Five months after Chinese and American labor watchdog groups petitioned Apple to investigate the use of potentially hazardous materials in its iPhone and iPad assembly process, the company has announced that it will make changes banning the use of at least two chemicals, the Associated Press reported today. The chemicals in question are benzene and n-hexane, which are tied to lukemia and nerve damage, respectively.

After conducting a four-month study, Apple says it determined that there was no evidence to suggest that these chemicals posed a threat to workers assembling its devices in twenty-two factories, but announced that it would take steps to ensure that it would not become a problem in the future. To that end, both benzene and n-hexane have been banned from the assembly line.

The move is likely too late to have much of an impact on the assembly of some iPhone 6 units, as two versions of that model entered production over the past few weeks. As more iPhone 6 units are produced, the change will help ensure the continued safety of the half a million workers assembling the device.

Update: Lisa Jackson has published a letter on the Apple website explaining the decision to remove these toxins from the assembly process and the company’s continued commitment to eliminating harmful chemicals. Along with the letter, Apple published its Regulated Substances Specification, which outlines the rules it holds its suppliers and manufacturers to regarding use of potentially hazardous substances.

The full letter is below: