I am interested in whether anyone who has purchased their Yunzi single-convex stones from YMI within the last year or so has tested them for lead. Specifically, I am interested in results using any of the EPA (https://www.epa.gov/lead/lead-test-kits) or Consumer Reports (https://www.consumerreports.org/lead-test-kits/how-to-test-paint-with-a-lead-test-kit/) recommended tests, such as the one from 3M.

First, a little background: I was newbie to go about ten years ago, and was looking to upgrade my "beginner" melamine single convex stones to something more substantial like Yunzi, but I was put off by the reports of surface lead found on Yunzi stones (http://chiyodad.blogspot.ca/2008/01/). Subsequent reports said YMI had contacted the Yunnan manufacturer and they had agreed to eliminate lead from Yunzi stone manufacturing, and so once I decided to purchase a set of size 5 single convex Jade Yunzi I emailed YMI regarding their lead content in September 2010. Janie from YMI replied "All of our Yunzi stones are lead free," so I went ahead and ordered a set. Upon receipt I then proceeded to test them for lead, and I vaguely recall the test I got from a local hardware store involved wetting a ceramic stick that you would scratch on the suspect surface, and if lead was present then it would leave a gold streak. No lead was detected this way.

Zoom ahead to this year, and I espy an identical set of Jade Yunzi for sale on eBay. Since these haven't been for sale in the US for years, I bought them since I liked the look and utility of the stones (and it doesn't hurt to have spares!). The seller told me he bought them new from YMI and they were unused, but he wasn't certain when he purchased them, so once I got them I decided to test them just to make sure. I got the 3M LeadCheck home test from Home Depot, and was shocked and dismayed when both the Jade and Black Yunzi stones exhibited a very strong and immediate "hot pink" reaction which indicated a high level of lead present. I then decided to test my own Jade Yunzi (which I had just washed and re-oiled with mineral oil the day before) and was very surprised when they also showed a strong and immediate reaction on the 3M test. This is profoundly distressing since this set of stones was my "go-to" set when I was teaching my daughter go over the past decade, as there is currently consensus that there is no acceptable minimum exposure level for lead for children (http://www.who.int/mediacentre/factsheets/fs379/en/).

Since I no longer want the stones because of the lead risk, I plan on reaching out to YMI to see if they will still honor their commitment to exchange leaded stones for lead-free ones, but only if I know from an independent source that the Yunzi stones they are currently selling are truly lead-free--thus this request. Thanks in advance to any lead testers out there!

You may first check with something that you are sure does not contain lead. It might be an issue with the 3M tester.

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Good, but... in addition, test something that surely contains lead ?
For m lead-things and n non-lead-things:
the larger m and n, the more confidence with the equipment.

Currently: m = n = 0.

Hi,
I read your source about the "no safe level of exposure". As already said in another tread here on Lin19x19, there is a big issue for the real comprehension of these data: the way of exposition.
Coming to lead, the exposition risk is only through ingestion and inhalation: both are not likely to happen with Go stones.
I recommend you to verify if the Mineral Oil you treated the stones with is just as low risk for your skin as is the lead inside the stones.
Many mineral oils are well known for risk of irritation in case of skin and/or eye contact. Mineral oil is a well known hazardous substance: e.g. listed with CAS 8012-95-1
Hope this can help to promote a better/real understanding about chemical risks.
Galation

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When you play Weiqi you are joining millions of people across four thousand years of time.
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Thanks to all for your replies.

In response to PnPProg, I did indeed test two sets of glass go stones (both Japanese and Korean) and they did not test positive.

In response to EdLee, I did not test a known source of lead because I have a high degree of confidence in a test endorsed by both the EPA and Consumer Reports that the chance of a false positive is very low.

