WARNING: Salt and other sources of sodium may be hazardous to your health.

That is the opinion of a growing number of scientists who believe that Americans can reduce the risk of having high blood pressure -- and ultimately a heart attack or stroke -- by reducing the amount of sodium in their diet. Keeping sodium to a minimum is particularly important for blacks and for the elderly, who are more susceptible to high blood pressure than the general population, the scientists say.

At present, Americans consume about 10 times the amount of salt they need for good health, according to published scientific reports. Some studies have indicated that adults eat the equivalent of two to five teaspoons of salt and other sodium sources each day, counting what occurs naturally in food, what is added at the factory during processing and what is added in the kitchen during cooking. That amounts to about 15 pounds a year.

Government agencies, including the Food and Drug Administration and the U.S. Department of Agriculture, have acknowledged the salt problem. The official U.S. dietary guidelines suggest that Americans reduce the amount of salt and sodium they consume. And one recent Agriculture Department publication sums up the issue this way:

"Excess sodium in the diet is believed to contribute to high blood pressure (hypertension) and stroke in some people."

The publication then suggests that individuals who want to limit sodium can do so by shaking less salt onto food and by cutting down on foods prepared in brine -- pickles, salty or smoked meat such as bologna, and salty or smoked fish such as anchovies and caviar.

Some health professionals. however, don't think the government has gone far enough.

Led by Michael F. Jacobson, executive director of the Center for Science in the Public Interest, a group of 5,769 professionals and students has petitioned the FDA to set limits on the amount of sodium that can be used in processed foods and to require that the sodium content be declared on food labels. CSPI wants products high in salt to show a picture of a salt shaker on the label, along with the actual sodium content.

FDA spokesman Wayne King said the agency would respond to the petition within the 180 days that the law allows in such proceedings.

The sodium level in some canned and processed foods is 700 times higher than in other foods, according to Jacobson. One-half cup of Minute Rice fried rice, for example, contains 700 milligrams of sodium, compared to one milligram of sodium in regular cooked rice, he said. Another example he cited was that one cup of canned peas contains 400 milligrams of sodium, compared to two milligrams in fresh cooked peas.

Jacobson said his comparison was based on figures obtained from an Agriculture Department handbook.

The petition submitted to the FDA last week is the second attempt by Jacobson's center to force the agency to act. In 1978 the center formally asked FDA to limit sodium that could be added to processed foods and to require labels disclosing the sodium content.

FDA spokesman Wayne Pines said both of the earlier petitions have been "folded into the [file of] information we have about salt and sodium." Pines said that a proposal on sodium labeling has been drafted by the agency but hasn't been approved. And he said that the draft must now be examined to determine if it is in compliance with President Reagan's Feb. 17 executive order on regulations. The Reagan order said that all major proposals and pending rules must be reviewed to determine the cost to the public before they are approved.

The Jacobson center isn't alone in the campaign for lower sodium diets.

A special committee from the Federation of American Societies for American Biology issued a report in 1979 saying that Americans eat too much salt and in doing so may increase their risk of high blood pressure. The report said that "available data suggest that 10 to 30 percent of the U.S. population is genetically predisposed to hypertension and is exposed to a higher risk by ingestion of sodium chloride consumption at current levels."

The committee went on to say that a reduction of salt by the population could reduce the frequency of hypertension. In its conclusion, the committee called for government guidelines restricting the use of salt in processed foods and for food labels that better identify the salt contents.

The report also said that the amount of salt that Americans should consume varies from one individual to another and may be further affected by sweating and diarrhea.

Salt historically has been considered an essential part of the diet and has been used as a preservative and seasoning agent. Today it is found in most homes and restaurants and is set on tables as a condiment. In the food industry, sodium is widely used as a seasoning agent, preservative and curing agent, nutritional supplement and dough conditioner.

Here is a summary of sodium content of various fresh and processed foods:

High sodium content: Protein foods including canned and smoked meats: meats, fish and poultry preserved with sodium nitrite such as ham, bacon, hot dogs; chipped beef; herring; peanut butter. Vegetables such as sauerkraut, canned vegetables, canned tomato products, spinach, beets, pickled vegetables, frozen and instant potatoes. Grains such as salted crackers, prepared seasoned mixes of rice and pasta, breads with salted tops; buttermilk; miscellaneous foods such as bouillon cubes, monosodium glutamate, soy sauce, olives, nuts, canned soups, potato chips, baking powder, fast foods such as pizza, fish and chips, hamburgers.

Moderate sodium content: Milk products (other than buttermilk) such as cream, sour cream, cream cheese, cottage cheese, other cheeses. Vegetables such as carrots and celery. Protein products such as shrimp, salt-water fish, oysters, liver, eggs, beef, pork, poultry. Miscellaneous such as salad dressings, sunflower and sesame seeds.

Low sodium content: All fruits.Cereal such as puffed wheat and rice, shredded wheat, cream of rice, oatmeal.

Sodium has been linked to hypertension in a number of studies in recent years. In one case, scientists found that the diet was twice as high in salt in the northern islands of Japan as in southern japan. The incidence of hypertension in the northern islands also was twice as great. In another study, a scientist divided a group of adults into three sectors, according to how much sodium each consumed. The scientist found that hypertension was precent in 10 percent of the high-intake group, in 7 percent of the average-intake group and in less than 1 percent of the low-intake group.

Dr. H. Blackburn, a professor at the University of Minnesota who worked with Michael Jacobson on the salt petition, said the kidney and body regulation of blood pressure may be overwhelmed by excess salt in the system.

Reducing excess salt consumption and preventing overweight are important in preventing hypertension, he added, explaining that the alternative to such preventative measures is drug therapy -- an "expensive, inadequate and dangerous alternative."