Nickel Allergies - How low of a percentage of nickel can be in stainless steel?

[Bridget]

Hi Cove Members!
I thought I would see if there is any one who can answer this or point me to some supporting evidence in regards to allergic reactions to nickel in stainless steel. These days there are more and more patients becoming sensitive to nickel and some device manufacturers are advertising that their products are nickel free. So my question is -how low of a percentage of nickel can be in stainless steel and be considered to be "nickel free"? Seems like there would be some guidelines from FDA on this...
Bridget

[Randy]

I've reported 1% on my TRI. If it has any, it ain't!

Here's some gobblety goop I found:

Nickel-Free stainless steel for biomedical applications

The invention concerns a high specification non-magnetic stainless steel which is corrosion resistant in physiological media and which can be produced at atmospheric pressure, characterized in that its composition in % by weight is as follows:

Mn 15% to 24% Ti .ltoreq.0.020%
Cr 15% to 20% Al .ltoreq.0.020%
Mo 2.5% to 4% S .ltoreq.0.0020%
N 0.6% to 0.85% B .ltoreq.0.020%
V 0.1% to 0.5% Nb + Ta .ltoreq.0.5%
C .ltoreq.0.06% Co .ltoreq.0.5%
Ni .ltoreq.0.25% Cu .ltoreq.0.5%
silica .ltoreq.0.25%

and from 0 to 0.5% of each of elements Cu, Co and of the sum Nb+Ta, the remainder being constituted by iron and impurities, and in that its composition satisfies the following conditions: (%Cr)+2.5(%Mo).ltoreq.27 (I) (%Cr)+3.3(%Mo).gtoreq.26 (II); and Log(%N)+0.0605(%N)=-1.3+[125(%V)+80(%Nb)+52(%Cr)+19(%Mn)].times.10.sup.-3 -[4.3(%Cr).sup.2 +0.35(%Mn).sup.2 ].times.10.sup.-4 +0.17(%Cr).sup.3.times.10.sup.-5 (III).

Montagnon, Jacques; Moraux, Jean-Yves
Societe Industrielle de Metallurgie; July 31, 2001
#6267921

[Wes Bucey]

Originally Posted by Bridget

Hi Cove Members!
I thought I would see if there is any one who can answer this or point me to some supporting evidence in regards to allergic reactions to nickel in stainless steel. These days there are more and more patients becoming sensitive to nickel and some device manufacturers are advertising that their products are nickel free. So my question is -how low of a percentage of nickel can be in stainless steel and be considered to be "nickel free"? Seems like there would be some guidelines from FDA on this...
Bridget

I'm sure there are some stainless steel formulations which contain little or no nickel, since there are over 100 varieties of stainless steel alloy.

I have a question, though (preceded by an explanation.)

Stainless steel is "stainless" (actually, it is "corrosion resistant") because it contains chromium, which forms a thin layer of chromium oxide (Cr2O3) over the surface of the product once in contact with oxygen. This layer is "impervious" to the further action of chemicals, thus conferring the "corrosion resistant" property. If scratched, it repairs itself with new Cr2O3.

The question: Does the nickel component of ANY stainless steel leach through the Cr2O3 layer to trigger an allergy?

Note: there are some grades of "free-machining" stainless steel that have high (relatively) amounts of sulfur which makes them machine better, but the sulfur reduces the corrosion resistant properties slightly and may thus allow leaching of the nickel through the Cr2O3 layer because of the disruption of the layer by Sulfur diOxide (SO2) molecules.

For the most part, none of the so-called "surgical stainless steels" are in the high sulfur category.

[Randy]

Looky here...


Essentially Nickel-Free Stainless in Cannulated Bar Stock for Implantable Orthopedic Uses

An essentially nickel-free austenitic stainless steel is now available from Carpenter Technology Corporation (NYSE:CRS) in cannulated bar stock with a hole from end to end and a heavy wall for implantable orthopedic applications.

BioDur(R) 108 alloy (UNS S29108 ASTM F2229), designed to minimize problems associated with nickel toxicity, in cannulated bar form can be considered for bone screws, intramedullary nails for the femur, instruments and any other trauma devices requiring a hole from end to end.

The hole in the cannulated stock allows space for bone marrow to grow, and facilitates the insertion of guide pins for bone screws used in fracture fixation. Cannulated bar also can eliminate or minimize the need for costly drilling operations currently required when using solid bar stock.

BioDur 108 alloy offers corrosion resistance similar to that of nickel-containing 22Cr-13Ni-5Mn alloy (ASTM F1314) at significantly higher strength. The Carpenter alloy has a typical yield strength of 230 ksi (1586MPa) and tensile strength of 250 ksi (1924MPa). Typical values for the 22Cr-13Ni-5MN alloy are 170 ksi (1172MPa) yield strength and 190 ksi (1310MPa) tensile strength.

