Giant Food and Safeway are pulling away from their competitors and now ring up more than 69 cents of every dollar spent in Washington area supermarkets, the latest study of the local grocery business shows.

Giant's sales in metropolitan Washington jumped 29 percent in the past year to an estimated $1.16 billion and Safeway's volume climbed almost 17 percent to $890 million, according to the annual market study by Food World, a trade publication based in Columbia, Md.

In the District of Columbia, Safeway continues to outsell Giant by better than two to one. The 26 Safeway stores in the District sold $233 million in groceries, more than 48 percent of total D.C. supermarket sales. The eight Giant units in the District had sales of $94.9 million--not quite 20 percent of the total.

But while Giant and Safeway are booming, their smaller competitors are in trouble. Third-ranking Grand Union and No. 4 A&P both lost business and closed stores in the past year; Acme Markets, the 10th-largest chain in the region, closed its last four stores this weekend.

The result is increased concentration in the Washington-area grocery market, with more and more of the busineses being handled by fewer and fewer competitors.

The increasing dominance of Giant Food and Safeway is evident in Food World's "share of the market" estimates, which show the portion of total business accounted for by each chain.

Giant's share of the metropolitan Washington market has grown by more than two percentage points, from 37.1 percent to 39.2 percent, and Safeway's share is up almost as much, from 28 percent to 30 percent, in the past year.

At the same time, the market share controlled by Grand Union stores and the Grand Union-owned Basics warehouse outlets has slipped from 9.8 percent to 8.8 percent. A&P's share plunged from 6.7 percent to 3.4 percent when it closed 17 stores, and the closing of two A&P-owned Plus stores slashed Plus's share from almost 1.5 percent to 0.8 percent. The combined A&P-Basics share dropped from 8.2 percent to 4.2 percent.

"What our numbers show is that it's down to Giant and Safeway, there's nobody else left" to provide serious competition, said Food World Editor Jeffrey Metzger. He and partner Richard Besteny own two weekly industry publications: Food World, which covers the Washington-Baltimore market, and Food Trade News in Pennsylvania.

Food World's annual study of the local supermarket business is considered the most accurate assessment of the industry in the Washington-Baltimore area. Its sales figures for the 12 months ended April 30 are based not only on information supplied by retailers, but also on data from distributors who supply goods to local stores.

The Food World executives say Giant and Safeway both benefited significantly from last year's bitter price war. By cutting prices sharply, the two chains took back some business they were losing to cut-rate, no-frills stores like Basics and Plus.

At the same time, the agressive advertising by Giant and Safeway took business away from smaller conventional supermarkets like Grand Union, A&P and Acme. With fewer stores, they can't match the advertising budgets of Giant and Safeway.

Food World figures on Washington and Baltimore show sharply contrasting developments in the two cities. While the Washington supermarket business is becoming more and more dominated by Giant and Safeway, the Baltimore market is much more competitive.

In the Washington area, the 10 largest supermarket chains did more than 90 percent of the business and Giant and Safeway alone accounted for 69 percent of the total. But in Baltimore the top 10 chains accounted for only 64 percent of total sales and No. 1 Giant took in only about 19.4 percent of the total.

Giant's 34 Baltimore stores had sales of $417 million and Giant increased its market share from 18 percent in 1981 to 19.4 percent in the latest year, Food World estimated.

Food-a-Rama knocked A&P out of second place in that market by taking over several Pantry Pride stores when that company went out of business in Baltimore. Food-a-Rama's annual sales jumped from $172 million to $269 million, while A&P slipped from $209 million to $174 million. Safeway ranked fourth in the Baltimore market with 20 stores and sales last year of $135 million, up from $124 million.

Acme was the fifth-largest supermarket chain in Baltimore last year, but all 23 Acme's in that area closed last month, leaving more than $100 million a year in grocery sales up for grabs.

Acme's closing of its Washington area stores will have much less impact, because there were only four of them and many of their customers fled before the stores closed. A year ago the four Acme units in the Washington area sold $16.8 million worth of groceries, according to Food World, but in its final year sales slipped to $12.5 million.

Despite the demise of Acme and Pantry Pride and the dominance of Giant and Safeway, some local independent supermarket operators are prospering here, the annual study shows.

Jumbo Foods grew from six stores to eight in the past year and its volume climbed from an estimated $52.6 million to $75.9 million, making Jumbo the sixth-largest food retailer in the Washington area.

Magruder's, with just three stores but all of them extraordinarily successful, remained the seventh-largest Washington area chain, with sales of almost $50 million. Magruder's has the highest average sales per store--more than $16 million--of any local chain, but Food World ranks the Safeway on Wisconsin Avenue just above Georgetown as the highest volume store in the Washington area.

Also expanding significantly was the Virginia Cooks chain, which grew from four stores to six, pushing volume from $25 million to $35.9 million, and moved to eighth place in the market.

As the Memco discount store chain has expanded in the last year, so have adjacent Memco supermarkets, which, with sales estimated at $85.7 million, are now the fifth-largest chain in the market. A division of the giant California-based Lucky Stores, Memco is now building its ninth Washington area store in Prince George's County.