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Author: Subject: The POTENCY of carcinogens.
Jor
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[*] posted on 9-12-2008 at 15:53
The POTENCY of carcinogens.


As I work with nickel compounds, chromium compounds, and also sometimes with CHCl3/CCl4, I was really interested in the potency of these materials carcinogen. There's all carcinogens, but the how powerful of a carcinogen a material is, that'what interests me.

I found this.
http://www.springerlink.com/content/p85680g33770047k/fulltex...

This gives a table (table 4), wich gives a median relatlive potency, with dimethylnitrosoamine as reference (=1).

However, arsenic, chromium and some others are missing.
Does nayone have another table? I have been looking on google for quite some time now, and it;s hard to find a good wich gives the potency for these materials, and not just : 'it's very potent'.

I'm surprised that benzene, CHCl3 and CCl4 aren't as badass carcinogens as I initially thought. They are quite weak actually, one of the weakest of the list.
I'm also surprised that cadmium is one of the strongest carcinogens, it's extremely potent! TCDD (the famous dioxin) is incredible.

Due to my lack of Engish, I do not understand what the numers on the right in table are. Hydrazine has a very high number, 2200. What does this say?
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[*] posted on 9-12-2008 at 18:14


Interesting data. It leads me to wonder why people get so freaked out about stuff like benzene and CCl4 when the are apparently very low on the list. Hell, they're only ~10-20 times higher that saccharine! Maybe the potential for chronic exposure to them increases the risk?
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[*] posted on 9-12-2008 at 19:05


Some time I came upon a compound called propane sultone which is said to be an extremely potent carcinogen: http://linkinghub.elsevier.com/retrieve/pii/S037842740400083... I wonder how it would fare against any of those.

Quote:
Originally posted by Jor Due to my lack of Engish, I do not understand what the numers on the right in table are. Hydrazine has a very high number, 2200. What does this say?


That is the interquartile range. Statistics. Shortly put, the middlespread: http://en.wikipedia.org/wiki/Interquartile_range They are saying this is for the activity profile. To which: "The range of relative potency values represent the "activity profile" for the test compound relative to the reference compounds".

[Edited on 9-12-2008 by Formatik]
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Jor
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[*] posted on 10-12-2008 at 01:24


Yes, it seems that benzene and CCl4 are indeed not so strongly carcinogenic. I read before that people only really get cancer on working for long times with this chemical.
Please remember that CCl4 is still a very strong liver toxin.

You also indeed have the very potent carcinogens, and I too have come across propane sultone. This one has caused tumors in laboratory animals after a single exposure. I would guess things like TCDD and cadmium could do the same.

I also found out that solubility of compounds doesn't say much on the potential carcinogenity. For example, of all Cr(VI)-compounds, the soluble ones ar emore carcinogenic than insoluble, but slightly soluble ones are the worst. Zinc chromate is the strongest carcinogen used in industry, followed by strontium chromate AFAIK.

For nicke-compounds it's the opposite. I read yesterday in a very long article, that insoluble nickel's are much more carcinogenic than soluble ones, due to their higher bioavalbility (I wonder why, maybe only inhalation?).

Saccharine is somethign else than saccharose! It's and articifial stweetener, found to be carcinogenic in humans.

Anotehr parameter for the potency is the TD50 of a chemical, wich is the dose in mg/kg/day for a long period wich causes cancer in 50% of the laboratory animals.

EDIT: I'm scared to hell. Chromium is said to be more than 30 times as potent as cadmium and 5000 times more potent than benzene. :(
And when I waking K3CrO8, I think I have inhaled some small droplets of hexavalent chromium. Am I at high risk now? :(

http://74.125.77.132/search?q=cache:avInsSpog58J:ftp://ftp.arb.ca.gov/carbis/board/books/2006/092806/06-8-3pres.pdf+extremely+potent+carcinogen&hl =nl&ct=clnk&cd=14&gl=nl

page 7


[Edited on 10-12-2008 by Jor]
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[*] posted on 10-12-2008 at 04:49


Quote:
Originally posted by Jor
Yes, it seems that benzene and CCl4 are indeed not so strongly carcinogenic. I read before that people only really get cancer on working for long times with this chemical.
Please remember that CCl4 is still a very strong liver toxin.

[Edited on 10-12-2008 by Jor]


Our chemistry teacher told us that CCCl4 was used as a hand wash for coal miners. Apparently they started to get skin cancer on their hands after long periods of time working with the stuff. Makes me think whether it was the CCl4 or the coal dust itself that was doing the harm though. Probably both at the end of the day.




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[*] posted on 10-12-2008 at 08:40


Quote:

I'm scared to hell. Chromium is said to be more than 30 times as potent as cadmium and 5000 times more potent than benzene. :( And when I waking K3CrO8, I think I have inhaled some small droplets of hexavalent chromium. Am I at high risk now? :(



Just try to be more careful, work in a hood if you think the solution will splash.

They are useful compounds, but yes they are quite toxic. On the other hand, we're exposed to all kinds of carcinogens everyday. I think you'll be ok, just try and be more careful with potentially toxic compounds. Try and understand the hazards of said chemicals before you work with them.
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[*] posted on 11-12-2008 at 00:07


Jor, you still must put things in perspective. The article you posted is talking about probabilities like 100 out of 1000.000, which is just 0.01% after low-level exposures, which lasted for years.

