The Occupational Safety and Health Administration (OSHA) in March mailed out 9,414 letters of warning to American businesses that reported above-average illness and injury rates.

OSHA administrator David Michaels, whose signature appears on the letters, said that up to 2,500 of those receiving letters could be inspected, with those with the highest rates being inspected first.

The largest category of recipients was manufacturers (4,899 letters), followed by wholesale trade establishments (1,352). The business category with the most listed establishments was nursing homes, convalescent homes and other residential medical care facilities (1,005).

The letters went only to workplaces in states covered by Federal OSHA. States with their own OSH programs were not included.

The letters, and any subsequent inspections, are all part of OSHA's Site-Specific Targeting Program announced in January of this year.