OCR Text |
Show cerclasls or River blindness, by the fresh water Simullan fly and the very sensitive to DDT; Leish- maniasis by the mosquito; filarlasls or the hideous elephantiasis by the mosquito; salmonellosis, by the fly; disease by the kissing bug; and Chagas the fever by tick, and many more. spotted With virtually all these vectors persistence In a pesticide is a necessity to provide prolonged protection and DDT is the cheapest most effective and unquestionably the safest pesticide of choice. For In spite of all the furious clamor of late by a vociferous and clearly irresponsible minority no evidence of Injury, cancer or death after twenty five years of use, where at least one billion humans have been exposed, has ever been authoritatively reported with medical annotation. There have been Invidious claims made but not one has ever been medically established. Even workers In DDT manufacturing and formulating plants heavily exposed to the technical compound daily, at a level at least 200 times that of the general population, dally for upwards of 19 years revealed no significant clinical effects at all. As a matter of fact the Incidence of cancer among them was lower than that found in the general population, while the number of children they sired was above the average of the U.S. population. There have been a number of efforts to try and prove DDT is a carcinogen, or cancer Inducer, going back to the absurd assertions of Morton Bisklnd, and Hueper, up to a recently published paper from the National Cancer Institute. None of these statements can withstand scientific scrutiny and analysis and a recent summary of the situation prepared byDr. Wayland J. Hayes of Vanderbilt University Medical College and formerly head of the Pesticide Division of CDC at Atlanta as presented to the hearing examiner of the Washington State Legislature reasserts his repeated position of the past, "There Is no valid evidence that DDT Is a carcinogen". The repeated claim that although the acute effects of DDT may not be serious In man, we do not know what the long term effects will be, is obviously specious. All drugs exhibit a dose -- response effect and If DDT does not, It Is the first drug discovered that doesnt. Obviously a continuous exposure over 20 years at a level of 200 fold the normal without clinical effect Is more than equivalent to a normal continuous exposure of 4000 years. Surely no one Is going to demand experimental proof that extends for longer than 4 millenla. Perhaps the most crucial and cogent evidence that the correct use of DDT and other pesticides Is safe, lies In the fact that the Insurance companies which underwrite the workers In pesticide plants or In pest control operator companies do not demand a higher risk premium for such coverage. They do not do this out of any misplaced generosity of spirit, but merely because they cannot point to an actuarial risk history that would justify such Increased premiums. organo-chlori- ne The concern that the organo-chlorlpesticides, particularly DDT, may be steadily Increasing In our food and water supply Is not founded In fact. Extensive market basket analyses of all the major groups of pesticides made on samples of typical American diets taken in some 20 cities across the country and based on the prodigious food Intake of a 19 year old American male reveal the maximum Intake of any one pesticide or the total of all pesticides falls below 10 of the FDA and FAO-U- N allowable tolerance. Furthermore these analyses Indicate there has been no Increase In levels of any one or all pesticides over the past 7 years since the Inception of the program. It Is Interesting to note also that the pesticide levels, including DDT, found In imported foods Is, on average, higher than those which are detected In similar domestic ne Parallel monitoring studies of DDT and related derivatives present In human tissues, chiefly fat, reveal no Increase, on average, over the past ten years among the general population. The recent deliberately sensationalized publicity concerning the presence of minute levels of DDT and derivatives found In mothers milk Is a totally Irresponsible effort to throw an unnecessary scare Into pregnant and nursing women solely for political purposes. Actually infants pick up more pesticide residues from other foods they eat than from their mothers milk, and furthermore In fact mammals are, In fact, more tolerant of DDT and derivatives than adults of the same species. The same cannot be said for the caffeine, nicotine or alcohol they may also receive from their mother, when she consumes coffee, smokes cigarettes or drinks cocktails. WILDLIFE CONSIDERATIONS: The essence of the concern of many ecologists and conservationists related to pesticides rests primarily upon the persistence of pesticides, chiefly the organo chlorines In the environment to which they are applied. It has even been stated that over 95 of all the DDT ever applied Is still present as such or as Its biologically active derivatives, and continues steadily to Impregnate the entire planet, land, water and air. To begin with the This is absolutely untrue. older pesticides such as lead arsenate, the mercur ies and coppers are Indeed permanent as their half lives are virtually