DTPA safety. Response to a Posting from Australia. This was describing Industrial use and not small volume Medical use.

On occasion, colleagues send me postings from Face Book or other social media sites, where something is written that has the potential to start a GDD- sufferer wide-spread panic.

In this case, I was sent a safety report from Roth, an organization in Australia, that describe safety of pure DTPA, it did not describe if DTPA was bound to some additional atom/molecule. I spent more time thinking about this warning, than I would like to have done. Primarily because I was wondering, if we inject into a vein 5 ml of Ca- or Zn-DTPA how is it that the warning is about eye irritation and lung toxicity if it is inhaled, and why is it described as essentially pure concentrated DTPA and does not mention a bound cation. After a 12 hour period following being sent this safety warning I realized what the report was: it is a report on working with DTPA at an industrial level. This is not a concern with 5 ml of Ca-DTPA in a 5 ml vial. This is working with huge volumes of DTPA in the 10s to 100s of liters in a factory setting. At that volume then huge volumes of DTPA poured into vats, some may splash in eyes and some may get aerosolized, especially if the factory temperature is also high - 30 degrees Celsius.

With that recognition then I had to think about the agents that I am really worried about, the nuclear medicine agents and PET tracers. A safety report on working with these radioactive agents would approach the safety concern of radiation workers working at nuclear reactors or working with uranium and plutonium to create nuclear weapons. A safety report on those would truly be frightening: beware of: all skin pealing off your body, immediate blinding, development of all cancers and malignancies with special attention to leukemia, breast and thyroid, fatal bleeding from your mouth or anus, etc.

I will just recap some of the points I have written in earlier blogs on the safety of DTPA, I direct the reader to look back at those for a more full description. DTPA is essentially the safest chelator available. Notably over 150 million doses of a DTPA molecule administered as a GBCA agent, and the DTPA component has never been observed to cause an adverse reaction . DTPA is the safe part of the molecule, and it has been used extensively because of intrinsic safety, binding strength with Gd or other metals, and ease of making the GBCA and other medical agents.

The Roth safety warning report describes eye irritation and that it should not be inhaled. We use either conjugated Ca-or Zn- to DTPA. It is not a free highly reactive acid. What I do find interesting is it describes it should not be inhaled. Why I find it interesting is that the earliest reports of using DTPA in humans as a chelating agent for toxins, was DTPA used as an inhalational agent to treat Radiation plant workers contaminated with inhaled Plutonium. So its initial use was as an inhalational agent. It still makes sense today, if the point of entry of a toxic metal is through breathing it in, using the chelator as an inhalational agent, follows the tracks of deposition that the metal will leave behind.. For treatment of PLutonium inhalational toxicity they nebulized the DTPA in normal saline to decrease the concentration of DTPA. Inhaling pure concentrated form I could imagine DTPA and everything else would be harmful

So DTPA is as safe as the safest things we use in medicine, the way that it is administered. But also like everything else that is a chemical nothing is 100% safe.. But perhaps as close as that can come in the real world.

So sage words I tell all GDD sufferers regarding everything. Stress makes everything, and especially GDD, worse, so stay calm. If I learn of anything regarding the safety of anything I advocate (or anything else in my sphere of knowledge) I will report it. Remember that until 2019 I have been and remain the most published author on the subject of the value of GBCA. But I learned the full picture and reported it. So if I was prepared to report on safety issues of GBCAs from the stature I had in the MRI and GBCA community, you can be assured I would not hesitate reporting serious safety issues with DTPA if they existed. I willingly made an enormous numbers of enemies pointing out safety issues with GBCAs, if safety issues were present with DTPA that were noteworthy, and I reported them, I would gain back thousands of supporters, and maybe lose 5 friends. So from a Machiavellian perspective reporting safety issues would be an obvious benefit for me.

I may stop spending time playing whack-a-mole with various odd posting that are brought to my attention. This was far too time-consuming.

Richard Semelka, MD