Bioavailability indicators of inhaled cadmium compounds

Area of Science:

• Environmental Toxicology
• Occupational Health
• Inorganic Chemistry

Background:

• Cadmium (Cd) is a toxic heavy metal with various industrial applications.
• Inhalation is a primary route of occupational and environmental exposure to cadmium compounds.
• Understanding the bioavailability of different cadmium compounds is crucial for risk assessment.

Purpose of the Study:

• To compare the lung bioavailability of three different inhaled cadmium compounds: cadmium chloride (CdCl2), cadmium oxide (CdO), and cadmium sulfide (CdS).
• To evaluate the role of lung compartmental cadmium and metallothionein content, and alveolar lavage analysis in assessing cadmium bioavailability.

Main Methods:

• Male Wistar rats were exposed for 30 days to submicron aerosols of CdCl2, CdO (0.1 mg/m3 Cd), and CdS (1 mg/m3 Cd).
• Cadmium levels were measured in lung homogenates, cytosols, and metallothionein at the end of exposure and after a 2-month recovery period.
• Alveolar lavage analysis was performed to assess cadmium availability in lung tissue.

Main Results:

• Higher cadmium concentrations were found in lung cytosols for CdCl2 and CdO compared to CdS.
• Lung cadmium and metallothionein content was twice as high for CdO compared to CdCl2.
• CdO demonstrated 10 times greater lung availability than CdS, despite a 10-fold lower exposure concentration.

Conclusions:

• Inhaled cadmium oxide (CdO) exhibits higher lung bioavailability than cadmium chloride (CdCl2) and cadmium sulfide (CdS).
• Lung compartmental cadmium and metallothionein levels, alongside alveolar lavage analysis, effectively characterize the bioavailability of inhaled cadmium compounds.