Infinite. This Is not true of the organic pesticides Including DDT and the other organo chlorines. Some, such as the organo phosphates have half lives measured In hours or days, although many of them are exceedingly toxic to wildlife for the period they are around. Others, such as DDT and the other organo chlorines have half lives measured in days, weeks, months and In a few specific cases, In Their rate of decay Is subject to many years. environmental factors Including temperature, moisture, light, and the presence or organic matter and micro flora. It Is the particular combination of these factors that determines the actual half life In each specific case. Organo chlorines are, as a group, highly Insoluble in water so their movement in water Is both slow and minute. They do, however, have a strong affinity for fats, oils and other lipoids and they tend to absorb strongly to organic matter. When streams or rivers do become contaminated at relatively high levels with DDT It is usually through erosion of treated soil by wind or water and the pesticide is carried Into the water absorbed onto soil particles, where it also re mains, settling with the soil Into bottom muds. There It slowly decays under attack by various benthic microflora or mlcrofauna. This has now been verified by long term monitoring assays of estuarine waters and bottom deposits at the mouths of our major river systems. .The delta of the Mississippi is of particular significance In these studies as this mighty river system drains such a vast agricultural area where millions of pounds of pestle ides are applied annually such that, If indeed there actually was a steady drift and accumulation of DDT and derivatives In our waterways, It would be the mouth of this great watershed that would reveal It. It does not, after nearly eight years of Intensive investigation. The alledge blame on the organo chlorines for the Mississippi fish fiasco, of a few years ago, was ultimately revealed as totally unfounded. As there was no decline in the Louisiana shrimp harvest, at the time, this should have really been patently obvious, for shrimp, being arthropods, are far more sensitive to these chemicals than are the sunfish, shiners and cat fish that died. In sandy, dry soils In mild climates DDT and derivatives do persist, In some recorded cases, with half life of up to ten years. Where soil Insect, or termite control Is important this Is, of course, a distinct advantage. DDT, the chief culprit in the present flurry of accusations degrades quite rapidly either to DDD or to DDE . Both of these forms are substantially less toxic to all kinds of vertebrate life than is DDT. DDDT Is about ll0th as toxic and DDE about 12 as toxic as DDT. It is true that minuscule quantities of DDT and derivatives have been detected, In remote and unlikely places on the planet where, presumably, no direct application has been made. This Is true of many other toxic substances also Including arsenic. Many of these assays are more of an accolade to the equlslte refinement of our modern analytical techniques than an ominous warning of the poisoning of the total environment. Furthermore it now appears that much of the earlier analytical work l.e. prior to 1967 - on DDT residues was obscured by an confounded with polychlorobiphenyls (PCB) which reveal coincident peaks in the gas -- liquid chromatoRecent studies from Sweden suggest that graphs. DDT resiperhaps the preponderance of dues found In marine waters and biota are In fact PCBs. so-call- ed The presence of DDT and derivatives among Antarctic penguins Is an oft quoted case. Actually, of course, the amount present in the penguins was so small, that If all the penguin population in Antarctica carried the same level, which they did not as most of them were negative, then the total amount of DDT or equivalent would aggregate about half a pound for the entire continent. As there was no DDT detected In the snow samples taken, there Is no evidence that the penguin and other Antarctic wildlife data Indicates a universal contamination of this remote area. It would seem far more probably that the observed DDT came from wastes and rubbish cast out by visiting Antarctic expeditions. Similar sources are suspect for the occurrence of DDT and derivatives among pelargic fish caught far out to sea. There have undoubtedly been fish kills among inlandstreams and water ways that are in small part, at least, attributable to pesticides, which entered the water either by direct application or by erosion of In a few cases the irrestreated nearby soils. ponsible dumping of residue spraus, old containers, etc. directly Into strains1' and ditches has killed fish. However, the published records of unnatural fish kills In the U.S. over the pat 7 years reveal that of the total kill can actually be assessed only against pesticides. Municipal and industrial wastes on the other hand account for over 70 of the kill each year. 1- -3 When the decision rests between producing food or fiber for our people and the protection of millions of acres of forest and billions of boardfeet of lumber, or alternatively preserving less than 0.1 of our fresh water fish, which rapidly replace themselves anyway, there really is no question as to which choice