DDT was taken off the market largely because it caused some bird eggs (mainly eagles) to become brittle and break before the chicks matured.
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VI. Egg-shell thinning
DDT was alleged to have thinned bird egg shells.
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Many experiments on caged-birds demonstrate that DDT and its metabolites (DDD and DDE) do not cause serious egg shell thinning, even at levels many hundreds of times greater than wild birds would ever accumulate.
[Cecil, HC et al. 1971. Poultry Science 50: 656-659 (No effects of DDT or DDE, if adequate calcium is in diet); Chang, ES & ELR Stokstad. 1975. Poultry Science 54: 3-10 1975. (No effects of DDT on shells); Edwards, JG. 1971. Chem Eng News p. 6 & 59 (August 16, 1971) (Summary of egg shell- thinning and refutations presented revealing all data); Hazeltine, WE. 1974. Statement and affidavit, EPA Hearings on Tussock Moth Control, Portland Oregon, p. 9 (January 14, 1974); Jeffries, DJ. 1969. J Wildlife Management 32: 441-456 (Shells 7 percent thicker after two years on DDT diet); Robson, WA et al. 1976. Poultry Science 55:2222- 2227; Scott, ML et al. 1975. Poultry Science 54: 350-368 (Egg production, hatchability and shell quality depend on calcium, and are not effected by DDT and its metabolites); Spears, G & P. Waibel. 1972. Minn. Science 28(3):4-5; Tucker, RK & HA Haegele. 1970. Bull Environ Contam. Toxicol 5:191-194 (Neither egg weight nor shell thickness affected by 300 parts per million DDT in daily diet);Edwards, JG. 1973. Statement and affidavit, U.S. Senate Committee on Agriculture, 24 pages, October 24, 1973; Poult Sci 1979 Nov;58(6):1432-49 (”There was no correlation between concentrations of pesticides and egg shell thinning] .”) ]
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Experiments associating DDT with egg shell thinning involve doses much higher than would ever be encountered in the wild.
[J Toxicol Environ Health 1977 Nov;3(4):699-704 (50 ppm for 6 months); Arch Environ Contam Toxicol 1978;7(3):359-67 (”acute” doses); Acta Pharmacol Toxicol (Copenh) 1982 Feb;50(2):121-9 (40 mg/kg/day for 45 days); Fed Proc 1977 May;36(6):1888-93 (”In well-controlled experiments using white leghorn chickens and Japanese quail, dietary PCBs, DDT and related compounds produced no detrimental effects on eggshell quality. ... no detrimental effects on eggshell quality, egg production or hatchability were found with ... DDT up to 100 ppm)]
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Laboratory egg shell thinning required massive doses of DDE far in excess of anything expected in nature, and massive laboratory doses produce much less thinning than is seen in many of the thin-shelled eggs collected in the wild.
[Hazeltine, WE. 1974. Statement and affidavit, EPA Hearings on Tussock Moth Control, Portland Oregon, p. 9 (January 14, 1974)]
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Years of carefully controlled feeding experiments involving levels of DDT as high as present in most wild birds resulted in no tremors, mortality, thinning of egg shells nor reproductive interference.
[Scott, ML et al. 1975. Poultry Science 54: 350-368 (Egg production, hatch ability and shell quality depend on calcium, and are not effected by DDT and its metabolites)]
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Egg shell thinning is not correlated with pesticide residues.
[Krantz WC. 1970 (No correlation between shell-thinning and pesticide residues in eggs) Pesticide Monitoring J 4(3): 136-141; Postupalsky, S. 1971. Canadian Wildlife Service manuscript, April 8, 1971 (No correlation between shell-thinning and DDE in eggs of bald eagles and cormorants); Anon. 1970. Oregon State University Health Sciences Conference, Annual report, p. 94. (Lowest DDT residues associated with thinnest shells in Cooper’s hawk, sharp-shinned hawk and goshawk); Claus G and K Bolander. 1977. Ecological Sanity, David McKay Co., N.Y., p. 461. (Feeding thyreprotein causes hens to lay lighter eggs, with heavier, thicker shells)]
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Among brown pelican egg shells examined there was no correlation between DDT residue and shell thickness.
[Switzer, B. 1972. Consolidated EPA hearings, Transcript pp. 8212-8336; and Hazeltine, WE. 1972. Why pelican eggshells are thin. Nature 239: 410-412]
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Egg shells of red-tailed hawks were reported to be six percent thicker during years of heavy DDT usage than just before DDT use began. Golden eagle egg shells were 5 percent thicker than those produced before DDT use.
[Hickey, JJ and DW Anderson. 1968. Science 162: 271-273]
To the extent egg shell thinning occurred, many other substances and conditions could have been responsible.
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Oil has been associated with egg shell thinning.
[Anon. National Wildlife Federation, Conservation News, pp. 6-10, October 15 1979. (Embryonic mortality from oil on feathers of adults birds) ; Hartung, R. 1965. J Wildlife Management 29:872-874 (Oil on eggs reduces hatch ability by 68 percent); Libby, EE. 1978. Fish, wildlife and oil. Ecolibrium 2(4):7-10; King, KA et al. 1979 Bull Environ Contam Tox 23:800-805 (Oil a probably cause of pelican mortality for six weeks after spill);Albers, PH. 1977. Fate and Effects of Petroleum Hydrocarbons in Marine Ecosystems, Pergamon Press, N.Y. (Chapters 15 & 16; Dieter, MP. 1977. Interagency Energy-Environment Research and Development Program Report, pp. 35-42 (5 microliters of oil on fertile egg kills 76 to 98 percent of embryos within; birds ingesting oil produce 70 percent to 100 percent less eggs than normal; offspring failed to develop normal flight feathers); Szaro, RC. 1977. Proc 42nd N Amer Wildlife Nat Resources Conference, pp. 375-376]
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Lead has been associated with egg shell thinning.
