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Migration of Epoxidized Soy Bean Oil (ESBO) from lids of glass jars into oily foods |
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Recently the Official Food Control Authority of the Canton of Zurich detected compounds from the lids of glass jars in oily foods in concentrations far exceeding the legal limit.
Introduction
Many types of foods are sold in glass jars with metal lids. To ensure tight closure and fairly easy opening, the lids contain a gasket of rather soft PVC with 40-45 % plasticizer, usually Epoxidized Soy Bean Oil (ESBO). Migration from these lids has repeatedly been an issue of concern: ESBO, ESBO-derivatives formed with HCl from the PVC, semicarbazide from the blowing agent and 2-ethyl hexanoic acid. Industry works on replacing the azodicarbonamide which is responsible for the semicarbazide, but the much older problems regarding ESBO remained unresolved.
Migration of ESBO
The Official Food Control Authority of the Canton of Zurich checked the ESBO content in a broad vari-ety of oily products from glass jars, since edible oil is known to extract plasticizers from PVC. When ESBO was used as the main plasticizer, the (Swiss and the European) legal limit of 60 mg/kg was exceeded by far. 60 mg/kg is not only the Overall Migration Limit (OML), but also the Specific Migra-tion Limit (SML) calculated from the toxicologically derived Tolerable Daily Intake (TDI) of 1 mg/kg body weight (hidden because SMLs corresponding to the OML are not listed).
The high migration of ESBO is predictable. Of the gaskets tightening against the rim of the jar, 60-250 mg (average 165 mg) is in food contact. If ESBO is used as the principal or only plasticizer, its concen-tration in the gasket is typically between 40-45 %, i.e. on average 70 mg ESBO is in food contact. After exposure to olive oil during four weeks at ambient temperature, all the ESBO was transferred, which means that almost complete migration must be expected when oil is in contact with the gasket. 70 mg ESBO in a 250 g jar results in a concentration of 280 mg/kg; in a 100 g jar it is 700 mg/kg. In oily foods, the predicted concentrations are indeed approached.
The 48 oily sauces analyzed with ESBO as the main or exclusive plasticizer in the lid, such as spa-ghetti sauces, olive pastes, pesto or basil and other herbs in oil, contained 47-580 mg/kg ESBO, with a mean value of 183 mg/kg (three times the limit); only 2 products complied with the limit. The 38 prod-ucts immersed in oil, like dried tomatoes, stuffed peppers, artichokes or fish, contained 85-350 mg/kg ESBO (mean concentration, 145 mg/) and not a single sample complied with legislation.
The products of concern are normally consumed in limited quantities. For this reason an immediate risk to human health of the consumer seems improbable.
Measures
Industry knows about the high migration of ESBO into oily foods for years. The Official Food Control Authority of the Canton of Zurich pointed possible problems out in the yearly report of 2001. On the Swiss market, products with a value of about € 40 Mio are affected by ESBO; in the EU the estimates are in the region of € 2000 Mio. It seems that at the present the food industry has no possibility of clos-ing their jars in a way respecting the legal limits. In fact, industry does not seem to have a rapid solu-tion at hand.
On November 5, 2004, the Swiss Federal Office of Public Health (SFOPH) issued letter nr. 3 interpret-ing for the Swiss enforcement the facts, rules, measures to be applied and the obligation for self con-trol regarding ESBO. Enforcement was advised to give distributors and producers time to restore the legal situation and to find technical alternatives complying with the rules. In addition, the SFOPH in-structed the enforcement that according to Art. 28/4 LMG non-compliance with the measures may be followed by removal of the products from the market even if there is no health risk.
At the present, the main distributors and industries study measures which ensure that the products with the highest ESBO concentration are detected and removed from the market, and that maximum concentrations are reduced stepwise to the legal limit.
For food producers and distributor, the present situation is a nightmare. Many producers protected themselves by certificates, but the case shows that they still missed most relevant information about the lids and that without the disclosure of the composition of packaging materials there is no reliable control. It is, therefore, indispensable that the producers of food packaging material disclose the com-position of their products to the food producers.
16. November 2004
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