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It is common assault it was just an in a past a sad is it is undesirable. Well if the best sad mostly on the planet long enough to do the job then it's not resistant to know. Eventually the ecologist is convinced that we're going to have to learn to control insects by non-chemical means don't think it would be proper to say that we could get along without pesticides. Today. We have an. Absolute requirement for chemicals to control some kinds of pests in some situations. Pesticides our incomplete knowledge part to one program in the series. The circumstance of science exploring the forces of contemporary science and technology and their possible effects on society. Our discussion of chemical plasticized continues as we look at the use of persistent or hard past decides and the alternative methods of past control. There is new evidence that accumulating residues of the insecticide DDT in
soil and water is a threat to wildlife. About one year ago a team of researchers from the Atomic Energy Commission's Brookhaven laboratory and the State University of New York found residues in the soil of a Long Island river estuary averaged more than 13 pounds per acre. It was noted that observations by other scientists among widely scattered bird and fish populations of the continent show similar concentrations. We discussed the implications of the finding with several of our program participants. First Dr. John Buckley director of the office of ecology of the Interior Department £13 breaker of a company which is known to have some metabolic effects suggests that this will be picked up by invertebrates living in the marsh and in turn that these invertebrates will be fed upon by the birds that move over and through the marshes. It's quite possible that the the levels may be
sufficiently high that. It eventually will have some effect on bird life and media in the area. It's also when one finds levels of the sort of soil it's quite and especially in wet soils it's quite possible that this may be eroded away and carried right into the surrounding waters. So my concern with that I think is simply that here is a. Fairly vast storehouse of DDT which is not serving any useful purpose in insect control but is in a sense available to the biological world and I'd rather it wasn't there isn't I can't label it dangerous in the sense of anything that's likely to happen to humans or or animal life in any immediate direct way. It is an occurrence such as this one relatively commoners is a rare example. You know I can't answer that very well either. It would be rare indeed to find a soil in which it's not possible to
detect DDT on the other hand £13 breaker I'm sure is higher than. In most areas though I'm sure there are some other styles which will contain very much more than 13 pounds per acre of DDT. How are concentrations such as this one form. I suspect that they're formed by continued use of the compound in those areas in a marsh area where DDT is found it's almost certainly there as a result of mosquito control. Carried out over a period of years in lesser concentrations and this sometimes occurs as a result of drift sometimes occurs as a result of washing in. We asked Congressman Jamie Whitten of Mississippi and chairman of the House Appropriations Subcommittee for agriculture if the Long Island finding of £13 per acre was a dangerous level. Well of course I'm worried but dangerous to what now under what conditions. And you Wade it's £18 that's a tremendous amount but when you see 30000 pound
make of that mean 13 parts per million. So it didn't sound near so scary when you put it in a nother describe it in a different way. That is not desirable I have object a scientist in the Department of Agriculture and in the government and they say that under normal use and that that is no reason to fear that it being dangerous in the least. Under present conditions where people don't want to the environment change or seem to think they don't cause all our standard of living is change the environment if we hadn't changed it throughout history we'd still be living in caves I reckon. Or perhaps I didn't have keys to start it but 13 parts of any thing that doesn't break down is not what is desired at the present time but I know no one who would say that 13 parts per acre. Since we don't need acres I would be in the danger of course if you brought it all together in a package and
misused the thing and in this whole subject it frequently bypassed his dosage to much of anything and a proper amount is not dangerous according to all the tests that will help you understand it just don't run the gauntlet and get clear about all the various government agencies. It just doesn't get on the market start with Roland S. climate vice president of the nice thought about society. Another aspect of this same study on Long Island is that if we also analyze the organisms present in this environment as was done by this study team we find that the DDT levels in the organisms increase as these. Achieved high positions in the what is called a pyramid of numbers. In other words the predatory farms that feed on the lower farms will have more DDT in them than the lower farms that feed on vegetable debris. So
this is an indication of serious contamination. This is just a freak occurrence this £13 per acre as this thing that we could expect of commonly almost anywhere. Well first of all the DDT levels in that particular salt marsh ran from about 5 pounds to as high as thirty two pounds to the acre. So the 13 pounds was simply an average. I expect that this is something we would find on almost any salt marsh along the Atlantic Coast where many as of mosquito control by the use of DDT ban the practice. And I think that this is the kind of situation we could expect to find almost anywhere we look for it. If there's ben a long continued use of Long live chemicals like DDT not too long ago a group of scientist and interested citizens took legal action in Michigan to prevent the use of the so-called persistent
