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A new study shows that toxic chemical compounds—methyl mercury, DDT and mysterious PCBs—are present in our most popular saltwater fishes. Now rising residue levels endanger human health as well

In the past fewyears there has been considerable scientific concern about chemical residues infish, but almost all investigations have been limited to freshwater lakes andstreams. Yet some species of coastal fish have gone into what John R. Clark,curator of the New York Aquarium, describes as "a disastrous decline, avirtual wipeout. The total commercial catch on the Middle Atlantic in 1969 wasdown to about one-tenth of the 1960 catch. The multimillion-dollar menhadenfishery was nearly eliminated in the late '60s, and weakfish, croaker, spot,porgy and fluke are close to disappearing in the Northeast. Pollution is amajor cause. Coastal waters are infested with pesticides, metals and othertoxic pollutants, and these poisons can kill fish, their young and theorganisms they feed on."

It is alsopossible that this pollution, unless checked, may kill people. A studysponsored by SPORTS ILLUSTRATED reveals that poisonous chemical compounds inthe flesh and eggs of some of the most popular American saltwater sport fisheshave reached levels that are alarming to health authorities and fisherybiologists. The study, the first ever to involve fishes from the Atlantic, Gulfand Pacific coasts of the U.S., was conducted for this magazine by WARFInstitute, Inc. in Madison, Wis., a highly respected laboratory that has doneresearch for the Federal Government, various states and private industry.

Specifically, thestudy shows that the flesh of spotted seatrout from Louisiana, striped bassfrom California and Spanish mackerel from South Carolina contains more mercurythan allowed by the U.S. Food and Drug Administration in fish sold for humanconsumption.

Other testsdisclose that the reproductive process of at least four different fishpopulations may be threatened by high residue levels of chlorinated hydrocarbonpesticides in the eggs. High levels of DDT residues (a combination of DDT, DDDand DDE) are in the eggs of striped bass from California, from the HudsonRiver, New York, from the Rappahannock River, Virginia, and in the eggs ofbluefish caught off the coast of South Carolina. Moreover, the eggs of theCalifornia and New York bass have high PCB residues, an industrial compoundthat has escaped into the environment by accident.

The fish studiedwere all females close to spawning and were collected last spring and summer byfishermen, biologists and two state fish-and-game departments. The sampling ofeach species from a given location generally included from five to 15individual fish. All samples were wrapped in aluminum foil, frozen and shippedby air in containers with dry ice to WARF in Madison where Francis Coon, headof the chemical department, supervised the analyses. A complete list of fishspecies, location taken, residue data and analytical methods employed in thestudy is shown below.

In recent monthsthere has been public clamor about mercury residues in fish, residuessufficiently high to close or restrict fishing in such famous bodies offreshwater as Lake Champlain between Vermont and New York; the Lake St. Francissection of the St. Lawrence River between Quebec and Ontario; the Niagara andOswego rivers and lakes Onondaga and Ontario in New York; the Connecticut Riverin New Hampshire; the Savannah River and Brunswick Estuary in Georgia; MobileBay and the lower Mobile River, the Tombigbee River and the Pickwick Lakesection of the Tennessee River in Alabama; the Detroit River and Lake St. Clairin Michigan; and the Wisconsin River from its juncture with the MississippiRiver to Rhinelander, Wis. In fact, mercury polution is a problem in at least33 states and eight Canadian provinces.

Mercury pollutionoffish, shellfish and birds was first discovered in Japan and Sweden in the1960s. The pollution came from pulp mills, plastic and chlor-alkali plants andmercury-coated seeds. Despite warnings of mercury contamination elsewhere inthe world, nothing was done in North America until last year when NorvaldFimreite, a Norwegian graduate student at the University of Western Ontario,tested pheasants from Alberta. The residues were so high that Alberta closedthe hunting season. Still Canadian and U.S. authorities did nothing to try tohalt the poisoning. Fimreite then found high mercury residues in fish from LakeSt. Clair. The major source of the contamination was a Dow Chemical Companyplant at Sarnia, Ontario, which was dumping as much as 200 pounds of mercury aday into the St. Clair River. Subsequent investigations elsewhere haveuncovered other polluters. One reason that authorities were slow to act wasthat everyone apparently believed mercury was too valuable to be thrown away.Another reason was that most authorities mistakenly believed that any mercuryreleased to a waterway would sink to the bottom and be inert. However, Swedishscientists discovered that no matter what form of mercury is discharged to theenvironment, be it inorganic divalent mercury, phenyl mercury or alkoxy-alkylmercury, it can be eventually converted by either microorganisms or fish intothe most toxic form—methyl mercury.

