[HN Gopher] Things I Won't Work With: Dimethylcadmium
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Things I Won't Work With: Dimethylcadmium
Author : Bluestein
Score : 66 points
Date : 2024-08-10 19:11 UTC (3 hours ago)
(HTM) web link (www.science.org)
(TXT) w3m dump (www.science.org)
| kens wrote:
| An entertaining article. It's strange to see cadmium described as
| something obscure that hardly anyone encounters. NiCad batteries
| were pretty common as well as CdS photo resistors for anyone
| doing electronics.
| Bluestein wrote:
| Indeed. In fact, a recent participant around here spoke of
| dealing with huge amounts of such batteries on a daily,
| professional basis.-
|
| They were pretty common.-
| jaggederest wrote:
| Also just about every yellow or orange pigment, like in e.g.
| oil paint, is cadmium selenide or something in that family, as
| far as I am aware. Same for ceramics, if you want a nice yellow
| or orange it's cadmium time.
| Bluestein wrote:
| Stuff's ubiquitous once you start looking.-
| dhosek wrote:
| I remember seeing a cadmium spill on the edges of the sewage
| treatment plant near where I grew up. I was a nerdy enough
| kid to recognize it when I saw it.
| timr wrote:
| Again, the usual "hacker news learns about chemistry"
| disclaimer must be specified: _just because a chemical shares a
| part of another chemical does not mean that it shares the
| toxicity of that other chemical_.
|
| Chemistry is complex. Biology, even more so. You can't just say
| "oh, it contains cadmium", and assume that it's bad.
| Dylan16807 wrote:
| The comment you replied to does not say or imply anything
| about toxicity.
| timr wrote:
| I wasn't criticizing the parent. I was making a general
| comment -- the reason you see Cadmium-containing compounds
| in common products is that they're useful, and not
| necessarily harmful.
| Dylan16807 wrote:
| Then I strongly advise you change your wording. Without
| specifically saying it's a warning to future theoretical
| comments, phrases like 'the usual "hacker news learns
| about chemistry" disclaimer' and 'You can't just say "oh,
| it contains cadmium", and assume that it's bad.' come
| across as direct and harsh counterarguments.
| wisty wrote:
| With heavy metals like Cd, it's a good first order of
| approximation. It's not like flourine that's a vicious
| oxidiser when it's alone, and so stable the only real issue
| with it is you can't get rid of it when it's with friends.
| timr wrote:
| 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
| fortran77 wrote:
| I would guess that kens has a great deal of background
| knowledge.
| kens wrote:
| I don't understand your comment. I didn't mention toxicity,
| but nickel-cadmium batteries and cadmium sulfide are both
| toxic.
| supertofu wrote:
| A consumer report not too long ago found cadmium at unsafe levels
| in many dark chocolate brands:
| https://www.consumerreports.org/health/food-safety/lead-and-...
|
| The cacao was contaminated with cadmium from the soil during
| harvest.
| Bluestein wrote:
| > found cadmium at unsafe levels in many dark chocolate brands:
|
| That's just bonkers.-
|
| PS. _Lead too_ , apparently ...
| MattGaiser wrote:
| Chocolate production is a mess of child labour, toxins,
| violence, and poverty.
| Bluestein wrote:
| > child labour, toxins, violence, and poverty
|
| That does sound like a mess. I wonder if so called "fair
| trade" production is, in effect, helping much ...
| hansvm wrote:
| And I thought I was just allergic. Maybe it's heavy metals
| and a few biohazards.
| Bluestein wrote:
| Seriously, a lot of our developed alergies could just be
| perfectly natural reactions to the amount of chemicals
| and other garbage ... everywhere, these days.-
| perihelions wrote:
| Discussed on HN here (and a few other threads if one's
| motivated to search):
|
| https://news.ycombinator.com/item?id=38038465 ( _" A third of
| chocolate products are high in heavy metals
| (consumerreports.org)"_; 201 comments)
| duffpkg wrote:
| In short the article and conclusions are a total mess and made
| a nice attention grabbing headline with little to no substance.
|
| As someone that has built and managed clinical laboratories for
| human samples, I find this article from consumer reports
| extremely misleading. The describe results as a percentage of a
| theoretically acceptable level. For example, for cadmium, they
| are saying an acceptable level is 4.1 ug/day . Then they seem
| to imply that "TJ The Dark Chocolate Lover's Chocolate 85%
| Cacao" has 229% of the 4.1ug/day if a consumer ate a 30g piece.
|
| They never actually spell out what they mean or what the actual
| results they found were, or what the limit of detection of the
| methodology was or the error range of their tests. I guess they
| are saying that that chocolate has 9.3ug of cadmium in a 30g
| sample but it's impossible to say from what they wrote.
