Abstract: At approximately 2:56 p.m. on June 25, 2021, an employee working for an agricultural chemical supplier was pumping chemicals into an orchard irrigation tote at a field located near Stockton, CA. While performing the routine chemical transfer, the employee inadvertently pumped the wrong chemical, causing a rapid exothermic reaction that ruptured the tank and released chemicals over the employee. The chemicals involved included sodium chlorite (30%) and etidronic acid. The employee was badly burned on the chest and lower body and suffered lung damage from inhalation of vapors. The employee was transported to a burn unit for hospitalization and treatment. The investigation found the labeling, hoses, totes, and equipment were nearly identical and lacked mechanical safeguards to prevent cross-contamination.