As a traceelement, mercury is found naturally in minute amounts in man. According to Dr.Henry A. Schroeder of the Trace Element Laboratory of the Dartmouth MedicalSchool, the human body contains about 0.2 parts per million of mercury.(Chemical residues are measured by scientists on parts per billion and partsper million basis; in layman's language, one part per million, 1.0 ppm, is theequivalent of one ounce of vermouth in 7,812 gallons of gin—the ultimate drymartini.) The danger to man from eating mercury-contaminated fish or birdscomes from raising levels in the body. The World Health Organization hasrecommended that no human food contain any trace whatsoever of mercury, whileJapan and Sweden, both countries with strong commercial fishing interests, haveset a standard of 1.0 ppm. In Sweden scientists have criticized this maximum asexcessive, and one prominent toxicologist has said that the maximum should belowered to 0.2 ppm. The Swedish government has stuck, by the 1.0-ppm standardbut recommended that consumption offish be limited to one meal a week. In theU.S. the Food and Drug Administration maximum in fish is 0.5 ppm.

The humantolerance level of mercury is not precisely known. From 1953 to 1960, 121persons in Minamata, Japan were killed or severely disabled as the result ofeating mercury-contaminated shellfish from Minamata Bay. The mercury levels inthe shellfish averaged 20 to 30 ppm. The mercury had been discharged into thebay over a period of years by a plastics plant. In the U.S. three members ofthe Huckleby family in Alamogordo, N. Mex. suffered severe brain damage aftereating a hog that had been fed grain treated with mercury.

Symptoms ofmercury poisoning may occur weeks to months after exposure. The symptomsinclude a numbness and tingling sensation in the hands and feet, disturbedspeech, inability to coordinate muscle movement, impaired vision and hearingand emotional disturbances. The 19th century expression "as mad as ahatter" came from cases of insanity suffered by hatters who inhaled vaporsof mercury that was used to cure felt. In severe cases the symptoms of mercurypoisoning are irreversible. A report submitted by an international committee inStockholm last year stated: "In infants born to mothers with large amountsof methyl mercury, the symptoms are somewhat different. Most children hadmental retardation and also cerebral palsy with convulsions."

The highestmercury residues found in the SI study were in the flesh of spotted seatroutfrom Hackberry, Cameron Parish, La. The initial analysis by WARF Instituterevealed 2.2 ppm of mercury, four times more than the FDA maximum of 0.5. In arepeat analysis by WARF, the level was 1.8 ppm. The seatrout were procured froma commercial fish company in Hackberry, and they had been caught in adjacentLake Calcasieu, a brackish body of water connected to the Gulf of Mexico. Onthe Gulf coast, seatrout are generally not migratory but localized in oneestuary. Last July after SI obtained the fish, the FDA, in an entirelyunrelated move, halted interstate shipments of crabs, spotted seatrout, redfishand flounder from Lake Calcasieu because of high mercury levels.

The flesh ofstriped bass from California also surpassed the FDA limit on mercury. TheCalifornia Department of Fish and Game took the flesh and eggs from 15different females caught in the Delta near Antioch, composited flesh and eggsamples separately and forwarded them to WARF Institute. The departmentretained the remainder of the flesh and eggs for testing on its own. At WARFInstitute initial flesh analysis was 0.70 ppm; the repeat analysis was 0.68. Inorder to obtain California striped bass for testing, SI agreed to allow theCalifornia Department of Fish and Game to review the results before publicationand then to comment upon the significance. After reviewing the data, L. H.Cloyd, deputy director of the department, says that the WARF finding "forthe level of mercury was consistent with one of our state laboratoryreports." Cloyd also points out "the levels of mercury in stripers, aswell as in some catfish, sturgeon—and pheasants—have prompted our governor toassemble a special task force of state agencies and cooperating federalagencies to investigate mercury pollution in California."

