detailed records of use of pesticides by employers and by self-employed persons should be kept as well as records of use by workers" could well affect the decision of a grower whether or not to apply a pesticide himself.

Mr. C. A. Emery asked if the Ministry was going to persist in not stating tolerances, and said that the lack of a stated tolerance posed great difficulty in registration overseas.

Mr. Bates replied that since there were no recorded instances of harm to consumers from food after the proper use of a pesticide the Ministry had not thought it wise, at this stage, to embark on a system of statutory residue limits. The recent Review of Safety Arrangements recommended that more data should be obtained on the levels of residues in home-produced and imported food, and that when sufficient data had been collected, "consideration should be given to the need for establishing limits." He appreciated the problems involved when a company could not quote a United Kingdom tolerance in support of registrations overseas, but the primary concern was for the protection of the public in this country. Some guide figures were occasionally given in official recommendations, but these only indicated the maximum level of residues to be expected from "good agricultural practice" and should in no way be regarded as statutory.

REFERENCES

1. Bourcart, E., 'Insecticides, Fungicides and Weedkillers,' London: Scott, Greenwood and Son, 1913, 272.

2. Anon, Royal Commission on Arsenic, 1903. London: HMSO.

3. Cunningham, G. H., 'Plant Protection by the Aid of Therapeutants,' New Zealand: John McIndoe, Dunedin, 1935, 177.

4. Anderson, R. J., 'Scientific Aspects of Pest Control,' National Academy of Science, 1966. Publication 1402, 385.

5. Report on Agricultural Chemicals and Recommendations for Public Policy. State of California, 1960.

6. Pest Control Products Act, Canada Gazette (Part II) 22 December 1954. Tolerances, Food and Drug Directorate, Trade Inf. letter No. 290. 15 September 1967.

7. Thompson, F. B., N.Z.J. of Agric., 1964, November.

8. Agricultural Chemicals Registration Procedures, 1966-The Agric. Chem. Board, Wellington, New Zealand.

9. Williams, F. H., Med. J. Aust., 1966, 973.

10. Pesticides Legislation in the Netherlands, published by Plant Protection Service, Wageningen, 1968.

11. Bates, J. A. R., Public Health, 1965. LXXIV (2), 100–12.

12. Anon. Inf. BIBRA 1967, 6, (6), 29.

13. Report of Pesticide Residues Committee of the National Academy of Sciences-National Research Council, Washington, 1965.

14. Irving, G. W., Agric. Chemicals, 1967, 22 (12), 16.

15. Goddard, J. L., Federal Register, 9 February 1968.

16. Restrictions on the Use of Pesticides in Hungary from 1 January 1967. EPPO Reporting Service 67/6-297.

17. Dormal-van den Bruel, S., Residues Reviews, 1967, 17, 73.

18. Netherlands Pesticide Residues order of Amendment, 17 March 1967. Nederlands Staatscoorant, 27 April 1967 (No. 82).

19. Federal German Pesticide Residues Order, 30 November 1966; Bundesgesctzbatt (Official Gazette) 1, No. 53, 667–75. 10 December 1966.

20. Principles Governing Consumer Safety in Relation to Pesticide Residues; Meeting Report PL/1961/11, Rome: Food and Agriculture Organisation, 1961. 21. Evaluation of the Toxicity of Pesticides Residues in Food; Meeting Report PL/1963/13. Rome: Food and Agriculture Organisation. 1964.

22. Evaluation of the Toxicity of Pesticides Residues in Food; Meeting Report PL/1965/10. Rome: Food and Agriculture Organisation. 1965.

23. Pesticide Residues in Food. Tech. Report Series No. 370. Geneva: World Health Organisation. 1967.

24. Bro-Rasmussen, Finn., Journ. AOAC, 1965, 48(1), 29–34.

25. Report of the Third Session of Codex Alimentarius Commission, Alinorm 65/30, Geneva: World Health Organisation, 1965.

26. Report of the Second Session of the Codex Commission on Pesticide Residues. Alinorm 68/24. Geneva: World Health Organisation, 1968.

