# Association Between Low-Level Lead Exposure and Serum Gamma-Glutamyl Transferase Concentrations as a Biomarker of Oxidative Stress in U.S. Adolescents Aged 12–19 Years

## TL;DR

This study finds that even low levels of lead exposure in U.S. adolescents are linked to higher levels of a blood enzyme that indicates oxidative stress.

## Contribution

The study provides new evidence linking low-level lead exposure to oxidative stress biomarkers in adolescents using national health data.

## Key findings

- Adolescents with blood lead levels ≥0.70 µg/dL had significantly higher serum GGT concentrations.
- Higher lead exposure (quartile 4) was associated with increased GGT levels after adjusting for confounders.
- No significant association was found in lower lead exposure quartiles.

## Abstract

Objectives: This study aims to investigate the potential relationship between low-level lead exposure and serum gamma-glutamyl transferase (GGT) concentrations, which may serve as a biomarker of oxidative stress in U.S. adolescents. Methods: We used NHANES data from 1999 to 2000 to 2017–2018. Analyses were limited to adolescents aged 12–19 years with blood lead levels (BLLs) below 5 µg/dL (n = 11,978). BLLs were categorized into either two groups based on the median BLL (i.e., <0.70 µg/dL and ≥0.70 µg/dL) or four quartiles (i.e., quartile 1: <0.46 µg/dL; quartile 2: 0.46–<0.70 µg/dL; quartile 3: 0.70–<1.00 µg/dL; and quartile 4: ≥1.00 µg/dL). Multivariable linear regression analysis was conducted to assess the association between BLLs and serum GGT concentrations among U.S. adolescents aged 12–19 years. Results: Adolescents with BLLs ≥ 0.70 µg/dL showed significantly higher serum GGT concentrations compared to those with BLLs < 0.70 µg/dL (geometric means: 13.94 vs. 12.80 U/L; p < 0.001). The multivariable linear regression analysis indicated that, after adjusting for potential confounding factors, natural log-transformed serum GGT concentrations were higher among adolescents in BLL quartile 4 compared to those in BLL quartile 1 (β-coefficient = 0.0607; 95% CI: 0.0306, 0.0908). However, no significant associations were observed between BLLs and serum GGT concentrations among adolescents in BLL quartiles 2 and 3 when compared to quartile 1. Conclusions: In the present study, we observed that higher BLLs were associated with higher serum GGT concentrations in U.S. adolescents aged 12–19 years. Further research is needed to substantiate the positive relationship between BLLs and serum GGT and explore the mechanisms underlying their interaction with oxidative stress in adolescents.