A study of newborn blood samples tested at the Iowa State Hygienic Laboratory revealed surprising results that affect both rural and urban Iowans.
The research, published earlier this year in the scientific journal PLOS ONE, showed one in five newborns had high blood lead levels, regardless of whether their mother lived in a city or a rural area. “That was always thought to be an urban problem,” said Donald Simmons, manager of the Ankeny laboratory and co-author of the study. “In Iowa, it’s all over the place.”
Simmons said previous studies have shown concentrations of children with high blood lead levels in cities such as Baltimore, but little research exists into blood lead levels in newborns, particularly in rural settings.
The higher levels statewide likely are related to the amount of pre-1940s housing stock in Iowa, when lead paint was commonly used, he said, adding, “the older the housing, the more risk of lead being in the house because of the paint.”
Other sources of lead include factories, coal mining and vehicle exhaust from leaded gasoline – banned in 1996 for sale in the U.S. for on-road vehicles – and even from soil, where lead accumulates.
Lead can cross the placental barrier, according to the U.S. Centers for Disease Control & Prevention (CDC), meaning pregnant women who are exposed to lead also expose their unborn child, which can damage the developing baby’s nervous system. Even low-level lead exposures in developing babies have been found to affect behavior and intelligence, the CDC notes. Lead exposure can cause miscarriages, stillbirths, infertility and, at very high exposure levels, even death.
Staff tested 2,300 dried blood spots collected within one to three days of birth from Iowa newborns which were linked with the area of the mother’s residence at the time of birth. The blood was collected under the Iowa Newborn Screening Program. The program is part of the Iowa Department of Public Health, and is a collaborative effort between the IDPH, the State Hygienic Laboratory, the University of Iowa Stead Family Children’s Hospital and Central Delivery Service of Iowa.
Newborn screening, however, does not include routine testing for lead, Simmons noted, though the lab also performs blood lead screening for children in Iowa.
Researchers in the study found that one in five Iowa newborns exceeded the five micrograms of lead per deciliter of blood (μg/dL) action level set by the CDC.
In addition to the association to pre-1940s housing, the study used census data to determine that elevated blood lead levels were associated with childbearing-age women with low educational status in both rural and urban settings, which Simmons said is related to socioeconomic status and housing.
While the CDC notes that no blood lead level in children is currently thought to be safe, five μg/dL has been identified as the amount that should prompt further medical attention, with about one in 40 American children having at least that level in their blood.
The effects of even low levels of lead in blood, which include inability to pay attention and lower IQ, appear to be irreversible, according to the CDC, and children are more at risk than adults because their blood-brain barrier is not fully developed.
The article noted that analysis of newborn dried blood spots is an important tool for lead poisoning surveillance in newborns and can direct public health efforts towards specific places and populations where lead testing and case management will have the greatest impact.