Electronics > Beginners
Life expectancy vs Lead exposure?
janoc:
--- Quote from: soldar on August 20, 2019, 01:42:57 pm ---
--- Quote ---https://nypost.com/2019/08/19/lead-scrubbed-from-paris-streets-as-notre-dame-work-resumes/
PARIS — Specialists shoring up fire-damaged Notre Dame Cathedral returned Monday to the Paris site for the first time in nearly a month, this time wearing disposable suits and other protective gear after a delay prompted by fears of lead contamination.
Meanwhile, cleanup teams swept, sprayed and vacuumed neighboring streets Monday to scrub away any lead left over from the April blaze that destroyed Notre Dame’s roof and toppled its spire. Toxic dust spewed into the air as hundreds of tons of lead melted in the fire.
At the cathedral itself, activity resumed Monday under strict new lead protection measures for the stonemasons, cleanup workers and scientists working on the monument, according to the Culture Ministry. They include throwaway full-body clothing, obligatory showers and a new decontamination zone to ensure that no one tracks pollution outside the site.
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How is that relevant to this topic? Nobody is disputing that lead is toxic.
You do realize that there are a few hundreds of tons of lead melted there and toxic dust from the fire, right? None of which you are likely to have in your workshop.
Mr. Scram:
--- Quote from: janoc on August 20, 2019, 06:54:38 pm ---Christ ... Do you know that even drinking water can kill you? (no kidding). Or you could get hit by a meteorite. I guess we better don't drink and stay indoors 24/7 then.
It is not about disparaging anything but about evaluating the consequences vs real exposure risks instead of falling for hysterical alarmist bullshit.
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I'm sure the French government is spending millions to clean up due to "alarmist bullshit" instead of actual risks? Actual research shows lead intake is cumulative and definitely harmful at blood levels of 10 µg/dL. It could be worse though. "There is no known safe blood lead concentration. But it is known that, as lead exposure increases, the range and severity of symptoms and effects also increases. Even blood lead concentrations as low as 5 µg/dL, once thought to be a “safe level”, may be associated with decreased intelligence in children, behavioural difficulties, and learning problems." You won't keel over instantly and the biggest risk is definitely associated with children but it is a veritable toxin and should be handled with consideration.
Nominal Animal:
* Lead salts are most dangerous, because they are very efficiently absorbed into the body.
* When ingested, adult bodies absorb only about 1% of pure lead, the rest is excreted in a few weeks.
* When ingested, child bodies absorb about 33% of pure lead.
* Nanoparticles and very fine dust easily lodges in human lungs.
The smaller a particle has, the larger surface-to-volume ratio it has. Because the surface is where chemical reactions occur, the same weight or volume of nanoparticles causes an order of magnitude more chemical reactions than a single nonporous chunk. This is how car catalysers work.
Because of their reactivity, nanoparticles can easily embed themselves in lung tissue, and even enter the blood stream.
* Adult human bodies contain about 0.1g of lead, total, on average.
I recently ingested a cubic millimeter of 60-40 lead alloy, containing about 0.7 mg of lead. If this was pure lead, my body would retain about 1% of it, or about 1 µg. This increases the amount of lead in my body by about 0.001%. Let's say I repeat this every day for a year, accumulating about 400 µg = 0.4 mg of lead into my body. That is still only a 0.4% increase in the amount of lead in my body. I could do this for the rest of my life, and even if I were to live to be 100 years old, I'd only increase the lead content in my body by about 25%. It is not enough to raise the coroners eyebrow: where you live and what kind of air you breath, makes a bigger difference.
So, worrying about millimeter-sized lead or lead-alloy spherules only matters if you have kids.
Statistically, if we were to increase the lead load by 25% for an entire population, we'd likely see some negative health effects. This is why banning lead paint is a good idea, especially for toys. (The lead in lead paint is in suspension, and can be in basically nanoparticle form. Same for lead additives in fuels. Lead salts are even worse, because almost all of them get absorbed into the body when ingested.)
But, as you can see from the above calculation, the amount of lead in solder and how it is in a form so unlikely to get into human bodies, makes leaded/unleaded solder discussion completely wacky. Electronics already contain much worse chemicals making it necessary to dispose of them properly (to avoid negative health effects on the human population), and leaded/unleaded solder has an utterly insignificant effect there.
james_s:
--- Quote from: bjdhjy888 on August 20, 2019, 03:05:57 pm ---I felt super safe when I was reading you guys' replies.
Then....when I was soldering my STM32 a moment ago, my air quaility meter read:
PM 2.5 100+ ug/sq meters
PM 10 300+ ug/sq meters
OMG!
I tried to read the numbers with my door closed and open, while my fan was working, blowing fumes out of my window. Either way, the numbers were all above 100+, up to 300+
I used lead solder and solder paste.
The readings dropped to 63 and 109 respectively, after 30 minutes.
:palm:
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What exactly does your air quality meter measure? These are not typically precision devices, the one built into a room air filter thing we have pegs every time I fire up the gas oven in the kitchen or use a squirt of canned air across the room. It only measures certain characteristics, it doesn't really tell you with any certainty what it has detected or whether it is harmful.
Mr. Scram:
--- Quote from: Nominal Animal on August 20, 2019, 07:51:35 pm ---
* Lead salts are most dangerous, because they are very efficiently absorbed into the body.
* When ingested, adult bodies absorb only about 1% of pure lead, the rest is excreted in a few weeks.
* When ingested, child bodies absorb about 33% of pure lead.
* Nanoparticles and very fine dust easily lodges in human lungs.
The smaller a particle has, the larger surface-to-volume ratio it has. Because the surface is where chemical reactions occur, the same weight or volume of nanoparticles causes an order of magnitude more chemical reactions than a single nonporous chunk. This is how car catalysers work.
Because of their reactivity, nanoparticles can easily embed themselves in lung tissue, and even enter the blood stream.
* Adult human bodies contain about 0.1g of lead, total, on average.
I recently ingested a cubic millimeter of 60-40 lead alloy, containing about 0.7 mg of lead. If this was pure lead, my body would retain about 1% of it, or about 1 µg. This increases the amount of lead in my body by about 0.001%. Let's say I repeat this every day for a year, accumulating about 400 µg = 0.4 mg of lead into my body. That is still only a 0.4% increase in the amount of lead in my body. I could do this for the rest of my life, and even if I were to live to be 100 years old, I'd only increase the lead content in my body by about 25%. It is not enough to raise the coroners eyebrow: where you live and what kind of air you breath, makes a bigger difference.
So, worrying about millimeter-sized lead or lead-alloy spherules only matters if you have kids.
Statistically, if we were to increase the lead load by 25% for an entire population, we'd likely see some negative health effects. This is why banning lead paint is a good idea, especially for toys. (The lead in lead paint is in suspension, and can be in basically nanoparticle form. Same for lead additives in fuels. Lead salts are even worse, because almost all of them get absorbed into the body when ingested.)
But, as you can see from the above calculation, the amount of lead in solder and how it is in a form so unlikely to get into human bodies, makes leaded/unleaded solder discussion completely wacky. Electronics already contain much worse chemicals making it necessary to dispose of them properly (to avoid negative health effects on the human population), and leaded/unleaded solder has an utterly insignificant effect there.
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Where did you grab those numbers on lead absorption?
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