For supporters of a bill that would ban the use of arsenic in Maryland’s poultry industry, celebration turned to frustration this week when they realized a last-minute amendment amounted to a poison pill intended to nullify its effects.

As amended, the bill “basically is a lot of verbiage which essentially does nothing,” said Sen. Paul Pinsky (D-Prince George’s). Pinsky crafted an amendment to restore the intent of the bill, which his committee on Thursday advanced on a 7-4 vote. The bill now heads to the Senate.

Pinsky said he hopes House lawmakers will “reconsider and realize that the amendment they adopted negated the whole bill.”

The bill targets roxarsone, a feed additive that Pfizer willingly pulled from the market last year after the Food and Drug Administration found low levels of inorganic arsenic in some chicken livers.

Shortly before the bill’s passage in the House, Del. Herbert McMillan (R-Anne Arundel) introduced an amendment, which lawmakers adopted, that would lift the ban should the FDA give the drug its approval.

But there was a catch, proponents say: Even though Pfizer suspended sales, roxarsone never lost its FDA approval.

The environmental group Food and Water Watch denounced the move in a statement: “At the last minute the poultry and pharmaceutical industries made changes to the bill to ban arsenic, effectively nullifying the bill’s intent. They then used their political clout to pass the gutted bill through the House of Delegates.”

Proponents of the ban say the drug could re-enter market any time, potentially allowing arsenic to accumulate in agricultural fields where chicken litter is applied and pollute groundwater and streams.

Opponents, including representatives from Delmarva Poultry Industry, told lawmakers last month that arsenic levels are too low to pose a risk.

Del. Tom Hucker (D-Montgomery), who has tried repeatedly to pass legislation banning the use of roxarsone and other arsenic additives by Maryland’s chicken farmers, was pleased that Pinsky’s amended version cleared the Senate panel.

“I’m not doing a touchdown dance until the touchdown,” Hucker said. We have a long way to go just to get it through the Senate floor. But I’m a lot happier today than I was yesterday.”