ETHYLENE dibromide (EDB) is not a household word, but Duncan Hines, Betty Crocker and Wonder Bread are. So when government officials recently discovered significant levels of the pesticide, a potent carcinogen, in a host of grain and cereal products, a warning cry went out. In the wake of these discoveries, and the public furor that followed, William Ruckelshaus, director of the Environmental Protection Agency (EPA), last week suspended the use of the chemical on grain products.

Ruckelshaus' move appeared dramatic, but, in fact, the action was long overdue. Scientists have long believed that the chemical, used primarily as a fumigant after the grain has been harvested, causes cancer and birth defects in laboratory animals, even in minute quantities. Industry spokesmen and EPA officials have often argued that there is no firm evidence linking the chemical to cancer in humans, but longterm studies have shown EDB to be carcinogenic in rats and mice. For the time being, consumers everywhere are the unwitting guinea pigs who will demonstrate the pesticide's effect on human health.

EPA first began to look closely at the chemical in 1977, and by 1980 had proposed to cancel all food-related use (EDB is also added to gasoline to prevent lead deposits in engines). But then came the change in administrations and, with strong chemical industry lobbying against any restrictions, no action was taken under now-infamous EPA administrator Anne Burford Last September, Ruckelshaus cancelled use of EDB as a soil fumigant, but only after significant amounts of residues of the chemical showed up in the ground water in several states. The current order extends the ban to use on grain after harvesting, but is by no means conclusive; citrus products, also often treated with EDB, are unaffected by the new decree.

And despite the headlines, Ruckelshaus' restrictions on EDB use have done relatively little to counter the still more widespread threat which the use and overuse of pesticides in America poses. When he presented the recent order, the EPA administrator reassured the press that the country is not facing a "public health emergency:" yet such a crisis may be just around the corner. EDB is only one of scores of pesticides in use across the country that are suspected of threatening human health, and are showing up in food and water supplies in many states.

Over one billion pounds of pesticides were used in this country last year. An overwhelming number of these chemicals have not been sufficiently tested to evaluate their health threat. For example, around 80 percent of the pesticide products now sold have not been tested for their ability to cause cancer, and in the case of over 60 percent of them, it is not known if they cause birth defects. In the 1970s, in one Kentucky county, the occurrence of a certain form of cancer quadrupled in the years after a new pesticide was put into use in the area.

In large part, this crisis of truly unknown danger is the long-term result of the lax requirements of the little-known Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), the law which governs the registration and use of pesticides. Dating from the 1940s, FIFRA has allowed many chemicals to be widely used despite a lack of information about their health effects. In recent years, its provisions have been strengthened, and pesticides introduced now do have to undergo thorough testing. A process of re-registration, carrying out and verifying new tests for chemicals approved under old standards, was also loosely mandated by the newer provisions of FIFRA, but the EPA has been slow to tackle this task. In 1972, Congress directed the agency to complete the re-registration process by 1976, but EPA then obtained extensions to 1977, 1978, and finally the removal of any set deadline. By the middle of last year, the EPA had a complete and comprehensive set of tests for only 47 of the 605 major active pesticide ingredients now in use.

In a sense, it is appropriate that the discoveries about the extensive presence of EDB in our food supply have surfaced recently, since far-reaching and badly needed amendments to FIFRA are now before both houses of Congress. These amendments would prohibit the application of pesticides which are still not fully tested for their threat to human health. This would bring a halt to the present EPA practice of allowing untested chemicals to be used while the studies are being carried out. In addition, the amendments would stop the granting of special "emergency use" permits for the use of pesticides which are known to be deadly--a practice which has skyrocketed during the Reagan Administration. And the proposed changes to FIFRA would direct special attention toward the threat of pesticides which contaminate food or groundwater. These amendments would help the EPA avoid more problems like the recent discovery of EDB-tainted cake mix and bread.

Not surprisingly, the organized and powerful chemical companies are lobbying hard against any tightening of the restrictions on the sale and use of their products. In the past, they have supported a weakening of the FIFRA requirements, and the companies have resumed that push this year. Positive change in an election year is always difficult, but Congress should have the courage to pass these needed amendments to the law governing the use of so many toxic chemicals.

At present, the bill's chances are not good unless Ruckelshaus throws his weight behind the measure now before Congress. Ruckelshaus has already compromised his office by avoiding any ruling on the use of EDB on citrus products--largely because of the potential effect on international trade--although residues of the chemical at 25 times the international limit considered safe for humans have been found in the pulp of fruits from Florida. In light of his sworn duties to protect the environment and human life, strong support of the Congressional measures should be foremost on Ruckelshaus' agenda.