or hard pesticides for the control of the Japanese beetle by the State Department of Agriculture and several Michigan cities. The court procedures became very tangled and eventually the Michigan court lifted a temporary injunction that was placed on the Agriculture Department spray program. However the pressures upon the local communities which plan to use the more persistent chemicals DDT dieldrin convinced many to switch to the less persistent the toxic lore. But I still Audubon Society has supported actions the C-Class persistent chemicals for Dutch Elm Disease Control. We discussed the DDT Dutch elm controversy with Mr Glanton vice president of the organization. We've been using DDT in Dutch Elm Disease Control now for 20 years or so and we have failed completely to control the spread of disease in the community of Greenwich Connecticut for example which was one of the first to develop a carefully tailored. Program of spray for
Dutch Elm Disease Control Program has failed. Twenty years ago Greenwich Connecticut had 60000 alums today it has less than 6000. So we are fading with DDT and it's time we gave it up because in addition to being incapable of controlling the problem we have been contaminating the landscape so that there is no choice where failing in any respect not only is Dutch elm disease continuing to spread but we have been killing off significant good populations. Could you describe for us what happens to the birds and other wildlife when. Elm trees are sprayed with beauty or dieldrin or some other chemical. Well in the case of DDT which is the one we know most about Dr. Roy Bacher of the University of Illinois had discovered what actually happens way back in
1958. We should have changed our methods after this but we did not unfortunately. What we found was that when we spray DDT on Elm foliage in the spring or summer for example. Whatever remains on that foliage will fall to the ground with the leaves in the fall of the year because it's a long lived chemical that lasts 10 15 or maybe more years. Now this foliage fallen to the ground will gradually become incorporated into the humans and will be chewed by earthworms who ingest not only the vegetable tissue of the leaves but the DDT therein. Now DDT as an affinity for fat. And therefore the earthworms will concentrate this DDT in their fatty tissues. They happen to be particularly resistant apparently so that they are not killed by the DDT but simply accumulate
this chemical in it tissues. Now the following year several months later when the robins come back from the south they are dependent on the newly emerging earthworms. And it's been established that. Sometimes as few as 10 or a dozen earthworms. So laden with DDT picked up from last spring spraying for example are enough to kill a rabbit. And not only this but even screech owls that may come along and feed on these dead Robins that night for example may themselves be poisoned. So it's a pernicious cycle and this is what causes us to be concerned and to insist that the long live chemicals that are cycled by natural mechanisms tend to be concentrated. We're going to have to go congressman with the fams the persistent chemicals as commonly thought the persistent.
In a pesticide I had undesirable. Well if the pesticide won't stay on the plant long enough to do the job then it's not possessed of them. No. Then his question arises you will have to break down into the original components and there are those that argue that that should be so that the environment would not be changed but actually from my own interviews with people who are experts in this field a non-persistent know a pesticide that breaks down very quickly could be far more toxic. So it's a matter of opinion as to which is which is the safer. That's a word you used I think is generally accepted now that after the job is done it is desirable that the pesticide break down is as readily as we can bring it to. To do that in 1984 the Department of the interior enunciated a policy for pesticide use on all areas under its control. In many
ways this use program as a model for proper use of chemicals. The policy rules out the application of persistent chemicals on a large scale. And Secretary you dollars noted thus far there is no evidence the conservation work has suffered because of it. Dr. Buckley of the Interior Department explains the procedure because he briefly stated that no persist. Pesticide would be used and interior lanterns. You know any large scale programs you know also. Left it possible to use. Any of these compounds. You could if this were the only possible means of control so that the Interior Department and other departments of government too for that matter I think look with more care now at the control programs that they're obligated to carry out than they did before. It's quite true that we practically never use highly persistent materials over any
large areas. Under the control of the Department of Interior. On the other hand in some of our park areas and some right dwellings and other places just as there are small scale uses of persistent materials and there must be. Until we find other ways of controlling pests than we so far have done. Wouldn't it be desirable to convince others such as state governments and perhaps even farmers to follow a similar type of program. Well yes I'm sure it would. Again that I think. Our government has done. Very well on this as it has a whole new interiors is certainly not the only agency that has enunciated such a policy. Some state governments have done this. But again there is there is a very widespread use of chemical Syrias still an abuse of them they're still
used in some cases and in many cases and on a preventive basis rather than Aima. Control bases just results regardless of whether it's it's good for agriculture. Or good for public health. Without debating the merits of that it certainly results in you know a larger use than would take place if the applications were made. Only when they were needed to control rather than on a preventive basis in coping with insects which develop resistance to one chemical after another. The science advisory committee said it is important to enlarge and improve our capability for controlling past as we enlarge the pesticide program with new chemicals and more widespread use. Can it be assumed that we will also find an associated increase in the various detrimental side effects such as poisoning of wildlife. Well I don't think that this necessarily follows in the first place.
