Cadmium regulation - are you prepared? The Birmingham Assay Office looks at the effects that new regulations will have on the jewellery industry.
The EU has extended the restrictions on Cadmium in the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) Directive. A new regulation, EU 494/2011, was issued on 20th May 2011 and has already come into force with effect from 10th December 2011. For jewellery the regulation restricts cadmium content to 0.01% (100 mg/kg) by weight of the metal and this applies to "metal beads and other metal jewellery components, metal parts of jewellery and imitation jewellery articles and hair accessories (i.e. bracelets, necklaces, rings, piercing jewellery, wrist-watches, wrist-wear, hair accessories, brooches, cufflinks)." These requirements are not applicable to jewellery made before 10 December 1961. Jewellers at all stages of the supply chain clearly will have to respond to regulation's requirements by ensuring that their products are compliant.
Cadmium may be present in jewellery as (a) part of the main jewellery alloy, (b) in a solder, (c) in gold coatings (electroforming/electroplating), or (d) as a pigment or stabiliser in non-metal components of a jewellery article. The literature based research so far carried out by The Birmingham Assay Office suggests that, while the use of cadmium in EU-based jewellery production appears to be low, such use is ongoing and widespread in other countries which export significant quantities of jewellery to the EU.
The data suggests that 273 tonnes of cadmium may be entering the EU on an annual basis in the form of jewellery articles. Most jewellery contains low levels of cadmium; however, concentrations of up to 15% to 200/0 and even higher in few cases have also been noted. High concentrations appear to be associated with costume jewellery imported from non-EU countries and is usually sold as 'silver' jewellery. About 1,000 tonnes of cadmium per annum is used in the EU for stabilisers, pigments and plating.
The prevalence of cadmium is particularly apparent when gold and sterling silver scrap is melted. While levels are generally low, below 300 ppm for 95% of the time, cadmium may be present at levels of 1,000 ppm or higher in gold or silver melts and occasional reports of content in the 2,000 ppm range have been seen. The Laboratory at The Birmingham Assay Office has even experienced silver melts containing in excess of 10% cadmium.
The dangers of cadmium
Cadmium is recognised to be toxic and carcinogenic regardless of the route of exposure ie inhalation, ingestion (eg children licking or sucking jewellery and other articles) or prolonged skin contact. Results on the migration of cadmium from tested jewellery articles have shown to be substantially high as to warrant action to ensure the protection of public health.
For workers in the jewellery industry, cadmium oxide is a major hazard. Cadmium melts at a relatively low 321[degress] C. If cadmium based solders are used some cadmium oxide will always be released during soldering and this can generate very harmful fumes. Research suggests that the use of cadmium-bearing solders is widespread, in fashion jewellery items imported from non-EU countries.
Overheating whilst soldering or the use of an incorrect technique during manufacturing and melting processes can result in the workplace exposure limit for cadmium being exceeded. Brazing and soldering with a hand held torch is the most risky process in terms of the potential for overheating because the common fuel sources have high flame temperatures. If a cadmium containing solder metal is melted directly by a flame it will readily vaporise. This will result in cadmium oxide fumes being liberated and is a dangerous situation. Cadmium oxide fume is a poison; chronic damage to the kidneys and lungs can stem from the inhalation of small quantities of fumes over a protracted period and cadmium oxide is also classified as a carcinogen.
Why is cadmium is used in jewellery?
When silver is melted it takes up oxygen about 22 times its own volume and the copper that is usually alloyed with it also introduces more oxygen in the form of cuprous oxide. This creates the phenomenon known as spitting or sprouting when silver cools after pouring. The presence of oxygen also interferes with rolling and drawing operations. Cadmium has proved to be the most effective de-oxidiser to resolve this problem.
Cadmium is used in gold alloys in place of silver to obtain different shades of colour such as pale-yellow or pink. Certain mixture of cadmium with gold gives green alloy, like the Cu-Cd-Ag-Au mixtures. Greenish 18ct gold alloys have traditionally been obtained with mixtures containing as much as 12.5% cadmium.
Sterling silver alloys containing cadmium are significantly more malleable and ductile, rendering them easier to spin and to draw. Cadmium may also be alloyed with tin to improve melt and flow.
This property has also resulted in cadmium being widely used in solders and such solders melt and flow better at a lower temperature than non-cadmium products. They are also widely used in gold and silver solder-filled wire.
Adhesion and corrosion resistance
Cadmium is used in some plating processes to promote adhesion and minimize corrosion. Plating baths may contain trace amounts of cadmium from earlier platings that could be incorporated in the final plated item.
Cadmium in paints, colours, and glaze Cadmium in various forms is used for colouring glass and porcelain and in the preparation of enamels. Such colours are absolutely stable on exposure to light and air, as none of the modifications of cadmium take up oxygen at ordinary temperatures. In addition to use in metals, solder, and solder-filled jewellery, cadmium is used as a stabilizer in certain plastics and may be used as a pigment in crystal, glass, ceramics, enamel or plastics, or in paint and surface coatings
Impact of European Legislation
Responsible EU retailers are alerted to the new legislation for cadmium and are requiring their suppliers to provide product which complies with the REACH Directive. This is inevitably having an impact throughout the supply chain.
It is not straightforward to quantify the costs and impact of implementation of the cadmium regulation on the jewellery industry. There are alternatives available for some, but possibly not all, applications of cadmium within the jewellery trade. Only a limited amount of this manufacturing takes place in the EU and thus it is not expected that operating costs in the EU will change significantly as a result of the restrictions on cadmium.
However, the current information available suggests that there will be higher costs. Expensive research and development on the part of Far East manufacturers will eventually result in a satisfactory alternative to cadmium but this will almost certainly be more costly and these costs will inevitably be pushed back down the supply chain. EU importers, wholesalers and retailers will have to pay higher prices and also need to introduce better quality controls and due diligence testing to ensure that their products comply with the restriction on the metal.
How will articles be tested for cadmium compliance?
The Laboratory at The Birmingham Assay Office has a variety of techniques available for measuring the concentration of base metals in jewellery. Most popular are: X-Ray fluorescence Spectrometry (XRF) Analysis and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES).
X-ray Fluorescence Testing (XRF) is reasonably accurate for measuring cadmium content but, as it is a surface analysis method, the presence of coatings on the tested item can interfere with the detection of metals below. The Birmingham Assay Office proposes that a proper validation of testing jewellery articles to the new cadmium levels using XRF be undertaken before making a final decision on the suitability of XRF for accurately determining the concentration of cadmium in articles.
ICP-OES is a destructive technique that is capable of reporting several elements simultaneously. The turnaround times are slightly longer than the XRF method of analysis; however, the accuracy levels are far superior. This method can only be used by accredited laboratories. When a sample of the jewellery article is dissolved, the method can find even trace elements; for metals the results can be at the level of parts per million. An estimate for the detection limit is 0.001 mg/kg so this method is currently the recommendation to ensure that products comply with the new regulations.
Regulation to protect the consumer and employees in the trade are necessary to restrict the potential danger of harmful substances. Alternatives are available and it is important that the jewellery and fashion accessories industry take a responsible view and ensure that products comply with these new regulations.
For more information about testing services provided by The Laboratory at The Birmingham Assay Office visit www.thelaboratory.co.uk
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|Date:||Jan 1, 2012|
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