[kragen]

well, it depends on what you do with the sand; things like sandblasting or desert sandstorms liberate plenty of the very fine powdered crystalline form that is the concern

your points about high short-term exposure and long-term low-grade exposure are well taken, and may also apply to phthalates, since humans evolved in an environment with many sources of phthalates, such as coconuts, poppy seeds, grapes, and kidney beans. see https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8310026/ and https://pubchem.ncbi.nlm.nih.gov/compound/Phthalic-acid#sect...