Quote from: Body Builder on March 13, 2021, 07:54:18 PMI have a question though. Could the corrosion of steel (or any metal in orthopaedic nails, plates etc), except from poisoning which you mentioned that is not the case, increase the possibilities of a tumor in bone or other organs?
This is the most important thing for me and I would like a clear answer if you can.
Quote from: Serilium on March 13, 2021, 08:27:52 PMHow does corrosion affect health in general
I'm not him of course but I was interested by this question so I tried to find some literature on it to get an evidence-based answer. Here is a very long article summarizing the expected toxicity potentials for metal implants:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6384782/
Their table 3 summarizes different materials' expected toxicities, which vary of course depending on the metal type.
It seems though we don't actually know what metals are going into these LL devices publicly because they just describe the Stryde as "stainless steel" and yet a user had elevated chromium from it. The rep said that was normal as chromium was also part of the design. What other metals are part of the design? Who knows. Will they tell us if we ask?
I guess if people really want to know the theoretical toxicity the first step would be finding out from NuVasive exactly what elements are used, then referencing table 3 there.
In terms of cancer, they say: "Corrosion is an important factor in the design and selection of metals and alloys for service in vivo. Allergenic, toxic/cytotoxic or carcinogenic (e.g., Ni, Co, Cr, V, Al) species may be released to the body during corrosion processes." So they are saying for example chromium is potentially carcinogenic and we have already seen one case of leaching of chromium with high blood levels from Stryde.
They also say in a general sense regarding all implants: "metal ions that are released as degradation products are transported by body fluids to remote tissues where they may elicit an adverse biological reaction (such as cytotoxicity, allergy or even cancer)."
To get a real world sense of the potential impact from this, I found this study of metal-on-metal hip implants which would be expected to grind and leach their metallic elements over time:
https://www.bmj.com/content/344/bmj.e2383
They found in the first 7 years after getting these hip replacement units, there was no increased rate of cancer, but also state: "These data are reassuring, but the findings are observational with short follow-up. The use of hospital episode statistics data might underestimate cancer diagnoses, and there is the possibility of confounding by indication. Furthermore, as some cancers have a long latency period it is important that we study the longer term outcomes and continue to investigate the effects of exposure to orthopaedic metals."
If we're sure chromium is the main leaching risk then we can discuss that in more detail. Chromium exists as Chromium III or Chromium VI. Chromium III is the natural form which we all need in our diet and is nontoxic. Chromium VI is usually the form that is used in metal plating (I believe). It would be really important to clarify if they are using chromium-3 or chromium-6 if you want a clear answer. The risks of chromium-6 exposure which include cancer are detailed here:
https://www.epa.gov/sites/production/files/2016-09/documents/chromium-compounds.pdf
In reality, whether chromium-3 or chromium-6, either way, I would guess cancer risk from one of these devices to be near zero. Potato chips are carcinogenic as well but it doesn't mean most people who have potato chips will develop cancer from them. Just because something is theoretically carcinogenic (or carcinogenic in very high levels) doesn't mean of course it will actually be carcinogenic (or carcinogenic in low levels).
If the levels are not very high or not very high for very long, then the body can usually tolerate things and have no harm done. It would be interesting and helpful perhaps if some current Stryde users could post their chromium levels as they lengthen to see how widespread/universal the issue is, how severe, and whether it lasts the full 2 years or if it's just temporary during distraction. Or ask NuVasive whether it is chromium-3 or chromium-6. Or what other elements are in the device so people know what else to have checked.
This sounds flippant but remember that even the act of living and existing is carcinogenic, as we will almost all develop cancer no matter what we do if we live long enough. We are all exposed to carcinogens every day in the smoggy air or in our food or water. It is somewhat a part of normal life and the big question is more about the severity and exact nature of the exposure, as for most of us, all carcinogens cannot be totally avoided even in normal daily life.