CLEVELAND -- A 5 On Your Side investigation has uncovered that drinking water in communities throughout Ohio contain levels of arsenic that are beyond what is considered safe.

Investigator Ron Regan reported that though the risk is small, doctors believe that arsenic found in small amounts in drinking water can increase the risk of bladder, kidney and lung cancer.

From neighborhoods to restaurants and even schools, more than 100 public water systems across Ohio were found to be pumping drinking water laced with arsenic.

At least 35,000 Ohioans are affected by drinking water in which arsenic exceeds federal safety standards, Regan reported.

In Chardon, arsenic is in every home. The town's building a new water treatment plant to filter it out, but the city manager downplays the threat.

"Do I consider the limits too strict? Yes. Do I think we have a health hazard in Chardon because of our water? No," said City Manager David Lelko.

While the experts admit that's true in the short run, it's prolonged exposure over the years that is causing real concern.

"There is a linkage between arsenic exposure, and that's primarily through drinking water, and cancer," said Dr. Cynthia Bearer of Rainbow Babies and Children Hospital.

Bearer served on the advisory team that created a new, tougher limit on arsenic in water. Her latest research shows that arsenic has now found its way into Cleveland's blood supply.

"And what we found was we could detect arsenic from all the donors in Cleveland's blood. We only tested donors from Cleveland, but we found arsenic in everybody's blood, which was surprising to us," Bearer.

Children are most at risk. At Stirling Elementary in Wayne County, children drink from well water that contains unsafe levels of arsenic, and it worries parents.

In the next few months, the school is planning to tap into a nearby town's safe, treated water system.

In nearby Seville, more than 1,000 customers were drinking too much arsenic in their water until a million-dollar treatment plant went online a few months ago.

For doctors, who are just now beginning to see how arsenic can find its way into the blood supply, there is genuine concern.

"To me, it raises the concerns about blood transfusions that adults are giving to children. In that, if we designate a donor to a child, and that donor has a higher level of arsenic, that child may be inadvertently exposed to a higher level of arsenic than would be good for that child," said Bearer.

In Ohio, arsenic naturally forms in groundwater, especially in water systems that draw from wells.

Click here for a list of Ohio companies and schools that tested over the federal safety standard limit for arsenic.

You can learn more about arsenic in drinking water from the Ohio EPA and the Natural Resources Defense Council.