Originally published on November 19, 2014, at NationofChange.org

A chemical leak killed four employees and left a fifth hospitalized at a DuPont plant in Texas this weekend. Since 2007, the Texas chemical plant has been cited dozens of times for violating state and federal laws. According to the U.S. Chemical Safety Board (CSB), a gas leak and an explosion at separate DuPont facilities in 2010 resulted in two more fatalities.

Around 4am on Saturday, approximately 100 pounds of methyl mercaptan leaked from the DuPont plant in La Porte, Texas. Methyl mercaptan is a toxic chemical used in DuPont’s insecticide manufacturing process. Company representatives claim a faulty valve caused the exposure resulting in four fatalities and a fifth employee hospitalized.

While working an overtime shift, Robert “Bobby” Tisnado ran into the facility to help another employee inside when the chemical leak occurred. After Bobby did not return, his older brother Gilbert “Gibby” Tisnado ran inside to help him. When Gibby found his brother on the floor, he placed his facemask on his little brother. Neither survived.

Along with the Tisnado brothers, Wade Baker and Crystle Rae Wise were also found dead. Baker was a supervisor who had worked at DuPont for 40 years. Wise had transferred to the plant eight months ago to be closer to her daughter and grandson in Houston. A fifth employee was transported to Bayshore Hospital for treatment and has been released.

According to a statement from DuPont, non-medically trained personnel contained the leak and found the bodies three hours later. At 1:30pm, the medical examiner pronounced them dead. DuPont began informing the families.

Charged with investigating industrial chemical accidents, the CSB sent eight team members to launch an investigation into the methyl mercaptan leak. While currently conducting interviews with DuPont personnel, the CSB investigators have been denied access to the area where the leak and deaths occurred.

“DuPont is taking steps to assure the area is safe to access,” stated CSB Investigation Supervisor Johnnie Banks. “We will be evaluating that process and when we determine it is safe for our team members to document the site we will enter. We don’t know how soon that will be. We have asked the company to preserve the status of the process, valve, and other equipment settings as close as possible to where they were at the time of the accident to aid in our investigation.”

Since September 1, 2009, the Texas Commission on Environmental Quality (TCEQ) has cited the DuPont chemical plant in Texas for violating state law over two dozen times. Although many of the violations involved recordkeeping infractions, the DuPont plant was also cited for failing to perform routine safety inspections, keep equipment in proper condition, and prevent hazardous leaks on at least four occasions.

On October 14, 2009, the DuPont plant accidentally spewed roughly 3,700 pounds of a hazardous pollutant called methylene chloride into the air for over seven hours. The TCEQ initially fined DuPont over $10,000 for failing to prevent the chemical leak and for reporting the incident five days late. DuPont ended up paying only $8,269 with the rest deferred.

In August 2013, the DuPont plant accidentally leaked 40 pounds of chlorine. In March, an open gas vent leaked 110 pounds of carbon monoxide into the air. And in late September, a malfunctioning valve released 36,500 pounds of sulfur dioxide into the atmosphere.

When the Occupational Safety and Health Administration (OSHA) last inspected the Texas chemical plant on January 25, 2007, DuPont was cited for four serious safety violations involving highly hazardous chemicals and fined $3,400. The Environmental Protection Agency (EPA) brought formal actions against the chemical plant for violations in 2012 and 2014. DuPont was charged $117,375 in penalties. Last month, DuPont reported $7.5 billion in quarterly sales.

According to the CSB, the agency has previously investigated four accidents at DuPont facilities. The DuPont plant in Belle, West Virginia, experienced three separate chemical leaks within the same week. On January 23, 2010, a phosgene gas leak killed a DuPont employee at the Belle plant. On November 11, 2010, two contractors were welding when sparks ignited flammable vapors and caused an explosion at the DuPont facility outside Buffalo, New York. The explosion killed one contractor and left the other seriously injured.

“There are no words to fully express the loss we feel or the concern and sympathy we extend to the families of the employees and their co-workers,” Texas plant manager Randall Clements said. “We are in close touch with them and providing them every measure of support and assistance at this time.”

Although the father of the Tisnado brothers does not blame anyone for the deaths of his sons, Gibby’s widow Michelle and Wise’s daughter Jasmine filed lawsuits against DuPont on Monday. Jasmine has also filed a temporary restraining order against DuPont.