Mercury in excessof the FDA limit of 0.5 was also found in the flesh of Spanish mackerel caughtfour miles off Charleston, S.C. Initial analysis by WARF Institute was 0.57 inthe flesh; the repeat analysis was 0.56. The Spanish mackerel is a pelagicfish, one that spends its life near the surface of the ocean and is not knownto frequent shallow water. The fish ranges off the coasts of the Carolinas andFlorida, and it may migrate into the Gulf of Mexico.

Other species hadmercury levels close to the FDA maximum. False albacore from South Carolina,another pelagic fish, had residues of 0.40 in the flesh; spotted seatrout fromShell Point Reef on the panhandle of the Florida Gulf coast had 0.40; stripedbass from the Hudson River, 0.34; bluefish from South Carolina, 0.31; and whiteperch from the James River, Virginia, 0.31. Little is known about the naturalor normal mercury level in the flesh of fish, but it is probably not more than300 parts per billion. The lowest level discovered by WARF Institute was 0.10parts per million found in the flesh of Atlantic mackerel from Long IslandSound, American shad from the James River and spotted seatrout from SouthCarolina. SI did not ask WARF Institute to analyze eggs for mercuryresidues.

The WARFInstitute analyzed the egg and flesh samples for DDT residues, dieldrin andBHC, all chlorinated hydrocarbon pesticides. These synthetic compounds haveseveral factors in common. They do not readily break down in nature; indeed, ittakes at least a decade for them to lose their toxicity. They are also highlypoisonous to a broad spectrum of living organisms. They are used to attackinsect pests because they can penetrate the external shell of chitin, a thinlayer of hard fatty material that covers an insect body. Once applied, be it oninsects, on the ground, on vegetation or in the air, these long-livingpesticides are spread by wind and water. Aerial applications of DDT can enterthe atmosphere and circle the earth in only two weeks. Last year Drs. Eugene F.Corcoran and Douglas B. Seba of the University of Miami reported surface slickscontaining pesticides washing into Biscayne Bay after heavy rains. These areaswere several miles long and from five to 300 feet wide, and they contained10,000 times more chlorinated hydrocarbon pesticides than the water surroundingthem.

Once introducedinto the food web, chlorinated hydrocarbons are able to move up fromphytoplankton to zoo-plankton to fish to bird or mammal, and they become moreand more concentrated as they are retained by a higher level of animals. Thechlorinated hydrocarbons tend to center in the body fats, such as those in thereproductive organs, and it is generally agreed that these chemicals are toblame for the current decline in North America of the brown pelican, theperegrine falcon and the bald eagle, our national symbol. All have fish intheir food web.

In the past twoyears the FDA has seized shipments of coho salmon from Lake Michigan and jackmackerel from the Pacific near Los Angeles for exceeding 5.0 ppm of DDTresidues, and the U.S. Bureau of Sport Fisheries and Wildlife has noted DDTlevels of from 31 to 45 ppm in the flesh of white perch taken from the DelawareRiver at Camden, N.J. Last month John MacGregor of the U.S. Bureau ofCommercial Fisheries announced that a federal study of fish from Santa MonicaBay contained new research information. The study showed DDT residues in thosefish to be astronomically high, ranging from 63 ppm in the liver of Dover soleto 1,026 ppm in the liver of starry rockfish. A major source of the residueswas two sewage plants emptying into the bay. The City of Los Angeles plant atHyperion was releasing one to seven pounds of DDT components per day, while theLos Angeles County White Point plant was daily discharging from 200 to 400pounds of DDT residues. However, none of the flesh samples tested for SI byWARF Institute approached the federal maximum. DDT residues were detected inthe flesh of every species submitted, but the closest to the FDA maximum werethe Hudson River striped bass that had DDT residues totaling 2.42 ppm.