27. Report of the Joint Meeting of the FAO Working Party on Pesticide Residues and WHO Expert Committee on Pesticides, December 1967 (to be published). 28. Barnes, J. M., Scientific Aspects of Pest Control. National Academy of Science 1966, Publication 1402, 435.

29. Mollenhauer, H. P., Residue Reviews, 1967, 19.

[From the New York Times Magazine, July 6, 1969]

OBITUARY FOR DDT-IN MICHIGAN

(By Hal Higdon)

Died. DDT, age 95, a persistent pesticide and onetime humanitarian. Considered to be one of World War II's greatest heroes, DDT saw its reputation fade after it was charged with murder by author Rachel Carson. Death came on June 27 in Michigan after a lingering illness. Survived by dieldrin, aldrin, endrin, chlordane, heptachlor, lindane and toxaphene. Please omit flowers.

LANSING, MICH.-In early spring, 1968, the coho salmon began their gradual migration up the eastern shore of Lake Michigan, feeding as they went, growing as they fed. Along with them came the army of sport fishermen, casting from piers and trolling from boats, pulling the fighting silver fish out of the water by the thousands. Yet thousands still survived until September, when the coho reached the mouths of the Manistee and Platte Rivers and Bear Creek in the north and started upstream to spawn.

Awaiting them was Marvin Blackport of Grand Rapids, Mich. Earlier in the year his Blackport Packing Company had outbid 25 others for the right to harvest salmon from the spawning streams. As the coho moved upstream state fishery workers trapped them in weirs. They stripped some of the fish of their eggs for use in nearby hatcheries; then as fast as the fish were caught they were trucked to Grand Rapids for dressing, canning or storage in a freezer. The operation continued well into December, when two million pounds of fish (for which the state would be paid 15.6 cents a pound) had been pulled from the rivers.

The first hint of trouble came in February, when the Michigan Department of Agriculture examined some cans of salmon and discovered a relatively high level of dieldrin, like DDT a member of the chlorinated hydrocarbon family of chemicals. (It is more toxic than DDT, but because it is much less frequently used poses a less serious threat.) Then the U.S. Food and Drug Administration examined several interstate shipments of coho salmon, found high levels of DDT and seized 28,000 pounds of fish. Eventually the state agriculture department embargoed 500,000 pounds of salmon that had been canned or was awaiting processing. Marvin Blackport, who had contracted for the fish with one government department only to see them confiscated by another, had cause to feel perturbed. If he was upset, he wouldn't admit it: "I'm not planning any lawsuits. There's DDT in everything we eat. Nobody's ever died of it. We're going to wait this thing out. In fact, I'm going fishing tomorrow and I plan to eat anything I catch."

While Blackport was probably correct in saying that nobody had died from an excess of DDT in food, the pesticide itself was in the throes of a fatal illness, partly because of the controversy arising from its discovery in the coho salmon. At no time since the publication in 1962 of the late Rachel Carson's best-selling book "Silent Spring" had DDT, the miracle chemical of World War II, faced such a concentrated attack. Sweden declared a two-year moratorium on its use (including a complete ban on home use of DDT and all uses of aldrin, lindane and dieldrin, its close relatives). After another DDT relative, endosulfan, was blamed for the deaths of millions of fish in the Rhine River late last month, French conservationists demanded that pollution by chlorinated hydrocarbons be ended. The pesticide boards of Maine and Massachusetts have banned DDT as a weapon to control Dutch elm disease. Arizona has halted agricultural use of the chemical for a year to prevent contamination of dairy products. In Wisconsin, DDT is on trial before the state Department of Natural Resources, charged with being a water pollutant. The California Agriculture Director has issued an order that will ultimately prohibit the use of DDT in households and home gardens and restrict its use on farms. At least a half dozen states have anti-DDT legislation pending; Senator Philip A. Hart of Michigan has begun subcommittee hearings in Washington on DDT (he plans further sessions in his home state this week); Senator Gaylord Nelson of Wisconsin has introduced a bill that would restrict the pesticide, and the National Audubon Society has announced a campaign to ban its use in the United States.

