How toxic is old thermal paste (beryllium oxide)?

[PatrickXT]

I was disassembling an Apple IIGS power supply with a rather unusual design where the heatsink is mated to the housing with thermal compound in between. Removing the circuit board from the enclosure exposes the compound. Normally I wouldn't think anything of this, but I recalled safety warnings on minuszerodegrees.net including one stating that "In old power supplies, the thermal paste used between semiconductors and heatsinks, typically contained beryllium oxide (BeO). Beryllium oxide is known to be carcinogenic."

I had heard about beryllium in magnetrons and very old fluorescent lamps, but was surprised it might be found in personal computers. Sure if it's in a solid form or encapsulated there's little risk, but it's fairly easy to come into contact with thermal compound while performing routine repairs. Were beryllium-based compounds really commonplace in the 1980s or might they have been less typical than minuszerodegrees suggests?

With fluorescent lamps, beryllium silicate phosphor could be released into the air during production or when a tube was broken, which is why manufacturers had changed to a beryllium-free alternative by 1950. My inclination is that if beryllium oxide thermal paste was in fact employed decades after the hazards were known, it must be a relatively safe form. Do any of you know if this stuff was actually made with beryllium and if it was, is it unlikely to degrade in a way that could release airborne particles when disturbed? I'd certainly hope it's not an issue, considering that airborne beryllium has been known to cause disease even in small quantities.

Searching the web I found only a handful of posts related to the topic, which were not all consistent regarding the prevalence and safety of BeO in thermal compound. I'm wondering what kind of precautions people ought to be taking when it's necessary to remove or otherwise disturb old compound.

 

[Chuck(G)]

BeO isn't particularly soluble in water and its biggest toxic effect is when it's inhaled as a powder (causes berylliosis, a lung disease). If you don't eat it or inhale it, you're fine.
You can find the metal being used in various industrial applications. It's one component used to harden copper, for example. As far as it's use as a thermal conductive substance in semiconductors, you'll find it in sparing amounts inside of old TO-3 transistors, and so on. I don't think it was ever commonly used in a thermal paste--too expensive.

 

[PatrickXT]

Right, I was thinking about costs too. I'd have to imagine that even several decades ago there were cheaper and safer formulations using zinc and aluminum that'd be more than adequate for PSUs and most personal computing needs. I wonder how the folks at minuszerodegrees reached the conclusion that BeO compounds were typical, or perhaps they merely worded it that way out of an abundance of caution. I do see other references to BeO being used in thermal paste, but haven't found any actual products. There are a couple assertions on an old TechSpot thread suggesting that the compounds often contain Be, but nobody supplies any evidence.

 

[Hugo Holden]

I think the main worry with BeO was in its ceramic form in transistors, if you ground it up you could inhale the particles and that is not good.

Like all "potential" poisons, it all depends on the dose, route of administration and chronicity of exposure. The only people likely to have an issue with it were those in the manufacturing plants working with it, when they worked there a few years. Not dissimilar to Carbon Tet in the dry cleaning industry, but if you had contact occasionally with it at home, no worries.

I think many of the white conductive pastes used Boron or Aluminium nitrides or some oxides like Zinc for the filler, possibly some did use BeO, but it is no worry in that form, just wipe the compound away and discard the cloth and don't eat it.

Its like the paranoia about the toxicity of other elements like Lead & Mercury. In their metallic form super low toxicity, you can have an Amalgam filling in your mouth for 70 years and its 50% Metal mercury by weight, or a sailor can handle Lead sinkers for that time and no worries. But those metals in various salt forms or complexed with organic material in a food chain, can be toxic. People have got worried about the Cadmium on Cadmium plated chassis, but you would really have to go out of your way to get poisoned by a radio or TV chassis, by scraping the oxides off 20 to 50 chassis and then eating it. Yet these days if somebody drops a Mercury thermometer on the floor, people start screaming, evacuate the building and call the hazmat team.

Before the polymers with the fillers turned up, just plain old Silicone grease was used and it worked fairly well. Then Sil pads got invented (but I don't like them) These days I have moved back to old fashioned mica insulators and clear silicone grease. The white grease unless used sparingly can get very messy.

Actually, people are very suggestible about poisoning. Back in the 1970's there was a university student capping week prank, where they got some 44 gallon drums, painted them beautifully with the chemical symbol for potassium cyanide and warning, deadly poison with the skull & crossed bones, filled them partially with dry ice, so white vapors were coming out of the tops and they pushed them off the back of a truck downtown. The whole area got evacuated by the authorities explaining there was a poison spill, until they figured out it was a prank. But the thing was, about 20 or more people presented at the local hospital emergency department over the following days with various symptoms suspecting poisoning from the event.

 

[Chuck(G)]

My particular US state has banned the sale of fluorescent lamps with a partial ban on CFLs in 2024 and a total ban on all including tube-type lamps in 2025. The reason? Trace amounts of mercury.
Forget the fact that a good fluorescent lamp can easily outlast most of the LED replacements.

I miss carbon tet and Freon TF. And a whole bunch of other things...

