Jonathan Long, a union representative for the Brotherhood of Maintenance of Way Employees Division of the International Brotherhood of Teamsters, titled the letter "Norfolk Southern Is Dangerous to America" and said about 40 workers were ordered by the railway to clean up the wreckage. 

Long said workers weren't given proper personal protection equipment to clean up the toxic wreckage. He said many workers weren't supplied respirators, protective clothing, or eye protection. 

As a result of the chemical exposure, many rail workers "reported that they continue to experience migraines and nausea, days after the derailment, and they all suspect that they were willingly exposed to these chemicals at the direction of [Norfolk Southern]."

Long added, "This lack of concern for the workers' safety and well-being is, again, a basic tenet of NS's cost-cutting business model."

Norfolk Southern released a statement to CNBC about the cleanup effort. They said:

Norfolk was "on-scene immediately after the derailment and coordinated our response with hazardous material professionals who were on site continuously to ensure the work area was safe to enter and the required PPE was utilized, all in addition to air monitoring that was established within an hour."