Parke Brinkley, president of the National Agricultural Chemical Association says the DDT market in the United States has dropped by a third. In 1968 the five American manufacturers of DDT produced more than 125 million pounds of the pesticide, valued at more than $20-million,' but 90 million pounds went to overseas markets.

To protect this profitable business, the five American DDT manufacturers (Montrose Chemical Corporation, Olin Mathieson Chemical Corporation, Allied Chemical Corporation, Diamond Shamrock Corporation and Lebanon Chemical Corporation) have organized a task force to defend their products against what they call "emotional" attacks. The DDT task force provided a number of witnesses at the hearings in Wisconsin. They testified that DDT does not harm humans and warned that its complete elimination would leave the state vulnerable to outbreaks of such diseases as encephalitis. In Michigan, meanwhile, the state Department of Agriculture moved to cancel licenses for the sale of the pesticide. Those interested in preserving DDT were given 60 days to present their case; the deadline was June 27.

DDT (dichloro-diphenyl-trichloroethane) was originally synthesized in a laboratory by Othmar Zeidlar, a German chemistry student working on a doctoral thesis, in 1874. It was a lesson in pure chemistry, he had no idea what this new compound would do. The chemical is one of a number of so-called chlorinated hydrocarbons, many of which have been used as insecticides. The insecticidal properties of DDT didn't become apparent until 1939. A Swiss chemist, Paul Mueller, while searching for a plant-contact insecticide one that need not be ingested by the insect-discovered that DDT when it contacted an insect's nerve endings caused muscle spasms and, eventually, death. For his work, Mueller received the Nobel Prize in 1948.

In 1942, the U.S. Army began testing the insecticide, and when the tests proved successful DDT played a significant part in World War II, particularly in malaria-control programs in the South Pacific. Largely because of DDT, it was the first war in history in which fewer soldiers died of typhus than of bullet wounds. DDT was used to reduce the incidence of 27 diseases, saving perhaps 10 million lives and eliminating an estimated 200 million illnesses in the human population. DDT was cheap. It was persistent; the chlorinated hydrocarbons are very stable compounds with half-lives as long as 15 years. This persistence contributed to DDT's low cost as well as its efficiency: a single spraying frequently produced lasting effects. It was the same characteristic, however, that was to cause most of DDT's problems.

After its military baptism the pesticide became available for civilian use, and Michigan, with its large number of fruit farms, was one of the first states to utilize it. One early use was to control flies on Mackinac Island, at the juncture of Lakes Michigan and Huron.

The first hint that DDT might prove a mixed blessing came around 1949. Traces of the chemical began to appear in milk. DDT sprayed on crop-producing lands drifted onto neighboring alfalfa fields where cows grazed and the chemical was also used in dairy barns. Nobody then-or now-could prove that DDT harms humans, but reckless and excessive spraying seemed unwise. As early as May 16, 1950, the Michigan State University Agricultural Experiment Station recommended in a newsletter: "DDT should be used in moderation on crops, only in amounts sufficient to get the job done." Since most Michigan farmers plant their crops, spray for insects and probably even shave in tune with the Agriculture Experiment Station, this recommendation reduced DDT usage. "There was concern over DDT contamination 20 years ago," says Dr. Gordon Guyer, director of M.S.U.'s pesticide-research center. "We haven't changed our philosophy at all. Research on this problem has been going on constantly. We have attempted to phase out DDT wherever substitute materials become available."

But the blame for polluting the environment, and particularly the Great Lakes, cannot be hung entirely on farmers. DDT is virtually insoluble in water; it will move downstream only if it is clinging to something else-most often a soil particle. And farmers are careful about their soil; they ordinarily take pains to guard against erosion. Many cities in Michigan-and even conservationists-are partly responsible for pollution. DDT seemed the perfect means for eliminating pesky mosquitoes. Conservationists sprayed it in the state parks. (many of which,

'DDT now sells for 17 cents a pound, compared with $1.19 a pound shortly after its discovery. A spokesman for the National Agricultural Chemical Association says the profit margin is relatively small because of competition and declining markets.

in Michigan, are near water), homeowners sprayed it in their back yards and municipalities used it along streets, where it often found its way into sewers, then rivers and eventually the Great Lakes. Slowly, the DDT residues built up in the Lakes, and Gordon Guyer admits, "We are all involved."

