Ah, the lowly earthworm. As the animal kingdom goes, it doesn't get more humble -- and as far as agriculture goes, it hardly gets more important. Without earthworms to plow up the undersoil and leave important nutrients behind them, our farms and gardens would be sad little places.
But a recent study by Environmental Science and Technology demonstrates that earthworms may also be the proverbial canary in the coal mine. You've heard of sludge fertilizers, right? That's where they take human "biosolids" from waste treatment plants, repackage them, and sell them as fertilizers. Along with human waste (which by itself would certainly be a valuable fertilizer), farmers and gardeners are treating their fields with a host of other household and personal care products. And the earthworms are soaking it up.
Not only are they absorbing the chemicals in the fertilizer (triclosan and synthetic fragrance chemicals, for example), but they're bioaccumulating them. That means the chemicals are getting stored in the worms' bodies, and it's adding up. In fact, for some chemicals, concentrations were an order of magnitude higher in the worms than in the soil.
This has a whole host of implications. What happens to animals that eat these worms? And to animals who eat those birds? For that matter, what happens to animals (including us) that eat plants grown in that soil?
Organic agriculture doesn't allow for the use of sludge fertilizers -- but even if you eat an all-organic diet, don't think that means you don't have to care. Runoff from sludge-fertilized non-organic farms easily contaminates organic fields. Even a ban on sludge fertilizers (which, for the record, isn't even being considered right now) would be a band-aid treatment. The only way to fix these problems is at the chemical and governmental levels, with toxic chemical reform legislation.