People who eat wild game killed with lead bullets tend to have higher levels of lead in their blood than people who don't, according to a first-of-its-kind study of 738 North Dakotans.

"People who ate a lot of wild game tended to have higher lead levels than those who ate little or none," Dr. Stephen Pickard, epidemiologist for the North Dakota Department of Health, said Wednesday.

The study also showed that the more recent the consumption of wild game killed with lead bullets, the higher the level of lead in the blood.

The blood lead levels of those tested were considered low, but even low levels can have adverse health effects, especially for children and pregnant women.

Officials recommended that pregnant women and children under 6 not eat any venison from deer killed with lead bullets -- the same recommendation made last month by the Minnesota Health Department.

"Children under 6 are particularly vulnerable because their brains are still developing," Pickard said. "It causes permanent brain damage even in very small quantities. There is no safe exposure level for small children. We see children with permanent lower intelligence and changes in behavior."

Lead can increase the risk that a pregnant woman could lose her baby or deliver it prematurely, Pickard said. In adults, lead can cause high blood pressure, hearing loss and infertility, though usually with higher lead levels.

The study, done by the U.S. Centers for Disease Control and Prevention (CDC) and the North Dakota Department of Health, appears to add to the evidence that using lead bullets can pose potential health problems for hunters and their families. A Minnesota study last summer showed lead bullets fired from high-powered rifles scatter lead fragments -- many too small to see or feel -- up to 18 inches from the wound.

The North Dakota blood samples were taken in May and June, and the study results were released just days before deer seasons open in North Dakota and Minnesota. Some 500,000 people are expected to hunt deer in Minnesota this fall. The study was conducted after lead particles were found in venison donated to food shelves last spring. Venison in Minnesota, Iowa and Wisconsin also was found to contain lead. North Dakota is limiting venison donations this year to deer shot by archers.

The study was limited in scope. It didn't determine if careful butchering practices would reduce lead levels and didn't examine whether people were having adverse health effects from the lead.

The lead levels ranged from virtually none to 9.82 micrograms per deciliter. Health officials consider 10 micrograms per deciliter in a child to be the level when "intervention" should occur. That "intervention" level for an adult is 25 micrograms per deciliter.

"But any level of lead in children below age 6 is of concern," said John Stine of the Minnesota Department of Health.

After ingesting lead, a person will slowly get rid of it. Pickard noted the blood samples were taken last spring, months after the North Dakota hunting season. Had they been taken during or shortly after the hunting season, he suspects the blood levels would have been higher.

North Dakota also recommended that older children and other adults should take steps to minimize their potential exposure to lead.

"There is reason to be concerned,'' Pickard said. "And if you're concerned, there is one sure way to avoid having lead contamination: Use non-lead bullets."

Doug Smith • 612-673-7667