Federal investigators have begun a crash study to determine if the pesticide dibromochloropropane (DBCP), which is banned in California and restricted elsewhere, is still reaching the public on some fruits and vegetables, officials said yesterday.

The Environmental Protection Agency ended the use of DBCP on 19 fruit and vegetable crops last year after the pesticide was linked to sterility among workers who made it and to cancer in laboratory animals.

In a letter to EPA Administrator Douglas M. Costle, the Health Research Group, a Ralph Nader-sponsored organization here, said it had recent test results from the California Department of Food and Agriculture showing varying levels of DBCP on several crops not included in the federal ban.

Generally DBCP in injected into a plant's root structure. Some of the pesticide apparently leaks up through the soil in vapor form and settles on the skin of the plant, researchers have found.

The recent studies -- done after DBCP was banned in California -- showed residues of it on peaches, oranges, grapes and lemons at levels that sometimes exceeded those that prompted last year's ban.

In its letter, which was released yesterday, the Health Research Group requested that EPA ban DBCP use on all fruits and vegetables. Dr. Sidney M. Wolfe, director of the health organization, said federal documents showed that EPA had recently confirmed the California test results.

The tests showed that average concentrations of the pesticide three months after it was applied remained at 40.8 parts per billion for oranges, with lesser levels for peaches, grapes and lemons. The EPA acted last year after levels of 10 parts per billion were found on some fruits.