other dusty place and seen the sunshine come in through the cracks you see the dancing dust in the sunshine, and that is the dust you have under consideration in preventing or trying to prevent silicosis. That dust is so fine that it floats and behaves a great deal like a gas. It is more like a gas than a particle floating around because it stays in the air for hours. That point also makes it more difficult to control. It is more difficult to catch and remove.

If one ventilates he might ventilate at the heading and that would carry the air back on to those who are not at the heading and the air would have a sufficient concentration to do harm.

One may get a good idea of this from tobacco smoke. Compare it to this dust and you will not be too far wrong in magnitude of comparison.

The third consideration is the concentration. We can have concentration ranging from none to billions and trillions. They are usually measured on the basis of number of cubic feet or on a weight basis. It is very difficult to get air much below, we will say, two,' three, or five, or perhaps eight million particles in a cubic foot. That range of concentration is usually considered the one that we will say is the threshold or the begining of the disease. That concentration you cannot see at all.

Any concentration above eight million or ten million particles in a range of 50 or 75 percent silica in the dust becomes harmful.

How soon it harms a man depends on how much higher the concentration is. If the concentration goes higher the time of occur、 rence becomes less and less.

It is not at all unusual to find billions and trillions of particles in an atmosphere around drilling.

I mentioned these because they lead to a point of control in which we are all interested.

The extent of injury can likewise range from insignificant to that which is significant. That is one of the difficulties in detection and diagnosis of the disease, when you pass the transition point. I doubt whether there are many persons who have lived in the country who do not show some slight trace of fibrosis. That is not demonstrable by X-rays. We have to go to a point where the amount of fibrosis becomes a significant condition. That is not too satisfactory because one man looks at an X-ray plate and says one thing and another man looks at the same X-ray plate and says something else. They are all relating it back to the normal workingman's chest and on the basis of experiment. That brings in some controversy and differences of opinion, and that is the reason we get one group giving one answer and another group giving another answer.

Mr. GRISWOLD. Going back to the Hawks Nest tunnel at Gauley Bridge, you say, as I understand, that as the concentration increases the man acquires the disease that much sooner!

Mr. YANT. Yes.

Mr. GRISWOLD. You are familiar with the concentration of silica at Gauley Bridge, are you not?

Mr. YANT. Only as it has been described here.

Mr. GRISWOLD. Taking into consideration that concentration of silica at Gauley Bridge, what would you say there as to whether or not it would show the disease developing rapidly or otherwise?

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Mr. YANT. I will say, taking the evidence given here to be correct, that if it was so dusty you could not see 10 feet, that it was silica and not fog from the drill-the exhaust from the drill puts out some fog but not enough to prevent vision at 10 feet-and if the men came out all white, I would say it was high enough to produce silicosis at the time stated, a year or two after exposure. That is a very high concentration of dust. That is out of the realm of what you would even consider a hygienic atmosphere.

Mr. GRISWOLD. Let us assume that the dust in the tunnel was so thick that one could not see 10 feet; let us assume it was dust and not something from the drills; let us assume that these men worked there for a period of 6 months 10 hours a day; how soon would that develop silicosis? How would those men develop silicosis from that condition?

Mr. YANT. If the statement of conditions is true, that was very bad indeed. If there was that must dust, it is almost outside of our consideration of dust production.

We say that a man can get silicosis in a year or two after exposure; but rerember, it takes a certain time for fibrous tissue to form. To dust a man up to that extent, I would say it is quite possible. I do not see how one could draw any different conclusion. Mr. GRISWOLD. We are assuming the statements that have been made before the committee are correct.

Mr. YANT. Yes. As you picture that dust concentration you can picture it as most anything, so that it is only a matter of how long it takes the fibrous tissue to form in order to incapacitate. It is entirely a matter of pathology, because the exposure is established beyond doubt.

Mr. GRISWOLD. You are not a pathologist, as I understand.
Mr. YANT. No; I am not. I am a chemist.

Mr. GRISWOLD. You have not had any experience in pathological findings in connection with examination of lungs?

Mr. YANT. Yes; I have. One could not work with this subject as long as I have and have been associated with doctors in connection with it without looking into those matters somewhat. This is a specialized field of work in which not many doctors have been or are engaged.