In response to Galation, I am aware that others have disputed the risk of surface lead in go stones as they are not ingested or inhaled, but what is not in dispute is the fact that since lead is always accrued by the body and never dissipated, and since it has deleterious health effects, any source (however minute) must be eliminated. Simply put, you place the go stones with your fingers, and whatever lead rubs off on your fingers can subsequently be rubbed in your eyes, or be ingested if one is eating a sandwich while playing over lunch (which I frequently do). Additionally, your comment regarding mineral oil is false equivalence, for I am not aware of it having the same deleterious effects as lead; in any case, the mineral oil I used is commonly available at the local pharmacy and is USP approved for ingestion as a laxative, so there is no health risk upon ingestion.

Thank you all again, and I do hope someone who has a "fresh" batch of Yunzi go stones will be able to test them, and report the results here.

Consider the children. Young children eat or mouth a lot of things. Go stones would be very likely to go in their mouths, no?

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The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

I'm not sure, but couldn't lead on the surface of glass stones be removed pretty easily?

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

In the case of Yunzi stones, the lead is not an incidental substance "dusted" on the surface and amenable to washing away, as lead is used in the manufacturing process and thus pervades the go stones. As I noted in my initial post, I discovered that my eight-year-old Yunzi stones also tested for lead, and these stones had gone through repeated washings without losing their lead potency, so there is no "fix" that would make the stones safe.

That's what I thought.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

Sorry to insist.
To answer Kirby and lead content in the Yunzi stones, please check this former discussion about the same topic https://lifein19x19.com/viewtopic.php?f=19&t=12790&p=200586&hilit=Lead+yunzi#p200586 and keep in consideration that in my fist post in this tread I stated that ingestion is at risk for lead: btw, children stop eating things after they age 3, so if you are teaching Go to a baby under 36 months: do not use Yunzi stones.
No, it is not. I stated the comparison correctly, to show that most toxicology info can be easily misunderstood.
This is exactly the point, I agree with you. I never said that there is a risk upon ingestion. If you check my comment, you will find that the risk I refer to is about skin and eye contact: any red eye after playing? Maybe your hands delivered some oil to your eye.
Anyway, the oil you applied on the stones prevent, in large part, the direct contact of your skin with the stone and with any lead inside.

Just for the sake of clarity, I will make some false equivalence: asbestos is well known as a carcinogenic. Several teams tried to demonstrate the opposite by eating asbestos: if you can eat it, it is not toxic. This is a false equivalence: you can eat (and drink) asbestos with no harm, but it is cancer-causing by lung exposure (mesothelioma).
Lemon juice is an healthy drink (with good intake of vitamin C), but your skin and eyes will suffer if directly exposed, since its pH is 3 or less.

Saying that Yunzi stones are a risk for health, due to lead content is far from correct.
I understand that what I say about lead is counterintuitive and unpopular, never the less it is accurate and true.

Galation

_________________
When you play Weiqi you are joining millions of people across four thousand years of time.
Jonathan Hop - So You Want to Play Go?

_________________
When you play Weiqi you are joining millions of people across four thousand years of time.
Jonathan Hop - So You Want to Play Go?

Sweaty or licked fingers wiping lead off the stones. Later the fingers go in mouths or on food that goes in mouths. Nobody is perfect about washing their hands. Children are less than perfect.

With bacteria, this isn't such a big deal. The body has evolved to deal with that threat. With lead toxicity the body does not have a mechanism to deal with it.

Lead is a big deal. Every contact with lead has been an unfortunate hidden disaster for people since at least the Ancient Greeks. Lead paint. Lead toy soldiers. Thomas Midgely's sad story of tetraethyl lead is a warning about an intelligent and knowledgable person who misjudged the danger of lead. This pattern of under estimation just repeats with every generation. We just take an intelligent guess that we know better than our ancestors. As they did with theirs, and yet every generation for 4000 years has failed to heed the warning from the previous generation.

So, no, Galation, your intelligent guess of "ingestion and inhalation: both are not likely to happen with Go stones". Nope. I'm not buying it. I think schwartzseer is right to take a 'no safe level' approach to lead.

