A misshapen tomato is "decidedly kidney-shaped, lopsided, elongated, angular or otherwise decidedly deformed," according to the U.S. Department of Agriculture. A defective tomato is one with cuts or broken skin, puffiness, catfaces, scars, growth cracks or insect injury, according to USDA grading standards. What a tomato tastes like is not addressed.

Devised to give industry a common language for buying and selling produce across telephone lines, the 300-plus grade standards established by the USDA for fruits and vegetables detail everything from the diameter of a "U.S. Fancy" broccoli stalk ("not less than 2 1/2 inches") to the proper color of a Grade A canned tomato (at least 90 percent "USDA Tomato Red").

But critics of such criteria are charging that this beauty is only skin deep. While producers say consumers want the best-looking produce, critics claim perfection comes at the cost of taste and nutrition. And worse yet, they say, the prettiest produce may not be the safest.

"We now have in place grading standards to ensure the quality consumers want. In many cases, they are having the opposite effect," said Sen. Wyche Fowler, Jr. (D-Ga.). "They keep produce off the market for reasons that have no real bearing on quality. They encourage excessive use of potentially dangerous agricultural chemicals, to meet purely cosmetic standards, even as consumers are increasingly concerned about food safety."

As Congress begins floor debate this week on the 1990 farm bill, one of the issues it will be arguing is an amendment introduced by Fowler requiring USDA to modify its grading standards for fruits and vegetables by de-emphasizing appearance and by including sugar content, nutritional value and flavor criteria.

"One of the great frustrations is when you purchase a high-gloss apple and it's mealy inside. Or you buy a red tomato and it's tasteless. Or peaches that look like the right color and they're hard as rocks. It's a great frustration that the produce system is not addressing consumer needs," said Tom Kuhnle, resource economist with the environmental group Natural Resources Defense Council.

The debate will be a tough one. "We are strongly opposed to the Fowler amendment," said Daniel Haley, administrator of the USDA's Agricultural Marketing Service, the division that sets grading standards. Haley said USDA will look into the issue, "but to conclude that grading standards increase the use of pesticides is really a disservice. There is not a scintilla of evidence to show that."

To charge that agricultural chemicals are used purely to make produce look more attractive is inaccurate, said John McClung, spokesman for the United Fresh Fruit and Vegetable Association. "We're not talking about face lifts for fruits. We're not talking about tummy tucks for tomatoes." McClung said that chemicals are used to "some degree" for cosmetic purposes, but that they also prevent pest damage, which can lead to decreased yields and, in some cases, loss of the crop altogether.

As evidence that the problem exists, Fowler points to a number of studies that come to basically the same conclusion.

In its 1989 report, "Alternative Agriculture," the National Academy of Sciences concluded that grading standards discourage alternative means of pest control. "Farmers use more pesticides to meet these standards and guarantee receipt of a top price," the report said.

A 1978 report by the Environmental Protection Agency found that an unnecessary amount of chemicals was sprayed on citrus, processing tomatoes and cling peaches solely to control the external appearance of the produce.

To make fruits and vegetables perfect, growers "use vast quantities of pesticides," according to a 1989 draft report prepared by EPA. "Many of these applications do not increase yields, but simply serve the purpose of maintaining cosmetic appearance of fruits and vegetables from minute defects, such as surface scarring or blemishes, or slight amounts of insect fragments," it concluded. The report indicted the produce marketing system for the pressure it puts on growers to produce the prettiest fruits and vegetables for the highest grades that command the highest prices.

Illustrating the point with case studies of fresh market tomatoes, processing tomatoes and apples, it quoted a researcher at the University of California at Davis who estimated that between 40 and 60 percent of the pesticides used on processing tomatoes are used simply for cosmetic reasons.

Pam Jones, executive director of the California-based Processed Tomato Foundation, said she believes the percentage is incorrect. What's more, Jones said, it's not a black-and-white issue. Worm damage in tomatoes may scar the surface of the fruit but it also makes the plant more susceptible to disease or attack by other insects, she said.

"I don't mean to make light of this," said Jones. "Growers are looking into it. They just get frustrated when it's characterized by people who are not actively engaged in farming or processing as such a simple issue. It's very easy to make judgments from San Francisco and Washington, D.C., rather than Modesto and Woodland."

