Success At Lowering Child Blood Lead Levels Make It Harder For Accurate Testing: Study

Tests used to check the amount of lead in children’s blood may be a victim of the country’s success at lowering incidents of lead poisoning, according to the findings of a new study. 

According to a study published in the medical journal Pediatrics, lead blood tests may be suffering accuracy issues as levels nationwide have dropped below the ability of many techniques to detect. However, even those low levels of lead poisoning could pose a serious risk to children’s health.

Researchers from the U.S. Centers for the Disease Control and Prevention (CDC), using data from the National Center for Health Statistics, wrote that blood lead levels have declined among children in the U.S. over time, with the 95th percentile of children having a mean blood lead level of about seven micrograms per deciliter in 1999-2000, to less than 2 in 2013-2014.

As a result, lead blood tests have had to improve their technology to decrease the level of detection (LOD), and manufacturers of those tests are struggling to keep up. That is difficult at that level, due to the risk that there may be tiny amounts of contamination, such as external skin contamination and even small amounts of lead in the devices use to collect blood samples, such as needles and vials.

“Because the CDC’s analytical LOD for lead in whole blood has decreased over time, and BLLs in the United States population have decreased over time, lot screening has resulted in more “failures” due to unacceptable lead contamination,” CDC researchers wrote. “Between January 2009 and February 2016, the laboratory screened 359 manufacturing lots of needles, blood collection tubes, cryovials, and other items for lead. The decline in LOD and BLLs in children 1 to 5 years old was accompanied by an increase in the percentage of lot screen failures.”

Researchers concluded that manufacturers of blood collection items need to increase awareness and determine what actions they need to take to avoid potential lead contamination, since screening the devices for such small amounts of lead is not feasible for most laboratories. Labs need to understand potential sources of lead contamination, and adjust their own methods to be able to detect low concentration measurements, the researchers noted.

“Manufacturers of devices used in blood lead sample collection could identify potential sources of lead contamination and take actions to reduce these sources,” CDC researchers determined. “Clinicians should understand the factors affecting accurate measurements at low blood lead concentrations to better interpret BLLs and assess whether small changes are real or indicate measurement variability.”

The study comes on the heels of an FDA warning that some blood lead level tests were inaccurate when drawing blood from veins, however the agency’s investigators have found problems at the manufacturing facility involving those tests, and it is unclear whether problems with those tests are connected to the concerns mentioned in this latest study by the CDC.

Lead Poisoning Risks

Elevated blood lead levels are an indicator that children may be at risk for side effects of lead poisoning, which can lead to serious nervous system injury, brain damage, seizures, growth or mental disability, as well as other severe health problems throughout the rest of their childhood and life.

One of the more common causes of of lead poisoning is lead-based paint, which was banned in the United States in 1978 due to the risk of severe and permanent brain damage and developmental problems, particularly in children. However, a number of older homes still contain the toxic paint on the walls, and if it flakes or peals off, young children could ingest the paint chips or breathe dust that comes from the paint, resulting in lead poisoning. Many of those homes are owned by HUD or receive HUD assistance.

In recent years, there has also been an increased focus on lead in drinking water, stemming from the recent and ongoing Flint water crisis, during which a change to the water system in the Michigan city resulted in high levels of lead in residents’ drinking water, causing thousands of children to suffer lead exposure and, potentially, lead poisoning.

The CDC estimates that 535,000 children ages 1-5, or about 2.6% of such children in the U.S., have levels of lead in their blood that place them at risk for adverse health effects. To come up with that number, the CDC analyzed data from the National Health and Nutrition Examination Survey from the years 1999 to 2002, and 2007 through 2010.

The majority of those children are poor and live in older urban areas, mainly in the inner city. Most are minorities, meaning such exposures add to numerous problems already plaguing inner city black and Latino youths, such as poverty, high crime and poor schools.