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I'm a beginning hobbyist with a pregnant wife, which makes me nervous about lead. I have a breakout board that is RoHS-non-compliant, very likely containing leaded solder. How worried should I be about handling this board? Everything else I use is lead-free, and I don't plan on melting the solder in the breakout board, but I can't avoid touching the board, and touching other things thereafter. My wife and future child won't touch any of this directly, but they'll be exposed to any contaminations I miss when cleaning up.

All the information I could find on lead in electronics seem to talk about:

  • The effects on the adult handling the material, not fetuses and infants around them.
  • Tearing apart electronics for recycling, presumably creating leaded dust along the way, which I won't be doing.
  • Lead leeching from landfills, which doesn't apply in my case.
  • Finished products that don't expose the solder, which the breakout board is not.
  • No research or data, just an "I've been doing this for years".

Is there any data / recommendations from a proper authority on the risks of just handling leaded solder without melting it, when there are small children around? Or is this situation just too niche for studies to be conducted?

(BTW: I'm aware of the dangers of flux, which tends to get mentioned in answers to questions like this. The solution there is simple, though: just ventilate. I'm more worried about lead because it doesn't readily disperse.)

Jun Inoue
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    Photos of the breakout board. Maybe you can just heatshrink it then wipe down the pins and heatshrink down with alcohol and use it. Or conformal coat it then wipe it down. Brinell Hardness of Pb which is the same as graphite/pencil lead is 5 which we do know visibly rubs off on your hands. The tin-lead alloy in solder has a hardness of 17 BHN. Copper is 35. Steel is 130. Take that as you will for how easily it can rub off. Interestingly, *pure* aluminum is only 15 BHN but most of us have probably never handled that. – DKNguyen Feb 13 '22 at 02:00
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    I'm OCD about secondary and tertiary transfer of lead and even I don't use lead-free it's such a pain in the ass. Get a really good soldering station and a cheap PCB preheater. Use big tips. – DKNguyen Feb 13 '22 at 02:04
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    There is no measurable risk. – Ian Bland Feb 13 '22 at 02:46
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    Environmental contamination is probably the biggest risk. If the board corrodes that could also free up the lead. Other than that, probably very low risk. We're engineers not chemists, but the general consensus among EE's seems to be that leaded boards and solder aren't something to worry about. I personally use all lead free stuff, but if I got a leaded board I would still use it, although I might wash my hands after working if I'd handled it. – Drew Feb 13 '22 at 03:27
  • @DKNguyen Thanks for that interesting piece of data! I didn't think of looking up hardness, I'll keep that in mind. The board I have is a Pro Micro, manufactured by some shop instead of Sparkfun, but that's kind of orthogonal to the question. There's plenty of other leaded components sold where I live, and if/when I want to use them, I'll face the same problem of gauging their safety. – Jun Inoue Feb 13 '22 at 12:48
  • @JunInoue If you want more things to worry about, [brass](https://en.wikipedia.org/wiki/Brass) contains lead (and arsenic). – Andrew Morton Feb 13 '22 at 12:56
  • @AndrewMorton Much less though. Most brasses that contain lead are like 3% lead. – DKNguyen Feb 13 '22 at 17:50
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    don't even think about it. No problem at all. – user158293 Feb 14 '22 at 08:26
  • I'd be careful but not very worried. [This answer of mine](https://electronics.stackexchange.com/a/19086/3288) re lead solder safety may be useful. – Russell McMahon Feb 14 '22 at 12:50

3 Answers3

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My brother once ate a strip of lead used to balance RC models. My father instantly called the Poison Control Center. They asked what kind of lead was digested. It turned out that simply waiting until the lead passed through was the recommended action. Why? Because pure lead is hardly absorbed by the body. It is much more dangerous if it is in a solved/gaseous/salt state because then the body can uptake it much more easily. By the way, this is the thing for much other dangerous stuff like asbestos. Additionally, heavy metal poisoning is often a long-term process. Short and massive exposure is in many cases less critical than a continuous one like if you work every day next to a quicksilver gas source or similar. TL;DR: just make sure that no one uses it as a pacifier or similar and everything is fine. We used to use lead soldered devices for decades and I would claim that the most victims are found in the recycling processes. Heck, we even used leaded gas for decades - which was not the smartest, to be honest.