In the nineteen-fifties Dutch elm disease threatened some of the lofty trees that lined the streets of many Midwest towns. In 1954, Michigan State University, which has a large number of elms on its East Lansing campus, began DDT spraying to kill elm bark beetles, which spread the disease. The beetles began dying, but so did large numbers of robins. Within a few years robins virtually disappeared from the campus. Soon zoologists discovered why. Leaves covered with DDT fell to the ground to become food matter for earthworms; the worms in turn were eaten by the robins. When the robins had eaten a sufficient number of earthworms their DDT levels rose to a point where they died of nerve poisoning.

Michigan State's experience is a demonstration of the phenomenon known as biological magnification. Although the DDT concentration in one area may be microscopically low, it can multiply through the food chain. Thus in the Green Bay area of Lake Michigan, the bottom muds contained 0.014 parts per million of DDT. Tiny amphipods living in the mud absorbed the chemical, concentrating it to 0.41 parts per million. Fish fed on the amphipods and, because of the volume of food they ate, soon had concentrations of 3 to 6 parts per million. Herring gulls ate large numbers of fish and their DDT level reached 99 parts per million. This won't kill the gulls (except under stress or starvation conditions), but it will impair their ability to reproduce, thus diminishing their numbers.

Several bird species along the Great Lakes, including the American eagle, are threatened with extinction because of DDT, which causes the liver to produce enzymes that attack the hormones governing calcium production. When the eagle's system produces less calcium, the egg shells become thinner and thinner, causing more frequent breakage and fewer baby eagles. (Sergei Postupalsky of the University of Wisconsin has reported having found an eagle egg without any shell on the shores of Lake Superior in northern Michigan. The embryo was enclosed only by a membrance, which had broken, allowing the contents to ooze through the bottom of the nest.) The osprey, peregrine falcon and mallard duck have problems similar to those of the eagle. And the Mink Ranchers' Association believes that DDT may be affecting mink reproduction.

Birds suffer the most because they cannot excrete liquids as rapidly as mammals can. When the DDT is not excreted it builds up in the birds' bodies. Humans, on the other hand, seem to eliminate DDT once it reaches a level of 10 or 12 parts per million. (Most Americans apparently have that level in their bodies.) Experiments in feeding prisoners massive DDT doses have uncovered no measurable dangers, and workers in DDT plants survive in apparent normal health. No human has died from DDT-yet. But there are hints that DDT may be more injurious to human health than current evidence indicates. Researchers at the University of Miami have discovered that people with several diseases, including leukemia, have high residues of pesticides. The National Cancer Institute has found a greater tendency for tumors in DDT-fed experimental mice. No reputable scientist will yet condemn DDT as poisonous to humans, but the pesticide has been in use less than three decades. Measurable effects could appear in two or three generations.

The publication of "Silent Spring" in 1962 brought to public attention the dangers of environmental poisoning by DDT. "You could see people standing around in the garden stores reading labels," says Paul Flink of the Michigan Department of Natural Resources. "They were aware there was a problem. That's the first step to cleaning things up: get people aware." According to Gordon Guyer of M.S.U., "Some of the things Rachel Carson said lacked perspective, but hers was an important book. It made people look at the issues." Robert Reinert of the Michigan Bureau of Commercial Fisheries adds: "Scientific progress and public pressure seem to go hand in hand."

Scientific progress appeared in the form of the gas chromatograph, which enabled scientists to measure minute levels of DDT in the environment. Some of the problems caused by DDT in the Great Lakes, for example, come from concentrations as low as two parts per trillion. One as two part million is the contents of a single one-ounce shot glass in that of a small railroad tank car; one part per trillion is the contents of a single one-ounce shot glass in that of a million tank cars. Yet such concentrations, through the process of biological magnification, have far-reaching effects.

