Like we said last week

Dispersants as bad as oil? Worse? Who knows?

Once they are dispersed, the tiny droplets of oil are more likely to sink or remain suspended in deep water rather than floating to the surface and collecting in a continuous slick. Dispersed oil can spread quickly in three directions instead of two and is more easily dissipated by waves and turbulence that break it up further and help many of its most toxic hydrocarbons evaporate.

But the dispersed oil can also collect on the seabed, where it becomes food for microscopic organisms at the bottom of the food chain and eventually winds up in shellfish and other organisms. The evaporation process can also concentrate the toxic compounds left behind, particularly oil-derived compounds called polycyclic aromatic hydrocarbons, or PAHs.

My pessimist's sense of things tells me that the primary advantage of dispersants is cosmetic. Keep as much of the slick off of the surface of the water and off of the sandy beaches as possible. But if it doesn't do anything to protect the fisheries and oyster beds then it certainly isn't doing anything to protect the people whose livelihoods depend on those things.