WASHINGTON — Food that is proclaimed to be "organically grown" will for the first time have to meet national standards under a little-noticed provision of the 1990 farm bill.

The provision will reassure both grocers and consumers that what they buy is authentic, said Bob Scowcroft of the California Certified Organic Farmers Assn.

"There is more organic rice sold than grown," quipped Russell Parker, purchasing director for Mrs. Gooch's Natural Food Markets, a chain of seven groceries in the Los Angeles area that sells mostly organic items. "We need a reliable standard for the industry."

Such a standard will go into effect in the fall of 1993.

Without those federal standards, "there was no way of telling for sure what the integrity of a product was, what with the words 'lite' and 'natural' having become essentially advertising slogans," said Jim Holt, manager of the Organic Foods Alliance, an industry lobbying organization.

BACKGROUND: The organic food industry is growing by 40%--or $1.25 billion--annually, according to Wendy Cohen, analyst at the Center for Resource Economics, an environmental organization based here.

Estimates of the number of organic farmers in the United States vary from 8,000 to 16,000 of the nation's 2.2 million farmers. In California--the nation's largest single supplier of organic foods--the total hovers around 1,100.

Twenty-two states, including California, have established their own standards for organic foods, according to the Senate Committee on Agriculture, Nutrition and Forestry. But standards vary so much among states that farmers are often limited to selling produce only within their own state.

California, in 1979, was the first state to enact an organic law. A more stringent version approved last month requires a three-year transitional period from conventional to organic farming so chemicals in the soil and plants have time to disperse, and it requires organic growers to register with the state. It carries a maximum $5,000 fine for violations, such as selling non-organic food under an organic label. The new federal law does not preclude the enforcement of state laws.

The federal law stipulates that the "organic" label will no longer be allowed on processed foods, such as cereal or spaghetti sauce, unless 95% of the contents (not including water and salt) are organic. Foods that have an organic content of between 50% and 95% may be labeled as "containing" organic ingredients.