Mr. MARCANTONIO. You say you have had occasion to see fibrous lungs?

Mr. YANT. Yes.

Mr. MARCANTONIO. Describe such.

Mr. YANT. I can send you some pictures that will probably be more helpful than anything I might say. I cannot well describe them. Those pictures are not difficult to get. We have them in the Bureau of Mines. In one of the publications that Dr. Sayers left with you yesterday there are X-ray pictures pointing out the nodules. One does not need to go into the details of the names of the different cells. The general mechanism is rather obvious to a layman even, if they are pointed out.

We have certain problems yet that face us. Merely passing a law concerning occupational disease compensation for silicosis is rather easy, but there are some obstacles, as I see the matter. We have given some thought to it. administering such a law. been enacted, he will find

There is a great deal of difficulty in As one goes over the laws that have them not entirely satisfactory, in my

opinion, from an administrative point of view. With the gradual development of silicosis you must look at it as a production affair, something occurs in 10, 15, or 20 years. Just when a man crosses the line, when he reaches a sufficient degree of incapacity to call it a disease, and when he comes within the realm of compensation, that is not a definite point. It is very hard even with an accident that occurs at a particular time to administer compensation. When we have something that is so transient and indefinite, it takes a pretty good man to actually administer such a law.

Further than that, another point of difficulty is that a man in 10 or 15 years has gone from one place to another, and it is very difficult to assess the injury he receives at this place and that place. Some place is responsible for the condition, but when the man moves about so much it is difficult to fix that responsibility.

Those are details that become rather difficult when one tries to work this matter out satisfactorily.

I am strong for compensation, but those are things that must be considered rather than merely saying that we will pay so much damage on account of silicosis.

Mr. GRISWOLD. You think there might have to be some way to apportion the damage between the various concerns on a comparative basis having in mind the different contributions of negligence?

Mr. YANT. Yes. You would take care of that which has been produced or is on the borderline in the beginning.

Mr. MARCANTONIO. And it would be necessary to pass laws providing for certain safety devices to be employed in this particular industry?

Mr. YANT. Yes. You are getting down to the thing that especially interests me. We have a silicosis production on the way. A certain number are going over all the time, and we must take care of those.

The real thing to be done is to stop production at the time, and that is what the Bureau of Mines is interested in, namely, prevention. We realize all the rest, and we want to cut down the production of silicosis.

Mr. GRISWOLD. My understanding of your testimony is that, in your opinion, doctors themselves might in early stages of silicosis differ in their diagnoses?

Mr. YANT. Yes.

Mr. GRISWOLD. They might diagnose it as something other than silicosis and do it honestly.

Mr. YANT. Yes; very honestly; because you differentiate between what is a normal tissue, what is the average workingman's chest, and when does fibrosis and silicosis come to the point of disability and to what we call a disease. That is the difficulty. It is hard to get around.

These are practical situations. If you pass silicosis legislation making it drastic, you might even prevent industry remaining within a section covered by the legislation. Industry would move to another place. Soon a State would lose its industry, and it would not want to do that. It would want the industry to remain. Therefore, after a few years, if the law should not work satisfactorily, the law would be repealed, the industries would have left the State, and nothing would have been gained. I can see that would be different if the legislation were national in scope.

Mr. MARCANTONIO. How long have methods of preventing silicosis been known?

Mr. YANT. Methods of prevention of silicosis were known, at least, talking from the viewpoint of the Bureau of Mines, since 1914. At the time we made the investigation in the Missouri district we recommended certain methods of prevention, and they are still used. today, and they are still cleaning up silicosis exposures. There is a great deal of change in those preventive measures.

At the time the report was made in connection with the Missouri situation, we recommended wet drilling. We recommended wettingdown the muck piles before they were shoveled up. We recommended that there be no blasting during the working shift, because blasting maks dust and stirs up dust already made and settled. We recommended adequate ventilation.

Mr. MARCANTONIO. Referring to the matter of blasting during the working shifts—in your opinion, is that practice dangerous? Is it dangerous, extremely dangerous, to send men back into a tunnel or a mine right after a blast has been fired?

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Mr. YANT. Yes; before there has been proper ventilation. should first have to know what ventilation was going on and how effective it was and how it cleared out the tunnel. Ventilation could be done in such a manner that the men could go back to work reasonably soon.

