Why materials from countries without strict quality control requirements are unacceptable for jewelry
by Brian W. Skellie, APP Medical Director
Does it matter where a biomaterial we use comes from?
Biomaterials made in the USA and in a short list of countries who maintain reciprocal quality control agreements can currently be verified as ASTM or ISO compliant. Those materials made outside of these qualifying countries cannot due to a lack of quality control protocols and lack of consequences for substandard and falsified products. The provenance of the material should be listed on the certificate of tests.
Is knowing the chemistry enough?
Learning what the ingredients are, as well as the proportions of a material, is a minimum step in the right direction to indicate that it does contain what we need, and does not contain harmful impurities over a certain threshold. Chemical tests are not confirmation of quality by themselves. The only way to be sure about the quality of the material is to have reliable chemical and microstructure tests performed under strictly regulated controls during the final purification melt and on the ingot (block of metal) produced, prior to forming it into bar, wire, sheet, etc. We must be assured that the correct ingredients have been mixed and cooked together in the correct way, and that the material has been treated and handled correctly during the process according to the ASTM and ISO specifications. There is more to the ASTM and ISO standards than chemistry. So if a certificate says “chemistry only” the material has not been fully tested to fulfill the material properties required by the standard, and may break or include foreign matter among other disadvantages. Basically, we want the raw materials to fully meet the standards for surgical implant, and we want documented proof that it was tested and completely fulfills all the requirements during the melting of the alloy. No misleading shortcuts. No half-steps. Add a proper surface finish, cleaning, passivation, and sterilization and then we can wear it with a clear conscience.
Currently, our requirements for gold, niobium, and platinum are measured based on chemistry alone. We have a strong theoretical rationale to use them based on the fact that they are three of the most biocompatible elements and have a longstanding history of acceptable level of response in the body. Unfortunately, they are not as strong when compared to other biomaterials, and do not have the same sort of detailed specifications for use in the body. For gold and platinum, because of proprietary alloys and strict legal regulation for the karat content, the chemical analysis is all we have access to if we don’t use gold or platinum group metal alloys that have already been through ISO 10993 testing for biocompatibility. Gold and platinum group metals are frequently mentioned in biomaterials and dental implant science texts as inert substances with low potential for allergy
“CORROSION AND CORROSION CONTROL IN THE BIOLOGICAL ENVIRONMENT
“The need to ensure minimal corrosion has been the major determining factor in the selection of metals and alloys for use in the body. Two broad approaches have been adopted. The first has involved the use of noble metals, that is, those metals and their alloys for which the electrochemical series indicates excellent corrosion resistance. Examples are gold, silver, and the platinum group of metals. Because of cost and relatively poor mechanical properties, these are not used for major structural applications, although it should be noted that gold and its alloys are extensively used in dentistry; silver is sometimes used for its antibacterial activity; and platinum-group metals (Pt, Pd, Ir, Rh) are used in electrodes.”
1 Biomaterials science: an introduction to materials in medicine, Buddy D. Ratner https://books.google.com/books?id=Uzmrq7LO7loC page 434
For this reason, and historical antecedents we feel comfortable with some gold alloys for initial piercing jewelry. Most of our evidence related to gold for use in jewelry is based upon historical, that is to say experiential and anecdotal sources. Gold has been used in jewelry fabrication since prehistoric times, and has had a similar length of history in surgical and dental applications.
Gold implants are used in various medical procedures, including reconstructive surgery of the middle ear, upper lid closure in facial nerve paresis-induced lagophthalmos, drug delivery microchips, antitumor treatment, treatment of rheumatoid arthritis, use on the surface of voice prostheses, and endovascular stents, with sound clinical results.
2 Demann, Eric TK, Pamela S. Stein, and James E. Haubenreich. “Gold as an implant in medicine and dentistry.” Journal of long-term effects of medical implants 15.6 (2005). https://www.ncbi.nlm.nih.gov/pubmed/16393135
Who should understand our jewelry standards?
Our standards are necessary for jewelers and regulators as well as piercers, healthcare professionals, and the public. APP publications have previously addressed the general public as the primary audience for our jewelry standards. Our simplified explanation of the rationale for our jewelry standards is helpful for clients, but not specific enough for regulators, and missing information for jewelers. We have chosen to rely firmly upon specifications that have been pulled from medical and dental implant sciences, and voted to allow to permit the use of certain traditional jewelry materials that are composed of biocompatible elements which seem to demonstrate an acceptable response in the body. This represents two categories of materials: specified and agreed upon.
The specified biomaterials are exact standards for materials that can be purchased ready to use for making body jewelry based on evidence that meets CDC recommendation Category IA: Strongly recommended for implementation and strongly supported by well-designed experimental, clinical, or epidemiologic studies.
This would include all biomaterials which have been developed using ASTM and ISO standard specifications for implantation.
The agreed upon materials of gold and platinum alloys, niobium, and fused quartz, soda lime, and borosilicate glass are within the ideal of CDC recommendation Category II: Suggested for implementation and supported by suggestive clinical or epidemiologic studies or by a theoretical rationale. For example, there is strong evidence that the pure elemental form of each of these materials are well accepted by the body, and they should retain that quality when alloyed until a threshold level of sensitizing or toxic elements are added to the mix. ASTM F2999 and F2923 limit the harmful levels of toxins based on California Prop 65.
Why are material standards important to understand?
Our standards are based on utility rather than our own invention. We use existing medical and dental expertise for materials that are currently being used in human implants and prosthesis. We rely upon a body of evidence and experimentation that we as an industry have not yet become capable of doing ourselves. For this reason, it is important for us to find and understand reliable information from other fields that can be applied to our own.
Why is the language we use important to describe standards to the public, jewelers, and regulatory authorities?
Simple descriptions should be clear for the biomaterials we choose for body jewelry. Existing materials which are made to ASTM and ISO implant specifications are tested according to consensus based scientific standards to ensure long term safety in the body. We choose these material specifications to avoid reinventing the wheel, and the ISO 10993 series of tests for those new wheels can be prohibitively expensive. We use the specifications F67, F136, F138, F1295 etc as a summation of what we need for safe materials, before they are formed into jewelry. We should not have to elaborate the minutiae of these specifications to know that they are applicable and achievable for our purposes. Can get away with less precision? Not without introducing high levels of risk.
Understanding biomaterials is one of my goals as both an experienced professional piercer and long time member of ASTM Committee F04 on Medical and Surgical Materials and Devices. I hope that some of the information we have to share is helpful to you.
Footnotes:
1 Biomaterials Science: an Introduction to Materials in Medicine, Buddy D. Ratner http://books.google.com/books?id=Uzmrq7LO7loC page 434
2 Demann, Eric TK, Pamela S. Stein, and James E. Haubenreich. “Gold as an implant in medicine and dentistry.” Journal of long-term effects of medical implants 15.6 (2005). https://www.ncbi.nlm.nih.gov/pubmed/16393135