PORTLAND, Ore. – Two children showed elevated lead levels in their blood during a lead poisoning screening at Rose City Park School, but health officials now say the children were poisoned by household sources and not from drinking water at the school.

The two children were the only people who showed elevated blood levels among the 519 Creston and Rose City Park students and staff tested in June, according to the Multnomah County Health Department.

An investigation found the source of lead exposure was from a home and did not come from drinking water.

"Over the last several years, the Health Department has not connected anyone with elevated lead in their blood in Multnomah County to drinking water from any source," said Multnomah County Health spokeswoman Julie Sullivan-Springhetti.

According to Sullivan-Springhetti, an elevated blood lead level test shows that a person has been exposed to lead in the past three months. Lead can harm the developing brain and other organs.

In March, parents of Creston and Rose City Park students requested lead testing of the water at the two schools. Tests found lead at up to three times the action level set by the Environmental Protection Agency. The school system is now testing every building for lead this summer.

So far, 23 tests have been released. All of the school buildings tested showed high levels of lead, some at levels much higher than those seen at Creston or Rose City Park.

Anyone worried about lead poisoning should get tested, Multnomah County health officials said.

All school-age children can get tested at one of four testing clinics in July.

Full coverage: Lead in Portland schools

Learn more: Lead poisoning prevention

What parents should know about lead