of population exposure if enough is known about corresponding differences in sensitivity.

This, to me, is the kind of objective, nondogmatic statement that I would expect from the scientific approach to the problem. It seems to me more enlightening and useful than some of the other statements to which reference has been made today.

How would you respond to this, ignoring my editorial opinion? Mr. MACKENZIE. I would only comment that I am in agreement with the excerpt that you have read, sir.

Senator MUSKIE. How much research has your division of Public Health Service devoted to the specific question of subclinical effects from low-level exposure to lead?

Mr. MACKENZIE. I think very little, sir. I would have to examine our records to answer your question specifically, but I would respond as of now by saying that our current program includes only a nominal attention to it.

Senator MUSKIE. Do you have authorization for this?

Mr. MACKENZIE. Certainly. This is one of the areas, I think, that we should look hard at for followup in connection with further lead studies.

Senator MUSKIE. Would you think you ought now to have more funds for that research?

Mr. MACKENZIE. I wouldn't want to respond to this as of now, until our planning is more definite, sir. I think we will certainly need funds to do it, but I am not prepared to say how much or whether this can be accommodated within our proposed budget estimates.

Senator MUSKIE. You don't think you may want to ask the committee for more money before we finish consideration of the pending legislation? We may be in a generous mood now.

Mr. MACKENZIE. Your offer sounds very tempting. We would appreciate the authorities for appropriation as currently proposed in the act.

Senator MUSKIE. The report from which I just read also reads as follows:

The most important air pollutants which need a more systematic investigation of their effect on humans, animals, plants and materials are: Highest priority, sulphur dioxide, carbon monoxide, fluoride, ozone, sulphuric

and so on.

The report then notes high priority, with another list of pollutants. With respect to that statement, which will be included in full in the record, has your division assigned any priority to these substances in your research?

(The excerpt referred to follows:)

EXCERPT FROM "RESTORING THE QUALITY OF OUR ENVIRONMENT," REPORT OF THE ENVIRONMENTAL POLLUTION PANEL, PRESIDENT'S SCIENCE ADVISORY COMMITTEE, THE WHITE HOUSE, NOVEMBER 1965

The striking increases in illness and death that occur in acute air pollution incidents show clearly that specific types of pollution above a certain level may seriously affect health. At lower levels of exposure we find marked irritation of eyes, nose, and throat; and damage to vegetation. In addition, depending

on the type of pollutants, corrosion of metals, damages to wooden structures and streaking of paint are common. Dirt and grime deposited by airborne particulates are everywhere.

In order to balance the advantages of control measures against economic disadvantages the effects of the pollutants must be understood. In principle, the dispersing of non-toxic products into the air is acceptable but limits have to be defined.

At present our knowledge regarding toxicity of air pollutants is not adequate to allow us to know how to safeguard the health of the variety of people making up a community.

The most important air pollutants, which need a more systematic investigation of their effects on humans, animals, plants and material are :

Highest priority: sulfur dioxide, carbon monoxide, carbon dioxide, fluoride, ozone, sulfuric acid droplets, oxides of nitrogen, carcinogens (various types), peracyl nitrates, gasoline additives including lead and asbestos particles.

High priority: benzene and homologues, alkyl nitrates, alkyl nitrites, aldehydes, ethylene, pesticides, auto exhaust (raw), amines, mercaptans, hydrogen sulfide, and beryllium particles.

In addition the effects of the simultaneous presence of aerosols and gases have to be studied. The particulate matter may be of inorganic or organic nature. Special attention should be given to the effluents of combustion, which always carry particulate matter even when control equipment is installed. The present tendency to increase the fraction of particulates and condensation nuclei smaller than 0.1 of a micron in diameter needs evaluation.

There are a number of pollutants which are of local interest, such as the release of chemicals from a particular industry or from agricultural operations. Pesticides are often considered only as agricultural hazards. With the encroachment of urban development on agricultural areas, communities will be exposed with increasing frequency to the action of various pesticides. This is a distinct area of interest and active investigation by the Department of Health, Education, and Welfare and the Department of Agriculture.

Toxicological studies, especially the study of pretoxic phenomena of agricultural and home poisons, need expansion. It is disturbing to see chemicals used in the home with a total disregard of possible adverse effects. Acute and long range study of small concentrations is needed for: cleaning solvents and other household chemicals (volatile or sprays), specific chemical effluents from industry, household chemicals, lacquers, etc.

The products of imperfect combusion are a major cause of motor vehicle air pollution problems in every metropolitan area.

