MORRISVILLE - County and state investigators are looking into an explosion that injured a worker at an organic chemical company late last month, the second blast at Natland International in two years.

The Natland International employee told officials he was cleaning equipment in a lab Aug. 30 when he improperly mixed chemicals, said Morrisville Fire Chief Todd Wright.

The worker was taken to Duke Hospital for treatment, and his condition remains unknown. Wright declined to release the worker’s name, citing federal health privacy laws.

The Wake County’s Fire Services Division and the state Occupational Safety and Health Division, part of the N.C. Department of Labor, are investigating the explosion.

The state office has up to six months to complete an investigation and could issue fines to the company if safety violations are found, said spokeswoman Dolores Quesenberry.

Sodium azide, one of the chemicals the worker mixed, is a toxic substance found in automobile airbags, chemicals in hospitals and labs, pest control and detonators, according to the Centers for Disease Control and Prevention.

Explosions can occur in metal drain pipes if the chemical isn’t properly flushed, according to the U.S. Food and Drug Administration.

The small blast at 3000 Bear Cat Way caused about $5,500 in damages in a lab area, Wright said. Some other workers for businesses that share space at the corporate park felt the blast, he said.

“The damage included cracked door glass, displaced ceiling tiles ... and shattered glass from the broken test beakers,” Wright said.

The incident wasn’t the first explosion at Natland’s Morrisville lab. In September 2010, about 50 people were evacuated from the company’s site, then at 2700 Gateway Centre Blvd.

The explosion occurred while an employee was mixing chemical compounds. No injuries were reported, and damage was limited to cabinets and ceiling tiles.

The Occupational Safety and Health office issued the company four serious violations and a fine of $2,000 after the first blast. The violations included not keeping exposure levels low, not having proper flushing facilities near the work area and not inspecting fire extinguishers monthly.

Natland International was also fined $450 in March 2011 for not notifying the state safety office of any abatement or remedies to the violations. A follow-up inspection showed the company was compliant.

Natland did not return calls for comment.

.