The mounting evidence of DDT's hazards led to an increased threat of regulation. In addition, many insects began to develop resistance to DDT. This prodded the chemical companies to find substitute pesticides. Many of the substitutes are organophosphates and carbamates, which also attack insect nervous systems but have shorter lives than the chlorinated hydrocarbons-often a matter of days or weeks instead of years. Because the substitutes are less persistent, they must be used more frequently than DDT and are therefore more expensive.

As other insecticides became available, the Michigan State University Agricultural Experiment Station gradually eliminated DDT from its recommendations for insect control. It suggested the other chlorinated hydrocarbons only in cases in which no adequate substitute was available. Between 1962 and 1967, DDT was dropped from half the recommendations for control of vegetable insects. Where it was still recommended, prescribed dosages were reduced. In 1967, M.S.U. suggested that methoxychlor, a chlorinated hydrocarbon but a much less persistent chemical, be substituted for DDT in Dutch elm disease control programs. At about the same time, the Environmental Defense Fund, a New York group, took 56 Michigan cities into Federal court in an effort to halt their use of DDT in fighting Dutch elm disease. Detroit rebelled at first but eventually capitulated. The following year, M.S.U. removed DDT from its mosquito-spray recommendations and the Michigan Department of Agriculture moved to guarantee that the recommendations would be followed.

Under Michigan law, the agriculture department can, upon the recommendation of the M.S.U. Agricultural Experiment Station, cancel the license under which a pesticide is sold in the state. The department can't prohibit the use of a pesticide, but the cancellation of its license has the same effect. When the department moved against DDT in April, those involved in its sale appealed to the state agriculture commission. The commission has agreed to only three minor exceptions to the ban: it said DDT powder could be used against bats or mice in buildings, against body lice or in "emergency" conditions (an encephalitis epidemic, for instance). The sale of DDT for all other uses was forbidden, and the order became final on June 27. Michigan conservationists expected, however, that the chemical companies would ultimately test the prohibition in the courts.

As DDT was taking its toll in Michigan and the other Great Lakes states, the area was suffering another-and totally unrelated-ecological disaster. Since the glacial era, sea lampreys-sucker-mouthed eels that feed on fish-had lived in Lake Ontario. Until the opening of Welland Canal in 1833, the lamprey and another ocean resident, the herring-like alewife, had been unable to bypass Niagra Falls and enter the upper Great Lakes. The lampreys didn't reach Lakes Huron and Michigan until the nineteen-thirties, but within a decade they and overfishing had virtually eleminated the lakes' large commercial and sport fish. In the process, the lampreys killed off the predators that would have controlled the alewives, which multiplied rapidly. When the alewives died (from the stresses of overpopulation, not from DDT, as some have suggested), their bodies washed up by the millions on beaches. The problem reached its peak in 1967.

Meanwhile, aquatic biologists at the University of Michigan discovered that they could control the lamprey by pouring the pesticide TFM (which is not related to DDT and does not, if properly used, harm other fish) into its spawning streams. With the lamprey threat eliminated, biologists sought to restock Lake Michigan with sport fish: coho salmon, Chinook salmon and lake trout. The quickly maturing coho salmon, released as fingerlings in the spring of 1966, found a ready source of food in the alewives, all part of the plan. By the following spring the coho had grown to a size of two to four pounds. When the ice broke in 1967 they were congregated, along with the alewives, in the warmer southern waters of Lake Michigan. Through the summer they moved gradually north toward their spawning streams. They grew rapidly, and that fall fishermen pulled in 15-pound and 20-pound fish. The word spread fast. By 1968 most of the fishermen in the Midwest had been transformed into coho maniacs.

The result was a bonanza for the Great Lakes states, particularly Michigan. Fishermen descended by the thousands on Michigan lake villages, buying bait, tackle and gasoline, renting boats and motel rooms. One survey of the Michigan Department of Natural Resources indicated that expenses for the average angler amounted to $19.50 a day. The department estimated that by 1972 the sport would bring close to $100-million into the state, largely because of the coho salmon. The coho would also control the alewife population, which would no longer wash up on the beaches.

But that optimistic prediction failed to take into account the factor of biological magnification. The coho fed on the alewives, which fed on the microorganisms