Chemical Controversy

The more chemical pesticides are put to practical use on farms and gardens, the more controversy rages about their possible hazards. The most recent acrimonious debate has focused on U.S.

rivers where fish have died in conspicuous numbers.

Are pesticides to blame? The Public Health Service said they were when 5,000,000 fish died last fall in the Mississippi Delta. After a hurried investigation and an analysis of the remains of ten dead catfish, PHS blamed the entire slaughter on endrin, an insecticide used on cotton and sugar cane in the farms around the lower reaches of the river. No significant amount of endrin was found in the water where the fish died, reported Cincinnati's Dr. Donald Mount. But in the blood of the dead catfish, he said, enough endrin was found to be fatal.

Agricultural and chemical interests pointed out that endrin is a notably safe and useful insecticide, and that it was hardly proper to indict the chemical on the evidence of so small a samling. Most of the dead Mississippi fish, PHS critics argued, were menhaden, an almost inedible saltwater inhabitant.

No menhaden were analyzed, and since they normally live in the sea, there was little chance that they could be affected by insecticides anyway.

Fat Theory. The PHS withdrew its claims about the menhaden, which left about 175,000 fresh-water fish believed to have died of endrin. But how did the poison get into the fish while the water in which they lived was essentially free of endrin? The PHS believes fish gradually concentrate the insecticide, which lodges in their fat. When the fish consume their fat in time of food scarcity, enough endrin is released into their blood to kill them.

This interesting theory has not yet been proved by experiments. Besides, asked the critics, how did a large amount of endrin get into the Mississippi in the first place? For a while, PHS blamed the Velsicol Chemical Corp., which manufactures endrin at Memphis. But the company had a ready reply. "If our endrin got into the river," asked a Velsicol official, "why weren't thousands of fish killed around our plant, instead of 770 miles downstream?" PHS answered that the doomed catfish probably got poisoned near Memphis and swam to the river's mouth before they died--a theory that hardly accounts for the fact that the catfish analyzed are not migratory species and do not commute to salt water.

Common Death. The Mississippi fishkill is still a live subject in Washington, but Secretary of Agriculture Orville Freeman announced: "None of the evidence presented was scientifically adequate, in the judgment of the department, to justify withdrawal of endrin, aldrin or dieldrin from farm use."

Another fishkill in Missouri last month only added to the confusion. Once more PHS was quick to blame insecticides; once more the evidence did not confirm the charge. Only a few fish died, and no poison has been found in them. Suffocation is the more likely cause of death since decomposing raw sewage dumped into the river at Kansas City had used up an inordinate amount of the Missouri's oxygen. Future kills may yet be traced to insecticides, some of which are toxic to fish in amounts that are harmless to humans. If so, Government authorities may be forced to choose between the interests of catfish and farmers.

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