Silica encapsulation reduces bioavailability

Lead chromate pigments can be encapsulated within an amorphous silica coating. This reduces both the chemical teachability and the biological availability of the constituents. The chromate moiety is inactive in in vitro mutagenicity assays, even in the presence of a strong chelating solubilizer under conditions where the unencapsulated material gives positive results. Rodent feeding studies demonstrate much reduced absorption of both lead and chromium from the encapsulated lead chromate compared to the analogous unencapsulated material. Encapsulation also reduces the leachability of both lead and chromium in tests used to define the applicable environmental disposal methods for lead chromate pigments. These findings have important implications for health and environmental issues surrounding the use of lead chromate as a pigment material.