Big difference between wet natural sand grains and dry nano-sized dust. It is like comparing an elephant to a bacterium.
It seems far-fetched to call silica a *toxin*. It is, actually, inert. However, dry silica dust is a lung irritant. However, this is wet sand, not silica dust.
We have a sandblaster. It is enclosed. It uses recoverable glass beads. It produces a fine glass dust. A mask is advised during use. We use sand in our pool filter. It is advisable to not refill the filter on an extremely windy day. Observation of beach sand shows that the dry particles normally rise a small amount and I cannot ever recall inhaling sand at the beach.
Put a tarp over the rail cars. Non-problem solved.