|
| The FDA states that the maximum daily consumption of cadmium
| should be limited to 0.21-0.36ug per kg of body mass. For an
| avg american male that would mean a threshold of
| 17.64-30.24ug/day. A typical salad containing 250g of romaine
| lettuce has 2-14ug of cadmium in it. Lettuce and cereal grains
| are the most common sources of cadmium in american diets.
|
| The amounts we are talking about are extraordinarily small and
| difficult to measure. We are talking 5-100 quadrillion
| individual atoms of cadmium.
|
| https://article.images.consumerreports.org/image/upload/v167...
| https://www.fda.gov/food/environmental-contaminants-
| food/cad....
| Bluestein wrote:
| > Lettuce and cereal grains are the most common sources of
| cadmium in american diets.
|
| Lettuce has cadmium. TIL.-
|
| > threshold of 17.64-30.24ug/day.
|
| So; it I am not mistaken; by these measurements the amount
| claimed to be contained in the article, for chocolate; would
| be within bounds ...
|
| (It's just you then could not go ahead and have a salad :)
| Waterluvian wrote:
| > The amounts we are talking about are extraordinarily small
| and difficult to measure. We are talking 5-100 quadrillion
| individual atoms of cadmium.
|
| I get what you're saying but I think it's kind of funny how
| impossible it is for a layperson to have any clue if that
| number is a lot or a little.
| fortran77 wrote:
| Maybe it's the "Cad" in Cadburry?!
| teractiveodular wrote:
| (2013)
| mhb wrote:
| et alia:
|
| https://hn.algolia.com/?q=things+i+won%27t+work+with+
| DylanSp wrote:
| https://www.science.org/topic/blog-category/things-i-wont-
| wo... links to all of Lowe's posts in this category. The How
| Not to Do It series is also great -
| https://www.science.org/topic/blog-category/how-not-to-do-it.
| mech422 wrote:
| Derek Lowe's stuff is awesome - Probably the most famous
| 'stuff I won't work with' is 'sand won't save you this
| time' ...
|
| 1) https://www.science.org/content/blog-post/sand-won-t-
| save-yo...
|
| edit: full index here: https://www.science.org/topic/blog-
| category/things-i-wont-wo...
| Ekaros wrote:
| Are dimethyls with wrong sort of metals all really nasty stuff?
| Just wondering as dimethylmercury is also nasty stuff.
| ta988 wrote:
| It seem so, but it is a bit more complex in reality
|
| https://pubs.acs.org/doi/10.1021/acs.organomet.7b00605
| zdragnar wrote:
| Methyl groups play heavily in organic chemistry. As an organic
| compound, it allows otherwise fairly inert metals to be easily
| absorbed into body tissues and interfere with the chemical
| processes therein.
|
| To take mercury for example, you can stick your hand in a vat
| of elemental mercury and be fine. A few drops of
| dimethylmercury on your skin can be fatal.
| Bluestein wrote:
| > A few drops of dimethylmercury on your skin can be fatal.
|
| Sounds like a state actor's weapon of choice ...
| Ekaros wrote:
| Only if your agents are ready to commit painful suicide...
| Dimethylmercury can pass through gloves...
| Bluestein wrote:
| Nasty stuff.-
| User23 wrote:
| Methylating is like acetylating. It's kind of a go-to thing
| to try in medicinal chemistry.
| monktastic1 wrote:
| Indeed. I am reminded of the sad and horrible story of
| https://en.m.wikipedia.org/wiki/Karen_Wetterhahn
| culi wrote:
| Yeah I find this interesting too. A methyl group separates the
| street drug meth from the prescribed drug amphetamine. The main
| role that methyl group plays is the way it crosses the blood
| brain barrier. During the process of crossing the methyl group
| is lost. Which means with both meth and regular amphetamine the
| chemical that reaches your brain is the same.
|
| I wonder if the dimethyl plays the same role here. Allowing it
| to cross the blood brain barrier faster
| cperciva wrote:
| _[I]ts odor is variously described as "foul", "unpleasant",
| "metallic", "disagreeable", and (wait for it) "characteristic",
| which is an adjective that shows up often in the literature with
| regard to smells, and almost always makes a person want to punch
| whoever thought it was useful._
|
| No need to punch them; if someone has been exposed to enough
| dimethylcadmium to describe its odor as "characteristic" they
| probably don't have long to live...
| lifeisstillgood wrote:
| >>> Cadmium compounds in general have also been confirmed as
| carcinogenic, should you survive the initial exposure.
|
| I have heard of gallows humour, but its the gallows sarcasm that
| gets me :-)
| fortran77 wrote:
| Cadmium used to be all around us in Nickel-Cadmium batteries, and
| in Cadmium Sulfide "electric eye" photoresistors, that lower
| their resistance when exposed to light, and increase their
| resistance in darkness.
| (https://en.wikipedia.org/wiki/Photoresistor).
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