'Made in USA' label -- getting harder than ever to find

''Today, when you go around the world, you need an FBI investigator to find a product made in the United States,'' quipped a Democratic politician recently.

Right here at home, Americans need the talents of a Dick Tracy - not a Sherlock Holmes, he's a foreign import - to track down US-made products.

How easy is it for consumers to ''Buy American?''

Purists would say it's nearly impossible. A ''Made in USA'' label, if a manufacturer even chooses to use it, doesn't guarantee that 100 percent of a product's components are American-made.

For example, a piece of clothing can simultaneously bear the all-American union label, the Sears label, and a Taiwanese label. The fabric may come from Taiwan, and the individual pieces may have been cut out there; while American union workers did the sewing and Sears stuck its label on the dress.

A consumer doesn't need an econometric model and research staff to recognize the slip in the US share of the world's total gross national product - the total of output of goods and services. The US share, which was 39 percent in 1950, dropped to 30 percent in 1970, and 22 percent in 1980. The consumer can see this reflected on retail shelves.

It's a challenge to find the ''Made in USA'' label amid the stocks of Japanese autos and electronics, French perfume, Hong Kong clothing, German cheese, Korean rubber goods, Italian shoes, and Taiwanese imitations of just about everything.

Even the familiar ''baseball, hot dogs, apple pie, and Chevrolet'' ad campaign pales embarrassingly when a consumer scrutinizes labels. While there's no evidence that imported apple pies and hot dogs are flooding the US, most baseball gloves are now made in the Orient, nearly all baseballs are made in Haiti, and the engine for the Chevrolet Chevette is made in Japan.

''There's nothing here that's totally American,'' explains a Boston-area Sears saleswoman, gesturing to several hundred products in her home-entertainment department. ''Even Zenith is assembled in Mexico. Fifteen years ago, most items with a Sears label were American brands. But they were coming back (for repair) faster than we could sell them. Today . . . customers specifically ask for Japanese products,'' says the saleswoman, who asked not to be named.

Consumer and labor groups suggest that the average American pays little attention to the label on everyday purchases. But they say that the consumer can and should look at labels - turn that television around and study the metal stamp on the back, feel around inside a garment for the label, and check the fine print on packages.

Ironically, a point that can lead to consumer confusion is that all imports must be marked with the country of origin while American-made goods don't have to be, and often aren't, marked, explains a US Commerce Department spokesman. It is generally accepted, he says, that any product is American-made if 50 percent or more of its value - in components or labor - originated in the US.

Further, a label that names a recognized American brand is not synonymous with ''Made in USA.'' Nor does ''distributed by,'' or ''made for'' labeling mean that the product originated with the company it was distributed by or made for. The ''printed in the USA'' label on packaging is another flag for consumers, because it does not mean that the contents are American-made. An absence of labeling generally means a product is made in the US, but absence of labeling on the packaging of a product does not mean the product itself won't have a foreign label on it.

Cost and quality aside, it is argued that consumers could bolster the sagging economy by pumping their spending dollars into American-made products. The United Automobile Workers union estimates that with every percentage point of foreign content in a car, 30,000 jobs are lost. As the situation currently stands, 25 percent of all components used in domestic autos come from foreign sources, says Sheldon Friedman, research director for the UAW. The union has backed pending legislation requiring major auto manufacturers selling cars in the US to build a portion of them here.

''Consumers are not going to have any income to spend at all if they don't look at the international market'' and recognize the need to support American products, says Stephen Brobeck, executive director of the Consumer Federation of America. This is a tough issue, he says, because ''there shouldn't be any trade barriers at all that would restrict consumer options.''

On the other hand, Virginia Knauer, who heads the White House consumer affairs office, opposes the ''buy American'' movement on the grounds that it is at cross-purpose to the competition needed in a free enterprise economy. Further , Mrs. Knauer's staff explains, trade barriers at any level - mandated or voluntary - might invite foreign retaliation that would hurt efforts to increase American exports.

Tomorrow: Buying American can still mean buying the best.