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think we need further delineation of that but it sure points in that direction. With the increased number of automobiles, the increased consumption of gasoline, one would make the assumption that the amount of lead going into the atmosphere is going to increase.

Senator MUSKIE. And the amount that is being retained in the atmosphere is being increased ? Dr. STEWART. That is right.

Senator MUSKIE. If that is correct and if there is a direct relationship, and the evidence suggested in your statement indicates there is, between lead in the atmosphere and health, the fact that it is accumulating there creates a considerable urgency does it not with respect to final determinations?

Dr. STEWART. I think it creates an urgency when you also recognize that more of the lead that you breathe in is absorbed by the body than what you ingest. So that the change in the way lead is coming into the body adds to this urgency, with all indications that if all things stay as they are now the amount of lead put into the atmosphere is going to increase.

Senator Muskie. You also say that the bones of the human body tend to store lead ?

Dr. STEWART. That is right.
Senator MUSKIE. Is there any doubt on this point!
Dr. STEWART. No, there is no doubt on that.
Senator MUSKIE. If that is the fact, then the amount of exposure
which the human can take must be constantly reduced ?

Dr. STEWART. Well, the body reached an equilibrium in the amount
it is taking in and the amount that the body is putting out, plus this
storage factor. There is no solid evidence that the storage factor, that
the storage of lead in the bones is itself harmful. Where I was mak-
ing inference here is that when that storage is suddenly released because
of some other event you suddenly have a lot of lead in the body that
is released from the storage in the bones, like a fracture or like a severe
bleeding.
Senator MUSKIE. But the release is unpredictable?
Dr. STEWART. That is right, it is unpredictable.
Senator MUSKIE. If it is unpredictable, you have to assume, do

you not, that the release will take place?

Dr. STEWART. I think so, given some event and the release of the lead depends on how susceptible this person is to lead intoxication.

Senator MUSKIE. I am tempted to ask this next question then. It would strike me as a layman that the evidence you have presented to us this morning is such as to suggest we ought to lose no time in reducing or eliminating the threat of the discharge of lead into the atmosphere.

I ask the question not because I have reached that conclusion but because I think you ought to respond to it.

Dr. STEWART. I think we should do everything possible at the present time to make sure that a minimum amount of lead in gasoline that is necessary for its functions is what is in gasoline.

Senator Muskie. Would you say that if there is another way of producing the same benefits for gasoline that the use of lead now provides that we ought to eliminate the use of lead for the same purpose ?

Dr. STEWART. If the substitute is not also toxic.
Senator MUSKIE. Assuming that.

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Dr. STEWART. Assuming that, I would say yes.

Senator MUSKIE. In other words, if there was a substance that would provide the antiknock qualities of lead in gasoline, that we ought not to use lead for that purpose ?

Dr. STEWART. That is correct.
Senator MUSKIE. If the substitute is not toxic.
Dr. STEWART. That is right.

Senator MUSKIE. So that our inhibition about our eliminating the use of lead in gasoline is related to its economic necessity ?

Dr. STEWART. Yes, I think so. Mr. MacKenzie has shown me a graph which plots the effect of the amount of lead in gasoline to the octane effect that it has. It is not a straight line. It is a curved line so that the effect you get on the first cc. or 2 cc.'s is much greater than the effect you get on the last 1 cc. up to the 4 that they presently have. Now I am beyond what I should be technically but from looking at this graph it looks to me like there is some room here on the use of lead in gasoline as to whether it really needs to be four or not.

Senator MUSKIE. In your statement you describe the effects of lead poisoning. You appear to make a distinction between what you describe as clinical lead poisoning, that is lead poisoning which in your own words creates demonstrable injury or disease, and lower levels of exposure which do not produce demonstrable injury or disease. You raise the question then whether low levels of exposure in themselves produce serious effects on human health. Now if they do, then they become clinical poisoning, do they?

Dr. STEWART. Yes; they would. If one knew that it was specifically due to the lead. The difference here is that lead intoxication that produces clinical disease comes out in three forms. The most common one of occupational exposure is weakness and gastrointestinal disturbances, severe pain and anemia. If it goes on for a long time the muscles begin to atrophy and waste away. The third one is in children mostly:

It is a type of mental encephalopsy, sort of like encephalitis, à brain damage affair. These are all clinical. They have been described. If you are alert to lead intoxication when you see a person like this you can make the diagnosis. When you get down to the subclinical area you find increased destruction of blood cells in a person exposed to low level of lead intoxication. There are many other things which can cause destruction of lead-of blood cells which may also be acting as a factor. We-so it is nonspecific. We don't know at this time whether it is lead or other factors or factors acting in combination. The same thing is true in interference with enzyme activity.

