Effects of Blood Lead Levels <10 µg/dL in School-Age Children and Adolescents: A Scoping Review.

CONTEXT: Lead exposures among school-age children are a major public health issue. Although the harmful effects of lead exposure during the first years of life are well known, there is not as much understanding of the effects of low levels of lead exposure during later childhood. OBJECTIVES: To review the effects of blood lead levels (BLLs) <10 µg/dL in school-age children and adolescents. DATA SOURCES: We searched Medline, Embase, Global health, CINAHL, Scopus, and Environmental Science Collection databases between January 1, 2000, and May 11, 2023. STUDY SELECTION: We included peer-reviewed English-language articles that presented data on the effects of BLLs <10 µg/dL in individuals ages 5 through 18 years. DATA EXTRACTION: Data on country, population, analytic design, sample size, age, BLLs, outcomes, covariates, and results were extracted. RESULTS: Overall, 115 of 3180 screened articles met the inclusion criteria. The reported mean or median BLL was <5 µg/dL in 98 articles (85%). Of the included articles, 89 (77%) presented some evidence of an association between BLLs <10 µg/dL during school age and detrimental outcomes in a wide range of categories. The strongest evidence of an association was for the outcomes of intelligence quotient and attention-deficit/hyperactivity disorder diagnoses or behaviors. LIMITATIONS: Few articles controlled for BLLs at age <5 years, limiting conclusions about the relation between later BLLs and outcomes. CONCLUSIONS: BLLs <10 µg/dL in school-age children and adolescents may be associated with negative outcomes. This review highlights areas that could benefit from additional investigation.

Decreases in Young Children Who Received Blood Lead Level Testing During COVID-19 - 34 Jurisdictions, January-May 2020.

Exposure to lead, a toxic metal, can result in severe effects in children, including decreased ability to learn, permanent neurologic damage, organ failure, and death. CDC and other health care organizations recommend routine blood lead level (BLL) testing among children as part of well-child examinations to facilitate prompt identification of elevated BLL, eliminate source exposure, and provide medical and other services (1). To describe BLL testing trends among young children during the coronavirus disease 2019 (COVID-19) pandemic, CDC analyzed data reported from 34 state and local health departments about BLL testing among children aged <6 years conducted during January-May 2019 and January-May 2020. Compared with testing in 2019, testing during January-May 2020 decreased by 34%, with 480,172 fewer children tested. An estimated 9,603 children with elevated BLL were missed because of decreased BLL testing. Despite geographic variability, all health departments reported fewer children tested for BLL after the national COVID-19 emergency declaration (March-May 2020). In addition, health departments reported difficulty conducting medical follow-up and environmental investigations for children with elevated BLLs because of staffing shortages and constraints on home visits associated with the pandemic. Providers and public health agencies need to take action to ensure that children who missed their scheduled blood lead screening test, or who required follow-up on an earlier high BLL, be tested as soon as possible and receive appropriate care.

Integrating Childhood and Adult Blood Lead Surveillance to Improve Identification and Intervention Efforts.

The Centers for Disease Control and Prevention (CDC) collects information on blood lead levels (BLLs) in the United States through the Childhood Blood Lead Surveillance (CBLS) system (<16 years of age) and the Adult Blood Lead Epidemiology and Surveillance (ABLES) program (≥16 years of age). While both of these state-based national programs share the mutual goal of monitoring and reducing lead exposure in the US population, blood lead data for children and adults are maintained in separate data collection systems. This limits the ability to fully describe lead exposure in the US population across these 2 distinct population groups from sources such as take-home and maternal-child lead exposure. In addition, at the state level, having a unified system to collect, maintain, and analyze child and adult blood lead data provides a more efficient use of limited resources. Based on feedback from state partners, CDC is working to integrate CBLS and ABLES data collection systems at the national level. Several states have developed or are developing an integrated child and adult blood lead data collection system. We highlight efforts undertaken in Wisconsin, Minnesota, North Carolina, Iowa, and Oregon to investigate workplace and take-home lead exposure. Integrating blood lead surveillance data at the national level will enhance CDC's ability to monitor sources of lead exposure from both the home and work environments including paint, water, soil, dust, consumer products, and lead-related industries. Together, an integrated child and adult blood lead surveillance system will offer a coordinated, comprehensive, and systematic public health approach to the surveillance and monitoring of reported BLLs across the US population.

