uranium-235. The dose rate at the surface of the powder was 8 micro-Sv/h. Jewelry pieces identified as made with this enamel powder were enamel plates, pendants, and rings. The dose rate at the surface of the jewelry pieces was 6.7 micro-Sv/h.
The powder is sold at a price of 480 FF (US$ 74) per kg incl. tax by Cristallerie de Saint-Paul at Condat-sur-Vienne (Haute-Vienne), the only producer of enamel powder for use on copper, silver, and gold in France. Until very recently, the powder was sold without any mention of its hazards.
For the handicraft-artists using the powder for manufacturing enamel jewelry, the powder presents an inhalation hazard. The annual dose limit for the public of 1 mSv corresponds to the inhalation of 14 - 45 milli-grams of the powder (depending on age).
For the users of the jewelry, there exists the external radiation hazard to the skin: for continuous exposure, the skin dose would be 58.7 mSv per year. There moreover exists the risk of dissolution of toxic uranium from the enamel.
Nothing is known so far on the source of the depleted uranium used in the powder. But, it most probably comes from Cogema's Pierrelatte facility, where depleted UF6 is being converted to the form of U3O8 for long-term storage in the Bessines storage facility.
Uranium was widely used as a coloring matter for porcelain and glass sin the 19th century. The total production of uranium colors was 260 tonnes (with an uranium contents of 70%), 150 tonnes of which were used for uranium glass. While the uranium in those times had to be mined at high cost, depleted uranium now is available at virtually no cost, since it is a waste from the uranium enrichment process.
This use of depleted uranium in enamel resumes, after nearly 100 years, the practice of dispersing the radiating and toxic uranium in everyday's items, a practice that was believed to be a matter of history.