First, companies should set up clear drug-free policies and programs. Ground rules should specify what types of behavior are prohibited, the consequences of a violation and what opportunities there are for treatment.

The U.S. Labor Department runs a Web site to help companies build their own workplace policies. The Drug-Free Workplace Advisor is available at www.dol.gov/asp/programs/drugs/workingpartners/dfwpadvisor.asp.

Second, it's important to communicate substance-abuse policies to employees.

Third, employers should educate employees about substance abuse. They should be told how addiction can interfere with their lives and put their co-workers in danger.

Fourth, use a "carrot and stick" approach to encourage staffers to own up to their addiction and seek help. Most companies outsource initial assessments to an Employee Assistance Program provider, which pairs counselors with staffers for short-term sessions.

Telling an employee, "Either you seek treatment or you're fired" is not necessarily a bad thing. Such workplace interventions can be very effective, experts say.

Fifth, companies need to offer healthcare plans that cover inpatient and outpatient treatment for addiction. Right now, many providers offer only minimal coverage — some as low as $50 a year.

When someone returns to work after rehabilitation, experts say, an employer should take pains to respect that worker's privacy. Alcoholics Anonymous or Cocaine Anonymous meetings between shifts may even be a good idea.