Your exposure will however be MUCH lower than what this article is about (workers in chrome processing industries). I once had a talk with a chemist, who is working here in a lab near where I live. He compares working with hexavalent chromium with smoking cigarettes. Each experiment you do, which is not carried out that carefully (e.g. inhaling some droplets with dissolved dichromate) can be regarded as smoking a cigarette. This is not good, but you also understand that all those persons smoking several cigarettes, every day, run a much higer risk of getting cancer.

The point is, your hobby imposes some risk, just like someone else's hobby imposes other risks. ALL activities in life impose some risk. It is our responsibility to reduce risks as much as possible, but we cannot eliminate risk and at the same time have fun in our life :P. We do many things which impose risks. Drinking a few beers or wines can be a pleasant experience, but I'm quite sure that this also introduces a certain risk of cancer (formation of acetaldehyde in the body). I still do accept that risk.

In your case, doing the K3CrO8 experiment every day would be a serious risk, but your one-time or two-times experiment is not a problem at all. Just work cleanly next time and try not to panic.

Many carcinogens have linear probability profiles for getting cancer. E.g. when exposure to 0.001 mg every day for 5 years results in a chance of 0.01%, then exposure to 0.001 mg for only 1 out of 10 days for 5 years results in a chance of 0.001%.




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[*] posted on 11-12-2008 at 08:42


Quote:

Many carcinogens have linear probability profiles for getting cancer. E.g. when exposure to 0.001 mg every day for 5 years results in a chance of 0.01%, then exposure to 0.001 mg for only 1 out of 10 days for 5 years results in a chance of 0.001%.


Carcinogens are funny that way, It's not so black and white. It's a more complex system. Some people can work with cancer causing chemicals for years and have no issues, others aren't so lucky. Our bodies do have ways to mitigate damage to our DNA (DNA damage happens all the time). Hell, sometimes things go wrong without over exposure to chemicals. So perhaps life can be called a carcinogen as well.

There are some studies I tend to take with a grain of salt, like showing a chemical causes cancer by exposing cancer prone mice to ludicrous levels. Without any evidence it actually causes problems in humans.
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[*] posted on 17-12-2008 at 08:19


Related to hexavalent chromium, I just read an article about a female worker that has been expozed to potassium dichromate for like 20 years, and she got a chronical disease that perforated the septum from the interior due to the airborn particles of K2Cr2O7. Now that's an exposure! It looks like this is a common disease for the people who would work with K2Cr2O7, sort of what "phossy jaw" is to WP.
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[*] posted on 28-12-2008 at 12:29


Jut found this: http://potency.berkeley.edu/index.html

It looks like an interesting read.
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[*] posted on 28-12-2008 at 17:45


I will merely note that propane sultone has functionality similar to some of the NCI Standard Agents, in particular busulfan and Yoshi-864. Very good leaving groups, them alkylsulfonates...

sparky (~_~)




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[*] posted on 24-1-2021 at 15:10


Can someone tell me what's the safest way to concentrate 4L sodium chromate? Made by reacting stainless steel with acid and then NaOCl?
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[*] posted on 25-1-2021 at 03:23


Everything that is not either having water as only volatile compound or the volume of harmless liquid is very low to evaporate, I always use closed distillation apparatus to concentrate stuff. This is probably the most common and safest method for any use. If volatile, toxic, malodorous or otherwise harmful stuff is distilled, put a tube into inverted funnel large enough for the purpose into a scrubbing liquid proper for the purpose, or alternatively just exhaust it to suction line that goes outdoors, or lead a long enough tube to outdoors. Some people scrub gases through the toilet water lock by just putting the tube through it.

For the carcinogens, most common stuff that is considered health hazard is designated for occupational point of view. Minor or single exposure few times during a life is generally of no issue unless dealing with bioaccumulative or extreme stuff, but people working with them can literally rinse their hands multiple times a day with something an consider it a good practice, hence the exposure is just absolutely enormous. I don't stress minor stuff like toluene at all, because I handle them so little and even then I may get an occasional whiff of the already extremely low odor treshold.

I'm extra careful with bioaccumulative stuff though, as single exposure will take decade to leave your body.
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[*] posted on 25-1-2021 at 03:37


What do you mean by closed distillation apparatus? Apparatus can't be closed during distillation as it can be disassembled in a violent and quick way. Traps and leading the fumes outside is good option when there is no fume hood available.

For benzene and similar carcinogens - it's not that bad, single exposure is not likely to do the harm. But there is also a seriously nasty stuff but it definitely shouldn't be messed with without appropriate infrastructure.
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[*] posted on 25-1-2021 at 06:22


Closed apparatus means behind a water lock or some other dynamic phase barrier, like I described. Not an actual closed setup, of course. This is supposedly only appliciable when protecting passive reagents from air, or if intentionally creating a pressurized vessel.

Open apparatus is something that is freely accessible to surrounding air. A distillation setup with bare vacuum outlet is what I also consider open device, or at least semi-open, as any fumes can freely escape.
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[*] posted on 25-1-2021 at 13:07


Cigarette equivalents could be a useful comparison unit, or perhaps for the more potent carcinogens "average smoker weeks/months/years"
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[*] posted on 28-1-2021 at 17:57


I still have scads of old books on cancer and mutagenicity, toxicology and more. If you have specific topics, contact me and I can see if I have any books on any topics you want. I likely have some books on Chromium toxicity, but they are pretty dry reading, I will warn.
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[*] posted on 31-1-2021 at 03:30


Is naphthalene a carcinogen? Some sources say it is while others say it's not.
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