The WARFInstitute also tested all eggs for chlorinated hydrocarbon residues. Inasmuchas these pesticides have an affinity for fat, it came as no surprise that therewere higher residues in the eggs than in the flesh. DDT residues in the eggscan affect reproduction or the survival of young fish. In Jasper National Park,Canada there was a 70% mortality of brook-trout fry hatched from eggs with 0.46ppm of DDT residues. In Michigan 700,000 coho salmon fry died in hatcheries in1968. They had been hatched from eggs with DDT residues of 1.5 to 3 ppm. Whenthe larval salmon were three weeks old and absorbed their yolk sac during theso-called "button up" stage they died. DDT residues were in the yolk,and quickly made contact with the central nervous system. Dr. Philip A. Butlerof the Bureau of Commercial Fisheries Laboratory in Gulf Breeze, Fla. reportsthat in a joint study with the Texas Department of Parks and Wildlife virtuallyno young spotted seatrout were observed in the Laguna Madre in 1968 and 1969.The gonads of females had DDT residues up to 8.0 ppm.

Different speciesof fish seem to have different levels of tolerance to DDT residues in the eggs.Precise levels are simply not known for most marine fish, but based on theabove 0.5 ppm seems to be cause for concern and 1.5 ppm serious cause forconcern about survival of the young. According to WARF Institute results, thehighest DDT residues in eggs were in the California striped bass, 9.05 ppm.Commenting upon DDT residues in California stripers, L. H. Cloyd of theDepartment of Fish and Game notes: "Numerous studies conducted by ourdepartment of the levels of recruitment of striped bass demonstrate no adverseeffects from the levels of DDT and its metabolites in striper eggs and larvae.We are, however, continuing to investigate this aspect."

Striped bass fromthe Hudson, which migrate to New Jersey, New York and Connecticut coastalwaters, had 7.40 ppm of DDT residues in the eggs. They also had 0.33 ppm ofdieldrin. By FDA standards, the eggs of these striped bass should not be eaten.Dieldrin is more toxic than DDT, and the FDA has imposed a maximum of 0.30 ppmof dieldrin on fish products.

The eggs ofbluefish caught off South Carolina contain 4.11 ppm of DDT residues. Accordingto Dr. Lionel A. Walford, director of the U.S. Bureau of Sport Fisherieslaboratory at Sandy Hook, N.J., where most of the research on Atlantic coastbluefish has been done, these South Carolina bluefish were probably migratingnorth from Florida when caught. Baby bluefish spawned in Carolina offshorewaters in the spring eventually grow up to supply an important sport fishery asfar north as southern New England. Striped bass from the Rappahannock Riverhave 2.03 ppm of DDT residues in the eggs. Striped bass from this river andothers tributary to Chesapeake Bay, the single most important striper spawningground on the Atlantic coast, migrate from Virginia to Massachusetts. Themajority offish tested also had traces of BHC, another chlorinated hydrocarbon,in the flesh and eggs. The effect of BHC on fish reproduction is unknown, andthe Food and Drug Administration has set no maximum on BHC in fish. As TaylorQuinn of the FDA remarked as this article was being prepared, "It'sunusual, to say the least, to find BHC in fish."

WARF Institutealso tested all egg and flesh samples for residues of PCBs, the abbreviatedname given to the poly-chlorinated biphenyls, a synthetic chemical compoundused by various industries. PCBs are heat resistant and are widely used in theelectrical industry as insulating fluids for transformers and capacitors. Theyare also used in plastics and adhesives.

PCBs have beenmade in the U.S. since 1929, but they were not identified as such in fish andbirds until a few years ago. Chemically similar to DDT, they baffledinvestigators who reported finding "unknown but chlorine-containingcompounds." In 1966 Dr. Soren Jensen, a Swedish scientist, was able toseparate the compounds from DDT and identify them as PCBs in a sea eagle and inthe bodies of more than 200 fish taken from different parts of Sweden. Dr.Jensen then analyzed eagle feathers in a museum collection. Some of thefeathers were collected as far back as 1880, but Dr. Jensen first found PCBresidues in feathers collected in 1944. After Dr. Jensen published a paper onhis findings, Dr. Robert Risebrough of the Institute of Marine Resources at theUniversity of California at Berkeley found PCBs in a number of Californian,Mexican and Arctic sea birds. He noted that the highest levels of PCBs in birdswere from those closest to industrialized areas. In a later investigation healso found PCBs in samples of mother's milk from women in San Francisco and LosAngeles. In a paper in Environment early this year he called for theestablishment of tolerance limits of the compound in human food. Thus far, theFDA has set no standard.