P.S: lead water tubes are a thing as well, and the "safe limit" for lead content in water is 0,010 mg/l in Germany. Assuming a consumption of 2l per day, it totals to a "safe" exposure of 7.3 mg per year. We can try to estimate the typical amount of solder used on the board. But I am pretty sure, that it will be hard to reach that exposure with just one board. The real (environmental) issue is the sheer amount of lead we face due to mass production.

Christian B.
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    Thanks, your answer is so far the most convincing argument I've seen on this issue. It does seem practically impossible to accidentally rub off 7.3mg per year of lead from the amount of electronics I handle. Add to that the limited absorptivity, and it becomes pretty reassuring. I'll wait and see for another day or so if anyone chimes in with more direct data, and unless that happens, I'll accept your answer. – Jun Inoue Feb 13 '22 at 12:38
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    ‘heavy metal poisoning is a long-term process’ Usually, but not always. Thallium, for example, has some pretty acute toxicity even in small amounts, and just being _near_ metallic osmium without proper protection can land you in the hospital. – Austin Hemmelgarn Feb 13 '22 at 13:56
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    @AustinHemmelgarn good point. Acute reactions are a thing. I adjust the part accordingly. – Christian B. Feb 13 '22 at 15:57
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    Where I'm from lead detailing on fancier residential windows is still very common, and I'm sure those get touched with bare hands fairly often. – Crazymoomin Feb 13 '22 at 16:18
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    Exactly. Solid lead is just about harmless. Ingesting dissolved lead or lead fumes is where you should take the precautions (especially near unborns and infants, adults can take quite a bit), not on any of the solids. – Mast Feb 13 '22 at 16:22
  • @AustinHemmelgarn Metallic osmium is not toxic. – Riley Scott Jacob Feb 14 '22 at 00:40
  • @RileyScottJacob That's my understanding, also--I remember running into a thing on a site that sold to element collectors discussing the hazard. Get it hot enough that oxide forms and you've got big trouble. That takes red heat, though. – Loren Pechtel Feb 14 '22 at 04:27
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Lead solder doesn't emit gasses, so the only way it will contaminate other things is by being touched, losing lead via abrasion, and then you transferring that around.

but I can't avoid touching the board, and touching other things thereafter.

And who is making you touch the board? Yes you can avoid it, you can choose what you touch. If you touch do the board, make the next thing you touch soap and water, followed by a towel.

That might become too much of an impediment to touching the board at all, so it might force you to devise a technique to avoid touching the board.

I suggest you put the board in a box. Make one from cardboard and tape, now, then buy a plastic project box. You don't have to suffer the problem of trying to avoid touching the board.

Why do I recommend a box?

While I suspect that the likelihood of you causing the damage you fear is very, very low, your child is yours, not a statistic. You would probably never forgive yourself if they had problems into the future, and you felt that you had not done everything you could to have avoided that. Some children will be born with difficulties, there's a non-zero chance yours might be, whether caused by lead contamination or not. Why put yourself in the position of forever beating yourself up, when you can simply take steps to avoid your causing a potential problem?

Neil_UK
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  • "it might force you to devise a technique to avoid touching the board." - that's what I meant that touching the board is unavoidable. That I'll exercise proper hygiene is a given, but even then there's always the problem of residues and missed spots, which is why I wanted information to help me gauge the risks. – Jun Inoue Feb 13 '22 at 12:27
  • But you have a good point about staying on the safe side. Maybe I should just shell out more time and money to avoid all this, even if just for the sake of peace of mind. – Jun Inoue Feb 13 '22 at 12:28
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    My answer is not about lead toxicity, or doses, it's about your fears and working practices. Have you done everything you can to minimise the risk? In five years time, when your kid fails some milestone, will you reflect and think that maybe I shouldn't have handled that board, however small the risk, for your peace of mind? I stopped gliding when my wife and I decided to start a family, YMMV. – Neil_UK Feb 13 '22 at 13:41
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I believe most equipment destined for the military or space has waivers for the RoHS requirements to use lead-free solder. This equipment is handled all the time without protective gear (gloves, etc) being worn. Where things like finger cots or gloves are worn, it is done more to protect the equipment from contamination from things like oils on the skin, than to protect the handler.

SteveSh
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