Abstract Body (Do not enter title and authors here): Background: Toxic metal exposure is a growing public health concern due to its potential long-term effects on cardiovascular health. However, limited studies have evaluated the cumulative effects of metal mixtures on cardiac biomarkers in a nationally representative population.
Objective: To examine the association between exposure to a mixture of environmental toxic metals and changes in cardiac biomarkers C-reactive protein (CRP), high-density lipoprotein (HDL), and total cholesterol (TC) among US adults.
Methods: Data are obtained from three pooled survey data from the National Health and Nutrition Examination Survey (NHANES) 2015–2023, comprising 21730 adult participants. Cardiac biomarkers include CRP, HDL, and TC. Exposure variables consist of blood levels of lead, cadmium, mercury, manganese, and selenium. Weighted Quantile Sum (WQS) regression is used to estimate the effect of metal mixtures on cardiac biomarkers. Trend analysis is performed across NHANES cycles using survey-weighted generalized linear models.
Results: The study population has a mean age of 42.1 years (SD: 20.9). Among cardiac biomarkers, the weighted mean (SD) of CRP is 3.46 mg/L (7.06), HDL is 53.95 mg/dL (15.40), and total cholesterol (TC) is 182.64 mg/dL (41.26). For toxic metal exposures, mean levels are lead 0.94 µg/dL (SD: 1.06), cadmium 0.36 µg/L (SD: 0.47), mercury 1.12 µg/L (SD: 1.82), manganese 9.90 µg/L (SD: 3.64), and selenium 2.35 µg/L (SD: 0.35). Trend analysis shows a statistically significant increase in CRP levels over time (p = 0.002), while HDL and TC showed no significant trends (p > 0.45). In multivariable WQS models, toxic metal mixture exposure is significantly associated with all three cardiac biomarker changes. Specifically, a per-quantile increase in toxic metal mixture is associated with a 6.57% (4.00% - 9.20%) increase in CRP levels, a 3.17% (2.47% - 3.87%) increase in HDL, and a 7.01% (6.37% - 7.65%) increase in total cholesterol. Manganese (64.9%) and cadmium (32.2%) have a high contribution in CRP, while lead and mercury primarily influence HDL and TC.
Conclusions: Exposure to mixtures of toxic metals is significantly associated with increases in key cardiac biomarkers, including CRP, HDL, and TC. These findings suggest that even low-level environmental exposure may have cumulative effects on cardiovascular health over time. Further studies should focus on longitudinal studies to reduce environmental metal exposure in vulnerable populations.