Soybeans are a legume, are in the pea family, and as such are naturally high in aluminum. Organometallic aluminum, not synthetic aluminum or a chemical aluminum compound. Not the aluminum that cookware or airplanes are manufactured from. In talking with chemist Tom donVito of SUN Chemical, I learned that clay, another source of naturally occurring aluminum, is also a component of soy-based ink. If you garden in clay, you garden where aluminum silicate naturally occurs.
All soils save sand contain clay.
Your concern is that it may then become part of your family. Dr. Leon V. Kochian's extensive research at the U.S. Plant, Soil, and Nutrition Laboratory at Ithaca, N.Y., indicates that aluminum is excluded from plant tissue through a pretty fantastic process. When released, these acids form a complex with the toxic aluminum, preventing the metal's entry into the root. He feels that we get more aluminum from the unwashable-offable soil particles that cling to food than we do from the aluminum absorbed by the plant. Although volumes of recent research dispute the validity of the earlier 1970s-'80s association of aluminum and Alzheimer's disease, that is not the issue here.