A recent case of lead poisoning in a Flathead County child has health officials flummoxed.

All lead poisoning cases reported in children under 12 in the United States are investigated to find the cause and eradicate it.

The most recent one has no readily apparent cause.

“This one has been a little bit of a head-scratcher for us,” said Hillary Hanson, Flathead Deputy Health Officer.

Tests for lead content in the blood are done through a capillary test. Hanson said physicians and Head Start, which is federally required to test for lead, most often report positive results.

Once a child shows levels of lead higher than 5 micrograms per deciliter of blood per Centers for Disease Control guidelines, a secondary blood test is taken to confirm the levels.

At that point, the Flathead City-County Health Department goes to a lead risk assessor, in this case the Community Action Partnership of Northwest Montana.

Margie Jones, the Weatherization Department director at the partnership, is trained to do those risk assessments and has worked with health department nurses to do them.

“We go to the child’s house and do lead swab tests,” she said. “Is it something which can be easily looked at? We saw one case where the parents had sanded the floor and kicked up lead. The baby was crawling around in it.”

The leading cause of lead poisoning has been and remains lead paint chips. Other causes include toys from China, fishing weights, guns being loaded and pottery from outside the United States.

“Lifestyle is a big thing we look at,” Jones said. “If a parent is a big hunter or fisher, there could be higher levels of lead in that household.”

Once a child tests positive for high levels of lead in the bloodstream, the health department searches for the source, eliminates it, and the child must pass two consecutive months of below-threshold levels before the case is dismissed.

The team hasn’t located the source of lead for the most recent child, who was too young to leave the house.

“It’s really got us scratching our heads,” Jones said.

In the last 12 months, Flathead County has had eight cases of lead poisoning in children under 12, making it an uncommon but not rare situation, Hanson said.

“It really depends on where you live,” she said. “Butte still has a big problem with lead poisoning, but other Montana counties haven’t had a case in years.”

Paint companies in the United States stopped putting lead in their paint in 1978, but houses older than that can still be environmental factors for children. Lead poisoning has many symptoms, ranging from insomnia to memory loss to kidney failure.

The investigation into the mystery case of lead poisoning is ongoing.

Reporter Ryan Murray may be reached at 758-4436 or by email at rmurray@dailyinterlake.com.