should be made. The concern over the impact of pesticides upon terrestrial wildlife particularly birds Is not entirely vole of justification but again it has been exaggerated out of all proportion to the actual facts. There is actually no valid evidence, despite the and assertions In the press, that any registered pesticide applied correctly and In accord with approved federal and local recommendations has ever Invoked massive Irreversible bird kills of any species. Even where accidental spills or Irresponsible, exposures have, on occasion, occured the resulting kills have been Insignificant, compared to kills elicited by winter wastage, storms, disease and such other man made hazards as sky scrapers, TV towers and traffic. emotional Contrary to the oft quotedmyth initiated In Rachel Carson's Silent Spring, where the main concern was over the alleged rapid decline in bird life In America, careful bird counts made over the entire country and published by the National Audubon Society reveal that many favored species of birds have actually very substantially Increased in numbers In many areas of the country rather than have declined . Thus robins (which were mourned as approaching extinction on page 118 of Carsons book), starlings, sparrows, seagulls, ducks of several species, wild turkeys, blue jays, cardinals, pheasants, quail and grackles have all Increased at least two fold and some more than 40 fold in the past 25 years since the organic pesticides (including DDT) were widely introduced. Surprisingly a number of raptorial (Hawk) species, which being at the top of the carnivorous food chain are alleged to being rapidly poisoned into extirpation, have also shown that they are either holding their own or are increasing. Unfortunately several do show a steady decline and Include among their number Coopers Hawk, the magnificent Golden Eagle and the Peregrine Falcon. These declines, however, appear to be more related to the encrochment of mans civilization upon their wild breeding and feeding haunts than upon the direct effect of any pesticide. Certainly the Peregrine Falcon was driven from the Hudson River escarpments by man's Intrusion long before DDT was discovered to be a pesticide. All over the world this superb raptor has shown a decline regardless of whether DDT was used In Its environment or not. The fish hawk, or osprey, on the other hand, though driven from Its shore line haunts on the east coast has reinforced Its numbers inland and a significant rise in the migration count has been recorded for several years now at the Hawk Mountain Sanctuary Observation Post on the Great Appalachian Fly Way. There is much press publicity that residues of organo chlorine pesticides particularly DDT, Impair fertility, eggshells and hatchabllity of eggs and reduce the survival of nestlings among many species of wild birds, specifically ducks, quail, pheasants, pelicans and particularly raptors such as the bald eagle. Most of the reports published on this subject are patently assumptive and equivocal, although admittedly in some species excessive exposures, many fold that experienced under field condltons, do reveal some of these effects. There Is considerable evidence with domestic fowl, turkeys and ducks that this does not occur even at doses 10 fold natural exposure. In any case there could hardly be a population explosion of bird life in America If these assertions were, in fact, generally true. Sportsman's clubs report that In recent years the bag has been i more then adequate for sporting birds, and the same is reported for all the major species f hunting mam mallanwlldllfeover the past 25 years. Finally the argument is repeatedly raised that even though the levels of DDT and derivatives and other organo chlorine pesticides present in waterways, lakes and ponds may be Innocuously low there is a magnification process up the food chain which culminates In an accumulation to lethal levels at the top of the chain. This important hypothesis has been critically investlgaged recently by the OregonStatlon. They find that. Indeed, certain aquatic flora and fauna do pool organo chlorines, but that It does not consistently mount up the food chain and certainly not at the rate and magnitudes claimed. Furthermore, the actual evidence reveals that fish at the top of the food chain, e.g. trout - absorb some 85 of the pesticide they accumulate directly from the ambient water and only 15 from their food; that the level to which the compound accumulates is a direct function of the concentration in the water; and that such accumulation attains a steady state above which it does not rise unless the concentration In the ambient water is also raised. Thus where the level in the water is less than 1 ppb, and many waters show concentrations in the 10 -- 100 ppt range, the accumulation in the fish is essentially Innocuous to the fish and harmless to man should be catch and consume. Admittedly, higher levels of DDT and derivatives than 1 ppb have, an occasion occurred, following heavy rain erosion from neighboring recently treated fields or to the deliberate Illegal dumping of residual spray tanks, drums etc. but these are not. approved methods of application and are quite regional and ephemeral in effect. |