Effects of environmental levels of cadmium, lead and mercury on human renal function evaluated by structural equation modeling

• SEM is a novel method to model multi-variable, biological issues.
• The impact of cadmium on renal function was sigmoidal.
• The impact of lead on renal function was linear.

A relationship between exposure to heavy metals, including lead and cadmium, and renal dysfunction has long been suggested. However, modeling of the potential additive, or synergistic, impact of metals on renal dysfunction has proven to be challenging. In these studies, we used structural equation modeling (SEM), to investigate the relationship between heavy metal burden (serum and urine levels of lead, cadmium and mercury) and renal function using data from the NHANES database. We were able to generate a model with goodness of fit indices consistent with a well-fitting model. This model demonstrated that lead and cadmium had a negative relationship with renal function, while mercury did not contribute to renal dysfunction. Interestingly, a linear relationship between lead and loss of renal function was observed, while the maximal impact of cadmium occurred at or above serum cadmium levels of 0.8 μg/L. The interaction of lead and cadmium in loss of renal function was also observed in the model. These data highlight the use of SEM to model interaction between environmental contaminants and pathophysiology, which has important implications in mechanistic and regulatory toxicology.