According to what you said about the "heavy risk" in playing Go with yunzi stones, I understand that your risk profile is absolutely perfect and that you hard and pure apply it to any and all aspect of your life up to the no safe level.

I suppose that you long decided to

1. absolutely avoid self fueling your car
you know, benzene, as well as many other chemical components of diesel, is highly risky both as carcinogen and is toxic by inhalation, contact and obviously ...by unintentionally ingestion (when it came in contact with your hands and you then take it to your mouth)

2. completely banish tuna cans from your diet, due to mercury concentration
mercury is at least as toxic as lead... oops seems that it is actually MORE toxic: LD 50 in rat tests is between 1-100 mg/kg for mercury and over 105 mg/kg for lead

3. totally keep off from all fried food
due to acrolein presence (known both as toxic and carcinogenic)

4. entirely avoid alcohol drinking
known killer due to liver toxicity (up to hepatitis and cirrhosis)

I am not buying it.
OK, sorry for being sarcastic. I didn't meant to be offensive.

What I would like to point out is that we* are not so rational as we like to think we are, especially when we refuse to take in consideration scientific evidencies and prefer to apply our self made house rules, valid here and there and only about the risks we have been warned about.
* yes, me too

If you really believe that lead in yunzi stones is a risk for health why do not involve the public authority and take a civil action to remove it from commerce?

Galation

_________________
When you play Weiqi you are joining millions of people across four thousand years of time.
Jonathan Hop - So You Want to Play Go?

Your list is about balancing opportunities to reduce risk against practical engagement in society.

It is quite a good list of environmental factors people need to take a view on, though I do think you should have included smoking.

The answer is I do avoid your list, where practical.

That practicality caveat does matter. Engaging in society and avoiding all fried food are at odds with each other. I do fill a car with petrol, but not diesel. Children playing Go without suffering lead toxicity isn't a practical matter of engaging in society. As the majority of glass Go stones don't contain lead anyway, just avoiding creating a new situation where a child is exposed to lead by not buying the child Go stones containing lead seems sensible. They get the most severe damage from lead to brain development.

Actually lead in children's toys is heavily prohibited by public authorities, so I will not need to join you in your suggested Don Quixote & Sancho Panza adventure of us against the World.

My list have been built in a few minutes and is not analytic, my toxicology teacher back at the university used to have a better one. He presented it alphabetically ordered, at the beginning of his course, asking for students to put it in proper risk magnitude. I was said that he made this test every year and he concluded that people were quite confused by ignorance and fears misjudging the real impact of many of the factors involved.
My point is: since lead is not transmitted through the skin, yunzi stones are... not in the list (and yes, very very far from smoking, that is indeed a big risk for health).

Avoiding self perceived risk is a matter of personal choice that have not to be justified. Defending it with strange theories (not based on any quantitative analysis) is not a good thing.

I will put two more (sad) examples to try sharing my thoughts about this matter.

What will you say to someone making a discrimination about HIV-positive people?
Maybe deciding that they do not want to sit in the same room because they are being exposed to increased risk of AIDS and not wanting to hear/discuss any scientific/medical evidence about "no real risk" according to wrong deduction as "the virus is present, so the risk is higher".

Anti-vaxxers are stating similar theories to support their position, that in the end is putting at real risk people that cannot be vaccinated (e.g. newborn babies).

Again, sorry for being too direct and for proposing examples that may sound offensive.
It is very clear to me that avoid buying/using yunzi stones is a matter of personal choice that do not negatively affect other people like in both of mine examples.
Nevertheless, I do not like when this kind of personal choice is cloaked with (fallacious) logic.

I wish you all the best,
Galation

_________________
When you play Weiqi you are joining millions of people across four thousand years of time.
Jonathan Hop - So You Want to Play Go?

Somewhere on this forum, this was already discussed. The most recent, relevant contribution to this discussion was accompanied with the results of a lead test by a professional laboratory. I can't find the post at the moment, but I copied the lab results:
Combined with other people's comments about ingestion, I consider this to be (almost) zero risk.