(Providence, RI)--The Rhode Island Department of Health says samples are being taken this week from about 50 water systems to examine possible contamination.The state says it will work with researchers from Brown University to look for PFAs, chemicals that have been mostly phased out of use in the U.S. because of concerns about health effects.In previous rounds of sampling, one water system, located in Burrillville, was found to have exceeded EPA health advisory levels, according to the health department.