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CDC reduced the blood lead reference value (BLRV) for its first update in nearly 10 years while maintaining that no safe blood lead level (BLL) exists.

BLRV is determined by the 97.5th percentile of the blood lead distribution in children ages 1 to 5 years. The initial BLRV of 5.0 µg/dL, established in 2012, has been lowered to 3.5 µg/dL, Perri Ruckart, MPH, of the CDC, and colleagues reported in the .

Healthcare providers will now be able to provide nutritional counseling and identify exposure sources for children with BLLs less than 5 µg/dL but greater than 3.5 µg/dL, Ruckart's group noted. "Before this update, these actions were not recommended to occur for BLLs <5 μg/dL."

The change should also prompt more stringent lead testing practices, as laboratories may need to update their testing practices, get better equipment, and reduce contamination, the CDC group suggested.

The revision of the BLRV to 3.5 µg/dL had been based on the 2015-2018 National Health and Nutrition Examination Surveys (NHANES).

"Although it is encouraging that progress has been made toward lowering population average BLLs, geographic, socioeconomic, and racial/ethnic disparities in lead exposure, especially among young children, persist," Ruckart's team said.

"Efforts should be put in place focusing on eliminating lead exposure among the most vulnerable in the population, young children aged 1-5 years, and should become an environmental public health priority," the authors urged.

The BLRV is not a safety threshold, the CDC group cautioned, as have shown there is no safe level of lead.

Elevated BLLs in children can result in . While lead impacts children more severely than adults, can still result in infertility, high blood pressure, and kidney disease.

Lead is pervasive in many environments, with the CDC citing old paint, water, imported toys and candies, and areas near airports as .

Due to , fewer children have been tested for elevated BLLs. An estimated 10,000 children with elevated BLLs may have been missed as a result.

CDC introduced the BLRV in 2012 to identify children The BLRV was meant to be reevaluated after every 4 years, but it did not see any changes under the Trump administration.

In the 1970s, when the CDC first began defining abnormal BLLs, the "undue or increased lead absorption" level was 40 µg/dL. Back then, the median BLL was over 15 µg/dL. In the , the average BLL in children older than 1 year was 0.82 µg/dL.

A recent study in JAMA Pediatrics reported that over half of children tested had detectable lead levels in their blood. The literature points to elevated BLLs in vulnerable populations in particular, namely children who are Black, living below the poverty line, or living in old housing.

"[These children's] ongoing lead exposure reflects persistent structural inequities in the built environment and access to health care," Ruckart and colleagues wrote. "In addition, the pernicious and irreversible effects of lead exposures perpetuate ongoing structural inequities and injustices."

"Lead exposure can be considered both a result and cause of health inequity and environmental injustice," the group said.

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