[Bellrose, RC. 1959. Ill Nat Hist Survey Bull 27:235-288 (Lead poisoning in wildlife)]
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Mercury has been associated with egg shell thinning.
[D’Itri, FM & PB Trost. 1970. International Conference on Mercury Contamination, Ann Arbor, September 30, 1070; Scott, JL et al. 1975. Effects of PCBs, DDT and mercury upon egg production, hatch ability and shell quality. Poultry Sci 54:3350-368; Stoewssand, GS et al.. 1971. Shell- thinning in quail fed mercuric chloride. Science 173:1030-1031; Tucker, RK. 1971. Utah Science June 1971:47-49 (Effects of many chemicals on shell thickness).; Tucker, RK & HA Haegle. 1970. Bull Environ Contamin Toxicol 5:191-194]
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Stress from noise, fear or excitement and disease are associated with egg shell thinning.
[Scott, HM et al.. 1944. (Physiological stress thins shells) Poultry Science 23:446-453; Draper, MH & PE Lake. 1967. Effects of stress and defensive responses. In Environmental Control in Poultry Production, Oliver and Boyd, London; Reid, BL. 1971. (Effects of stress on laying birds) Farm Technology, Fall 1971; Sykes, AH. 1955 (Adrenaline excess inhibits shell formation) Poultry Science 34: 622-628]
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Older birds produce thinner shells.
[Sunde, ML. 1971 (Older birds produce thinner shells) Farm Technology, Fall 1971]
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Normal egg shells become 5 percent thinner as developing embryos withdraw calcium for bone development.
[Romanoff, AL and AJ Romanoff. 1967. Biochemistry of the Avian Embryo, Wiley & Sons, N.Y.; Simkiss, K. 1967. (Shells thinned by embryo development within) In Calcium in Reproductive Physiology, Reinhold, NY, pp 198-213]
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Larger birds tend to produce thicker-shelled eggs.
[Asmundson, VS et al. 1943. (Relations between the parts of birds’ eggs) Auk 60:34-44]
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Dehydration is associated with thinner egg shells.
[Tucker, RK and HA Haegle. 1970. (30 percent thinner shells formed after quail were kept from water for 36 hours) Bull Environ Contam Toxicol 5(3): 191-194]
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Temperature extremes are associated with thinner egg shells.
[Romanoff, AL and AJ Romanoff, 1949. The Avian Egg, Wiley & Sons]
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Decreased illumination is associated with thinner egg shells.
[Peakall, DB. 1970. (Shells not thinned even after illumination was abruptly reduced from 16 hours daily to 8 hours daily and high DDT dosage begun simultaneously) Science 168:592-594; Day, EJ. 1971. (Importance of even illumination on laying birds) Farm Technology, Fall 1971;Houser, EJ. 1962. Pacific Poultryman, August 1962; Morris, TR et al. 1964. (The most critical area of light duration is that between 16 hours and 8 hours daily) British Poultry Science 5: 133-147; Ward, P. 1972 (Physiological importance of photo period in bird experiments) Ibis 114: 275]
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Human and predator intrusion is associated with thinner egg shells.
[Beatty, RG. 1973. The DDT Myth, John Day Co., N.Y. 201 pages; Anon. 1971. Hawk Chalk 10(3):47-57; Cade, TJ. 1960. Ecology of the peregrine and gyrfalcon populations in Alaska. Univ Calif Publ Zool 63(3): 151-290]
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Simple restraint interferes with the transport of calcium throughout the body of birds, preventing adequate calcium from reaching the shell gland and forming good shells.
[Sykes, AH. 1955. Poultry Science 34:622-628]
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Uncovering eggs after parent birds are removed or frightened off exposes eggs to potentially fatal chilling, especially in northern or high altitude locations.
[Cade, TJ. 1960. Ecology of the peregrine and gyrfalcon populations in Alaska. Uni Calif Publ Zool 63(3):151-290]
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Phosphorus deficiency is associated with thinner shells.
[Crowley, TA et al. 1963. Poultry Science 54: 350-368]
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Calcium deficiency is associated with thinner shells.
[Greely, F.. 196 (Effects of calcium deficiency) J Wildlife Management 70:149-153; Romanoff, AL and AJ Romanoff. 1949. The Avian Egg, Wiley & Sons; Scott, ML. 1975. Poultry Science 54:350-368; Taylor, TG. 1970. How and eggshell is formed. Scientific American 222:89-95; Tucker, RK and HA Tucker. 1970. Bull Environ Contamin Toxicol 5(3):1191-194]
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Egg shell deficiencies were attributed to DDT and DDE by U.S. Fish and Wildlife researchers even though the birds had been placed on low-calcium diets.
[Bitman, J et al. 1969. Nature 224: 44-46; Bitman, J et al. 1970. Science 594-595. ]
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Cutting illumination from 16 hours daily to 8 hours daily at the same time as DDT feeding began had no significant adverse effect on shell quality. Shell quality was only adversely impacted after large amounts of DDE were injected into birds.
[Peakall, DB. 1970. Science 168:592-594]
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DDT was blamed for egg shell thinning even though a known egg shell thinner (dieldrin) was also added to the diet.
[Porter, RD and SN Wiemeyer. 1969. Science 165: 199-200]
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No significant correlation between DDE and egg shell thinning in Canadian terns even though the eggs contained as much as 100 parts per million of DDE.
[Switzer, BG et al. 1971. Can J Zool 49:69-73]
Well, well, well — yet ANOTHER (REDUNDANCY ALERT!)GOVERNMENT LIE.