The major emissions from the automobile are: carbon dioxide, carbon monoxide, gasoline, oxides of nitrogen, aldehydes and acids, nitrogen-containing organics, phenols, particulate matter, and lead salts.

There are four main emission points; tailpipe exhaust, crankcase vent, carburetor, and gasoline tank.

Hydrocarbon emissions, expressed in percentages of gasoline used, amount

In addition, three pounds of poisonous carbon monoxide and two ounces of oxides of nitrogen are formed for every gallon of fuel burned. The average amount of gasoline used per day per average driver and car is 2 gallons. The energy loss through incomplete combustion is about 15% of the fuel heat value and is equivalent to one million gallons of gasoline daily for Los Angeles. For the nation this amounts to a loss of energy corresponding to 10 billion gal lons of gasoline per year. Not only air pollution control but also conservation and wise use of our natural resources demand careful attention to the reduction of this detrimental waste.

The hydrocarbon emissions from the crankcase, about 30% of the total, will in the foreseeable future be nearly 100% controlled. However, considering the difficulty of enforcement and effective inspection, we may not reach more than a 50% reduction of the other emissions.

It is predicted that the increase in automobile population will continue with the same rate for many years. Gasoline consumption in the U.S.A. rose from 40 billion gallons per year in 1950 to an estimated 70 billion in 1964. By 1980 the use of gasoline in the Los Angeles area will have increased by a factor of four since smog was first noticed around 1945. Parallel with the increase of fuel is the emission of pollutants. The partial control of emission predicted for the coming years cannot keep up with this increase.

Research and development directed towards improvement in combustion and greatly reduced emissions should be promoted at universities and government laboratories. These studies should include radical changes in engine design and the development of, for example, the fuel cell for practical use.

Other aspects of this pollution problem which need study are analytical problems, control of oxides of nitrogen, and control of the use of lead and other additives in gasoline.

Biological research needs.-There are two main approaches to the further study of pollutants: epidemiological and experimental.

Epidemiology: Substantial evidence on the health effects from air pollutants may be accumulated from epidemiological studies, even though in many cases the complexity of their air pollution defies accurate specification of the particular agent responsible for the observed effect. Nevertheless this method of approach has the advantage that it deals with man.

Experimental toxicology and physiology: Due to the inherent limitation of epidemiological studies, direct experiments on plants, animals and man are necessary.

At present we have too few data on too few species of animals for too few pollutants. Lacking are also data relating effect to concentration and duration of exposure. Much of the available information deals with concentrations which are to be found in occupational situations. The lower concentrations of special interest in community health problems are far more difficult to study experimentally. Studies of single pollutants do not necessarily apply to combinations of pollutants, which may show adverse effects at lower exposures.

Since a population is made up of individuals with a whole spectrum of sensitivities, the absence of toxic or adverse symptoms in a single group of healthy subjects does not establish safety for the whole community. Accordingly we must also measure the typical extent of individual differences, whether these be due to transient states of ill health or to continuing differences in physiology. When more is known about the range of variation, communitywide effects can be more accurately predicted.

Such studies cannot be confined to toxic or adverse symptoms alone, since measurable changes in normal physiological behavior often occur at lower concentrations and can provide useful indications of population exposure if enough is known about corresponding differences in sensitivity.

Animal experimentation: Inherent in such toxicological research is the need for long term animal experimentation. Especially when studying the effects of low concentrations, this work requires care, insight, and intelligence, both in proper execution of exposure and in observation of symptoms. Some of these symptoms may have been foreseen at desk level; others will be discovered by keen observers while experimenting. Many experimenters entering this field face for the first time a situation where the concentration of the gases arising from the natural emissions of the animal may easily equal or exceed those of the pollutants whose actions are to be studied.

It is essential that the personnel conducting such experiments, including those responsible for feeding and proper maintenance of animals, meet higher standards than are often thought adequate. Often too many aspects of this important work are delegated to animal keepers who do not have the knowledge necessary for the proper execution of the experiments. Adequate supervision can help but cannot be a substitute for properly qualified workers.

Mr. MACKENZIE. Yes; we have, in general. We have been devoting, I would say, perhaps the highest priority to the oxides of sulfur. I include here not only sulfur dioxide, but also sulfuric acid mist, which I believe has been mentioned in that listing.

Following this, we would, in my opinion, give priority to carbon monoxide, to the oxidants as a class, deriving from motor vehicle pollution, and the oxides of nitrogen.

In preparing criteria for air quality for the guidance of State and local agencies, I think our priority is indicated by the order in which we have undertaken to develop these. The first of these is related to oxides of sulfur. The second is the oxidant grouping of pollutants. We have under consideration as the next two, carbon monoxide and oxides of nitrogen. So I think this is a general indication of our view with respect to priorities.