Anotherscientist, Robert Huggett of the Virginia Institute of Marine Science, says thetoxicity of PCBs to marine animals seems to be about the same as that of DDT.At present, the Virginia Institute of Marine Science is conducting studies todetermine the levels of PCBs in estuarine sediments, oysters, fish and crabs inthe Chesapeake. The institute is also trying to locate the origins of the PCBs.At the Bureau of Commercial Fisheries lab in Gulf Breeze, Dr. Thomas Duke andassociates have found that only 1.0 part per billion of PCBs in water willadversely affect the growth of oysters.

The precisesignificance of the WARF findings of PCB residues in the eggs and flesh of thefish submitted by SI has yet to be determined. However, PCBs are present in theflesh and eggs of all samples. The WARF findings, it should be noted, areestimates based on one peak on a gas chromatogram, but scientists who havereviewed the data for SI and who have experience in the field say the estimatesare valid. The highest PCB residues in flesh are in the Hudson River stripedbass, 4.01 ppm. The California striped bass had the highest PCB residues ineggs, 17.0 ppm. Other egg residues of possible significance were Hudsonstripers, 11.4 ppm; South Carolina bluefish, 2.81; and Rappahannock stripers,2.31.

In assessing theWARF findings for SI, Dr. Robert Smolker, an ecologist at the State Universityof New York at Stony Brook, said, "I'm horrified by some of the data. I amquite surprised to find such residues in fish from the ocean, but I certainlydon't think people should panic." What, then, should the public do ordemand? There are a number of steps that can be taken.

For one, thestudy is merely a first effort, and nationwide monitoring programs of moresamples are needed to determine the presence and levels of contaminants inwildlife. Moreover, considerable research needs to be done on the ecologicalside effects of new pesticides coming on the market. This research is veryexpensive. It now costs as much as $10 million to clear a new pesticide forfederal registration. As of this year, however, the Department of the Interiorhas a ceiling of $3 million in appropriations for all pesticide research, andof that less than $700,000 is allotted to the Bureau of Sport Fisheries andWildlife for fish research. Several scientists have proposed that theadditional needed money come not from Government funds but be raised instead byimposing a small excise tax, based on volume sold, on pesticide manufacturers.No scientist queried doubted the need for pesticides; the only question waswhich pesticides will not damage the environment. At present, problems remainconsiderable and seemingly insoluble. There has been a great deal of talk aboutphasing out DDT, but DDT continues to be used on a substantial basis, and thesame is true of other persistent chlorinated hydrocarbons. For instance, therehas been a rapid increase in the use of two chlorinated hydrocarbons, chlordaneand toxaphene, as substitutes for DDT, and both these compounds, which can bediscerned in animals only after very involved laboratory testing, are startingto turn up in all sorts of places.

Not long ago Drs.Richard Schoettger and David Stalling of the U.S. Bureau of Sport Fisheries andWildlife pesticide laboratory in Columbia, Mo. began a study of still anotherchlorinated hydrocarbon, endrin, in fish. They planned to feed the fish foodcontaining endrin residues of 0.1 to 0.5 ppm. They ordered their test fish,channel catfish brood stock from national hatcheries and, as a routine check,they analyzed some of these fish for endrin. To their dismay, they discoveredthat the catfish already contained 0.5 to 0.88 ppm of endrin, more than was tobe given them in the test food. This should not be surprising. Schoettger hasyet to find a commercial dry fish food for sale in the U.S. that is notcontaminated by chlorinated hydrocarbons.

Besidesestablishing a constant monitoring program of contaminants in fish andwildlife, efforts should be made to determine harmful levels to variousspecies. Although worrisome, DDT residues in eggs are meaningless until we knowthat 5.0 ppm of DDT residues in conjunction with 8.0 ppm of PCBs, or whateverthe figures may be, kill off a certain percentage of the hatch, be it none, athird or 90%. Then, of course, we need to know what levels may be harmful tohumans.

Writing inPesticides, Dr. Robert van den Bosch of the University of California atBerkeley points out that the public good requires that salesmen for pesticidemanufacturers be brought under control. "The salesman is the key to thesystem, for he serves as the diagnostician, therapist and pill dispenser,"van den Bosch says, "and what is particularly disturbing is that he neednot demonstrate technical competence to perform in this multiple capacity. Inother words, the man who analyzes pest problems, recommends the chemicals to beused and effects their sale is neither required by law to demonstrate (byexamination) his professional qualifications (as do medical doctors, dentists,lawyers, veterinarians, barbers, beauticians, realtors, etc.) nor is helicensed. Yet this person deals with extremely complex ecological problems andutilizes some of the most deadly and ecologically disruptive chemicals devisedby science."

