Comment by timr | Hacker News Reader

Comment by timr | Hacker News Reader

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I don't disagree at all, but unfortunately, the usual reflex amongst non-chemists is to go far in the other direction: assume that anything containing the toxic thing is evil and wrong. So therefore you get people calling out (for example) ceramics containing CdS glazes, which haven't been shown to harm anyone using them (the finished ceramics, not the glazes themselves).

But of course, even for definitively "toxic" things, one must differentiate between exposure channels. I wouldn't care if I handled a piece of Greenrockite [1], but I wouldn't want to breathe the stuff in powdered form. Same with Cadmium glazes: orange pottery doesn't concern me, but I'd want to be careful if I were handling Cd-containing powdered glazes. You don't want your dry cleaner dumping used methylene chloride in the river, but it's commonly used in decaffeinating coffee.

The reason the author won't work with this particular compound isn't the fact that it contains Cadmium, but rather, that this particular compound has nasty tendencies, in addition to being toxic, that make it particularly dangerous.

[1] https://en.wikipedia.org/wiki/Greenockite

> I wouldn't want to breathe the stuff in powdered form.

This makes me think of wood dust being dangerous to inhale [1], despite wood being a perfectly safe material for furniture at home.

[1]: https://en.wikipedia.org/wiki/Health_impacts_of_sawdust

Regolith is also considered safe, but that’s only because it’s about one light-second away.

Regolith is just a layer of rock. We have plenty of that around here.

Lunar regolith or Arean regoliths are quite different. You were presumably talking about lunar regolith.

Per my sibling comment, I think thought must be given to the likelyhood of distribution of a "channel" or material state, not just the fact that one exists.

Particularly, wood is fairly recognizable, and almost certainly not liable to spontaneously implode into a cloud of dust. Plus, I'm fairly confident it is biodegradable (even in dust form).

Not sure the same can be said for most other materials, such as cadmium, or the parent mentioned naturally occuring compound.

Kind of a digression, but wood dust absolutely does present an explosion risk, when mixed in the right ratio with air. It's a thing that happens, and people worry about it in industrial settings.

https://www.youtube.com/watch?v=LPIZ5Movuiw

https://www.youtube.com/watch?v=70fZqHsEdMo

These are the first few sentences of the article:

> Cadmium is bad news. Lead and mercury get all the press, but cadmium is just as foul, even if far fewer people encounter it. Never in my career have I had any occasion to use any, and I like it that way.

It seems clear that he doesn’t want to work with cadmium, regardless of the compound.

I mean, sure. But then you read past that sentence, and you see that the rest of the article is about this particular compound, and it's unique tendency to explode, form toxic gases when burned, and so on.

I can't speak for the guy, but lots of things are "bad news", colloquially, and yet we work with them in the laboratory as an accepted everyday risk. I am not an inorganic chemist, but I'm pretty certain that they work with far riskier things than inorganic Cadmium on a regular basis.

> used methylene chloride in the river, but it's commonly used in decaffeinating coffee.

Where was it that folks found that decaf coffee was eating into their styrofoam cups (decaf alone), so they concluded that the solvents used during the decaffeination process must have been seeping into the coffee ...

I don't know, but without proof, this sounds apocryphal.

Found it!

- https://news.ycombinator.com/item?id=41070152

"one must differentiate between exposure channels"

I think this is a mistake, though.

I mean, yes, exposure "channels" are absolutely important, but its the (false) assumption that one "safe channel" lowers the general risk of the other channels being an issue.

Your particular example mentions powder - what happens to the substance after it is crushed in a landfill? Or involved in a high speed collision, exposed to high heat, uv rays, microwaved, etc.

Potential harm should include the risk posed by all channels as a function how likely they are to be in that state. If the likelyhood is at 100% over any "reasonable" period of time, then you don't get to ignore the effects of that "channel".

Worse, if any of the channels are difficult to detect, then the risk should be compounded - I know about wood dust and can both easily see it and am amply aware when it is an issue and can take precautions. I'm not sure I can even identify the material you mention nor would be able to distinguish it from just "normal" dust.

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