Most dental offices should be exempt from the government`s hazardous communication standard, the American Dental Association says. That standard requires training employees in chemical-safety procedures and providing written safety materials. But ADA says dental offices don`t use many hazardous chemicals and have good safety records. Dentists receive safety training in school, ADA says. Saying the costs outweigh the benefits, it urged a government advisory panel to exempt dental offices with 10 or fewer employees.