The same thing is true with kidney and liver functions. There are many things that affect kidney and liver function which could be working and one is ascribing it to the lead but it may be something else or they may be working in consonance.

Senator MUSKIE. Is there any connection between lead and leukemia ?

Dr. STEWART. Not to my knowledge.

Senator MUSKIE. There are certain segments of the public who have a greater exposure to lead in the atmosphere than others!

Dr. STEWART. This is correct.

Senator MUSKIE. Service station people, traffic policemen, and others. Is a special effort being made to evaluate the effect of ex

posure by them? Presumably this represents a longer range exposure than to the public at large.

Dr. STEWART. Yes, there is, Mr. Chairman, called the "Three Cities Study” done by the Public Health Service. There were somewhat over 2,000 people examined for lead levels. About 11 of them had levels which one would say are out of line with the normal. But we did not have any representative population at that time of these high risk groups. We think this is terribly important to do and I think this is one of the proposals that Dr. Prindle will be talking about.

Senator MUSKIE. Dr. Prindle will describe what the Public Health Service is now doing to develop answers to the questions which you have raised this morning?

Dr. STEWART. Yes, sir. Senator MUSKIE. Is this a program which in your judgment carries considerable urgency!

Dr. STEWART. Yes; we think it carries considerable urgency. I don't know whether lead is more urgent than all the other contaminants

. It probably is because of the evidence of the increasing amount and this evidence of possible association with human hazards at these low levels.

Senator MUSKIE. I have one or two more questions based upon testimony we received yesterday, Dr. Stewart. Mr. Norman Cousins yesterday noted the need for a combined study of the effects on health of all environmental contaminants. We tend to consider, he said, each of the individual contaminants relative to its toxic effect on the human body.

The question in the long run, and I am paraphrasing what he said, and perhaps in the short run, must be the final deteriorative effect on the human body caused by the total poisoning of the atmosphere. Is there any relationship presently known or under study which might indicate that excessive exposure to a variety of contaminants might have adverse effect even though no single contaminants are concentrated in the atmosphere such as to have a toxic effect by itself?

Dr. STEWART. Yes, I think there is, but one can visualize that there are several contaminants in the atmosphere which all act on the respiratory tract. The combination of all of them would add to more insult than would any one.

I think this would depend on concentrations too. A certain concentration of the oxides of sulfur would not make

any difference whether he had any or not. A study of the London episode of excessive deaths from the smog episode they had in 1957—this was a combination of contaminants, all of which could have caused the effect in which the oxides of sulfur played a prominent role here I would think more logically it would be that that may have been the primary but the others were contributing to it. There is one other effect that I think is important.

There is some evidence, and this is quite by inference, that the one material being in the environment may potentiate the action of something else. Now I do not have one that is for air pollution but we are just getting rather interested in this. We do have some evidence to show that animals exposed to chlordane insecticide in the environment~this has a potentiating effect on certain alcohols, particularly the barbiturates that are given to these animals—it takes a smaller dose to have the same effect on the animal who is exposed to an environment of chlordane than if they were not in that environment.

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It was inadvertently found because we were using chlordane to eliminate insects where the animals were kept. The synergist effect of something else. I don't have an example that an air pollutant does this but it is possible too.

Senator Muskie. Are you conducting research in this field?

Dr. STEWART. Yes, we are. This synergistic effect on things is going on both in the Bureau of State Services and at the National Institutes of Health. This has great bearing on drug therapy, carcinogenesis and other things. Actually what is happening here is that we have now developed a whole field of molecular biology which allows us to operate at a molecular submolecular level to find out what these things will do.

This action of chlordane has been traced to an enzyme level in liver which stops the action of the enzyme which does away with the alcohol, therefore the alcohol has more effect, this alcohol being a class of compounds.

