Lead in Glazes- Labelling

Following concerns expressed by some of our customers on reading labels on Duncan and Gare lead-containing glazes, we have been in touch with the Health and Safety Executive to try to clarify the official position. We have now received information from the HSE Metals & Minerals Unit which substantially clarifies the position as follows. I have abbreviated a long document but the italic sections are taken verbatim from the HSE reply to me.

The Approved Supply List classifies chemicals and preparations according to the most dangerous component, so a lead-containing glaze would attract a Toxic label as lead on its own is toxic. Labels on American products follow the same principle of labelling as the Approved Supply List, so they describe the dangers of lead, as a raw mineral. This is inaccurate in the sense that it takes no account of the fact that the lead in Duncan and Gare glazes is made safe having been chemically stabilised by the “fritting” process. This is acknowledged by the HSE as follows.

However, if the lead is not biologically available and does not present a danger to human health by inhalation, ingestion or contact with the skin, or to the aquatic environment in the form in which it is supplied, then that classification may not be appropriate. This issue was explored with the industry in some depth in the late 90s, at which time it was concluded that a lead frit does NOT come under the generic entry in the ASL for lead compounds. As a consequence, suppliers were advised that they should self-classify their products based on the available scientific/toxicological information and taking into account the evidence on the 'bio-availability' of the lead.

We are advised that we could self classify Duncan and Gare lead-containing glazes at the lower level “Harmful”. Lead present in these glazes is in a “fritted” form that is chemically stabilised by being melted with silica, in effect wrapped in glass. HSE scientific advisors agree that the lead present in this form is not readily “bio-available” and therefore does not represent the level of risk associated with “Toxic” substances.

Please see also my notes “Lead in Glazes.“ If you would like more information or wish to discuss this topic please feel free to contact me.

Ken Shelton