Mr. GRISWOLD. But it would be dangerous to the men to send them back to work before the place had been ventilated after a blast? Mr. YANT. Yes; that dust is just as bad as dust produced by drilling. There is no differentiation there.

Mr. GRISWOLD. You have spoken of the Missouri district. I presume you refer to the district around Joplin in Jasper County? Mr. YANT. Yes.

Mr. GRISWOLD. They mine lead, zinc, and jack down there?
Mr. YANT. Yes.

Mr. GRISWOLD. In what minerals do you find silica in the greatest quantities?

Mr. YANT. It is widely distributed. One finds it in connection. with practically all mineral-mining operations. One finds silica and silicates. They are largely the chemical compounds one finds.

The silicates have not been found to be nearly so harmful, and even in tale mills very little trouble has been experienced. The silica is the far more important offender.

Mr. GRISWOLD. And that is what they have in West Virginia. Mr. YANT. Yes. That is a high concentration of silica. It is not a silicate.

Mr. GRISWOLD. Is there any lead and zinc mined in West Vir ginia-any appreciable amount?

Mr. YANT. I do not think so.

Mr. GRISWOLD. They do not mine it generally as they do in JasperCounty, Mo.?

Mr. YANT. No; but the silica can be from 25 percent to 75 percent in any ore.

We find some carbonates; but they are not found to be bad.. Limestone-no; there is no condition similar to silicosis produced by limestone.

Mr. GRISWOLD. How about coal mines? How much silica orsilicates do we find there?

Mr. YANT. The trouble there is in connection with rock tunneling and in cleaning up strata above or below the coal.

Mr. GRISWOLD. What is the ordinary percentage of silica in rocks? Mr. YANT. In a vein like there is at Gauley Bridge it is practically pure silica. In sand mining we find practically a pure silica. Mr. MARCANTONIO. And in quartz?

Mr. YANT. That is pure silica. It is crystalized silica. It can run all the way down. There is no particular concentration associated with any mineral.

Mr. GRISWOLD. Do you say that you do not find it in limestone? Mr. YANT. Two or three percent, or one percent.

Mr. GRISWOLD. But you do have some silica in limestone?

Mr. YANT. Yes.

Mr. GRISWOLD. You usually get considerable dust in limestone, do you not?

Mr. YANT. Yes. That is carbonate.

Mr. GRISWOLD. But you get more dust in limestone than in ordinary drilling, do you not?

Mr. YANT. It depends on the kind of drilling done.

Mr. GRISWOLD. Take limestone quarrying around Bedford, Ind. That work whitens everything.

Mr. YANT. We do not experience any reaction from limestone, such as silicosis. You could not expect anything in Indiana like what there is at Hawks Nest tunnel at Gauley Bridge.

Mr. GRISWOLD. You are familiar with the situation in Joplin, Mo. Do you know anything about the sand mines around Pacific and Valley Park, in the glass industry?

Mr. YANT. Yes. East St. Louis also has that.

Mr. GRISWOLD. I mean where they have these glass plants there in Missouri.

Mr. YANT. The silica there is high. Sandstone contains a high concentration of silica. It is largely silica. In sandstone quarries, where they make grindstone, sandstone building blocks, and so forth, there is just as much silica as you have at Gauley Bridge.

Mr. GRISWOLD. People employed in other industries such as we have in mind are just as apt to be affected as were the people at Gauley Bridge, if proper preventive measures are not used.

Mr. YANT. Yes; except modified by the amount of silica in the dust. We do not distinguish much between dusts.

I mentioned the methods of prevention, and they are wet drilling, wetting down before mucking, and they could wet down before blasting the walls, where the dust might have settled on ledges.

Mr. MARCANTONIO. These preventive methods were known as far back as 1914, as I understand you?

Mr. YANT. Yes.

Mr. GRISWOLD. They were known before that, I believe.

Mr. YANT. Yes.

Mr. GRISWOLD. That was when they were dealt with first in official publications, I believe?

Mr. YANT. Yes.

Mr. MARCANTONIO. The Bureau of Mines publication was issued. in 1915, was it not?

Mr. YANT. I believe that is right.

Mr. GRISWOLD. You embodied in the publication your experience up to that time, 1915?