Tuberculin Skin Tests versus Interferon-Gamma Release Assays in Tuberculosis Screening among Immigrant Visa Applicants.

Objective. Use of tuberculin skin tests (TSTs) and interferon gamma release assays (IGRAs) as part of tuberculosis (TB) screening among immigrants from high TB-burden countries has not been fully evaluated. Methods. Prevalence of Mycobacterium tuberculosis infection (MTBI) based on TST, or the QuantiFERON-TB Gold test (QFT-G), was determined among immigrant applicants in Vietnam bound for the United States (US); factors associated with test results and discordance were assessed; predictive values of TST and QFT-G for identifying chest radiographs (CXRs) consistent with TB were calculated. Results. Of 1,246 immigrant visa applicants studied, 57.9% were TST positive, 28.3% were QFT-G positive, and test agreement was 59.4%. Increasing age was associated with positive TST results, positive QFT-G results, TST-positive but QFT-G-negative discordance, and abnormal CXRs consistent with TB. Positive predictive values of TST and QFT-G for an abnormal CXR were 25.9% and 25.6%, respectively. Conclusion. The estimated prevalence of MTBI among US-bound visa applicants in Vietnam based on TST was twice that based on QFT-G, and 14 times higher than a TST-based estimate of MTBI prevalence reported for the general US population in 2000. QFT-G was not better than TST at predicting abnormal CXRs consistent with TB.

Variability of the QuantiFERON®-TB gold in-tube test using automated and manual methods.

BACKGROUND: The QuantiFERON®-TB Gold In-Tube test (QFT-GIT) detects Mycobacterium tuberculosis (Mtb) infection by measuring release of interferon gamma (IFN-γ) when T-cells (in heparinized whole blood) are stimulated with specific Mtb antigens. The amount of IFN-γ is determined by enzyme-linked immunosorbent assay (ELISA). Automation of the ELISA method may reduce variability. To assess the impact of ELISA automation, we compared QFT-GIT results and variability when ELISAs were performed manually and with automation. METHODS: Blood was collected into two sets of QFT-GIT tubes and processed at the same time. For each set, IFN-γ was measured in automated and manual ELISAs. Variability in interpretations and IFN-γ measurements was assessed between automated (A1 vs. A2) and manual (M1 vs. M2) ELISAs. Variability in IFN-γ measurements was also assessed on separate groups stratified by the mean of the four ELISAs. RESULTS: Subjects (N = 146) had two automated and two manual ELISAs completed. Overall, interpretations were discordant for 16 (11%) subjects. Excluding one subject with indeterminate results, 7 (4.8%) subjects had discordant automated interpretations and 10 (6.9%) subjects had discordant manual interpretations (p = 0.17). Quantitative variability was not uniform; within-subject variability was greater with higher IFN-γ measurements and with manual ELISAs. For subjects with mean TB Responses ±0.25 IU/mL of the 0.35 IU/mL cutoff, the within-subject standard deviation for two manual tests was 0.27 (CI95 = 0.22-0.37) IU/mL vs. 0.09 (CI95 = 0.07-0.12) IU/mL for two automated tests. CONCLUSION: QFT-GIT ELISA automation may reduce variability near the test cutoff. Methodological differences should be considered when interpreting and using IFN-γ release assays (IGRAs).

Within-subject interlaboratory variability of QuantiFERON-TB gold in-tube tests.

