WASHINGTON (AP) -- The Environmental Protection Agency is warning residents who live near medical sterilizing plants in 13 states and Puerto Rico about potential health risks from emissions of ethylene oxide, a chemical widely used in their operations.

The EPA says 23 communities, including Laredo, Texas; Ardmore, Oklahoma; and Lakewood Colorado, are at the highest risk from ethylene oxide emissions.

The EPA warning follows a recent survey of emissions data from almost 100 commercial sterilizers nationwide.

Ethylene oxide is used to clean everything from catheters to syringes, pacemakers and plastic surgical gowns.

A proposed rule to update the control of air toxic emissions from commercial sterilizers is expected by the end of the year.