Concern is surging again over the use of pesticides. In Washington, the Environmental Protection Agency (EPA) is looking beyond ethylene dibromide, or EDB, to such substances as Telone II, methylbromide, and pesticides containing carbon tetrachloride.
After one emergency investigation, the EPA last week announced it intends to ban the use of the pesticide dicofol. Dicofol, popular with citrus growers and home gardeners, contains DDT, which was banned in 1972.
And in California, the Legislature is embroiled in debate over a bill that calls for immediate investigations on 200 of the 1,200 active chemical ingredients in pesticides used in California.
Overseas, there is growing concern, too.
About 10 years ago, West Germany tightened its allowances on malathion residues to 1/16th of United States tolerance levels. Since then, Sweden and Finland have followed suit on benomyl, a fungicide that keeps mold from forming on apples and other fruits. Canada, too, has lowered tolerance levels on captan, a fungicide used on cherries, and amitraz, an insecticide for a parasite commonly found in pears. Japan, meanwhile, has shown repeated concern over orthophenylphenol, or OPP, a fungicide used on imported oranges, lemons, and grapefruits.
So far, these pesticides have received little attention - partly because they are not as commonly used as EDB, on which the EPA issued curbs earlier this year.
Nevertheless, the issue of pesticide use is gaining enough attention that many observers say it will become a major concern in coming years.
''I think that agriculture's ability to use agriculture chemicals is going to be one of the principal problems agriculture faces in the rest of the decade,'' says William Quarles, vice-president of government affairs at Sunkist Growers Inc.
The public, listening to alarms warning of chemical-pesticide residues on food, is already finding it difficult to discern what is a really dangerous situation, says Fred Tschirley, professor and pesticides coordinator at Michigan State University. ''Any chemical, I don't care what it is, is toxic. . . . (The) hazard depends on dose.''
Consider Japan's complaints about OPP.
While the US classifies it as a fungicide used on harvested fruit, Japan considers it a food additive - and thus has tested it at far higher doses on laboratory animals, says Marguerite Leng, a research assistant in international regulatory affairs with Dow Chemical Company. In their tests, the Japanese have fed the animals a solid form of OPP (called orthophenylphenate). But when the chemical is used as a pesticide on citrus, US growers dissolve the solid in water, treat the peel of the fruit only, and then ship the fruit, allowing hours if not days for the pesticide residue to evaporate before the fruit reaches the consumer.
Is OPP a risk? That depends on how you look at it, observers say.
One problem is that scientists have made much more progress in measuring low-level residues than in determining their effects on humans, Dr. Tschirley says. Fifteen years ago, scientists measured parts per million. Now, they commonly count parts per trillion - a measurement 1 million times more accurate.
As measurements have grown more precise, legislation has been tightened.
In the years following World War II, chemical pesticides began to come into general use and faced far less scrutiny than today. But in 1972, in the midst of the furor over DDT, Congress passed the Federal Insecticide Fungicide Rodenticide Act. This law not only tightened registration procedures, it also called upon the EPA to do a thorough review every five years of already registered pesticides.
Not surprisingly, the law has increased chemical companies' costs of bringing a new pesticide to market. In 1956, the chance of a new chemical becoming an agricultural product was 1 in 5,000, says Howard Washer, a group vice-president with Velsicol Chemical Corporation. Now, the ratio is 1 in 20,000 - at a cost of
Any pesticide curbs would probably have a far greater impact on the relatively small fruit-and-vegetable industry, rather than on the huge grain industry.
Chemical companies are much more interested in developing alternative pesticides for large grain crops, observers say. When chemical plants manufacturing minor pesticides for fruits become outdated, chemical companies often shut down the operation rather than upgrade the plant, observers say. Dow, for example, quit making methylbromide because the market was too narrow, a company spokesman says.
The West is especially concerned. ''There is almost no crop in California that would not be affected by a ban of these products,'' says John E. Browning, president of the Western Agricultural Chemicals Association.
In the Pacific Northwest, pear shippers have lost business to Canada, which in mid-1982 made clear that the insecticide amitraz fell under a strict residue standard. Fresh pear exports to Canada fell from $10.9 million in 1981-82 to $8. 1 million in 1982-83, says Chris Schlect, president of the Northwest Horticultural Council.
A branch of the United Nations is responsible for establishing a worldwide system of tolerance levels. Presumably, Japan will allow that office to determine the safety of OPP, observers say.