California legislators are considering a first-in-the-nation bill that would regulate the use of employe urine testing, limiting companies to licensed labs and requiring that workers be warned of the tests in writing.

Increasingly, companies are requiring urine samples to screen employes or job applicants for evidence of drug use. Among the firms using the tests are AT&T, Exxon, Ford, General Motors, The New York Times Co. and TWA, said Assemblyman Johan Klehs, a Democrat, who is sponsoring the legislation.

But as use of the tests becomes more widespread, concern about their accuracy persists. Last year, a federal study found "serious shortcomings" in quality control of the testing labs, with error rates as high as 69 percent for detection of certain drugs. Some registered false positives -- indicating the presence of drugs that were not really there.

The California legislation, attempting to address those problems while avoiding the central issue of the constitutionality of drug testing, would require: state licensing of labs, with surprise inspections; confidentiality of results; written rules for discipline resulting from the tests, and appeal procedures; a second, different test of all positive results.

At last count, some 25 percent of the Fortune 500 companies were using drug testing to some extent, Klehs said.