We now expect to have. Side effects whereas a few years ago these came as a surprise to us and the knowledge that such things may happen and permits us to examine me how likely effects before they take place so that in the process of pesticide registration for example only department the interior advises the secretary of agriculture as to whether. A proposed registered use will have adverse effects on wildlife. And while we may on occasion. Overlook some possible ill effects. At least we have an opportunity now to always comment. Secondly. I think the. Compounds that are being devised and I will be used more only future will be those which are. Better tailored to the particular job that they're intended to do. And for that very reason will tend to have less
side effects than many of the compounds formerly used. The 1963 report of the president's science advisory committee noted that more than 100 established past have developed resistance to one of more previously effective chemicals. Is there an indication here that maybe pesticides a reached an optimum of effectiveness. No I don't think I would interpret it that way. The trouble with a statement such as that is that it's true but any other kind of control that we exercise against the past is almost certain to result in the same kind of resistance thus if we if we find a virus or something of this sort we're likely to find resistance developing the same thing. All resistance implies is that the genetic adaptability of the past has permitted and
a shift in its needs make up to the point that it's able to cope with whatever is present in the surroundings and whether this is a chemical or a virus or. Even a change in temperature of physical conditions and still resistance and in that sense. So I I don't think that I don't think that this is a problem that's new or related only to chemicals. One more comment on that. We can learn to cope with this too by the devising I think of the new chemicals by judicious use of the chemical. Only under the circumstances where it's likely most practical. How do we keep up with past that establish resistance to past decides. Dr TC by our late director of the cooperative state Research Service of the US Department of Agriculture we have to release first so those that will be resistant burst through basic research were gaining increased knowledge of what the resistance is. So if we know what makes a
flood resistant to the oregano first rate first so we may and probably will be able to make a small modification for a sensible attitude that will overcome the resistance of the resistance of a particular insect. So we're making real progress in this area. Congressman Whitten I guess the test is where they work and I read and hear. And whether we are running great Arista been known what happens to our crops and whether we can get rid of the roaches manse in our homes where they can get rid of the termites to destroy the wood in your buildings. We have to look around us to see whether what we are using is doing the job. But I have read for years as had one hundred fifty insects had to develop a tolerance or developed resistance. I guess as human beings have a tendency under certain circumstances. So we just have to go back and rely on the long and which as you know it required all sorts of tests before you
can. And register your sail in a thing that is poison for use as a pesticide. It has to clear if there is any danger to human beings I mean if it's a food for a human being that has to have a tolerance established by the Food and Drug Administration and all these tests are time consuming very expensive and one of the things that you have to have in addition to governmental research if industry is going into this business I have some degree of security that the market will be large enough for them to get the money back. So they've got see a great expectation expectancy in the new product because they've got to run the gauntlet of all these government tests. And some degree of assurance that they would be permitted tomorrow. But so far we have handled it all right as I say the government has been in with one and I and research in this area than phone line.
Mr. Kleiman of the Audubon Society. Eventually the ecologist is convinced that we're going to have to learn to control insects by non-chemical means that chemical should be used as a surgical tool is very specifically on prescription not in a and to support tare fashion as it is being used today. The trouble is we've been creating pests and we're going to have to modify the agricultural approaches themselves in order to cope with pests letting nature do most of the work using biological controls wherever possible and using selected chemical controls when it is necessary to tip the scales. The whole program of pest control right now is out of balance. Pesticides in your estimation reached an optimum of activists. I don't know what an optimum is I think possibly a pest. I would say definitely that where using too many pesticides a
President's Science Advisory Committee in 1965 said that the necessary pest control in this country could be accomplished with 50 percent of the pesticides that we're now using. And incidentally I'm not absolutely against chemicals as you can infer but certain chemical uses are going to have to go and we're going to have to reduce our dependence on these chemicals. Is it possible to fight past with methods other than chemicals. The answer is probably a qualified yes. There are now alternative means of controlling vast such as the use of insect enemies. There are no proper careful flora and fauna. Dr. Buckley I suppose the most effective ones are those that I would call environmental. Management or environmental manipulation. Any living organism has certain limits within which it. Can Survive and within this a zone where things are optimum. And.