BACKGROUND: The QuantiFERON®-TB Gold In-Tube test (QFT-GIT) is a viable alternative to the tuberculin skin test (TST) for detecting Mycobacterium tuberculosis infection. However, within-subject variability may limit test utility. To assess variability, we compared results from the same subjects when QFT-GIT enzyme-linked immunosorbent assays (ELISAs) were performed in different laboratories. METHODS: Subjects were recruited at two sites and blood was tested in three labs. Two labs used the same type of automated ELISA workstation, 8-point calibration curves, and electronic data transfer. The third lab used a different automated ELISA workstation, 4-point calibration curves, and manual data entry. Variability was assessed by interpretation agreement and comparison of interferon-γ (IFN-γ) measurements. Data for subjects with discordant interpretations or discrepancies in TB Response >0.05 IU/mL were verified or corrected, and variability was reassessed using a reconciled dataset. RESULTS: Ninety-seven subjects had results from three labs. Eleven (11.3%) had discordant interpretations and 72 (74.2%) had discrepancies >0.05 IU/mL using unreconciled results. After correction of manual data entry errors for 9 subjects, and exclusion of 6 subjects due to methodological errors, 7 (7.7%) subjects were discordant. Of these, 6 (85.7%) had all TB Responses within 0.25 IU/mL of the manufacturer's recommended cutoff. Non-uniform error of measurement was observed, with greater variation in higher IFN-γ measurements. Within-subject standard deviation for TB Response was as high as 0.16 IU/mL, and limits of agreement ranged from -0.46 to 0.43 IU/mL for subjects with mean TB Response within 0.25 IU/mL of the cutoff. CONCLUSION: Greater interlaboratory variability was associated with manual data entry and higher IFN-γ measurements. Manual data entry should be avoided. Because variability in measuring TB Response may affect interpretation, especially near the cutoff, consideration should be given to developing a range of values near the cutoff to be interpreted as "borderline," rather than negative or positive.

The effectiveness of group-based comprehensive risk-reduction and abstinence education interventions to prevent or reduce the risk of adolescent pregnancy, human immunodeficiency virus, and sexually transmitted infections: two systematic reviews for the Guide to Community Preventive Services.

CONTEXT: Adolescent pregnancy, HIV, and other sexually transmitted infections (STIs) are major public health problems in the U.S. Implementing group-based interventions that address the sexual behavior of adolescents may reduce the incidence of pregnancy, HIV, and other STIs in this group. EVIDENCE ACQUISITION: Methods for conducting systematic reviews from the Guide to Community Preventive Services were used to synthesize scientific evidence on the effectiveness of two strategies for group-based behavioral interventions for adolescents: (1) comprehensive risk reduction and (2) abstinence education on preventing pregnancy, HIV, and other STIs. Effectiveness of these interventions was determined by reductions in sexual risk behaviors, pregnancy, HIV, and other STIs and increases in protective sexual behaviors. The literature search identified 6579 citations for comprehensive risk reduction and abstinence education. Of these, 66 studies of comprehensive risk reduction and 23 studies of abstinence education assessed the effects of group-based interventions that address the sexual behavior of adolescents, and were included in the respective reviews. EVIDENCE SYNTHESIS: Meta-analyses were conducted for each strategy on the seven key outcomes identified by the coordination team-current sexual activity; frequency of sexual activity; number of sex partners; frequency of unprotected sexual activity; use of protection (condoms and/or hormonal contraception); pregnancy; and STIs. The results of these meta-analyses for comprehensive risk reduction showed favorable effects for all of the outcomes reviewed. For abstinence education, the meta-analysis showed a small number of studies, with inconsistent findings across studies that varied by study design and follow-up time, leading to considerable uncertainty around effect estimates. CONCLUSIONS: Based on these findings, group-based comprehensive risk reduction was found to be an effective strategy to reduce adolescent pregnancy, HIV, and STIs. No conclusions could be drawn on the effectiveness of group-based abstinence education.