Senator MUSKIE. One other question. Mr. Cousins raised the question as to whether or not the devices to control automobile exhausts contaminant pollution would in themselves release more oxides of nitrogen and thus increase the exposure and whatever hazards to health may derive from the presence of oxides of nitrogen in the air.

Dr. STEWART. Would increase the amount ?

Senator Muskie. I think that is the question he raised. I don't think he drew any conclusions on this point but he raised the question. I have seen the question raised before and discussed it with people in the Public Health Service. I thought it might be well to have a comment by other Public Health Services on that question in the hearing because of Mr. Cousin's testimony yesterday.

Dr. STEWART. Mr. Chairman, I don't know the answer to the question. Dr. Prindle says he knows the answer.

Dr. PRINDLE. I think first we have to look at the purpose of these which has primarily been aimed to control of the hydrocarbon which has been the chief and major constituent we have been concerned with in the formation of photochemical smog. I think our feeling at this present time is unlikely this will increase nitrogen of oxides but I think by decreasing again the sort of synergistic picture and getting at one of the major constituents it probably is more beneficial even if there is a slight rise in this other constituent. Getting rid of it totally may be more important than slight changes in balance here.

Senator MUSKIE. You are convinced that the device with the standards that have been promulgated—will require-will be a net improvement?

Dr. PRINDLE. Yes, sir.
Dr. STEWART. Yes, sir.
Senator MUSKIE. And a substantial improvement?
Dr. STEWART. Yes, sir.

Senator Muskie. Thank you very much, Dr. Stewart. I understand you do have to testify elsewhere. We will be happy to excuse you.

Dr. STEWART. Thank you, Mr. Chairman. Dr. Prindle and Dr. Blomquist will stay if you wish.

Senator MuskIE. I think we have a statement from Dr. Prindle. Our second witness is Dr. Richard Prindle, Chief of the Division of Public Health Methods, Public Health Service.

STATEMENT OF DR. RICHARD PRINDLE, CHIEF, DIVISION OF

PUBLIC HEALTH METHODS, PUBLIC HEALTH SERVICE

Dr. PRINDLE. Thank you, Mr. Chairman. I am grateful to have this opportunity to participate in these hearings on air pollution and other problems of environmental contamination. My purpose here today is to supplement the remarks that have been made by Dr. Stewart, Surgeon General of the Public Health Service, with specific reference to the research and other activities that we feel may be required to insure that lead and other potential environmental contaminants do not unnecessarily threaten the health of our people in our country.

As both Secretary Gardner and Dr. Stewart have indicated, our awareness of the hazards of our environmental contamination is still in a rather embryonic stage of development. Our current concern with lead as an envionmental contaminant can best be understood in this context.

In the 19th century the symptoms of toxic lead poisoning had already been clearly associated with the occupational hazards of lead miners. During the current century, preventive measures and statutory legislation to safeguard the health of industrial workers from lead poisoning have been well established in the United States and abroad.

Special controls have been inaugurated in an attempt to curtail lead poisoning from food, contaminated water, and from medicines and cosmetics,

Nonleaded paints are now employed routinely in the interiors of homes and other buildings as a means of protecting children who, at one time, were exposed to the hazard of lead poisoning through the ingestion of lead-containing paint on walls, furniture, and toys. In short, we have learned that lead is poisonous and that we must avoid dosages sufficiently high to cause acute clinical illness.

Control activities by industry and government have been predicated on this knowledge and have not been concerned with the possible hazards to the general population of breathing or ingesting small amounts of lead over long periods of time.

Before 1923 when tetraethyl lead was first used commercially as a Zasoline additive, it is doubtful that any serious consideration had ever been given to the possibility of broad environmental contamination by lead with its possible hazard of prolonged, low-level exposure to the population.

In this regard it is instructive to note that the attention of the Public Health Service was first focused on the problem because of the deaths of a number of workers exposed to the new fuel additive in their occupations.

At the suggestion of the Surgeon General of the Public Health Service the distribution of tetraethyl lead and the sale of leaded gasoline were temporarily discontinued on May 5, 1925.

On May 20, 1925, the Surgeon General called a conference to look into the problems associated with the manufacture, distribution, and lise of tetraethyl lead. The conference called for the formation of an expert committee of seven recognized authorities in clinical medicine

, physiology, and industrial hygiene to present to the Surgeon General à statement as to the health hazards involved in the retail

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