Senator MUSKIE. Îs your research solely directed toward reduction of emissions through automobile control devices, or are you also considering methods of improving combustion or alternative nontoxic gasoline additives?

Mr. MACKENZIE. One important element in studying methodology for decreasing pollutants from automobiles is associated directly with the efficiency of combustion, because this is the preferred way, really, of reducing emissions of unburned hydrocarbons and of carbon monoxide.

We are interested also in the effects of additives. So far as we have been able to see, additives in gasoline, in many instances, serve some useful purpose. I am not completely sure that all of the additives that are used in gasoline are perhaps as useful as some of the advertising claims that are made on some of them, but this is an iconoclastic viewpoint, perhaps. Nevertheless, they do serve useful purposes in considerable degree.

We have been interested in what effect these have, or what contribution they may make to pollutant emissions from the vehicles. We are consequently interested in what Mr. Gammelgard was talking about earlier here as part of the project which the API has contracted for, with the Bureau of Mines.

There is other work that has been undertaken along the same lines. With respect to lead as a specific substance, this, of course, does contribute to the pollution directly, since it is not consumed in the engine. It contributes adversely to some methods of attempting to deal with exhaust emissions. I am referring to the poisoning of catalysts which might otherwise be useful in cleaning up vehicle exhausts. There also have been questions as to whether the deposits in engines may increase the pollution emission potential from engines in which such deposits accumulate. There is no clear answer available to me on this latter question.

So far as we know, the presence of lead in gasoline does not have any appreciable effect on the emissions of carbon monoxide, unburned hydrocarbons, and oxides of nitrogen. Certainly in the few tests from which I know the results, of running cars in parallel with leaded gasoline and unleaded gasoline, the evaluations of the pollutant emissions were not significantly different.

Senator MUSKIE. During the water pollution hearings, the subcommittee spent a day discussing the question of water pollution from erosion of the radioactive uranium mill tailing piles in the Colorado River Basin. Has your division investigated potential hazards to health from air erosion of these exposed piles?

Mr. MACKENZIE. We have not directly participated in studies that have been made on this problem, Mr. Chairman. A member of my staff, however, has been assigned to keep in close touch with this problem, which has been of concern to the Atomic Energy Commission,

the Federal Water Pollution Control Administration, and to the Public Health Service through the Division of Radiological Health. Since that latter division has been participating in some studies in evaluating the airborne elements of possible hazard associated with these tailing piles, we have not undertaken work directly but have attempted to keep informed on it.

Briefly, as we view the problem at the present time, it has not been demonstrated that there is a significant and immediate hazard associated with these piles. There is sufficient external radiation, associated with them so that if somebody undertook to live on top of the pile, we think he should be taken away and not permitted to stay there.

With respect to the dust-blown material, however, evaluation of several radioactive substances that are included in the pile substance, namely, radium 226, thorium 230, and polonium 210, the values of these in wind-blown materials sampled in at least two communities immediately adjacent to such piles showed the levels to be far lower than the maximum permissible concentrations which are currently accepted for general population exposure.

There is one other aspect, however, that we think needs further study and which is now scheduled for evaluation. This is the problem of possible radon hazard, on which studies have not been specifically made. Further, we believe that it would be desirable to stabilize these piles in any event if this can be arranged.

I would merely say at this point that we believe we should look further at the problem, and that as of now we think the piles should be stabilized in one way or another, so as to eliminate further distribution of possible radioactivity generally in the environment around the piles.

Senator MUSKIE. One final question: Again referring to the recommendations of the Environmental Pollution Panel, there is this one:

We recommend that the principle of requiring registration before use should be extended to the addition to motor fuels of substances which are not eliminated by the combustion process.

Are you presently studying the effects on public health from the release of phosphorus, boron, and nickel?

Mr. MACKENZIE. We have looked at the problems of boron and nickel. We have not looked specifically at the phosphorous compounds because phosphorus is a very common substance in detergents and other products generally distributed widely through public use.

We have been concerned about possible pollution from boron compounds and nickel compounds and have made preliminary evaluations of the possible dangers associated therewith.

The evaluations made to date on both of these substances, in our opinion, would not indicate the presence of any hazards. There have been proposals which we have dealt with in the past that would have involved more toxic substances than those which you have mentioned, but which, on discussion with the original proponents, were withdrawn.

Senator MUSKIE. So you are maintaining some kind of a monitoring program on these additives?

Mr. MACKENZIE. We try to keep up on what is going on, Senator, and if something is bothering us, we try to look into it. We do not