Despite its higher strength, BioDur 108 alloy has fabricability and ductility similar to that of 22Cr-13Ni-5Mn alloy. BioDur 108 alloy is available in cannulated bar with outside diameters of 0.118-in. (3mm) to 0.750-in. (19mm), with inside diameters of 0.055-in. (1.4mm) to 0.354-in. (9mm). Typical OD dimensional tolerance is ±0.001-in. (+0.025mm), and ID tolerance is ±0.002-in. (+0.05mm).

This alloy has resistance to pitting and crevice corrosion that is superior to Type 316L alloy (ASTM F138) and equivalent to that of 734 alloy (ASTM 1586) which, like 22Cr-13Ni-5Mn alloy, are nickel-containing grades. It is produced by the electro-slag remelting (ESR) process to assure its microstructural integrity and cleanness.

For more information about BioDur 108 alloy and other Carpenter products, you can access the company's technical database at www.cartech.com or call 1-800-527-6900.

Carpenter Technology Corporation, based in Wyomissing, PA, USA, is a leading manufacturer and distributor of specialty alloys and various engineered products. Carpenter had sales of $977 million in fiscal year 2002 (ended June 30, 2002).

Company Information:
Name: Carpenter Technology Corp. - Engineered Products Operations
Address: P.O. Box 14662
City: Reading
State: PA
ZIP: 19612 4662
Country: USA
Phone: 888-488-6596
FAX: 610-208-3580
http://www.cartech.com

[Wes Bucey]

For all the Carpenter Stainless Steel and super alloys we bought when I was in the machining business, I am amazed their sales are less than $1 billion USD!

Unsolicited testimonial: (I am no longer in machining business.) Everyone at Carpenter from sales through metallurgists to delivery drivers always seemed "customer-centric" to me. We paid more for their products, but were convinced we got value back in customer service and consistency of material from heat to heat which allowed us to maintain Cpk in the 2.0 range. One stellar area of service was Carpenter coordinating with tool bit producers to help us find the optimum tool bit for cutting a specific shape in a specific grade of alloy.

[Al Rosen]

If this is for a Medical Device the bottom line is that you will need to show biocompatability in accordance with ISO 10993.

[Charmed]

Dear Bridget:

Her's some more info on nickel allergies - especially in orthodontics which might be of interest.

On Nickel Allergies (very complex question)

http://jorthod.maneyjournals.org/cgi.../full/30/2/171

Nickel is the most common metal to cause contact dermatitis in orthodontics. Nickel-containing metal alloys, such as nickel-titanium and stainless steel, are widely used in orthodontic appliances. Nickel-titanium alloys may have nickel content in excess of 50 per cent and can thus potentially release enough nickel in the oral environment to elicit manifestations of an allergic reaction. Stainless steel has a lower nickel content (8 per cent). However, because the nickel is bound in a crystal lattice it is not available to react. Stainless steel orthodontic components are therefore very unlikely to cause nickel hypersensitivity. This article discusses the diagnosis of nickel allergy in orthodontics and describes alternative products that are nickel free or have a very low nickel content, which would be appropriate to use in patients diagnosed with a nickel allergy.

Most research concludes that stainless steel is a safe material to use for all intra-oral orthodontic components for nickel sensitive patients. Reduced nickel content stainless steel is also available, but appears to be unnecessary.

Conclusion
Top Abstract Introduction Biology of the reaction Occurrence of nickel allergy Diagnosis of nickel allergy Alternative materials for nickel... Conclusion References

The craze for body piercing in younger age groups may mean that an increased number of our patients may have been sensitized to nickel by the time they reach our door. Severe intra-oral manifestations of nickel allergy are thankfully rare, although extra-oral reactions are more common. Stainless steel orthodontic wires, brackets, and auxilliaries appear to be safe. However, high content nickel-titanium wires should be avoided in nickel sensitive patients, as nickel-free alternatives are available and should be considered for these patients.

http://www.winter-branch.com/nickel-allergies.html

Ban On Nickel
...This problem is so prevalent that, since January 2000, the European Union has imposed a nickel ban on all jewelry sold there. The European nickel free standard states that items labeled nickel free” may contain no more than 0.05% nickel (no more than 1 part in 2000 that is nickel.)

http://www.skinsite.com/info_nickel_allergy.htm

http://www.goaskalice.columbia.edu/1083.html

http://allergies.about.com/cs/nickel/a/aa011000a.htm

On stainless steels (Type 304 and 316 are commonly used for hypodermic needles)

http://www.efunda.com/materials/allo.../stainless.cfm

http://chemistry.about.com/cs/metals...a071201a_2.htm

Hope this helps.

Charmed

[Bridget]

Charmed, Randy, Al and Wes, you have provided me with some great information this morning. I will look over all of the links everyone has provided and share it with the rest of my team.

Randy, the Bidour 108 is one grade of stainless that we use however it does have .05% of nickel in it which is considered as nickel free. I have an ISO standard, ISO 6871 that states .05% is allowable but how would the FDA look on it if we used the phrase "nickel free" for a medical device? What I need to prove to my boss is that the FDA will accept the .05% as nickel free.

As the terminator says "I'll be baaack"!

Thanks,
Bridget