FMF - Friends of Minerals Forum, discussion and message board

[Riccardo Modanesi]

Hi to everybody!
First of all, I fully agree with Tracy: even water is toxic if drunk in a high enough amount. Therefore minerals are toxic if accidentally eaten or inhaled in high enough amounts as well! But I don't think it is the case of our collections. In mine I have been having a drusa of potassium ferrocyanide (nice red crystals) for over 20 years, but I neither move it from its transparent small box nor I open the box! And I have asbestos specimens as well, but they are all involved in a transparent plastic film, so that they are secured and prevented from being toxic!
I participated to a similar discussion once about mushrooms and poisonous plants: when the speaker was asked "what kinds of mushrooms are edible", he answered: "All kinds of mushrooms, but some of them just once!!!" Hahahahaha!!!
Greetings from Italy by Riccardo.

[Tracy]

There are 3 primary routes of exposure through which a chemical can enter the body: ingestion, skin contact, and inhalation.

If a chemical has a low oral LD50 in rats, does that mean it has a low oral LD50 in humans? we do not test for these kinds on information, thank goodness. And doing the crudest form of conversion, by body weight: if we assume that humans are as sensitive as rats (which is often a stretch), and also that the average human weighs 60 kg, a rat LD50 of 15 mg/kg is equivalent to a human LD50 of about a gram, which doesn't sound quite as scary.

Also, if the oral LD50 is low, does this mean that it will be absorbed through the skin? The toxicologist's favorite answer: it depends...on a variety of other chemical characteristics. Low oral LD50 means don't eat it, nothing more. Whatever else the teachers tell you is overcaution, and understandably so - who wants to take a chance on the health of someone else's child and they want to teach you to respect hazardous things. The perspective is lost on children. And most elementary and high school teachers aren't toxicologists.

"Sweat dissolution due to large skin surface contact" only makes sense if you like to lie on all your specimens together, on a hot day, without clothes. I do not mean to sound flippant, but it is simply not a realistic scenario for a collector. For a miner, perhaps?

In addition to being a toxicologist, I do risk assessments for a living. And the cardinal rule of risk assessment is: risk is a function of both the inherent hazard and the exposure potential. If either of these parameters drops to or near to zero, then there is no/negligible risk. There is little to no exposure potential to arsenic when it is one of many elements embedded in a complex crystalline structure, and the specimen itself is small to begin with. There is zero exposure potential to arsenic in a specimen if you keep it on your shelf/cabinet. No plastic coating or boxes needed either, unless you want to protect the SPECIMEN from moisture or light or heat (sorry Riccardo). Washing hands after handling is always a good idea.

One of the most potent carcinogens on earth is produced by mold inside the shells of peanuts. And some of it ends up in peanut butter during processing of the nuts. However, the amount present is so small that if you ate 40 spoonfuls of peanut butter every day for the rest of your life, you would only increase your risk of getting cancer by 1 in 1,000,000. Highly hazardous, virtually zero exposure potential. So you don't have to throw away your peanut butter! There are parallels to arsenic-bearing minerals.

To Cascaillou's last question: Yes. Poor solubility in water/HCl usually means low likelihood of GI absorption, but there are always exceptions. And enzymatic transformations by your body or by bacteria living in your gut can give rise to all sorts of chemical byproducts, some of which might be more soluble than the parent compound. What's more, the pH changes as you travel through the GI tract, so something that isn't absorbed in the stomach (low pH) might be more easily absorbed in the intestines (higher pH).

I am getting preachy and frustrated and am taking this discussion very far afield from its origin (I'm also not getting my work done!). My apologies if any of my comments were interpreted as harsh or overly sarcastic. I am happy to discuss any of this further by PM.

- Tracy

[Riccardo Modanesi]

Hi Tracy!
What should you be frustrated for? You commented the issue as an expert (it's what you are), and gave us a complete and exaurient explaination of the theoretical toxicity of dome minerals and chemical substances. Those explaination should be given also to the guys ruling us, who always forbid one or two chemical substance/s per day "because of its unsafety"! A good example is tethra-iodo-ethylene in the Anderson solution for a gemmological refractometer, this substance was forbidden by the EU in 2009 or 2010, I don't remember anymore the date, but it's not important.
The discussion could continue furthermore also for foods, because of individual alimentary intolerances (for example for mushrooms, or for milk derivates, or for cucumber, etc.).
Back to the issue: we all just have to thank you so much, Tracy! Don't worry if a comment appears "sarcastic" or "harsh". It is an expert guideline ALWAYS!!! Moreover: you all should have realized from time to time I like joking as well!
Greetings from Italy by Riccardo.

[Tracy]

...Frustrated only in that I was starting to repeat myself plus I wish I were still on vacation. I feel better now. Thanks Riccardo. :-)

- Tracy