WASHINGTON -- The manufacturer of d-CON, a widely sold and popular brand of rat poison, is taking the rare step of challenging the Environmental Protection Agency’s decision to prohibit the over-the-counter sale of one of the nastiest and most effective of the poisons sold to consumers.

Most of the 30 manufactures that make such products agreed to the ban, but Reckitt Benckiser Inc., the maker of the 12 separate d-CON products targeted by the EPA, challenged the agency’s decision March 6. The company asked for an administrative hearing to overturn the EPA decision. It’s the first time in 20 years that a company has defied an EPA pesticide ban, and it took the agency and many consumer groups by surprise.

“The impact of these rodenticides on wildlife is staggering,” Greg Loarie, an attorney with the environmental advocacy group Earthjustice, said in a statement. “Study after study has documented anticoagulant rodenticides in more than three-quarters of necropsied raptors, wildcats and canines. The measures put in place by EPA to protect wildlife do not go nearly far enough, and yet Reckitt is refusing to accept even those baby steps in the right direction.”

Companies have had three years to comply with the ban, which took effect this month. It requires companies to stop selling loose pellets of rat poison to consumers, to keep pets and children from accessing them. It also ends the sale to consumers of so-called “second generation” anti-coagulants: brodifacoum, bromadiolone, difenacoum and difethialone.

Those cause rodents to bleed to death. The poison doesn’t break down quickly, and it takes several days to kill the rodents. So when other animals higher in the food chain – such as hawks and coyotes – catch and eat the weakened animal, they also ingest enough poison to be fatal.

Humans can be exposed, too. The 2011 annual report of the American Association of Poison Control Centers’ National Poison Data System listed 8,500 exposures to anti-coagulant rodenticides among children under 12 years old – almost all of them among age 5 and under.

“The poisonings have been a problem everywhere we’ve looked,” said Cynthia Palmer, the pesticides program manager for American Bird Conservancy, a group that works to conserve native birds and their habitat. “These products are so widely used. They’re so quick to become part of the food chains, so we have found poisonings throughout the country.”

Professionals still would be able to buy and apply the stronger pesticides and loose bait for residential and agricultural use, and pest control service companies support the ban.

The EPA said it is “confident it will prevail in the hearing,” but that it is disappointed with Reckitt Benckiser’s move. It will “result in continued unsafe exposures of d-CON products to children, pets and wildlife while the hearing takes place,” the agency said. No hearing date has been set, but many consumer groups worry the appeal could drag on for several years, even as the products remain on the market.

The agency, which replied to questions from McClatchy in writing, said in a statement that there are more than 30 mouse and rat poison products available to consumers that meet the agency’s more protective standards. It hasn’t received any reports of children being exposed to bait contained in bait stations for products that incorporate the new standards.