Now, get off my lawn or I'll point this 866 rectifier at you!

 

[Hugo Holden]

My particular US state has banned the sale of fluorescent lamps with a partial ban on CFLs in 2024 and a total ban on all including tube-type lamps in 2025. The reason? Trace amounts of mercury.
Forget the fact that a good fluorescent lamp can easily outlast most of the LED replacements.

I miss carbon tet and Freon TF. And a whole bunch of other things...

Now, get off my lawn or I'll point this 866 rectifier at you!

One of my favorite episodes of Lost in Space , Will Robinson went back to Earth in an Alien machine, to buy a bottle of Carbon Tet to help fix the Jupiter 2. I have posted a photo before of him with the carbon Tet bottle, I don't have it on this computer. I loved carbon Tet back in the 70's because it was perfect for cleaning rubber, especially drive belts and pinch rollers in cassette tape decks.

 

[Hugo Holden]

Here is the photo, its a decent sized bottle of Carbon Tet. The episode was Return From Outer Space.

 

[Timo W.]

Pretty much anything in a computer is toxic in some way, that's why we bring e-waste to a recycler and not just put it into the domestic waste.

Wash your hands after you did such work and you'll be fine. Doing any sort of soldering with good old lead-based solder is more dangerous, yet no one ever died because of that (at least not that I know of).

 

[Chuck(G)]

I don't get the danger from lead-based soldering. The solder for electronics is usually 73% tin and the soldering heat doesn't get anywhere near the boiling point of lead.
Yet we thought nothing of filling our gas tanks with fuel that contained a very toxic (and it's been known as such since the 1930s) organic lead additive. Heck, gasoline itself is a potent carcinogen and we allow people to slop it all over the place at self-serve filling stations.

 

[syzygy]

I don't get the danger from lead-based soldering. The solder for electronics is usually 73% tin and the soldering heat doesn't get anywhere near the boiling point of lead.
Yet we thought nothing of filling our gas tanks with fuel that contained a very toxic (and it's been known as such since the 1930s) organic lead additive. Heck, gasoline itself is a potent carcinogen and we allow people to slop it all over the place at self-serve filling stations.

I am unaware of any accepted evidence suggesting that gasoline is a carcinogen. See https://wwwn.cdc.gov/TSP/ToxFAQs/ToxFAQsDetails.aspx?faqid=467&toxid=83 not that it is without plenty of toxic potential.

On the lead/solder issue that comes up repeatedly on many sites: My two cents is to take simple steps to avoid solder FUMES. I am not crying chicken little lead poisoning and I am not saying have a BSL-3 fume hood installed, but take some common-sense steps. I use a small exhaust fan and I know it only dilutes and dissipates the fumes, but I don't get them in my eyes and on my skin. If I were doing a whole lot of soldering, I would increase the safety precautions (mask and hood). When I am drilling and cutting with a Dremel and the like I always use a mask. I have built (interfaced is more accurate) particle sensors and I know what certain-sized small particles can do, and I know how long they linger. If I found myself being particularly sensitive to any of this stuff, I would avoid it completely or take extra precautions.

I figure it like this: If I were teaching my son or daughter (grandson/granddaughter) electronics and soldering, would I not make sure that they used some safety precautions?

I also am aware of and have used MSDS for all kinds of products, e.g., https://ors.od.nih.gov/sr/dohs/safety/laboratory/BioSafety/Pages/material_safety_data_main.aspx

I know you didn't say anything to the contrary (apart from the carcinogen point), but I have seen so many of these threads get derailed into what I would consider, bad advice. /end soapbox

 

[3lectr1c]

Isn't flux more of what you have to worry about? The stuff I use is supposed to be safer (REACH compliant) but I still use a fan and an open window (and an n95 mask) to help avoid inhaling stuff. The solder I use is lead-based.

 

[Chuck(G)]

I offer this re the harmlessness of gasoline: https://pubmed.ncbi.nlm.nih.gov/1780852/ and https://www.propublica.org/article/epa-approved-chevron-fuel-ingredient-cancer-risk-plastics-biofuel
But then, we still sell tobacco products, don't we?

 

[syzygy]

I offer this re the harmlessness of gasoline: https://pubmed.ncbi.nlm.nih.gov/1780852/ and https://www.propublica.org/article/epa-approved-chevron-fuel-ingredient-cancer-risk-plastics-biofuel
But then, we still sell tobacco products, don't we?

"Heck, gasoline itself is a potent carcinogen".... that is exactly what you said...and that is wrong and I am not apologizing for saying and citing why it is wrong and if you can't admit that it is wrong, I am not about to apologize for that either. I respect you as a person and I admire your skills and willingness to help others, but in this case, you are wrong.

C'mon Chuck, I don't want to get into a war over this.

 

[Chuck(G)]

I'm a more careful reader, apparently.

How likely is automotive gasoline to cause cancer?

The Department of Health and Human Services (DHHS) and the International Agency for Research on Cancer (IARC) have not classified automotive gasoline for carcinogenicity. Automotive gasoline is currently undergoing review by the EPA for cancer classification.

