The National Institute for Occupational Safety and Health plans to interview Hanford tank farm employees during a visit to the nuclear reservation July 25-28.
The agency, called NIOSH, is a branch of the U.S. Centers for Disease Control focused on work place safety and health.
NIOSH announced last month that it planned a short-term evaluation related to Hanford worker exposure to chemical vapors associated with waste held in underground tanks.
NIOSH investigators also plan to observe work practices in Hanford tank farms, review programs and speak with management and union leaders in addition to workers during the visit.
Employees of Washington River Protection Solutions have been forwarded a NIOSH memo that includes the times and locations that employees they may voluntarily meet with investigators to discuss their concerns.
Despite a stop work order called by the Hanford Atomic Metal Trades Council, two more Hanford workers reported symptoms consistent with chemical vapor exposure last week at Hanford.
They bring the number of workers receiving medical checks for possible chemical vapor exposure to about 55 in recent months.
All were cleared to return to work, however, workers are concerned that exposure to the chemicals can result in serious respiratory or neurological illnesses.