HAMPTON, N.H. – The latest estimate of how many plastic disks were washed out of a New Hampshire wastewater treatment plant into the Merrimack River may reach 8 million.

Officials originally said hundreds of thousands of the 2-inch wide disks were swept downriver from the Hooksett treatment plant after heavy rains earlier this month. On Wednesday, an Environmental Services spokesman said the latest estimate is 4 million to 8 million disks out of approximately 39 million were released. The disks are used to promote growth of bacteria that feed on waste.

Officials say the disks, which washed ashore in New Hampshire and Massachusetts, pose little health risk.