That doesn't deny the carcinogenic property of gasoline (although diesel is probably far worse), just that it hasn't been classified as such--yet. The NIH study seems to say that it is.

Take your pick. Gasoline itself isn't a pure substance; it's more like a soup of petroleum products.

 

[rittwage]

I'm a more careful reader, apparently.

That doesn't deny the carcinogenic property of gasoline (although diesel is probably far worse), just that it hasn't been classified as such--yet. The NIH study seems to say that it is.

Take your pick. Gasoline itself isn't a pure substance; it's more like a soup of petroleum products.

Supposedly, Gasoline was a byproduct (waste) of producing Kerosene and was "discarded" for decades.

 

[stepleton]

I don't get the danger from lead-based soldering. The solder for electronics is usually 73% tin and the soldering heat doesn't get anywhere near the boiling point of lead.
Yet we thought nothing of filling our gas tanks with fuel that contained a very toxic (and it's been known as such since the 1930s) organic lead additive.

At least some people knew that TEL was not great for you fairly early on:

“We could not get this across to the boys,” he said. “We put watchmen in at the plant, and they used to snap the stuff [pure tetraethyl lead] at each other, and throw it at each other, and they were saying that they were sissies. They did not realize what they were working with.”

The second and by far the largest manufacturing operation was built at du Pont’s dyestuffs division in Deepwater, N.J., across the bay from Wilmington, Delaware. Du Pont began with a 100 gallon per day “bromine” process unit in August of 1923, and increased production in the summer of 1924 to 700 gallons per day. A second 1,000 gallon per day unit using Standard’s “chloride” process began operations in January, 1925. The first du Pont worker died in September, 1923; three more died over the summer and fall of 1924 when bromine unit production was stepped up; and four more died in the winter of 1925 in the new chloride unit. Workers who were aware of the effects of tetraethyl lead called the factory the “House of Butterflies” for the hallucinations they experienced.

From Kovarik (1994), Charles F. Kettering and the 1921 discovery of tetraethyl lead. SAE Fuel and Lubricants Division Conference, Baltimore. Read on for the harrowing description of what Du Pont process chemists found at Standard Oil's Bayway production facility at about the same time. Anyway, this awareness appears conveniently to have escaped the public consciousness for many years... same as it ever was.

In conclusion, don't pulverise and huff your NS32332 processor:


From this bug sheet.

 

[Chuck(G)]

Supposedly, Gasoline was a byproduct (waste) of producing Kerosene and was "discarded" for decades.

From my reading, apparently true. Often discarded into waterways.

 

[Caluser2000]

I'll

"Heck, gasoline itself is a potent carcinogen".... that is exactly what you said...and that is wrong and I am not apologizing for saying and citing why it is wrong and if you can't admit that it is wrong, I am not about to apologize for that either. I respect you as a person and I admire your skills and willingness to help others, but in this case, you are wrong.

C'mon Chuck, I don't want to get into a war over this.

Without providing evidence of your claim I'm solidly with Chuck on this one...

 

[syzygy]

I'll

Without providing evidence of your claim I'm solidly with Chuck on this one...

Oh well, your taking sides - gee that changes everything because, yeah, it's always a matter of taking sides - got ya.

Did you read and understand this passage from what I cited?

How likely is automotive gasoline to cause cancer?​

The Department of Health and Human Services (DHHS) and the International Agency for Research on Cancer (IARC) have not classified automotive gasoline for carcinogenicity. Automotive gasoline is currently undergoing review by the EPA for cancer classification.


Some laboratory animals that breathed high concentrations of unleaded gasoline vapors continuously for 2 years developed liver and kidney tumors. However, there is no evidence that exposure to gasoline causes cancer in humans.

However, there is no evidence that exposure to gasoline causes cancer in humans.

Science does not work by only looking at a single study in rats. I know this because I am a (retired) PhD scientist who has published many times in the peer-reviewed scientific literature, including Toxicology journals and I have published with colleagues from the EPA and the NIH. Have you and Chuck done that - please correct me if I am wrong to think that you have not. I'm not saying I know everything, but I know a lot of things in this context because I have spent decades in these fields. Do you think that there are no studies of tumors in rats following cell phone irradiation and many, many, other environmental and pharmacological insults of all kinds. Various agencies are ALWAYS evaluating them because that is their job.

Personally, if you and Chuck want to get together and give yourselves gasoline enemas, I am now ok with that, because your acting like together you have the inside track on gasoline knowledge. But if you want to throw shade at me, do it for some crappy circuit I built or some clownish soldering job and remember, I don't just post for your benefit or Chuck's, I know that many people read these messages and I stand by exactly what I said and now I am done with this thread. So have at it, tell me how you obviously hit a nerve or how it's my fault for overacting or you didn't understand this thing or that thing or you really meant something completely different than what you said or how well the two of you can cycle backwards.

 

[Chuck(G)]

Scroll down to "Toxicity" here: https://en.wikipedia.org/wiki/Gasoline
Benzene? https://www.cancer.gov/about-cancer/causes-prevention/risk/substances/benzene

That's okay, make yourself a petrol milkshake and get back to us.