There Is No Safe Level of Lead in a Child's Blood: CDC's Reference Value Is 3.5 Micrograms, and Medicaid Children Must Be Tested at Ages 1 and 2
The Centers for Disease Control and Prevention (CDC) states it plainly: no safe level of lead in children's blood has been identified, and even low levels can negatively affect a child's health. The difficulty is that most children with lead in their blood have no obvious immediate symptoms, so the only reliable way to know whether a child has been exposed is a blood lead test, which CDC puts at the center of childhood lead poisoning prevention.
Results are read against CDC's blood lead reference value of 3.5 micrograms per deciliter (3.5 μg/dL). The value is set at the 97.5th percentile of blood lead levels among U.S. children ages 1 to 5 in national survey data, so a child at or above 3.5 μg/dL is in the top 2.5 percent of blood lead levels nationwide and should receive confirmatory testing and follow-up services. The reference value is a screening tool, not a safety line: a result below it does not mean a child has had no lead exposure.
CDC lists the children who should be screened first: children who live or spend time in a house or building built before 1978, the most common source of lead paint and lead dust; children from low-income households; immigrant, refugee and recently adopted children from less developed countries; and children who live or spend time with someone who works with lead or has hobbies that expose them to lead. For children enrolled in Medicaid the test is mandatory at ages 12 and 24 months, and again between 24 and 72 months if the child was never tested, with the cost covered by the Centers for Medicare & Medicaid Services; many private insurance policies also cover blood lead testing.
Two kinds of tests are used. A finger-prick or heel-prick capillary test gives fast results and is usually the first step, but lead on the skin can push a result high, so a value above the reference value is confirmed with a venous blood draw. If a child's level is confirmed above the reference value, the doctor may recommend finding and removing lead from the child's environment, a diet high in iron and calcium, follow-up blood testing and connection to early educational services. Parents who are unsure whether their child needs testing should ask the child's health care provider, which is CDC's own advice. (Source: Centers for Disease Control and Prevention)
Source: Centers for Disease Control and Prevention
Published by GSM · USA (original Chinese edition)
Photo: Wikimedia Commons 摄影，CC BY-SA 4.0：工人为住宅清除含铅油漆（示意：1978年前住房的铅漆须专业处理）
