pathogens in a beverage at the moment of its ingestion renders completely inefficacious from a practical point of view, the experimental results observed by the Istituto Superiore di Sanità Italiano, according to which after 2 hours and in a period of up to 24 hours of contact, all beverages, especially those rich in carbon dioxide, cause a significant reduction in one particular strain of virus, an enterovirus, the only one employed in their experiments and initially inoculated into the beverages.

Based on research conducted at the University of Torino in 1997 in the laboratories of the Dipartimento di Sanità Pubbblica e di Microbiologia (The Department of Public Health and Microbiology) in which 227 samples of tins from different points of sale to the public throughout Italy were used to carry out microbiological analyses of the washing liquid for the entire lid, especially the groove around the rim, it emerged that the natural surface contamination of beverage tins exceeded legal limits. A microbe count which exceeds 1000 units in the colony formed on the lid is deemed unacceptable and nearly 12% of the samples examined were not acceptable because of environmental contamination while over 21% were not acceptable due to contamination caused either by people or animals.

Although to date no direct correlation has been established between the consumption of tinned beverages and episodes of illness, certain pathological conditions of the gastrointestinal system, ascribed to other causes, may have been caused, instead, by toxinfection caused by beverages packaged in tins whose lids were contaminated when they were drunk. The situation observed demonstrates the existence of a currently underrated risk. Considering the variety of causes and the heterogeneity of the possible contaminants involved, it is urgent that departments of health and those working in the sector become aware that this risk exists.