It goes without saying that a sober worker is less likely to be involved in a drug or alcohol related accident than an intoxicated one, but substance abuse can hurt your business in other ways and is more prevalent than you may think.
The United States Department of Labor (USDOL)'s compiled results from a number of independent studies on the Working Partners for an Alcohol and Drug Free Workplace section of their website indicating that 3.1% of American workers use illegal drugs before reporting to work and 2.9% work while high on illegal drugs. The problem of illegally drugged employees is nearly twice as high as the number of drunkards representing 1.8% of America's workforce who were caught drunk on the job while the exact number of those who only drank before work was not listed probably because those workers were able to stop whenever they wanted.
The dysfunctional habits of of substance abusing employees have had a direct impact on job performance and safety. They are more likely to skip work more than 2 times a month and miss at least 2 days due to injury of illness.
To help employees do what is best for businesses the USDOJ has compiled a comprehensive collection of online resources for employers seeking to eliminate drug and alcohol related incompetence. Their program as mentioned above is called Working Partners for an Alcohol and Drug Free Workplace. It provides a comprehensive guide to help employers screen workers for controlled substances with reliable testing, but also supports forgiving bosses with treatment resources that may help make their employees realize the benefits of working while sober.