In 1983, OSHA published its Hazard Communication (HAZCOM) Standard, which requires that the hazards of all chemicals used in the workplace be communicated to employees so that responsible protective measures can be taken. Today, HAZCOM remains near the top of the list of most frequently violated OSHA standards that result in a citation. The 1917 Halifax Explosion, one of the world's largest nonnuclear explosions, testifies to what can happen when you don't have-or don't follow-an effective HAZCOM program.