The lecture series “Limits for Metals – Trace Elements or Poison?” provides insights into the occurrence, technical applications, presence in food, and physiological effects of various metals on the human body. This final, fifth part addresses five additional elements: iron, titanium, mercury, thallium, and beryllium.
Previous lectures covered the 17 elements that must be monitored in food contact materials according to EN ISO 4531.
The five elements presented here are not subject to monitoring under EN ISO 4531, each for specific reasons:
Iron and titanium have such high tolerable limits that leaching significant amounts from vitreous enamel is practically impossible.
Mercury cannot be retained in vitreous enamel, as all mercury-containing raw materials or compounds would volatilize during the high-temperature melting process. Even if added at later stages—for example, as cinnabar pigment—the mercury would evaporate during firing and thus never become part of the glass.
Thallium and beryllium are not present as trace components in the raw materials used for enamel production. Nonetheless, these elements remain relevant in other contexts. Understanding their toxicological profiles, technological relevance, and potential risks in broader material applications contributes to a more comprehensive view of metal exposure and material safety.
This final lecture not only closes the systematic review of metals in the context of enamel coatings and food contact regulations but also broadens the perspective on how and why certain elements are excluded from existing standards—and whether future inclusion might become necessary.