Two-year responses of renal function to first occupational lead exposure

Analysis of relationship between mixed heavy metal exposure and early renal damage based on a weighted quantile sum regression and Bayesian kernel machine regression model

BACKGROUND

Occupation, environmental heavy metal exposure, and renal function impairment are closely related. The relationship between mixed metal exposure and chronic renal injury is inadequately described, and the interaction between each metal is poorly explored.

OBJECTIVE

This cross-sectional study assessed mixed heavy metal exposure in the general population and their relationship with early renal impairment, as well as possible interactions between metals.

METHODS

The study was conducted in two communities in Taiyuan City in northern China. Multiple linear regression, weighted quantile sum (WQS) and bayesian kernel machine regression (BKMR) regression were used to explore the relationship of mixed heavy metal exposure with indicators of early kidney injury (N-acetyl-β-D- glucosidase (UNAG), urinary albumin (UALB)). Meanwhile, BKMR was used to explore the possible interactions between mixed heavy metal and indicators of early kidney injury.

RESULTS

Based on the WQS regression results, we observed adjusted WQS coefficient β (β-WQS) of 0.711 (95% CI: 0.543, 0.879). Notably, this change was primarily driven by As (35.6%) and Cd (22.5%). In the UALB model, the adjusted β-WQS was 0.657 (95% CI: 0.567, 0.747), with Ni (30.5%), Mn (22.1%), Cd (21.2%), and As (18.6%) exhibiting higher weights in the overall effect. The BKMR results showed a negative interaction between As and other metals in the UNAG and UALB models, a positive interaction between Mn and Ni and other metals. No significant pairwise interaction was observed in the association of metals with indicators of early kidney injury.

CONCLUSION

Through multiple linear regression, WQS regression, and BKMR analyses, we found that exposure to mixed heavy metals such as Cd, Cr, Pb, Mn, As, Co and Ni was positively correlated with UNAG and UALB. Moreover, there are complex interactions between two or more heavy metals in more than one direction.

The risk of dental restoration-related lead exposure on renal function

OBJECTIVE

To explore the relationship between oral restoration count, blood lead (PbB) level, and renal function as potential heavy metal releases, and the related toxicity of dental restorative materials.

METHODS

A total of 3682 participants from the National Health and Nutrition Examination Survey (January 2017 to March 2020) were included in this cross-sectional analysis. We utilized multivariable linear regression models to investigate the associations between the number of oral restorations and PbB levels or renal function. The mediating effect of PbB on renal function indicators was analyzed using the R mediation package.

RESULTS

Based on the indicators of 3682 participants, we found that the elderly, females, and whites were fit with more oral restoration, which was accompanied by increased PbB levels and decreased renal function. Meanwhile, oral restoration count was positively associated with PbB level (β = 0.023, 95% CI: -0.020 to 0.027), renal function-related urine albumin creatinine ratio (β = 1.541, 95% CI: 0.615-2.468), serum uric acid level (β = 0.012, 95% CI: 0.007 to 0.017), and serum creatinine level, and negatively associated with estimated glomerular filtration rate (eGFR) (β = -0.804, 95% CI: -0.880 to -0.728). Furthermore, the mediation effect test confirmed that PbB played a mediating role in the relationship between restoration count and serum uric acid or eGFR, with mediation effects accounting for 98.0% and 71.0%, respectively.

CONCLUSIONS

Oral restoration negatively affects renal function. Oral restoration-related PbB level is a potential mediating factor.

Public and occupational health risks related to lead exposure updated according to present-day blood lead levels

Lead is an environmental hazard that should be addressed worldwide. Over time, human lead exposure in the western world has decreased drastically to levels comparable to those among humans living in the preindustrial era, who were mainly exposed to natural sources of lead. To re-evaluate the potential health risks associated with present-day lead exposure, a two-pronged approach was applied. First, recently published population metrics describing the adverse health effects associated with lead exposure at the population level were critically assessed. Next, the key results of the Study for Promotion of Health in Recycling Lead (SPHERL; NCT02243904) were summarized and put in perspective with those of the published population metrics. To our knowledge, SPHERL is the first prospective study that accounted for interindividual variability between people with respect to their vulnerability to the toxic effects of lead exposure by assessing the participants' health status before and after occupational lead exposure. The overall conclusion of this comprehensive review is that mainstream ideas about the public and occupational health risks related to lead exposure urgently need to be updated because a large portion of the available literature became obsolete given the sharp decrease in exposure levels over the past 40 years.