Factors moderating cadmium bioavailability: Key considerations for comparing blood cadmium levels between groups.

Cadmium (Cd) is recognized as a significant hazard to human health, with exposure linked to a variety of adverse outcomes including various cancers, cardiovascular diseases, chronic kidney disease, and osteoporosis. Residing in areas contaminated with Cd is undoubtedly a risk factor for developing the aforementioned conditions. However, the risk of developing Cd-related disorders is not uniform among individuals. Deficiencies in iron, zinc, and calcium, along with iron deficiency anemia, decreased lung function often seen in chronic obstructive pulmonary disease (COPD), and low circulating levels of parathyroid hormone (PTH), may enhance Cd intestinal absorption. Conversely, chronic liver disorders can lead to the progressive loss of hepatocytes and the release of free Cd into the circulation, resulting in elevated Cd blood levels. Moreover, studies comparing Cd blood levels between different regions within a country or between two groups of individuals, for example, those with and without osteoporosis, should consider all variables that may impact Cd levels. These include age, sex, alcohol consumption, blood levels of iron, calcium, and zinc, the presence of anemia, COPD, PTH levels, and the presence of liver or kidney disease. In this review, we delve into all factors that could influence Cd blood levels, providing a comprehensive analysis.