CLYDE, Ohio (AP) — Environmental regulators have started testing for contamination at 14 sites in a part of rural northern Ohio where cancer has sickened dozens of children for more than a decade.

The Blade in Toledo reports the U.S. Environmental Protection Agency began taking soil samples Monday in Clyde, nearly 40 miles southeast of Toledo. Most of the testing sites are former dump sites that have been closed for decades.

Some Ohio lawmakers and parents of sick children had urged the federal government to get more involved in investigating the source of the illnesses.

The odds are against finding an answer. The state has investigated for several years but found no clear explanation. It previously conducted a variety of tests, including air and groundwater sampling and radiation checks at homes and schools.