A 1988 report prepared by CalPirg, a California advocacy organization, found that the California orange industry spends more money on pesticides to get rid of citrus thrips than for any other bug. Thrips are tiny insects that feed on the rind of the orange, causing mainly cosmetic damage, according to CalPirg.

Joel Nelsen, president of California Citrus Mutual, a trade association of 800 citrus producers, said that the CalPirg study is "so full of holes it makes Swiss cheese look solid." Nelsen said thrips do cause scarring on orange rinds, but that if left untreated will multiply and weaken the fruit, causing it to drop from the trees.

In addition, Nelsen said, the Fowler Amendment is "far off the mark" because the USDA's grade standards are frequently exceeded by specifications set by individual commodity groups or supermarket chains.

For those reasons, said Leonard Gianessi, a fellow at Resources for the Future, a Washington-based agricultural think tank, "you could change the federal standards and that might not make a lot of difference."

But Ellen Haas, director of the consumer advocacy group Public Voice, believes that changing the federal standards would set the right example. "It will have a snowball effect," she said. "It gives a signal to the other programs."

Giant Food Inc. does not have a written set of its own produce standards, according to Mark Roeder, spokesman for the chain, but it visually inspects all produce as it comes into its warehouse and will set aside for a second inspection those items that don't meet its criteria. "We want the fruit to look as good as it possibly can," Roeder said.

Indeed, the Food Marketing Institute has consistently found that the number one reason consumers choose one supermarket over another is the quality of the produce. Karen Brown, spokeswoman for FMI, said the produce that consumers leave behind in supermarkets is frequently the ugliest. And that, in many ways, is at the crux of the issue.

"You can change the standards but just changing the standards won't convince the consumer to buy it," said Jones, who added that processors of canned tomatoes are quick to hear from consumers when their products contain an insect part or other extraneous material.

Even without changing the standards, Nelsen said that last year many orange growers, shell-shocked from the Alar episode, did reduce their use of chemicals. The result was a larger supply of "choice" oranges, which have more blemishes and irregular shapes than the next higher grade, called "fancy." But consumers didn't buy "choice" oranges, he said, so eventually neither did supermarkets. Many were turned into juice, or sold at a loss, said Nelsen.

A. Ann Sorenson, assistant director for natural and environmental resources at the American Farm Bureau Federation, is tabulating the results of a survey of 2,000 farmers on federal grading standards and pesticide use. From a preliminary scan of the results, Sorenson said "most of them say, 'it's up to the consumer.' " Some growers have written comments in the margins of the questionnaire such as "you've got to be joking if you think consumers will buy blemished, crummy-looking apples," she said.

Nevertheless, Gianessi maintains that consumers often don't have the information to understand the trade-offs. "We need to give the public a better idea of what the choices are. We need to spell it out: You can have this, and we use 100,000 pounds less of this {chemical}. We need to do a better job of explaining to the public what they're getting for pesticide use," said Gianessi.

A 1988 CalPirg study did just that. The advocacy group showed photographs of three different oranges to 229 shoppers in Los Angeles and San Francisco grocery stores. The first was cosmetically perfect, the second had thrip-scarred damage on 10 percent of the surface and the third was damaged on 20 percent of its surface.

When asked which orange they would select relative to the perfect orange, 79 percent said they would be less likely to buy the orange with 10-percent damage and 87 percent said they would be less likely to buy the orange with 20-percent damage.

Then they were told that half as much pesticide had been used on the scarred oranges as on the perfect orange. (If the respondents asked whether the pesticides were dangerous or were inside the fruit, the interviewer would not comment.) After the explanation, 63 percent of the customers said they would be more willing to purchase the orange with 10-percent damage and 58 percent were more willing to purchase the orange with 20-percent damage.

Whether consumers will act on what they say is unclear. "If consumers were unconcerned about blemishes and other defects, clearly organic food products would have had far more success than they have," said Roger Coleman, spokesman for the National Food Processors Association. "People equate wholesomeness with the standards they have come to appreciate with processed and fresh foods. When you see black spots on food, you don't like that, do you?"