Will Banning Arsenic in Chicken Feed Save the Bay?

Bill would ban arsenic in Maryland chicken feed:

ANNAPOLIS, Md. (AP) — Legislation in Maryland is seeking to ban arsenic compounds from poultry feed. Delegate Tom Hucker, D-Montgomery, and Sen. Paul Pinsky, D-Prince George's, announced the measure at a news conference Thursday with Maryland Attorney General Doug Gansler. Supporters of the bill say arsenic in chicken feed contaminates both chicken meat and chicken waste, which can end up in the Chesapeake Bay. They also say it increases risks of cancer, heart disease, and diabetes...

A small amount of an arsenic compound called Roxarsone is sometimes added to chicken feed to inhibit certain parasites that can sicken chickens and cause slow growth.  Roxarsone itself, like many organic arsenic compounds, is not highly toxic, but in sediments and soils breaks down to inorganic arsenic, the more toxic form.  Elevated concentrations of arsenic can be found in chicken litter, soils and sediments that receive chicken litter waste.  Most of that remains on, or in the ground, but some certainly washes into the Bay. However, attempts to show elevated concentrations of As in the Bay due to chicken feed have been largely unsuccessful.  The water in the Bay has a surprising amount of arsenic.  Concentrations of As in Atlantic seawater is approximately 1 part per billion (ppb), and while the concentration of As in freshwater is more variable, 0.2 ppb is a fair number for average surface freshwater entering the Bay.  As a result, to a rough degree, the amount of As in bay water is a function of the amount of seawater mixed in, near 1 ppb at the mouth, and closer to 0.2 ppb at the head.  There are some variations due to sediment  uptake and flux (arsenic been berry berry good to me), but in general that tells the gross story. Attempts have been made to tie high concentrations of As in some creeks after rain, or in groundwater to chicken feed, but these have been largely without a lot of support.  Some soils and ground waters in the bay area naturally have high arsenic concentrations as a result of the geology. In my county some fossil water, 300 or more feet deep and long isolated from any recent contamination, flirts with (and sometimes crosses) the 10 ppb limit on drinking water.

So, ban arsenic in chicken feed if you're worried about arsenic in chicken (I'm not, but that's another day), but it is not going to make a significant impact on pollution in the Bay.