Wichita postal officials said Thursday that 170 packages may have been contaminated by mercury that leaked from a package at the Wichita Processing and Distribution Center at 7117 W. Harry.
Postal officials said the area was secured, and hazmat crews were called in to clean up the mercury.
The packages in question have been isolated, and the Postal Service is working with health officials and companies that work with hazardous materials to determine whether the packages can be decontaminated and delivered.
Most of the packages were mailed from within a 50-mile radius of Wichita, postal officials said. Customers whose packages may have been contaminated have been notified by mail.
"As always our concern is first and foremost the safety of our employees and our customers," Wichita postmaster Mark Talbott said in a statement. "This is a rare and unfortunate occurrence. We will follow the advice of the experts as to what to do with the packages."
The individual who mailed the mercury has been identified, and the Postal Service is investigating.
Like virtually all hazardous material, mercury is not mailable, Talbott said.
Other common items that are restricted or considered hazardous by the Postal Service are perfumes, nail polish, flea collars and sprays, aerosols, bleach, pool chemicals, paints, matches, batteries, fuels, airbags, dry ice, mercury thermometers and cleaning supplies.