Instead ofpermitting salesmen stimulated by commissions and bonuses to sell pesticides tothe ultimate user, van den Bosch proposes that they be replaced by professionalpest-control advisers who would be subject to examination, licensing and a codeof conduct similar to physicians. This done, van den Bosch says, "Thecompany-affiliated salesman, with his built-in conflict of interest and salesmotivation, can be phased out of pest-control advisement. Direct contactbetween the salesman and the lay user of insecticides can be eliminated. Justas the drug salesman deals only with the physician, not with the patient, thesalesman of toxic pesticides can be required to deal only with the pest-controladviser."

Sources ofharmful pollution—mercury, PCBs or pesticides—must be identified and stopped.Monitoring and source identification must also be conducted on other probablecontaminants, including heat from power plants, radioactive wastes or heavymetals. Testifying last August before the U.S. Senate subcommittee onenvironmental pollution, Dr. Henry Schroeder of Dartmouth dealt with mercury,cadmium, lead, nickel, beryllium and antimony. "I must emphasize thatenvironmental pollution by toxic metals is a much more serious and much moreinsidious problem than is pollution by organic substances, such as pesticides,weed killers, sulphur dioxide, oxides of nitrogen, carbon monoxide and othergross contaminants of air and water.... Most organic substances are degradableby natural processes. Once we control their use, they will leave little or noresidue, but no metal is degradable. Once dug from the earth, metals stay withus and what we are now accumulating will be around as long as we are."

Governmentofficials must enforce antipollution laws and be on guard against the spread ofpossible contaminants. There have been all too many instances of cover-up. Lastmonth there was a ruckus when the Canadian government banned woodcock huntingin the province of New Brunswick because the birds were saturated with DDT. Thefact is that this danger was known five years ago when Bruce Wright, directorof the Northeastern Wildlife Station in Frederickton, published a paper aboutDDT and woodcock. Wright says he was told then that publication of his studywas "not in the best interests of the province." Wright says governmentfunds for support of the station were later cut. Last year the provincialgovernment finally abandoned using DDT, but New Brunswick will have the legacyfor years to come. Soil scientists report that DDT is at least eight inchesdeep in the forest floor.

Muchindiscriminate pollution of U.S. waters could be stopped by enforcement of theFederal Refuse Act passed back in 1899 by Congress. This act, in part, makes itillegal "to throw, discharge, or deposit, or cause, suffer, or procure tobe thrown, discharged or deposited either from or out of any ship, barge, orother floating craft of any kind, or from the shore, wharf, manufacturingestablishment or mill, any refuse matter of any kind or description whateverother than that flowing from streets and sewers and passing therefrom in aliquid state, into any navigable water of the U.S."

Laws may bepassed and laws may be broken. In the end, the enforcement and abatement dependupon public opinion. If one lesson is to be learned it is that we cannotrelease wide-ranging persistent poisons into the air or water. As Ovid wrote2,000 years ago: "Ill habits gather by unseen degrees. As brooks makerivers, rivers run to seas."

[This articlecontains a table. Please see hardcopy of magazine or PDF.]


All the figures shown on the chart are parts permillion. WARF Institute's procedures for determining chlorinated hydrocarbonresidues are in the "FDA Pesticide Analytical Manual," Volume 1, Jan.1968, sections 212 and 311. The mercury analysis follows "The Analyst,"Volume 86, page 608, 1961, modified by Atomic Absorption Spectrophotometry withboat technique.

Note: DDT residues are a combination of DDT, DDE andDDD. The U.S. Food and Drug Administration has set no tolerance standards forBHC or PCB residues in human food.



Menacing chemicals enter a predatory fish, such as this female striped bass, mainly from food. The stomach then digests the contaminated bait, and nutriments and poisons are spread throughout the body by the circulatory system where they can affect the central nervous system and eggs.







A coho salmon egg with high DDT levels can hatch, but the DDT concentrates in the oil globule in the yolk and when the yolk is consumed the poison kills by attacking the nervous system.