If we are able to manage an environment in such a way as. As to have it near optimum for other crops or whatever it is we're concerned with. But. Less. Further from the optimum for the past and this is quite. Quite a satisfactory way. This may sound idealistic but let's look at Rex for example learning that. This will keep us out of the insecticides and herbicides for the moment. But interact control why we can poison rats. But for the long term control the rats probably would do better to read proof buildings by closing the openings my covering these would screen by keeping food picked up a whole series of things this really is an environmental management. We're making things less suitable for the rats but mad at the same time not less suitable for a man. There are other examples where you can do this in terms of insects. We asked Dr TC by a lay of the cooperative state Research Service of the Department of Agriculture
to explain the research and usefulness of alternative methods of past control. Well it's called control and cultural physical control of a business or under study throughout. The world and several soldiers federal and state early in the States. And in other countries for biological control has certain limitations. Here we have a continuing debate as to whether or not a pest is likely to be eradicated when it can be eradicated. Seems to me it ought to be and I think there are enough examples of eradication of best to make us confident that they can be and therefore read occasions as good eradication generally involves some use of first said chemicals eradication is not likely to take place in biological control because if you have a predator or a parasite or a disease its existence its continuing existence
depends. Alternately on the host or at least on alternate host it would keep it going. Some of them are fairly sophisticated from that standpoint. We do follow through on biological control we always have. As a matter of fact to a point. The biological control Methodism of choice was respect protection goes for diseases of rotation which is one of the oldest cultural practices or principal protection of soil borne agents of a series of stills likely continue to be for quite a while until we know far more about so I recall Aji raps about. So I wonder why Alex uses chemicals and soils them we know this is an area of continuing exploration and one which requires more attention has been given the soil. But you think that perhaps we've been paying insufficient attention to the alternative means of production those means other than pesticides over the last 20 years very
definitely. We stopped thinking when DDT came along in 1946. And there are very few exceptions to this general rule that I've just stated. We've sort of been locked into an economic situation here and we're going to have to learn to rethink this whole problem this is obvious it's been said now by a lot of competent people including two presidents science advisory committees. What are some of the alternatives that we have to using chemicals. Well the first thing is to know the status of a past. There is incidentally no past per say past is a population of organisms that reaches population levels that are excessive from an economic or some other point of view. Unfortunately a lot of pest control activity is in anticipation of the existence of past
ages. Once we realize that it isn't necessary to spray in anticipation we will have begun on the road back to common sense here. Nature will do much of this work for us if we give her a chance. And we can modify our practices for example rotation which is almost gone out the window in the last 20 years because of the builder of the farmer to lean on chemicals to solve his problems. Rotation of crops is an old technique that I can come back and across. We can continue using chemicals in a more selective way and by a combination of all these approaches we can cope with our problems. It's been suggested for example. That today farming is such a big business that the farmer can't afford and would actually derive a net profit from employing a
pharmacologist to study his past problems and tell him when he needs to and when he does not need to resort to actual pest control like the use of chemicals do we have any alternative means of controlling us that are. Efficient and inexpensive. In some specific cases I think any of us here is yes. By and large. I don't think it would be proper to say that we could get along without pesticides that. We have. Absolute requirement for chemicals to control some kinds of pests in some situations. On the other hand we also have a capability of pest control means for some specific diseases. Weeds that are equally good. Or adequate at any rate. You mean no in chemical fields.
You've been listening to the eighth programme in the series the circumstance of science exploring the forces of contemporary science and technology and their possible effects on society. You're invited to be with us for our next discussion dealing with the deterioration of one of our most valuable resources water participants will discuss the problems of water pollution from a number of sources. Many of the manmade on our six lakes and streams. A transcript of this program is available without charge from W. K. our Michigan State University East Lansing. This series is prepared under a grant from the Lewis W. and Maude Hill Family Foundation of St. Paul Minnesota produced by Steve new Shea for Michigan State University Radio. This is our national educational radio.
The circumstance of science
Episode Number
Episode 8 of 13
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Michigan State University
WKAR (Radio/television station : East Lansing, Mich.)
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University of Maryland (College Park, Maryland)
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Producing Organization: Michigan State University
Producing Organization: WKAR (Radio/television station : East Lansing, Mich.)
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University of Maryland
Identifier: 68-23-8 (National Association of Educational Broadcasters)
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